Ann. Pule’ontol. (1999) 85, 2,99-153 0 Elsevier. Paris

Palaeoecology of non marine algae and stromatolites: Permian of France and adjacent countries

Pierre FREYTETa*, Nadkge TOUTIN-MORINbt , Jean BROUTINC, Pierre DEBRIETTEd, Marc DURANDe,

Mohammed EL WARTITIq Georges GANDg, Hans KERPh, Fabienne ORZAG’, Yves PAQUETTEg, Ausonio RONCHIj,

Janine SARFATIk

a 41, rue des Vuux mourunts, 91370 Verrieres le Buisson, France ; et laboratoire de pule’obotanique et paleoecologie, universite’ Paris-VI, 12, rue Cuvier 75005, Paris, France

b Universite d’Orleans (died January 7, 1998) c Laboratoire de paleobotanique et paleoecologie, universite’ Paris-VI,

12, rue Cuvier, 75005 Paris, France d HBCM, service technique, BP 534, 42007 Saint-Etienne, France

e Ge’ologie des ensembles sedimentuires, universite’ Nancy-I, fact& des sciences, BP 239, 54506 Vendauvre-les-Nancy, France

f Fact&e’ des sciences, departement des sciences de la terre, BP 1014, Rabat, Morocco R Centre des sciences de la terre, universite’ de Bourgogne, 6, bd Gabriel, 21000 Dijon, France

h Abteilung Palaobotanik, Geologisch-Pulaontologisches Institut, Westfiilische Wilhelms-Universitit Mtinstel; Hidenburgplatz 57, 48143 Miinster; Germany

i Institut des sciences de lu terre, bat. 504, universite Paris-Sud, 91405 Orsay cedex, France j Dip. Scienze della terra Univ. Di Pavia, via Abbiutegrasso, 27100 Pavia, Ituly

k Laboratoire de pale’obotanique, universite’ des sciences et techniques, place Eugene-Batuillon, 34095 Montpellier; France

(Received 26 March 1998, accepted after revision 15 February 1999)

Abstract - Some Permian, continental basins from Algeria, Morocco, France, Italy, Ger- many and Poland reveal algal remains and stromatolites, mainly during Lower Permian, but also during Middle and Upper Permian. The algae belong to 8 morphogenera and 12 morphos- pecies. Two species are new. The taxonomic attributions are difficult, even if some species resemble living species. The algae make unorganized masses, or laminated builtups (stromato- lites, oncolites, oolites). Algal masses and stromatolites are contained in fluviatile sediments (active or abandoned channels) and lacustrine deposits (playas, ephemeral lakes shorelines,

* Correspondence and reprints.

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2 PIERRE FREYTET ET AL.

lakes several meters or decameters deep). Considering the sedimentological context, the water salinity could range from karstic springs (hard water) to evaporic ephemeral lakes (playas). 0 Elsevier. Paris.

Permian / calcareous algae / stromatolites / oncolites / oolites / palaeoecology / continental environments

R&urn6 - PalCoCcologie des algues et stromatolites non marins du Permien de France et rkgions voisines. Quelques bassins permiens continentaux d’AlgCrie, Maroc, Sardaigne, France, Italic, Allemagne et Pologne renferment des restes algaires et des stromatolites, princi- palement au Permien inferieur, mais aussi au Permien moyen et supCrieur. Les algues appar- tiennent g huit morphogenres et douze morphoesp&ces dont deux nouvelles. Les attributions taxonomiques sont difficiles, m&me si certaines espkces semblent proches d’espkces actuelles. Les algues forment des masses inorganiskes ou des Cditices IaminCs (stromatolites, oncolites, oolites). Masses algaires et stromatolites sont contenus dans des sCdiments fluviatiles (che- naux actifs ou abandonnis) et lacustres (G playas D, littoraux de lacs CphCmkres, lacs profonds de quelques m&res B quelques dizaines de mktres. D’aprks le contexte Gdimentologique, la salinitC des eaux pouvait aller de celle de sources karstiques (eaux dures) g celle des lacs CphC- m&e? B Cvaporites (playas). 0 Elsevier, Paris.

Permien / algues calcaires / stromatolites / oncolites / oolites / palCoCcologie / milieux continentaux

INTRODUCTION

In the aim of a general review of continental limestones, one of the authors began the inventory (and the revision of the rare known forms) of the “calcareous algae” from Permian to Subfossil. This allows 16 genera and 56 species to be coined [ 14, 151. The biological remains that can be assigned to algae are of three types:

- masses of spherical cells (Chlorellopsis) fixed between two stromatolitic columns, or included in laminations;

- filaments closely packed, making small, millimetric colonies, grouped in large, pluridecimetric masses (Toutinella);

- filaments, prostrate/erected or only erected, parallel or radiating, making layers more or less extended (= laminations). These laminations are alternatively light and dark, with a variable crystallinity and thickness. The association of a light lamination with a dark one makes a doublet; the doublets are generally associated in sets of 5-20 doublets, and two sets are frequently separated by a discontinuity surface, that is often a surface of dissolution. Laminations (by definition), doublets and sets are characteristics of stromatolitic builtups, very varied in shape and size (some mm3 to

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PERMIANNONMARINEALGAEANDSTROMATOLITES 3

several m3). The relations between filaments and laminations constitute the “microstructure” sensu Bertrand-Sarfati et al. [6]. The builtups are rarely homoge- neous, made of identical sets of laminations. Most frequently, they exhibit an irregu- lar alternation of layers of sets made of continuous laminations and layers made of adjacent columns. The continuous laminations were named “Collenia structure” by Logan et al. [36], and “Cryptozoon structure” the layers with columns. We will use these terms in our descriptions, because they are clear, well defined, and easily iden- tifiable in thin sections.

In the literature, the free builtups, of any size, are named “oncolites” (often of irregular shape, of algal origin), and “oolites” (millimetric in size, spherical or ellipti- cal in shape, physico-chemical or unknown in origin).

In this paper, two new species are described, with respect to a first list, only taxo- nomic [ 14, 1.51. All the species are deposited in the laboratoire de pale’obotanique et paltotcologie de 1’universitC Paris-VI.

On the other hand, the study of the intramontane basins of Western Europe and North Africa showed the occurrence of carbonates in some of them [59], and also algae and stromatolites. The main difficulties of investigation are the small numbers of samples, and the effects of diagenesis, sometimes very strong, that delete all bio- logical features, leaving only vague laminations.

The studied basins were reported on a map at their possible location in the Hercy- nian Chain (figure I), from the maps of Ziegler [62], modified with data of Broutin et al. [7]. The palaeoecological reconstructions are picked from carbonate mineralogy, and analysis of enclosing series, fluviatile with channel and flood plain deposits, lacustrine sediments, sometimes with ashes and lava flows intercalations. It is only the sedimentary context that permits reconstruction of the life conditions of algae and stromatolites.

Dating of the basins is a very important difficulty. The recent data are somewhat contradictory [38, 521. We also have to define the ancient, purely lithostratigraphic terms. Correlations between marine and continental deposits are difficult, and the following equivalents will be used, bearing in mind that each term is imprecise, and possesses a variable, vertical extension.

- Lower Triassic = Scythian

- Upper Permian = Ufimian + Kazanian + Tatarian (facies “Thuringian” “Zech- stein”)

- Middle Permian = Artinskian + Kungourian (facies “Saxonian”, “Upper Rotliegende”)

- Lower Permian = Asselian + Sakmarian (facies “Autunien”, “Lower Rotliegende”)

- Uppermost Carboniferous = Gzhelian (facies “Stephanian”).

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PIERRE FREYTET ET AL.

Figure 1. Location of the studied basin. Map after Ziegler 1621, completed with Broutin et al. (71. A, Zechstein Sea (Upper Permian); B, B&aye Fault; C, Gibraltar Fault; D, Agadir Fault: E, Austro-Italian

Tethysian area: F, oceanic area; G, North-African area. a, detritic deposits; b, evaporitic deposits; C, carbonated deposits; d, oceanic crust. Basins: 1, Mechraa Ben Abou (Morocco); 2, Abadla (Alge- ria); 3, Tiguentourine (Algeria); 4, Sardinia; 5, Lodeve (France); 6, Bourbon I’Archambault (France): 7, Blanzy-Le Creusot (France); 8, Couy (France); 9, Toulon (France); 10, Orobic Alps (Lombardy. Italy); 11, Saar-Nahe (Germany); 12, Central German lakes; 13, Slawkow (Poland).

Figure 1. Localisation des bassins &dies. Carte d’aprts Ziegler [62], completee par Broutin et al. ]7]. A, mer du Zechstein (Permien sup.) ; B, faille de Biscaye ; C, faille de Gibraltar ; D. faille d’Agadir ;

E, domaine ttthysien austro-italien ; F, domaine oceanique ; G, domaine nord-africain. a, depots detritiques ; b, depots Cvaporitiques ; c, depots carbonates ; d, fond oceanique. Bassins : 1, Mechraa Ben Abou (Maroc) ; 2, Abadla (AlgCrie) ; 3, Tiguentourine (Algerie) ; 4, Sardaigne ; 5, Lodeve ; 6, Bourbon-1’Archambault ; 7, Blanzy ; 8, Couy ; 9, Toulon ; 10, Alpes Orobica, Lombardie. Italie ; 11, Saar-Nahe (Allemagne) ; 12, lacs d’Allemagne centrale ; 13, Slawkow (Pologne).

THE STUDIED BASINS AND THEIR AGAL AND STROMATOLITIC REMAINS

MechraS Ben Abou (Morocco)

Geological setting (after Toutin-Morin in Damotte [9])

This basin is located 200 km SSW of Rabat. It is an intramontane grdben, pre- served in several parts. In the most important one, the sedimentary series reaches a

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PERMIANNONMARINEALGAEANDSTROMATOLITES 5

thickness of up to 3 000 m. It is dated from the Lower Permian by ostracods [9]. The filling consists of two positive megasequences. It is fluviatile, on the form of alluvial fans, channel sediments, flood plain deposits with palaeosols and ephemeral lakes. The carbonates are rare, made of calcite, in the form of small layers 0.1-0.5 m thick.

At the site Douar Belgourch (upper part of the lower megasequence), three carbon- ate layers are made of micritic limestones with ostracods and vegetal remains (lower and middle layers), and a micritic limestone (upper layer) with ostracods, charophyts, algae and stromatolites (oncolites and vegetal remains encrustations) ([9] plate I, 14). The material consists of 7 thin sections (N. Toutin-Morin collection).

Palaeoalgological aspect

This site furnished the type of Toutinella marocana Freytet 1997. Encrustations made by Plaziatella colleniaeformis Freytet 1998 also occur there. 7: marocana is in the form of small remains, some millimeters in size, isolated (plute I a, b) or making up the nuclei of oncolites. The genus is characterized by thick filaments, packed, branched, with a lobate, transverse section, included in large sparite crystals. It is all that is known of this species, but in other species, the tufts of filaments make radiat- ing masses, l-2 mm in diameter. They are grouped in pluridecimetric edifices living on the bottom of lakes, under low bathymetry and detritic sedimentation. They are not stromatolites.

In this site, another alga occurs in small stromatolites (encrusted vegetal frag- ments and shells), with very thin laminations: Plaziatella colleniaeformis. The thin, erected filaments are included in dark and light micrite (plate I c).

Stromatolitic aspect

The stromatolitic builtups are only represented by oncolites (l-2 mm in diameter, plate I d) and encrusted vegetal remains (some millimeters in size). A substrate is blanketed with peloidal, entirely micritic coating or micritic coating with filaments of I? colleniaeformis. Laminations are thin (50-200 pm), few in number, up to about ten (plate I c). In thin section, oncolites and encrusted remains are plentiful, with a wakestone, sometimes a packstone fabric.

Palaeoecological aspect

In the basin, the carbonate layers are linked with black clays, and are located in the upper part of the two megasequences. The deposits are calcitic, not dolomitic, probably resulting from the lack of dolomites in the hinterland. It was a lake with hard water, not with confined - evaporitic sedimentation. The remains of Toutinella marocana may result from the erosion of previous, ephemeral lacustrine layers, a common phenomenon in fluviatile environment, and deposited in another ephemeral lake, probably in littoral conditions.

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Abadla (Algeria)

Geological setting [S]

The Abadla basin is located near Bechar. Above a marine, Lower Carboniferous, Westphalian is paralic, well dated by its floras. It is overlain by 2000-2500 m of flu- viatile formations, divided into a fluvio-lacustrine lower formation (conglomerates, sandstones of channels, mudstones of floodplain, mudstones and carbonates of ephemeral lakes) and an upper formation, made of red sandstones and siltstones. The basis of the lower formation is dated from the Lower Permian (“Autunian”) by fauna (Estheria) and pollens [ 111. The middle part of the Lower Formation contains three carbonated layers, 0.1-l m in thickness, rich in oolites. Stromatolitic builtups occur in the lower and upper layers. They can be laterally followed for 20 km, without important changes of facies and thickness.

Palaeoalgological aspect

The stromatolites of the lower layer (2 thin sections) exhibit typical filaments and microstructures of Broutinella variegata j incipiens (plate I e-g). The stromatolites of the upper layer (20 thin sections) (plate I h; plate II u-e) contain many filaments, described in detail by Bertrand-Sarfati & Fabre ([.5] figure 5; pl. I and II). Here, we only integrate the description of these filaments in the groups, genera and species coined by Freytet (1997-1998). Without any doubt, these filaments can be ranged in the genus Ponsinella Freytet 1998, but belong to a new species.

Genus Ponsinella Freytet 1998. Filaments prostrate, then inclined and erected; micritic coating; erected parts of the filaments making a regular turf-like layer.

Ponsinellu sahariana Freytet n. sp. (from Abadla, Sahara).

Diagnosis of species: filaments 5 pm in diameter, prostrate then erected, dis- tant from one another by 5-10 times their diameter; micritic, discrete coating; tila- ments making a continuous turf, up to 400 pm thick.

Holotype: plate II a. Thin section 167B, collection J. Bertrand-Sarfati. Garet el Hamra cliffs, 45 km north of Abadla, Algeria.

Description and discussion

The filaments are very frequently ferruginized, and, in this case, their diameter can reach up to 10 pm. They are contained in doublets made of a light (micritic or microspartic) lamination and a dark (always micritic) lamination. Dark laminations are always thinner than the light ones. The doublets are 200-250 pm in mean thick- ness, the extreme values are 50 and 400 pm. The same filament can cross two dou- blets and be visible on a length of more than 300-400 urn. The laminations are arcu-

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PERMIANNONMARINEALGAEANDSTROMATOLITES 7

ate to undulate, of Collenia-structure type, but they can occasionally form small columns (Cryptozoon-structure type) at all scales, from l-2 mm to l-3 cm high.

Ponsinella saharianu is very different from the other species of the genus. It is distinguishable from I? giguntea which has filaments of 40-50 pm in diameter, and from P cubitutu and P inopinutu which have filaments grouped in tufts (fascicles). Three species make a thick turf: R suhuriunu (200400 pm), P rupestris (700 pm), I? plicutu (1500 pm). Only P suhuriunu presents undulations passing laterally to small columns.

P. cubitutu (subfossil) is probably the fossil form of Plectonemu grucillimum (cyanobacteria Scytonemuceue) and t? rupestris (subfossil) is the fossil form of Scy- tonemu myochrous. l? plicutu, F! inopinutu and R gigunteu are Upper Eocene in age, and of uncertain taxonomic attribution. Actually, in living species, filaments first prostrate then erected occur in cyanobacteria (Scytonemuceue, and genera Amphitrix, Symplocu, Symplocustrum), Chlorophyceae and Xanthophyceae. The doublets light/ dark micrite are present in Pluzutiellu colleniueformis builtups, and the doublets light microsparite/ dark micrite are frequent in Broutinellu vuriegutu J: incipiens Qdunche If-g). But in th ese two species, filaments are rectilinear, not folded. In ancient times, in marine environments, some forms of Puruortonellu and Girvunellu could have had a similar habitus (see discussion in Freytet [ 151).

Stromatolitic aspect

The builtups of the two layers range from several centimeters in size (oncolites, flat nodules) to large masses 1.5 m in diameter and 0.4 m high. The diverse shapes are figured by Bertrand-Sarfati & Fabre, 1974, their figure 8 (partly redrawn$gure 9~1). Up to 5 cm long, the builtups can be returned, and can show opposite directions of growth. All builtups exhibit very important differences in thickness, from 2 to 10 times bigger at the top than at the bottom.

The builtups of the lower layer generally have thin laminations. The laminations rarely have a large lateral extension (Colleniu structure), most frequently they form adjacent columns, 2-3 mm wide, 5 mm to 2-3 cm high (Cvptozoon structure).

The flat nodules of the upper layer, with P suhurieiunu are 5 cm to several decimeters long. They consist of superimposition of sets of laminations 2-10 mm thick. The sets are made of undulating laminations (Colleniu structure) or of adjacent domes, hemispheres or columns (Cryptozoon structure). In thin section, the sets are made of doublets all of the same thickness, but the thickness of the doublets is vari- able from one set to another. Fenestrae are not rare, in part original, but they can be enlarged by dissolution.

The stromatolites are accompanied by oolites, rarely by quartz sand. Oolites @lute II e)

are small, 0.1-0.7 mm in diameter, with the mean being 0.4 mm. They contain a small number of regular laminations, up to 10, rarely more, micritic and sparitic.

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Palaeoecological aspect

The formation including the oolitic and stromatolitic layers is composed of con- glomerates and sandstones of channel filling, grey, green and mottled mudstones of floodplain, indicating a hydromorphic pedogenesis. In small shallow, ephemeral lakes, a carbonated sedimentation allows the development of oolites and stromato- lites. The lack of dolomite and silica suggests moderate evaporitic conditions.

Tiguentourine (Algeria)

Geological setting [4]

This site is located in the Illizi Basin, near the Lybian border. Between the marine Moscovian limestones, and the Triassic sandstones, the series of Tiguentourine, 200 m thick, is composed of two parts. The lower one is dated Uppermost Carbonif- erous - Lower Permian (“Stephano-Autunian”) by its Estheria; the upper one is of unknown age.

The lower part of the Tiguentourine series is silty-clayed with mud cracks, admit- ing sandstone layers with fishes, limestones with Estheria, and levels with gypsum and anhydrite. These facies are consistent with a Lower Permian age, because Ziegler [62] indicates evaporites on his map 11 (Early Permian) in the Gabes Gulf and in Cyrenaique. Two stromatolitic layers occur in this series with freshwater, brackish and hypersaline episodes. The builtups are always included in a dolomicrite showing several facies: (1) homogeneous; (2) peppered with large crystals; (3) slightly or (4) strongly peloidal (pellets up to 200 pm in diameter). This matrix is devoid of other fossils.

Palaeoalgological aspect

Despite a general recrystallization, some builtups of the lower layer locally con- tain traces of filaments, dark, prostrate then oblique and sigmoid, clearly separated from one another, 5-10 pm in diameter (plate IIf, drawn figure 2b). The voids between filaments are filled with chalcedony. The very particular habitus prostrate/ erected/prostrate resemble the Ponsinella sahariana of Abadla. The main difference is the oblique position of the erected part of the filament, which is vertical in P sahariana. However, we think that these filaments belong to the same species in the two sites. The vertical or oblique position of the erected parts of filaments is fre- quent in the modern Scytonemaceae (Thunmark [57] figure 4, Petalonema crus- taceum; Freytet & Verrecchia [22] figure 3g, Plectonema gracillimum; Freytet [ 151 plate 13g, Scytonema myochrous).

The builtups of the upper layer are too recrystallized to have filaments preserved. Therefore, the occurrence of thin laminations of “narrow, radial palisadic sparite” suggests some Broutinella at the beginning of the recrystalization.

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PERMIAN NON MARINE ALGAE AND STROMATOLITES

Figure 2. Tigucntourine Basin (Algeria). a. Lower layer, stromatolite with a first encrustation by small columns (1) and a second, continuous

encrustation (2); total thickness: I cm. b, drawing of photo ~[UIP //,f: Light and dark filaments are possibly Pon.sir~/la sahariarm. Scale bar: 500 f.tm. c, domal huiltup of the lower layer, location of growth anomalies: 1, upper surface; 2. edge. Evolution of a growth anomaly from the upper surface:

d, domal rihing: e, break: f, coating of the raised part: g, blanketing on the coated. raised part. h, drnw- ing from photo of the blanketing of a raised set of laminations. 1, micritic laminations; 2, lamination made of narrow radial sparite, with wide variations in thickness; 3, equant sparite filling a void. Scale

bar: 500 pm. Evolution of a growth anomaly on an edge: i. above a regular set (I), the set (2) is bro- ken and brecciated: j, the set 3 covers the broken zone of (2); k, set (3) covers the set (3) and the zone

of hrecciation.

Figure 2. Baaain de Tiguentourine (Algerie). a. niveau inf., stromatolite avec premier encrotitement en coloncur\ t I) et second encrofitement continu

(2) ; Cpaisseur totale : I cm. b. dessin de la photo pl. II f, filaments clairs et sombrea attrihuahles a Pon- tirzrlltr soharirr~. Bchelle : 500 pm. c, Cdifice en dome du mveau up., localisation des anomalies dc

croissance, 1, face sup ; 2, bordure. Bvolution d’une anomalie dc croi\\ance en position sommitalc : d, soulevement en dome ; e. rupture ; f. enrohement de la partie soulevee ; g, recouvrement de la par-

tie soulevee enrohCe ; h, dessin d’apri-s photo d’un enrobcment d’un set de laminations aoulevC. I. laminations micritiquea ; 2, lamination en sparite Ctroite tihro-radiee, montrant de grandes variations d’epaisseur ; 3. sparite isodiametrique de remplissage de vidc. Bchelle : 500 pm. Evolution d’une

anomalie de croissancc en position latcrale : i. au-des\us d’un set regulier (I). le set (2) est casse et hrcchitie : j, le set 3 recouvrc la rone br-is& de (2) ; k, le set (1) recouvre le bet (3) la zone de recou-

vrcment la zone hrechique.

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10 PIERRE FREYTET ET AL.

Stromatolitic aspect

The builtups of the lower layer are large, flat oncolites, 4-7 cm in diameter and l-3 cm thick. They are enclosed in a layer of micrite, 5 cm in thickness. The nucleus is large grains or platelets of oolitic and bioclastic limestone with phosphate grains. The algal encrustation is asymetric, 2-3 times thicker at the top than at the bottom. It is generally composed (figure 2~) of a layer of small columns (Cryptozoon structure) overlain by a layer of continuous laminations (Co2Zenia structure), containing the algal remains.

In thin section, the micritic laminations of the columns (internal envelope of nucleus) are variable in thickness (dark: 30-150 urn; light: 30-250 urn), and strongly wrinkled (plate II h). The laminations of the external envelope are identical, either purely micritic and dark, or made of filaments included in micrite patches separated by large fenestrae filled with chalcedony (plate II g,fi. The crystals of micrite are recrystallized, not in contact with one another, but lined by a dark line.

The builtups of the upper layer lie on a red clay. They are included in a micritic, homogeneous or clotted matrix. The higher builtups are blanketed with an oolitic sand with phosphate and quartz grains. The builtups constitute a remarkable biostrome. Covering an area 300 m long and 50 m wide, large constructions, 20-50 cm in diameter and 8-20 cm thick, are adjacent, deformed in contact with one another. Around this area, in a zone 200 m wide, the builtups are separated, 0.5-l m in diameter, 10-15 cm in height. Farther, up to 1.5 km, the size of builtups regularly decreases, the minimum size being l-3 cm in diameter and l-2 cm thick.

Under the microscope, the microstructures of these edifices are very different from those of the lower layer. The laminations are thin (40-120 urn), very varied, often rich in small quartz grains, and difficult to group into doublets (plate ZZ i, j). They are made of light, dark micrite, or of narrow, radial palisadic crystals. An inter- esting particularity is present at the upper part and on the edges of the largest builtups cfigure 2~). In any position, a set of lamination is raised as a dome (d> then broken (e). The following set surrounds the raised part (f, and the next set heals the irregular- ity (g). In detail, the laminations that act in this microconstruction exhibit a very par- ticular location of the narrow, radial palisadic sparite, with a maximal thickness on the dome, and a lateral decrease / disappearence @gure 2h). On the edges of builtups figure 2i-k), the fracture of a set is accompanied by the brechification of the sepa- rated part; the heal is of the same type, and the last set coats the irregularity and the brechic zone.

The large builtups sometimes contain very particular oolites between two sets of laminations, or in brechic zones. These oolites (plate ZZ k) are made of a small num- ber of laminations; the sparite with radial fabric has the same aspect as that of nar- row, radial palisadic sparite of some laminations, It is totally different from that of oolites of the oncolite nuclei.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 11

Palaeoecological aspect

Considering the environments, the two stromatolitic layers are included in fluvi- atile deposits in which are interbedded evaporitic deposits and sands with oolites, marine bioclastes, phosphate and quartz grains. These sands are sometimes lithified, giving gravels and platelets for stromatolite nuclei. They were probably deposited in lakes and lagoons at varying distances from the sea. An aeolian origin is possible for these grains, reworked from marine littoral to continental environments. The algal and stromatolitic builtups develop ultimately, in brackish or freshwater lakes or ponds.

The algal populations and biocoenosis are numerous and different: one is made by a Ponsinella, probably the same as in Abadla. Two others are made of two differ- ent forms of Broutinella. One or several others give wrinkled laminations, devoid of preserved filaments.

Sardinia

Geological setting [47]

The Lower Permian (“Autunian”) occurs in several intramontane basins, with a volcano-sedimentary filling, several hundred metres thick. There is sometimes a Stephanian basement, and they are frequently covered with continental Triassic deposits. Vegetal remains are frequent, but only two small basins revealed algae and stromatolites.

The basin of Perdasdefogu contains 300 m of conglomerates, sandstones, mud- stones, carbonates, coal, cinerites and lavas (dacite and rhyolite). Stromatolites are located in the middle part of the filling, alone in Riu su Luda, and associated with oolites in Nuraghe san Pietro.

The basin of Escalaplano is filled by 200 m of mudstones, cinerites, sandstones and lavas. Two layers of lacustrine pelites contain large masses, 0.5 m in diameter, built by Toutinella sardiniana (upper third) or 7: radiata (lower third) @late III 6).

Palaeoalgological aspect

The newly discovered Toutinella [14] make small, elementary edifices either erected, radiating (7: sardinina, plate III a, b), or subspherical, millimetric (7: radiata, plate III c). These edifices are assembled in large masses, some cubic decimeters in volume, living on the bottom of ephemeral lakes with a pelitic sedimentation. The stromatolitic builtups are laminated, strongly dolomitized, and devoid of preserved filaments.

Stromatolitic aspect

The masses with Toutinella (plate III d) are not stromatolites, because they do not possess laminations. Macroscopically, the true stromatolite builtups show @late III

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12 PIERRE FREYTET ET AL.

d> domes and undulations (I), planar laminations (2) and oolite layers (3). The latter (plate IZZJ) are deformed in contact with one another, and the internal laminations are badly preserved.

Palaeoecological aspect

The local context is that of small lakes with fluviatile intercalations, interrupted by layers of cinerites and lavas. Carbonates are rare, in the form of pedological nod- ules, stromatolites, algal masses, with any distribution, linked to a very quick varia- tion of the water chemistry, and not the organization in large positive sequences, as in the major part of the other basins.

Lodhe (France)

Geological setting (23, 24, 491

Located on the southern edge of the Massif Central, the Lodeve basin contains 2000 m of Permian deposits lying unconformably on basement, and Stephanian. It is composed of a Lower Permian (Formation of Usclas, 250 m thick, dated Upper Artinskian = “Autunien”), a supposed Middle Permian ((Formations of Loiras and Mas d’Alary, 200 m thick), and an Upper Permian (Formations of Viala, Rabejac and Salagou, 1500 m thick, the latter dated from Lower Kazanian).

The deposits are mainly detritic, made up of sandstones, mudstones rich in mud cracks, vertebrate footprints and remains of insects and crustaceans. Some carbon- ated intercalations occur at the base and at the top of the Formation of Salagou. At the top of the latter, some features, that can be interpreted as algolaminated sedi- ments are present in the Dio Carbonate Horizon. They are 20 cm thick, associated with siltsones, deposited in fluviatile channels.

Palaeoalgological aspect

Very small nodules, 3-5 mm in diameter (Plato III g) are deformed in contact with one another (pressure-solution features), underlined by iron oxides (recent alter- ation). Locally, one can see ram, radiating filaments, 10 ym in diameter, included in a dark micrite, of homogeneous aspect, or slightly laminated (/,lrrtc III h, i). Nodules make layers some centimeters thick separated by layers slightly clotted of micritc.

Stromatolitic aspect

In the zones devoid of nodules (plate III g, lower part), the micrite is clotted with a vague lamination. The latter is more obvious in the nodules (pltrte III h). A possible interpretation is a layer of algolaminated sediments, with planar or weakly undulat- ing laminations and very narrow, erected filaments. Locally, deformations affected

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PERMIANNONMARINEALGAEANDSTROMATOLITES 13

the parallel layers, giving small load casts, that were ultimately deformed in contact with one another. These nodules differ entirely from pedological nodules, that pos- sess very characteristic internal features, with curved fissures, patches of recrystal- lization, etc. [ 181.

Palaeoecological aspect

The undulations affecting the layers containing the filaments (not easily visible) are probably mechanical in origin. One has to speak more of algolaminated sedi- ments than stromatolites, the limit between the two materials being difficult to set. Using the sedimentological context, we are in a floodplain with wandering channels and ephemeral lakes (playas). The proliferation of algal felts in such environments is well known in modem analogues.

Bourbon I’Archambault (France)

Geological setting [lo, 421

This basin represents the enlargement of two smaller Stephanian basins (Deneuille-Buxieres or Aumance Basin to the SW, Noyant/Sillon houiller or La Queune Basin to the SE). In the area of Buxibres, the Lower Permian (“Autunian”) is 650 m thick. It is composed of the Formation of La Mouliere (conglomerates) and the Formation of Buxihes (sandstones, siltstones, bituminous shales, coal, carbonate layers). The probable Middle Permian (Formation of Reniere) is 450 m thick, made of red sandstones and siltstones. Toward the east, in La Queune Basin, the series is thinner (200 m), and represented by the upper terms of the Buxieres Formation (fine sandstones and mudstones, coal, carbonates more or less silicilied), lying directly on the metamorphic basement.

The stromatolites are located in the carbonated, often dolomitic deposits, some- times silicified, near the top of the Formation of Buxieres (“faisceau dolomitique”). They were discovered by Paquette [41] in Buxieres, and by Debriette (in Turland et al. [58]) in the La Queune Basin, near Souvigny.

Palaeoalgological aspect

In the basin of Buxieres, the silicified algal filaments were first observed by Paquette [41], re-studied by Freytet et al. [17]. One genus and two species were coined by Freytet [14, 151.

The algal remains are EZZenbergerella attenuata (Freytet [ 141 p. 307, plate I, j-k: filaments septate, 4 pm in diameter, attenuated at the extremity; cells quadrate or higher than wide), and Baltzerella aumuncianu (Freytet [ 151 p. 4; plate 8g-i hollow, erected, non septate filaments, lo-12 pm in diameter) cfigure 3a). E. attenuatu is extremely rare, while B. uumunciunu makes turfs reaching 500 pm high, and fasci-

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14 PIERRE FREYTET ET AL.

cles 500 pm wide and l-2 mm high (figure 3b; plate IV a, b). Two interpretations are possible: B. aumanciana is a species reduced to its sheath or cell-wall, and E. attenu- atu is another species, living in the mucilage of the first one. Or E. attenuata is a tri- chome and B. aumanciana its empty sheath. The observations picked from modern times cannot allow to choose. The accumulations of empty sheaths are frequent in tufas, some hundred pm under the living surface layer [20, 221. But one isolated species in a dense population of another species is also frequent [ 19-211. In all cases, the silicification is very early, probably occurring a few days or weeks after the death of the trichomes. The latter are very quickly destroyed while sheaths are clearly more resistant [2, 271. Locally, the filaments of B. aumanciana are included in a carbonate crystal, probably magnesite, also early in origin. Some other thin sections of silici- lied samples contain regular laminations, 50-100 pm thick, undulating but continu- ous over long distances CfiRure 3~). They include very thin, erected or radiating fila- ments, assignable to Plaziutella colleniaeformis (plate IVd-8.

The builtups of Souvigny have a very different macroscopical aspect (plate IV g), and contain badly preserved filaments. Their microstructures resemble some slightly recrystallized forms of Broutinella variegata$ incipiens [ 151 (plate IV II, i).

Stromatolitic aspect

In Buxibres, stromatolites construct columns 2-3 cm high, l-2 cm wide (figure 3b), and floors l-2 cm thick [41] his figure 34, p. 58) as well as coatings, a few millime- ters thick, around the roots of Psaronius ([41] figure 35, p. 60). These coatings can be broken and reworked, thus making brechic layers. In Souvigny, stromatolites buil- tups are pluridecimetric in size, with upper surfaces covered with adjacent small domes (cauliflower aspect), while vertical, lateral sections exhibit undulations, pluri- centimetric in wave-length (plate Wg).

The builtups with floors and columns of Buxieres are built only by Baltzerella aumanciuna, with occasionally some filaments of Ellenbergerella attenuatu @gure 3a). Light laminations are 200-500 l.trn thick, the dark ones are 40-80 pm thick. Fila- ments are well preserved in silica (p/ate IV a, b); they entirely disappear in the dolomitized zones, in which the laminations keep their thickness, but are obvious only by the difference of crystal size, and/or by the concentration of organic matter (previous dark laminations) (plate NC).

The silicified coatings on Psaronius roots are only a few millimeters thick. They rarely consist of laminations of B&et-ellu aumanciana, most frequently they are made of layers with Plaziatella colleniaeformis (figure SC; plate IVd-f). The lamina- tions are thinner, the light ones are 50-160 pm thick; the dark ones are 20-60 pm thick, and always very undulating. They form small domes, 200-500 pm in diameter, up to 500 ltrn high. But the domes do not correspond from one lamination to the next, or from one set to the next.

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PERMIAN NON MARINE ALGAE AND STROMATOLITES 15

: a

Figure 3. Bourbon I’Archambault Basin. a, drawing of the photo of E/lrrzher~erella (IUCNLUZ~~~ type (narrow filaments, with preserved cells or not)

between filaments of Bal~erella numanci~rzu (wide filaments). Scale bar: 50 Frn. b, drawing after

thin section, superimposition of a zone with narrow columns (low&r part) and wider domes (upper part); dots: internal sediment in a contact between the large domes. Scale bar: I cm. c, drawing after

photo of a thin section, thin encrurtalion around a Psnroniu~ root; laminations have two scales of

undulations: centimetric (vawes) and 100-200 pm (wrinkles). The predominant alga of this builtup is Plazicmllu cnlhiaeformis. Scale bar: I mm.

Figure 3. Bassin de Bourbon I’Archambault.

a, dessin de la photo du type d’Ellrnhergerel/a uttenuufu (filaments &roits, j cellules conservees ou non) dans des filaments de Baltzerdla crumancicuzct (filaments barges). fichelIe : 50 pm. b, dessin d’aprks

lame mince, superposition d’une zone % colonetteh Ctroites (moiti6 inf.) et de domes plus larges (moi-

tiC sup.) ; pointill : sCdiment internc dam une zone de contact entre gros dames. l?chelle : 1 cm. c, dessin d’aprtis photo de lame mince. encrofitement mince autour d‘une racine de Pscrrorzius : les

laminations presentent deux 6chelles d’ondulations : CentimCtriques (vagues) et 100-200 pm (rides).

L’algue predominante dans cet Cdifice est Pltr:intdln co//r,2itrr~~nni.s. I?chelle : I mm.

The builtups of Souvigny only make undulating floors, I to several cm thick. The laminations are very regular on hand-sample or under low magnification f&date Wg). Under higher magnification, one can distinguish two scales of laminations @late IV i, j): microlaminations (light: 50-300 pm; dark: 1040 pm) and laminations thicker (light: 200-800 pm; dark: 40-60 pm). The thick laminations are continuous and weakly undulating; the microlaminations are strongly undulating and draw very small, adjacent columns. All the material is silicified, but the filaments are rarely

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16 PIERRE FREYTET ET AL.

visible. In a purely morphological classification, this type of edifice can be inter- preted as a floor formed with Broutinetla variegataj incipiens.

Palaeoecological aspect

The algae are diversified, in at least three different associations. The stromatolites are centimetric columns, undulating floors and coatings on Psaronius roots. The car- bonated and silicified layers with stromatolites from the two sites (Buxibres and Sou- vigny) also contain ostracods, roots and mudcracks. They overlie bituminous shales rich in amphibian, fishes and ostracods. This environment is confined, with develop- ment of cherts, dolomite, probably magnesite. The organic matter is abundant, pre- served in the bottom of shallow lakes, in reducing conditions.

Blanzy - Le Creusot (France)

Geological setting [I3, ,251

The Permian series is very dislocated, up to 1500 m thick. It lies unconformably on the Stephanian. After the synthetic section of Gand et al. ([25] figure 12), one can recognize: (1) a Lower Permian (Grey Formation: grey sandstones and pelites, with coal and carbonates, 500400 m thick, dated Asselian by flora and pollens); (2) a Middle Permian (Alternating Formation: conglomerates, sandstones, red pelites, coal, carbonates, 300 m thick; Red Sandstone Group: red, coarse and fine sand- stones, red pelites, rare carbonates, 650-750 m thick, dated Kungurian by pollens).

Three sites with stromatolites were discovered towards the top of the Red Sand- stone Group. The first one is located near the shoreline of Grand Etang de Torcy (Les Corvees); the builtups were first interpreted as purely mineral, before a reinterpreta- tion as stromatolites by Gand et al. [25]. The second site, in Sanvigne, provided strongly recrystallized samples. From the third site, Les Pagnes, only some hand- samples and several thin sections remain. The stromatolites builtups and microstruc- tures were described by Stapf in Gand et al. [25]. We only add here some comple- ments on algae (Les Co&es) and the diagenetic recrystallizations (Les Corvees and Les Pagnes).

Palaeoalgological aspect

Builtups of Les Corvees are calcitic and varied in shape. Some small edifices contain zones rich in filaments, associated with recrystallized areas and laminations of two scales in thickness. These characteristics are those of genus Broutinella [ 151, but not of a known species. So, it is a new species.

Genus Broutinella. Filaments very thin, 3-6 pm in diameter; erected, packed or spaced, parallel or radiating; grouped in turf-like layers (f: caespitosa), or in fascicles of various shapes; including micrite, or diverse forms of sparite (microsparite, sparite equant, radial palisadic, etc); frequent internal microlaminations.

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PERMIANNON MARINEALGAEANDSTROMATOLITES 17

Broutinella blanzyana Freytet n. sp. (from Blanzy, name of the basin).

Holofype: pl.V b. Thin section BLl, proceeding from the locus typicus (Les Corvees).

Material: 11 thin sections, and rock fragments.

Diagnosis: Filaments are very thin, S-8 pm in diameter, radiating, appearing as light lines in a matrix made of light and dark micritic laminations. The filaments cross several laminations which are 20-50 pm thick (light) and lo-20 pm thick (dark). The light laminations rarely contain light/dark microlaminations 5-10 pm thick. The lami- nations are often widely extended, giving domes, colums and floors, sometimes unor- ganized masses. In some builtups, the micritic laminations with filaments are located on the edges of small columns; the central part is recrystallized in narrow, radial pal- isadic crystals, rich in inclusions ybrrna centrosparitica) (plate IVe,,fl.

Description and discussion: The species type was taken in a small elementary edifice having the shape of a folded column at the base, 6 mm high, and 8 mm wide at the top (plate V a). The adjacent columns are narrower (up to I.5 mm), and higher (up to 8 mm) (figure 4a). They are often simple, rarely bitide.

B. blanqmza differs from the other species of Broutinella because of very precise characteristics: (1) columns systematically folded at the base do not exist elsewhere; on the other hand, floors occur in B. arverrzensis and B. variegata. (2) the narrow, radial palisadic crystals are clearly narrower than in the other species, and less high, crossing only a few laminations; they never cut all the elementary edifice, as in B. arvernensis, B. variegata and B. pl~m~h.

At the upper part of the columns (figure 4al; plate Vc), and in the small domes (figure 4a4; plate V d) very small features can appear: domes, lobate/spatulate columns, with dark laminations thicker than the light ones, and progressively passing to peloides. Filaments are few or not visible. These small features can be interpreted in two different manners: (I) as a particular form Cfi>rnza) of B. blanryna which developed under different environmental conditions, interrupting the columnar growth; (2) as another species (or biocenosis) which developed under such new con- ditions. We prefer the first hypothesis, because there is a wide variety of shapes of elementary edifices (see below).

Strornatolitic aspect

In the work of Gand et al. [25]. Stapf studied and figured stromatolites. The buil- tups of Les Corvees are small, lo-15 cm long, I-3 cm thick, with a cauliflower-like upper surface (their plate I, figures l-2; plate 2, figures l-2; plate 3, figure I). These builtups grow on woody substrates, and were probably accumulated in an abandoned channel. In Les Pagnes, the builtups are bigger, and the shapes are floors and columns (their plate 3, figure 2). They are 20-60 cm long, 10 cm thick, and one sam- ple, of cauliflower shape is 25 cm high and 45 cm in diameter (their figure 7).

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18

b

Figure 4. Blanzy-Le Creusot Basin. a, Sample of Les CorvCes, drawing of thin section; complex encrustation on vegetal remains. 1, basal, pio-

neer layer, with adjacent domes, mainly thrombolitic @late Vd). 2, zone with small irregular columns. 3, zone with twisted small columns with uppermost zone with very small, dark columns @late V c). 4, column-type @late Vu). Scale bar: 5 mm. b, Sample of Les CorvCes, drawing of thin section; com- plex encrustation made of 1, large, regular columns; 2, small, irregular, thrombolitic columns (voids without details); 3, micritic floors or floors with narrow radial sparite crystals; 4, large columns; 5, small, irregular columns; 6, micritic floor; 7, small, irregular columns. Scale bar: 5 mm. c, Sample of Les Pagnes, sawing. Complex superimposition of floors and layers of narrow, adjacent or bigger, branched, spaced columns. Scale bar: 5 cm.

Figure 4. Bassin de Blanzy-Le Creusot. a, Cchantillon des CorvCes, dessin de lame mince, encroutement complexe sur debris vCgCta1. 1, couche

basale (pionniere), a domes juxtaposes, surtout thrombolitiques (pl. V a). 2, zone a colonettes irregu- lieres. 3, zone B colonettes tordues, avec partie sommitale a petites colonettes sombres (pl.V c). 4 colonette type (pl. V a). &helle : 5 mm. b, Cchantillon des Co&es, dessin de lame mince, encrou- tement complexe form& de 1, grandes colonettes regulibres ; 2, petites colonettes irregulieres throm- bolitiques (vides non detailI&) ; 3, planchers micritiques ou h cristaux de sparite ttroits radiaires ; 4, grandes colonettes ; 5, petites colonettes irregulieres ; 6, plancher micritique ; 7, petites colonettes irrCguli&res. fichelIe : 5 mm. c, Cchantillon des Pagnes, sciage. Superposition complexe de planchers et de grandes colonettes Ctroites et adjacentes, ou plus grandes, ramitiees et distantes. l%helle : 5 cm.

Microstructurally speaking, the builtups of Les Corvees have a thrombolitic basis and the main mass is of “biogenic geopetal fabric”. The builtups of Les Pagnes are “strongly recrystallized”.

In addition to the algal filaments (only present in 4 samples out of 1 I), we only add some details with respect to Stapf’s study. At the scale of the thin.section, Les Con&es samples contain some particular microstructures:

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PERMIANNONMARINEALGAEANDSTROMATOLITES 19

- cm-thick coatings developed on vegetal substrate (bark ?). A complete section (figure 4a; plate V a) shows a basal coating made of adjacent domes, a zone with small, irregular columns, and a zone with bigger, folded columns; the latter have micritic edges with filaments, a central part recristallized with concentric lamina- tions, and an upper part with dark, small features.

- fragments of complex floors cfigure 4b) with alternation of layers with large columns (5-10 mm wide, 4-9 mm high), layers with irregular columns (l-2 mm wide, 2-5 mm high), and undulating floors (1-5 mm thick). Frequently, the top of a floor suffered dissolution, and is the starting point of columns. In this type of builtup, the columns are made of micritic, light/dark laminations, or of an alternation of dark micritic laminations and light laminations with peloids (thrombolitic fabric, plate VI a). Within the columns, the peloids are sometimes grouped in clots resembling the fea- tures of the top of the folded columns (plate VI b). The floors consist of dark/light, micritic laminations with patches of recrystalization locally in narrow, radial pal- isadic crystals, similar to those of folded columns (plate VA.

- breccias. Some thin sections only contain more or less voluminous remains of floors, columns, unstructured masses and thin encrusted vegetal remains (2-4 mm thick).

In the site Les Pagnes, the stromatolitic biostrome (disappeared) was 2 m long and 0.5 m high. The remaining samples are sawings figure 4c) and thin sections. Sawings show floors l-2 cm thick, bearing small columns 4-6 mm wide and 1 cm high, or large columns 1 cm wide and several cm high. The columns are simple or branched, closely adjacent or separated by a void filled with an internal sediment, and locally covered by a floor. In thin section, the dolomitization is complete, with layers of crystals of two different sizes (15-20 pm and 60-80 pm). The dark lamina- tions appear in the form of dark inclusions in the large crystals (plate Vg) or in the form of layers of very small, dark crystals. The extreme irregularity of crystalline laminations (size of crystals, undulations) and of the alternations light/dark allows to suppose that the initial material could probably be of the type dark micrite layer/ layer with peloids.

Palaeoecological aspect

The builtups of Les CorvCes lie on green, fine grained sandstones, and are cov- ered by mottled mudstones. The builtups of Les Pagnes developed on black shales covering coarse grained, pebbly sandstones and are rich in Tetrapod bones. In both cases, they are deposits of channels, coarse (active channel) or fine (pond in an aban- doned channel), in which floating vegetal remains can be gathered. The numerous vertebrate remains correspond to an environment favourable to the preservation of bones (calcite in Les Corvees; dolomite in Les Pagnes). Breccias can be the product of mechanical reworking by the trampling of animals of few indurated stromatolites. We also notice that black, green and mottled deposits are exceptional in the Red Sandstone Group, and located in the upper part.

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20 PIERRE FREYTET ET AL.

Couy (France)

Geological setting

The Couy drilling crossed 115.5 m of red, grey and mottled detrital deposits (-8 10 to -925.40 m), attributed to the Upper Permian (ostracod fauna [35]). Carbon- ates are calcite and dolomite, in the form of cement in sandstones, matrix in pelites and layers of pure carbonates, sometimes with deformed oolites and stromatolites [ 17, 391. The stromatolitic horizon (-915.0 m) is calcitic and 3 cm thick. It lies on a desiccation breccia, 6 cm thick. It is covered with a laminated dolomite (2 cm), a layer of deformed oolites (5 mm) and a laminated dolomite (4 cm). The material con- sists of one thin section of the stromatolitic horizon, and 10 thin sections of the other facies.

Palaeoalgological aspect

The thin section of the stromatolitic horizon (figure 5~; plate VI c) contains sev- eral colonies of Hanskerpelh scripta, laminations with Plaziatella colletzia~fbrtnis and small columns of P c~lytozoot?iaeforttzi.s. These algae were described by Freytet (1997; 1998).

The filaments of H. scripta are solid, entirely micritic, 40-60 pm in diameter, 50-500 pm in height. The longest ones are erected, flexuous, slightly branched (plate VII CI). They can be cut on shorter distances and they take on the aspect of rods, 100-200 pm long, or even the aspect of elliptical or spheroidal peloids (plate VI d, e). The turfs with H. scripta display several habitus of lenses: elongated (plate VI e) or short (fi:gure 5 h, c; plate VI d; plate VII h), with all possible intermediates. Fre- quently there is a basal layer of cells or prostrate filaments. from which the erected filaments develop. These filaments make lenticular colonies (low domes. pltrtc VI d), subhemispherical colonies or the internal part of oncolites (plate VI g). The top of the domes and hemispheres is always impregnated with dark micrite.

The filaments of P col1etzin~fimni.s are difficult to see, often very located, and the enclosing layers can be mistaken for purely micritic laminations (plate VI d; plrttc 1’11 h). The builtups with P c.r~l,to,oottiuc~~trt~tis are small and rare, but easily recognizable owing to their spatulate shape and their internal microlaminations (plrrte V1.f).

Stromatolitic aspect

The main characteristic of H. scripfrr builtups is the lensoid shape of the colonies. which determines the lenticular shape of laminations. They are similar to the types”irrcgularly variable” of Grey ([38] figure 17~) and “lenticular” (figure 17d). They also resemble the “randomly stacked hemispheroids” of the spheroidal struc- tures of Logan et al. 1361. Laminations with P colletziaef~~rttzi,s arc widely extcndcd. and the minute shrubs of P ct.~lttn,nor?ictrfi,rtnis are anecdotic.

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PERMIAN NONMARINEALGAEANDSTROMATOLITES 21

Figure 5. Couy drilling. a, drawing of thin section, with several floors (lower third), two distinct columns (middle third) and sev-

eral floors (upper third). Oncolites are in the internal sediment between columns. Quadrangle repre- sents the surface of the photo plate VI c, circle the location of drawing 2, straight line the section of drawing 3. Scale bar: 5 mm. b, detail of lensoid laminations (white) and the undulating, dark, micritic floors (dots) at the top of a column. Scale bar: 1 mm. c, detail of the section of the uppermost floor, with many lensoid laminations (cf. p1.W d). 1, small column with I? cryptozooniaeformis. Scale bar: I mm.

Figure 5. Sondage de Couy. a, dessin de la lame mince, avec une serie de planchers (tiers inf.), deux colonettes separees (tiers median)

et une serie de planchers (tiers sup.). Les oncolites sont dans le sediment interne entre les colonettes. Le rectangle represente la surface de la photo pl. VI c, le cercle la position du dessin 2, la ligne droite la coupe du dessin 3. I?chelle : 5 mm. b, detail des laminations lenticulaires (en blanc) et des plan- chers onduleux micritiques sombres (pointille) au sommet d’une colonette. &helle : 1 mm. e, detail de la coupe du plancher sommital, avec de nombreuses laminations lenticulaires (cf. pl.VI d). I, colo- nette 2 I? cryptozooniaeformis. Michelle : 1 mm.

Palaeoecological aspect

The detrital sediments enclosing the carbonate layers with oolites (plate VI h) and stromatolites are laminated and rich in desiccation cracks. The most usual mineral is dolomite, which also makes nodules, which could be anhydrite pseudomorphosis. Silicifications were not found. An important, late ferruginization occurs, irregularly distributed in stromatolites and oolitic layers. The palaeoecological context seems to be small ephemeral, carbonated/evaporitic lakes, in a subsident basin with fluviatile sedimentation, under dry tropical climate.

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22 PIERRE FREYTET ET AL.

Toulon (France)

Geological setting, [8, 12, 601

In the Toulon area, we can find a probable Lower Permian (Formation of Ginou- viers lower part), and a probable Middle Permian (Formation of Ginouviers upper part and Formation of Salettes lower part), and an Upper Permian (Formation of Salettes upper part, Formations of St Mandrier and of Fabregas; the top of the For- mation of Salettes reveals an Ufimian flora). The complete series is more than 1000 m thick. Stromatolites are located in the Bau Rouge Limestone, at the top of the Formation of Salettes.

Palaeoalgological aspect

As the result of a strong dolomitization, no filament is preserved.

Stromatolitic aspect

Stromatolites make floors, domes and Conophyton-like builtups (figure 6), included in a layer more than 4 m high, and visible for a length of over 100 m, in the Carqueiranne country. Macroscopically, laminations are wide, 2-3 mm to 1 cm, very undulating, locally with a conical disposition.

Under the microcope, other laminations, 0.3-l mm thick, appear marked by the alternation of microdolosparite/dolosparite, the alternation of laminations devoid of

Figure 6. Toulon Basin. Strom- tolites from Les Salettes

Formation. drawing from il photo. An important mass

locally contain\ floors,

ploughed domes :md c‘ouo- phwwtype columns. Scale

bar: I m.

Figure 6. Bassin de Toulon,

stronutolites de Iti Fol-mn- tion des Saletteh. de\sin

d’apres photo. Uric masse importante prCsente locale-

ment des planchera. des

d8mes effondrk et des colonnes de type Cono~~k~-

PM?. lkhelle : I m.

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PERMIANNONMARJNEALGAEANDSTROMATOLITES 23

or rich in ovoid peloids (plate VII c), or by the occurrence of zones rich in ocraceous inclusions in dolosparite. Thick laminations (4-5 mm and thicker) are rarely consti- tuted only by oolites. These oolites present regular or wrinkled, concentric layers (plate VII 6).

Palaeoecological aspect

A narrow, deep lake developed in a small graben. The sedimentation begins with sapropelic, finely laminated deposits, with cinerites and detrital layers with plant remains. Carbonates appear, interrupted by an arkosic sandstone, then the giant stro- matolites proliferate, covered by other carbonates with black cherts. Laterally, the shorelines are underlined with silicified, oncolitic dolomites, pedologic dessication breccias, and deltaic detritic deposits.

Orobic Alps (Lombardy, Italy)

Geological setting [32]

Near the Lake of Come, a small graben named Orobic Basin ([32] figure 3) the Middle Permian (new dating) consists of 600 m of alluvial fan deposits (Ponteranica Conglomerate). The Upper Permian, lying unconformably, is the Val Gardena For- mation (new dating).

Stromatolites are located in the middle part of the Ponteranica Conglomerate, in a 0.8 m thick layer, and laterally visible for several meters. The most spectacular buil- tups are decimetric masses developed around conifers shoot (Cassinisia orobica Kerp et al.). This very particular type of fossilization also allows the preservation of thin ceI1 structures.

Palaeoalgological aspect

We can reinterpret the description of the builtups by Freytet et al. [ 161 as follows. - The spherical bodies, 100-150 pm in diameter (plate IV, 1, redrawn figure 8,

le-f, located between two stromatolitic columns are Chlorellopsis coloniata Reis. The attribution is uncertain: vegetal cells, insect or crustacean eggs or laying cocoons, or kysts.

- The early diagenesis here reaches a very strong intensity, the builtups are almost completely recrystallized. Fortunately, we can still find areas with preserved filaments and microlaminations @late VU e, fl. The shape of the builtups and the occurrence of these line, internal laminations are a good characteristic of Broutinella variegata. The modem analogues are built by some Schizothrix, including S. pulvinata.

Stromatolitic aspect

On the leaves and branches, the encrustation begins with a micritic layer with adjacent domes or mushroom-like edifices. They contain thin laminations, partly

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24 PIERREFREYTETETAL.

recrystallized in sparite (plate VU g). Above this pioneer coating, the main construc- tion results in a layer of adjacent columns, then undulating floors molding each leaf, and after undulating floors molding the whole builtup ([ 161 figure 4; plate I). All the material is recrystallized in radial palisadic sparite. A curiosity is the development of the main encrustation within the cavity led by the disappearence of a leaf, whose shape was cast by the pioneer encrustation (Freytet et al. [ 161 figures 2-10).

Palaeoecological aspect

The shoots of Cussinisia orobica are only known but their early encrustation by the algae, quickly calcified. This phenomenon probably occurs in an abandoned channel, within an alluvial fan. Such preservation of wood or shells is not rare, but the fossilization of vegetal tissues is exceptional.

Other basins (bibliographic data)

For comparison, we shall give some indications on algae and stromatolites from some other basins of Europe, to illustrate ecological particularities.

Saar-Nahe Basin, Germany [.51,54]

The sedimentation is very thick, continuous from the Lower Carboniferous: 4000 m for the Westphalian, 2500 m for the Stephanian, 1800 m for the Lower Per- mian (Lower Rotliegende, Formation of Kusel and Lebach), 1600 m for the Middle Permian (Upper Rotliegende, Formations of Tholey and of Nahe), followed by the Upper Permian (“Thuringien”, “Zechstein”).

The “algal carbonates” had been known for a long time, occurring as early as the Stephanian, well developed in the Lower Permian, and still present in the Middle Permian. Deposits are of fluvio-lacustrine type, with coal and black shales in the Lower Permian, and of type alluvial fan/plays during the Middle Permian. Diverse shapes of stromatolites were described ([5 l] p. 87):

- The “domical stromatolites” are algal domes, attached to a substrate of oncol- itic gravels. The diameter of the domes ranges from 1 to 20 cm, and the height is up to 10 cm. The domes are isolated or grouped in important layers. “Oncolites” are also present between the domes. The internal structure of the domes is columnar, the columns are branched, some mm in diameter and some cm high. The columns con- tain wavy and crinkled laminations.

- The “tabular stromatolites” are 5 cm thick, and laterally extended over several square meters. They develop on oncolitic sands and gravels. The internal structure is columnar or only laminated.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 25

- The “encapsulating stromatolites” and associated “oncolites” are very variable in shape and size, from spheres some mm in diameter to elongate bodies 1 m long, 0.7 m wide and 0.3 m high. They always result from the encrustation of a vegetal remain, trunk, branch, shoot, leaf.

In thin sections, there are no preserved filaments, because of an intense diage- netic neomorphism (high-Mg calcite, dolomite, ankerite). The photos given by Schlffer & Stapf ([51] figures 3-6) and Stapf ([54] plates 56, 57) show a great resemblance to the builtups of Blanzy-Le Creusot Basin.

Diihlen Basin, Germany [.53]

Located on the Elbe lineament, it is a graben occupied by lakes of varying depths. Its filling includes volcanic cinerites and lavas. The Lower Permian (Lower Rotliegende) is 2500 m thick.

The most interesting deposits are the Formation of Nederhblick Lake, situated at the base of the series, the richest in vertebrates of Europe. It is composed of con- glomerates (30 m), green-grey, sandy siltstones with volcanic tuffs (200 m) and marl horizons with layers of coal and carbonates (20-40 m); slumping figures and elastic sills are frequent. Carbonates make pluridecimetric layers, with laminated peloid limestones and dolomitic limestones with anydrite nodules. Fauna, very localised, is composed of amphibians and freshwater pelicypods. The flora contains “marine” algae: Girvanella, coccoid cyanobacteria, Chlorophyceae (dasycladacean, udotea- cean, halimediforms).

We have here the particular case of a lake with salt water related to volcanism. It has been colonized by wind-borne marine forms. The Tethysian Sea was less than 1000 km from the lake during that epoch.

The Slawkow graben (Poland) [SS, 561

The Slawkow graben is near Crakow, southern Poland. The Lower Permian is 700 m thick. The sediments are of alluvial fan (conglomerates)/playa (fine grained elastics with gypsum) types. Carbonates appear as pedological crusts (“caliche”) in the conglomerates and as karstic spring deposits on the boundaries of the lake. It is the “Karniowice Travertine”, rich in vascular plants. The spring deposits are associ- ated with lacustrine and palustrine formations.

The algal builtups are well preserved, and remains of several genera were identi- fied: Oscillatoria, Rivularia, Chara, Cladophora [55]; Rivularia, Oscillatoria, Stigonemales, ? Vuucheria, ? Cladophora [56]. The occurrence of low-Mg calcite and the isotopic composition indicate freshwater deposits, from karstic circulation. In the central part of the basin, the confinement by evaporation allowed the forma- tions of pedological crusts and evaporites.

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26 PIERRE FREYTET ET AL.

DISCUSSION

Geological setting

During the Permian, non-marine algae and stromatolites are very rare, mainly located figure 7) in the Lower Permian (Mechra2 Ben Abou, Abadla, Tiguentourine, Sardaigne, Bourbon l’Archambault, and also in Saar-Nahe, DGhlen and Slawkow basins), rare in Middle Permian (Orobic Alps, Blanzy-Le Creusot and Saar-Nahe) and in Upper Permian (Lodkve, Couy, Toulon). This represents only 13 basins among the 38 individual basins or groups of basins quoted in Western Europe and North

a b

3ooom

1

/

/

/

/

/

/

,’

/

d

2

.

i

i

g h i

m

2 IL i

S

Figure 7. Stratigraphical location of layers with algae and stromatolites (large black dots). a, Abadla (Algeria), 1, lower grey series; 2, upper red series: b, Tiguentourine (Algeria); c, Mechrad Ben

Abou (Morocco), I, lower megasequence; 2, upper megasequence; d, Sardinia (A, Perdasdefogu; B, Escalaplano); e, Orobic Alps (Lombardy, Italy), 1, Ponteranica Conglomerate; 2, Val Gardena series; f, Toulon (France): g, Lodkve (France), 1, “Lower Permian”; 2 and 3, “Middle Permian”, 4, “Upper Permian”; b, Bourbon I’Archambault (France), 1, “Grey Autunian”; 2, “Red Saxonian”; i, Couy (France): j, Blanzy - Le Creusot (France), 1, “Grey series”; 2, “Red Sandstones”; k, Saar-Nahe (Germany), 1, Kusel; 2, Lebach; 3, Tholey; 4, Nahe. Hatching: Lower Permian; white: Middle Per- mian: points: Upper Permian. Substrates: S, Stephanian; W, Westphalian.

Figure 7. Localisations stratigraphiques des niveaux B algues et stromatolites (gros points noirs). a, Abadla (AlgCrie), 1, sCrie inf. grise ; 2, strie sup. rouge ; b, Tiguentourine (AlgCrie) ; c, Mechral Ben

Abou (Maroc), 1 mCgasCquence inf. ; 2, mCgasCquence sup. ; d, Sardaigne (A, Perdasdefogu ; B, Escalaplano) ; e, Alpes Orobica (Lombardie, Italie), 1, Conglomerat de Ponteranica ; 2, sCrie du Val Gardena ; f, Toulon (France) ; g, Lodkve (France), 1, e< Permien gris >> ; 2 et 3, << Permien alternant >>, 4 << Permien rouge )> ; h, Bourbon I’Archambault (France), 1, << Autunien gris x ; 2, cc Saxonien x rouge ; i, Couy (France) ; j, Blanzy - Le Creusot (France), 1, <c Autunien gris D ; 2, Grks rouges ; k, Saar-Nahe (Allemagne), 1, Kusel ; 2, Lebach ; 3, Tholey ; 4, Nahe. Hachures : Permien inf. ; blanc : Permien moyen ; points : Permien sup. Substrats : S, StCphanien ; W, Westphalien.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 27

Africa by Toutin-Morin et al. [59]. Geographically (figure I), these basins are spread on the African continent (Tiguentourine), on the southern side of the Hercynian Chain (with marine Lower Carboniferous, Abadla, Algeria), and inside the Chain, in intramontane grabens (the other) except Couy, which is on a horst. The substrate is rarely the marine Carboniferous (Tiguentourine) or the continental Westphalian (Abadla, Saar-Nahe), most often the Stephanian, more rarely the metamorphic base- ment. The basins vary in shape, from large surfaces of several tens (or thousands) of square kilometers to the small grabens of a few or tens of square kilometers. The till- ings are often very thick, 1000-3000 m, but with little variation: fluvio-lacustrine or alluvial fan/plays, and “deep” lakes, probably some meters or tens of meters deep, with a wide (Bourbon 1’Archambault) or small, narrow extension (Toulon, Dohlen). Despite an important thickness of deposits, the lakes were never very deep, as in the Modern African Rifts. In all Permian cases, the sedimentation compensates for the subsidence. Volcanic material is sometimes important (Sardinia).

Palaeoalgological aspect

Vegetal remains: Fortunately, despite intense dolomitization, the vegetal remains are frequently well preserved in calcite, magnesite (?), silica and iron oxides. Algal remains can be grouped into 3 groups yigure 8):

- isolated remains and non-laminated masses (figure 8, la-jj.

Toutinella marocana (Mechraa Ben Abou)

7: sardiniana (Sardinia) 7: rudiata (Sardinia)

Chlorellopsis colon&a (Lombardy Alps)

(and Chara sp., Mechraa Ben Abou, Slawkow).

- not identifiable, erected filaments in algo-laminated sediments with mechanical deformations (Lodeve) (figure 8, 2g-h).

- filaments inside stromatolitic builtups cfigure 8, 3i-x). Plaziatella colleniaeformis (Mechral Ben Abou, Bourbon I’Archambault,

COUY) R cryptozooniaeformis (Couy) Ponsinella sahariana (Abadla, ? Tiguentourine)

Broutinella variegata (Abadla, Lombardy Alps)

B. blanzyana (Blanzy) ? B. sp. (Tiguentourine)

Baltzerella aumanciana (Bourbon 1’Archambault)

Ellenbergerella attenuata (Bourbon I’Archambault)

Hanskerpella scripta (Couy).

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28 PIERRE FREYTET ET AL.

m

Figure 8. Algal remains 1, algae making non laminated masses. a. Toutirtelltr muvocnncr (thallus and transversal section of tila-

merit). b. 7: sardiniana: c, 7: radiata. d. algal mass in a lacustrine mudstone. e, Ch/oru//opsis cohni- ntn, cells. f, id. between two stromatolitic, small columns. 2, algolaminated Sediments. g. laminations

and filaments; b, normal and deformed laminations by load cast figures. 3, Filaments. i. Plaziatella

cofienra&mis. j, micritic laminations. k, Pla:intrlla crvl’to~“o”in~~~lfi,rn,is. 1, micritic, small columns

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PERMIAN NON MARINE ALGAE AND STROMATOLITES 29

This list contains 12 species, including two new species. This is relatively few compared to the 58 species quoted by Freytet (1997, 1998). We shall keep in mind that living tufas delivered 210 species of cyanobacteria and eucaryotic algae, plus nearly 200 diatoms usual in this environment [22]. Also, more than 1000 cyanobacte- ria [26], and more than S-6000 eucaryotic algae dwell in continental waters.

On the other hand, as for the marine algae [29,45, 461, the described remains are morphotypes, often of uncertain taxonomic attribution.

Isolated remains and non-laminated masses: The small, elementary edifices of Toutinella are grouped in pluridecimetric masses, on the bottom of the lake. Their origin is uncertain: bacteria, cyanobacteria, eucarotic algae. 7: rudiata has a disposi- tion of the filaments resembling some planctonic forms of cyanbacteria and Chloro- phyceae. To this day, three species of Toutinella are Permian, another is Miocene. Chlorellopsis are a curiosity, noticed in Triassic, Oligocene and Miocene. It is uncer- tain in attribution, vegetal or animal [ 141. Chara are very rare, and not studied here.

Filaments contained in laminations (stromatolites): The algae constitute floors, columns, or both, but the observations are limited by the small number of studied thin sections. The diameter of the filaments, their habitus (parallel, erected, radiating) and the enclosing matter (micrite, sparite) allow a taxonomy to be made (‘j2g.ue 8). But they are only morphotypes, and two species of the same genus can belong to very different taxons (cyanobacteria, Chlorophyceae, etc.). We can attempt to distinguish the following groups:

- groups with a large stratigraphic distribution (Permian to Modern): l subgroup with prostrate then erected filaments (genus Porzsellu, solid filaments, and Ponsinella, hollow filaments). The species are Ponsinellu sahariana (Permian), Porzsellu cupuluta and P. sezamesis (Lower Eocene), Ponsella castel-landonica and

in other laminations. m, Ponsinella mhoriuna. n, micritic doublets. o, Baltzerellu uumuncinna (hol- low tubes) and Ellenhergerelln rrttenuata (tube made of a line of cells). p. small columns and floors (silica). g, Broutinella vclriegattrj incipicns. r, small column with micritic and narrow, radial sparite laminations. s, BroutineUu vuriegcltcz~cr,pine.spariticu. t, small columns and floors, radial palissadic sparite. u, Broutinellu hlanzyana. v, small column with internal part made of radial sparite and micritic peripheral part. w, Hanskerpelln scripta. x, small columns and floors with short, lensoid lam- inations.

Figure 8. Restes algaires. 1, algues en masses non IaminCes. a, Toutinellu mcrrocana (thalle et section transversale de filament).

b, T sardiniana. c, ir: r&into. d, masse algaire dans an mudstone lacustre. e, Chlorel1opsi.s colonintrr,

cellules. f, id. entre deux colonettes stromatolitiques. 2, sediments algolaminCs. g, laminations et fila- ments. b, laminations normales et d&form&es par figures de charge. 3, Filaments. i, Plazintella colle- niaeformis. j, laminations micritiques. k, Pin,-iatella cr~ptozounicr~~~rmis. I, colonettes micritiques dans d’autres laminations. m, Ponsinella srrhnriczna. n, doublets micritiques. CI, Bdtzrrelln c~u~nu~z- cinna (tubes vides) et Ellenhergerda attenuntu (tube divisC en cellules). p, colonettes et planchers (silice). q, Broutinellrr varie,guta,f incipiens. r, colonette B laminations micritiques et en sparite Ctroite radiaire. s, Broufinella vclrir~atn~copiuespuriticu. t, colonettes et planchers, sparite en disposition radiaire palissadique. u, Broutinelln hlanzymcr. v, colonette SI cceur en sparite radiaire et pCriphCrie micritique. w, Hanskerpelln scripta. x, colonettes et planchers B laminations lenticulaires courtes.

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30 PIERRE FREYTET ET AL.

Ponsinella inopinata, P plicatu and P gigantea (Upper Eocene), Ponsinella cuhitata = Plectonema gracillimum (subfossil) and P rupestris (Scytonema myochrous, subfossil and living). All could be Scytonemaceae, but other attributions are possible [ 14, 151.

l subgroup with thin, erected filaments, appearing as a light line in a dark matrix (genus Plaziatella). There are two species (P colleniaeformis and P cryptozooniaeformis), both going from Permian to modern. They can represent turfs of Schizothrix, or other forms.

l subgroup with thin, erected filaments, clear in micrite layers, dark in sparite crystals, with a number of crystalline shapes (genus Broutinella). One species (B. variegata) has

a wide distribution, Permian to modern, and with numerous forms (forma) including jI incipiens, in Abadla and$ copiaesparitica, in Orobic Alps. Other species have a restricted distribution (B. blanzyana, Permian; B. arvernensis and B. rumulosa, Oligo- cene; B. plumula, modern). Possible modern analogues are Schizotrix with microlamina- tions, but B. plumulu is constructed by Phormidium foveolarum.

l subgroup with erected, not branched filaments, lined with a dark coating (genus Baltzerellu). The species are distributed in the whole stratigraphic series: B. uumanciana (Permian), B. languedociana and B. demissa (Upper Cretaceous, Eocene, Oligocene), B. fluviatilis and B. herhacea (subfossil and modern). In modern times, the possible related species are numerous: Phormidium incrustatum, Gongrosira incrustans, Dichothrix sp., Homoeothrix sp., even if the first one is predominant.

- groups with a low stratigraphic distribution (Permian): Hanskerpella scripta (lensoid colonies) and Ellenhergerella attenuata (filaments with quadrate cells preserved).

Other algae from the literature: The occurrence of “marine” algae in salted, intramontane lakes [52] cannot be surprising. Some species of algae can suffer large variations of salinity. There are several modern analogues: Great Salt lake, lagoon and salt marshes of Baja California, Gulf of Mexico, Australia, Red Sea, Persian Gulf, etc.

On the other hand, it is hazardous to give names of living genera to fossil algae. For instance, the algal colony figured by Szulc ([56] plate 8 figure 5) and named Rivularia resemble our Ponsinellu cupulatu Freytet ([14], figure 4g and plate I, i). In modern times many genera and species have the same habitus among Cyanobacteria, Chlorophyceae, Xanthophyceae, Rhodophyceae, Chrysophyceae and diatoms (stalks of fixation). It seems more suitable to choose a “neutral” genus name and to empha- size the taxonomic doubt.

Organization of the algal remains in the builtups: In the studied builtups, there are occasionally 3 species, usually 2, sometimes only one.

- Plaziatella colleniaeformis - P: cvptozoonia<formis - Hanskerpella scripta

(COUY) - Chlorellopsis coloniata - Broutinella variegatat copiaesparitica (Orobic Alps) - Broutinella variegata - Ponsinella sahariana (Abadla) - Baltzerella aumanciana - Ellenbergerella scripta (Bourbon 1’Archambault) - Plaziatella colleniaeformis (Mechrab ben Abou, Bourbon 1’Archambault)

- 12th

PERMIAN NON MARINE ALGAE AND STROMATOLITES 31

- Broutinella blanzyana (Blanzy) - Broutinella variegata$ incipiens (Bourbon 1’Archambault). - ? Broutinella sp. (Tiguentourine).

The filaments (level of organization I of Grey [28], Freytet [ 141) make a continu- ous turf or fascicles (level of organization 2). They are contained in one homoge- neous layer (= one lamination, level of organization 3), or in a doublet (association of a light and a dark lamination), or several doublets (level of organization 4). This dis- position may be a specific character @gure 8). The shape of the laminations is also a specific character (figure 9): they can have a large, lateral extension (floors, = Collenia structure at the sense of Logan [36]), and be planar, incurved, undulating or wrinkled; or they can form domes and columns (lenticular/lensoid, = Cryptozoon structure), regularly continuous from one side to the other of the column (typically Plaziatella cryptozooniaeformis) or irregularly lensoid (typically Hanskerpella scripta). The same builtup can also enclose alternation of layers “Collenia structure” and “Cryptozoon structure” as in the sketches of Logan et al. [36]).

The set is an important level of organization (number 4). It is made of identical doublets, or identical adjacents domes or columns. Two successive sets differ by the aspect of doublets (thickness, undulations, darkness, crystallinity). Successive sets

can also be identical, but separated by a surface of discontinuity: dissolution, detritdl

Figure 9. Morphologies and grouping of laminations with preserved filaments a, shape of laminations: 1, planar or weakly undulating; 2, undulating; 3, wrinkled; 4, shortly lenticular;

5, small column with long, lenticular laminations; 6, column with short, lenticular laminations. b, superimposition of floors: 1, in an oncolite (MechraS Ben Abou); 2, superimposition of floors with

planar and wrinkled (x) laminations (Bourbon I’Archambault). c, superimposition of floors and layers with small columns. 1, Abadla; 2, Couy (x: layer with columns of Pltrriateh ~r~~:vprozoorziac~~rmis);

3, Bourbon I’Archambault, Orobic Alps; 4 and 5, Blanzy-Le Creusot.

Figure 9. Morphologie et groupement des laminations g filaments conserves.

a, forme des laminations : 1, plane ou peu onduleuse ; 2, onduleuse ; 3, rid&e ; 4, lenticulaire courte ; 5, colonette h laminations lenticulaires longues ; 6, colonette B laminations lenticulaires courtes.

b, superposition de planchers : 1. dans une oncolite (Mechrab Ben Abou) ; 2, superposition de plan-

chers b laminations planes et rid&s (x) (Bourbon I’Archambault). c, superposition de planchers et de couches 1 colonettes. 1, Abadla ; 2, Couy (x : couche g colonettes de Plnziotellrr cr~pf~ptozoorziaeformis) ;

3, Bourbon I’Archambault, Alpes Orobica ; 4 et 5, Blanzy - Le Creusot.

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32 PIERRE FREYTET ET AL.

layer, unsticking (Tiguentourine,$gure 2). Sets are rarely lacking; it happens when identical doublets constitute the whole builtup (Abadla, plate I e; Bourbon I’Archam- bault, plate IV g; Blanzy, plate V a, e; Orobic Alps, plate VII e ), or when very differ- ent laminations are superimposed in any manner (Abadla, plate 1 h; Tiguentourine, plate II h, i; Bourbon I’Archambault, plate IV d; Couy, plate VI d).

Stromatolitic aspect

Generalities: Laminations, sets, floors, columns are an important part of the life of algae and biocoenosis, but are also the characteristic features of stromatolites. The terminology is somewhat confusing, we therefore present some definitions and give our own vocabulary. Kalkowsky [3 I] opposed stromatolites (complete, fixed edi- fices, in situ edificated), stromatoides (fragments of builtups), ooids (mobile builtups,

of any size and shape), and oolites (mobile, spherical, millimetric in size). Ulti- mately, these terms received other meanings. For the mobile edifices, see for instance the “coated grains” of Peryt (431. Ooid is now a general term, sometimes it desig-

nates the marine oolites. For us, the definition of stromatolites and oncolites is simi- lar to those generally admitted [ 1, 331, with some precisions picked up from Freytet & Verrecchia ]2 1,221.

Definition: Stromatolites are laminated rocks, resulting from the induration of biological felts, trapping and binding particles and precipitating minerals. A biologi- cal felt is a complex biocoenosis including bacteria, cyanobacteria, eucaryotic algae, fungi and small invertebrates. It can cover a mineral (shell) or biological (moss) sub- strate, that can be enclosed in the whole builtup. In a biological felt, one or two species are predominant, but a great number of other species are present in small quantities, and can form local, important populations. The framework of the felt is defined by the irregular, seasonal growth of the predominant species, or/and the sea- sonal succession of different biocoenosis. The primary mineralizations (oxalates, micrite, diverse types of sparite) are linked in a specific or generic manner to the organisms of the framework, or to their epiphytes. Early recrystallizations in sparite of precise types are generally characteristic of particular biocoenosis.

This definition is inspired from modern tufas, and is suitable for travertines and stromatolites of all ages. We can illustrate it with Permian oncolites and stromato- lites. But stromatolites can suffer other phenomena. Early silicification allows the cells themselves to be preserved (Ellenbergerella atrenuara). Dolomitization rapidly destroys all the biological features but preserves laminations. Calcite can recrystal- lize giving marbles with laminations but without organic remains.

Macroscopic morphologies of unmoved builtups (stroma tolites sensu stricto): Joining the builtups containing preserved filaments and the recrystallized ones, several large morphological types appear cfiguve 10):

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PERMIAN NON MARINEALGAEANDSTROMATOLITES 33

a

i

Figure 10. Morphology of unmoved builtups. a, algolaminated sediments with load casts; b, floor more or less undulating; C, undulating floor; d, builtup with floors and small columns; e, root encrustation (P.~ror~ius); f, builtup with floor and large columns; g, encrustation of a vegetal shoot; h, “closed nodule”, .* flat nodule”; i, large, massive builtup; j. giant stromatolite with undulations and Con&x- ton-like columns.

Figure 10. Morphologic des Cditices immobiles. a, sCdimenla algolamin& A figures de charge ; h, plan- cher peu ondulcux : C, plancher onduleux ; d, Cdifice h planchers et colonettes ; e. encrofitement de rxine (P.~ro~~iu.c) ; f, Cdifice A planchcr et grosses colonettes ; g, encrotitement de rameau vt!g&tal ; h, (c nodule clos >), <( nodule plat x ; i, gros Cditice massif ; j, stromatolite gCam $ replis et colonnes de type Conophyton.

- rectilinear, extented floors (algo-laminated sediments), with badly preserved, not determinable filaments (Lodkve).

- undulating, extended floors, of homogeneous fabric (Sardinia, Bourbon l’Ar- chambault - Souvigny).

- extended builtups, associating undulating floors and small columns (Blanzy- Les Pagnes; Saar-Nahe).

- large, massive builtups, made of floors and columns (Blanzy-Les Pagnes; Saar- Nahe)

- vegetal encrustations (roots, Psaronius: Bourbon 1’Archambault - Buxikres; Conifers shoots: Orobic Alps).

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34 PIERRE FREYTET ET AL.

- closed nodules, flat nodules (Abadla; Tigentourine) - large, massive, homogeneous builtups (Abadla; Tigentourine) - giant builtups, complex association of floors, domes and C~~nophvton-like buil-

tups (Toulon).

All these types of builtups are more or less abundant in active or abandoned chan- nels, and in lake deposits in continental series, mainly from the Upper Cretaceous to Holocene. Oolites are often very abundant. Descriptive literature is considerable on this subject. For comparison, we will take two examples:

- The adjacent domes, then distant, passing to scattered flat nodules and oncolites (Upper level of Tiguentourine) have their analogue in the Altar’ Mountains Pliocene,

USSR [34]. - The builtups of Conoph~ton-type are present in the lacustrine Chateau Landon

Limestone, Upper Eocene, with Ponsella castel-landonica, Ponsinella inopinata and Broutinella variegata (Freytet [ 14, 1.51). Such builtups were also described in modem environments. The hot springs of Yellowstone Park reveal the association Phormid- ium tenue val: granulatum, Chlorqflexus aurantium, Synechococcus lividus, S. min- ervae, Pseudoanabaena-like sp., Spirillium-like sp. [61]. Antarctic lakes have small Conophyton-like with Phormidium frigidum, Lyngbya martensiana, Tetracystis sp.,

Figure 11. Morphology of mobile builtups. a, lar&e, flat oncolite; b, small irregular oncolite; c, encrusted shell; d, micritic oolite; e, micritic/radial

sparitic oolite; f, oolite with narrow, radial crystals of Fparite; g, oolite with regular concentrical layers in three dolosparite crystals; b, oolites with wrinkled, concentrical layers inside four crystals of

doloaparite.

Figure 11. Morphologie des Cdifices mobiles.

a, grosse oncolite aplatie ; b, petite oncolite irrCguli&-e ; c, coquille encro%Ce ; d, oolite micritique ; e, oolite micritique/sparitique radiaire ; f, oolite 1 sparite en cristaux Ctroits, radiaires ; g, oolite B

couches concentriques rCgulii?res dans 3 cristaux de dolosparite ; h, oolites St couches concentriques rid&es dans 4 cristaux de dolosparite.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 35

several species of diatoms; Protozoa, some small Metazoa and the moss Bryum algens dwell in the lateral, flat algal mats [37].

This perfectly demonstrates that very different biocoenosis can build identical external morphology.

Mobile builtups: They are encrusted on shells, oncolites and oolites. Figure 1 I shows the principal shapes and internal fabric of oncolites and oolites made of calcite or dolomite when the fabric is not too modified by dolomitization.

The oncolites are large, some millimeters to several centimeters (Abadla,$gure Ila). They are generally flat, with laminations and algal remains similar to those of large builtups. A small oncolite of Couy, irregular in shape (figure 1 lb; plate VI g) contains very dark laminations and an excrescence with short filaments of Hankerpella scripta. The encrusted shell of Mechraa Ben Abou (figure I Ic; plate I c) has light/dark laminations with filaments of Pluziutellu colleniueformis. So there is no doubt that oncolites are algal in origin, and constituted by the same biocoenosis as the large builtups.

Oolites are more difficult to interpret. The sample of Mechraa Ben Abou (figure II, d; plate I d> has concentric, micritic layers identical to those of other edifices of the thin section, including the encrusted shell, but have no visible filaments. The oolites of Abadla (figure Ile; plate II e) which are lacustrine in origin and the oolites associ- ated with phosphatic grains in the limestone acting as nuclei of oncolites in Tiguen- tourine (eolian transport of marine grains?) are very similar, made of thin layers of micrite and thicker layers of radial sparite. In these two sites, they resemble both the classical marine oolites and the oolites of the Great Salt Lake. For these latter ones, Khale [30] concluded a mechanism of formation identical to marine oolites. Accord- ing to Reitner et al. ([44] p. 212), the oolites of the Great Salt Lake contain organic matter, many bacteria and few cyanophyta, while Rothpletz (1481, p. 279) founded a great quantity of “colonies of Gloeocupsu and Gloeothece cells”. The large builtups of the upper layer of Tiguentourine contain in the brechic areas and between the sets of laminations very particular oolites (figure IIf; plute II k), but of narrow, radial sparite, identical to those of “recrystallized” laminations. Lastly, in the Toulon Basin, oolites are included in large dolosparite crystals; their concentricy layers are regular (figure llg; plate VIII d left part) or wrinkled figure ZOh; plate VIII d right part). This latter habitus suggests the juxtaposition of very small columns as in Broutinellu variegata j incipiens (plate If; g; plate IV h, i) and in B. blanzyanu (plate V d>. SO, there is no doubt that oolites result in algal activity, of the same species or biocoeno- sis as in the next oncolites and large builtups. For comparison, the oolites, “ooid-like oncolites” and “micro-oncolites” of the Oligocene lakes of Limagne d’ Allier ([ 181 plate 13) have the same internal fabric as large builtups ([ 181 plate 11). This type of fabric is now attributed to the alga Broutinella arvernensis [ 151. We propose that the oolites of Abadla could proceed from the activity of Broutinellu vuriegatu present in oncolites and large builtups of the lower layer (plate I e, .f>.

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36 PERREFREYTETETAL.

The algal origin of oolites is only an hypothesis, based on observations in non marine environments. This does not explain the convergence of crystalline habitus with the marine oolites, oolites of the Great Salt Lake (hypersaline) and Abadla (lake with hard waters). Nor is the mechanism responsible for the resulting shape known (columns, floors, oolites, oncolites).

Palaeoecological aspect

In the different studied basins, algae making isolated masses and stromatolites are located in fluvial channels, ephemeral or perennial lakes.

The extreme scarcity of algae and stromatolites is surprising, but fortunately they are very obvious in the field. However, many basins contain carbonates (calcareous pelites, pedological nodules), and algae and stromatolites must exist, but have not yet been discovered. This strongly contrasts with the fluvial molassic series of Pyrenees (Campanian to Pliocene), in which each channel is rich in oncolites, encrusted shells and often large builtups. This is also very different from the lakes rich in floors, giant spherical or columnar builtups, Conophyton-like builtups, oncolites and oolites dur- ing Upper Eocene (Chateau-Landon Limestone [ 14, 15]), Oligo-Miocene (Limagne d’ Allier, Rhine Valley) and in other parts of the world: the Andes (Upper Cretaceous- Pleistocene), USA (Eocene, Pliocene), African Rift lakes (Plio-Pleistocene), etc.

The role of water salinity is not clearly related to the algal growth in the studied and quoted sites. In Poland, in the Slawkow Graben, the maximum proliferation of algae (Karniowice travertine) coincides with karstic springs, while lakes and playas with evaporites were devoid of builtups. In contrast, fluvial channels and ephemeral or perennial lakes are rich in algal masses, stromatolites or oolitic layers, growing in magnesian-rich water, sometimes with silica.

What was the role of climate? The sites with algae and stromatolites are irregu- larly distributed throughout the Permian (fisure 7). During that epoch, it is generally admitted [40, 50,621 that Stephanian climate was equatorial, Lower Permian climate was humid tropical, and the Middle-Upper Permian climate dry tropical, either by migration of continents to the north, or by global climatic change. The reconstruction is complicated by the index of continentality, and the monsoon trajectories. The alti- tude of the Hercynian Chain is also debated, small hills for some authors, high range with glacial and periglacial deposits for others [3]. Algae and stromatolites do not provide any indication, they only require water, permanent or temporary.

CONCLUSIONS

From this brief contribution to algae and stromatolites of the Permian from France and some adjacent countries, we can draw some conclusions of more general value.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 37

- Calcareous algae and stromatolites are very rare in series which could appear as favourable to their proliferation by comparison with Pyrenean molassic series or large Tertiary lakes.

- Algal remains are preserved in unstructured, large masses (on the bottom of lakes) and laminated builtups (stromatolites, oncolites, oolites). Large builtups and oncolites often contain two species of algae, that build distinct parts of the same edi- fice. But, not unfrequently, some small columns of a species are scattered in the lam- inations made by another species. Three species rarely occur in a builtup, sometimes only one does. But, by comparison with modem times, we have to keep in mind that the fossilized filaments represent a very small part of the rich biocoenosis (bacteria, fungi, cyanobacteria, eucaryotic algae, and animals) dwelling in the felt, ultimately lithified.

- The genera and species of algae thus identified are morphotypes, and the com- parison with living forms is difficult. Many modem analogues still exist at all scales of taxonomy. By comparison with living tufas, it is possible that a morphotype corre- sponds to a particular biocoenosis in a sample, and to another biocoenosis in another sample.

- Most frequently the global morphologies of builtups and their content (floors alone, floors plus columns) correspond to different microstructures and algal popula- tions. So it is not possible to give a binominal nomenclature for the stromatolitic builtups, as it is usual for Precambrian and Paleozoic constructions. From the Car- boniferous-Permian, in non-marine series, we enter a different world which has to be studied differently. We must emphazise the aspect “filaments” and “microstructure” with respect to the gross morphology.

- In the same biostrome, the large, unmoved builtups, the oncolites and oolites exhibit the same internal fabrics, which allows us to speculate that all these edifices were constructed by the same algae and the same biocoenosis. But the factors that determine the final shape of builtups remain unknown.

Acknowledgements - Thanks to Mme Colette Aubelle for linguistic correction, and an anonymous reviewer for scientific suggestions.

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42

Plate I

Mechral Ben Abou Basin (Morocco)

a, oncolite with a nucleus made of a fragment of Toutinellu WIWX-~~~ and the coating is made of dark and

light micritic laminations with Plaziatella colleniae;fornzi.s. Scale bar: 500 pm. b, detail of Tourin& mnrocclncr showing the wide, branched, packed filaments. Scale bar: 100 pm. c, vegetal remain cov- ered with several dark/light laminations with thin, erected, clear filaments of Plnzinrelln collenicze-

fr,rmi.s. Scale bar: 500 ym. d, oolite made of many laminations of light/dark micrite, the last layer of variable thickness around a vegetal remain, replaced by equant sparite. Scale bar: 500 pm.

Abadla Basin (Algeria)

e-g, builtups of the lower layer: S, negative photo, small columns with very thin laminations. Scale bar:

500 pm. f, edge of small column showing the progressive ending of laminations (lenticular). The dou- hlets are often made of one lamination of radial sparite and one lamination of dark micrite. rarely

made of light/dark micritic laminations. Scale bar: 500 km. g, detail of the previous thin section, in a zone rich in light sparitic laminations; dark micritic laminations are very thin. Under this magnitica-

tion, the laminations are often weakly undulating, made of adjacent but not separated fascicles. Scale bar: 100 pm. h, builtup of the upper layer, negative photo. The laminations arc linked in sets of differ-

ent intensities of grey. They make more or less intense undulatings. Scale bar: I cm

Planche I

Bassin dc Mcchrad Ben Abou (Maroc)

a, CC oncolite D dont le nucleus est form6 d’un dChris de Tourinella murocc~ncr et I’enveloppe par des lam-

nations micritiquea claires et sombres h Pk~ic~rlla c.ollrflicr~~~r~7li.s. Echelle : 500 pm. h d&ail de fix- tirwlla ~wwc~~~~~~ montrant les filaments larges. ramili6, tassCs. ichelle : 100 pm. c, fragment v6gCtal

recouvert de plusieurs laminations clair/sombre avec dc tins filamente clairs dress& de Plazirrrelh colleni~lc~~,rmis. &helle : 500 pm. d, oolite form6 de plusieurs laminations de micrite claire/ sombre. la derniZrr d’epaisseur variable, autour d’un dCbris v&g&al remplacC par de la sparite. &hcllc : 500

pm.

Bassin d’Ahadla (AlgCrie)

e-g. edifices du nivcau infirieur. 5, photo negative. petites colonettes h laminations t&u finer. l?chclle : 500

pm f. bard de colonctte montrant la tcrminaison progressive des laminations (lenticulaires). Lea dou-

blets sent souvent fait d’une lamination de sparite radiCel lamination de micrite somhre. plus rarement dc laminations de micrite claire/sombrc. l?chelle : 500 pm. g, d&ail de la lame pr&?dcntc. dam une

i~nc richc cn laminations sparitiques claires: les laminations micrites sombreh sent tr& minces. On note 2 cc gros&xmcnt que les lamination? sent souvcnt laihlement onduleuses, formces dc fascicule\

6lCmentait-x juxtaposCs. mais non \CparCa. 6chelle : 100 pm. b, edifice du niveau superieur. photo

n$ativc. Lch laminations sent groupCes en sets bicn visiblcs par les diffkrences d’intensite de< gris. Elle? formcnt dea ondulations plu\ ou moln\ fortes. &helle : I cm.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 43

44 PIERRE FREYTET ET AL.

Plate II

a-e, Abadla Basin, upper layer

a, fonsinrlla sahariana, holotype. Calcitic filaments appear in the form of light lines inside a grey matrix; ferruginized filaments are black. The folded shape is sometimes visible in light filaments (arrow). The individual light/dark laminations have diffuse boundaries. Upper part of the sample piare I h. Scale bar: 100 pm. b, General view of the type area. Several doublets (with laminations with diffuse bound- aries) are superimposed and contain ferruginised filaments often showing their folded shape (arrow). The secondary, horizontal iron deposits underline the doublets. Scale bar: 500 pm. E, lower part of the sample plate I h; doublets are made of light microsparite / dark micrite and present undulations. Scale bar: 500 pm. d, middle part of sample plate I h; the doublets are very variable in thickness, with locally strong ferruginizations. Voids are growth gaps enlarged by surficial alteration. Scale bar: 500 pm. e, oolite, other sample. The laminations are variable in thickness, and cut by radial lines. Scale bar: 250 urn.

Tiguentourine Basin (Algeria)

f-b lower layer; i-k upper layer. f, Ponsinrllu sczhariaw. Prostrate and inclinated filaments are clearly vis- ible. This photo is drawn,figure 2h. Scale bar: 100 pm. g. laminations with p .scrhrrricrru separated by dark. micritic laminations; the light areas are tilled with chalcedony. Scale bar: 500 pm. h, wrinkled, recrystallized, dark and light, micritic laminations. Scale bar: 500 pm. i, PPL and j. XPL. very thin laminations in a builtup on the upper layer. The laminations made of narrow radial sparite clearly appear in XPL. Scale bar: 500 pm. k, oolite from a builtup of the upper layer.The narrow radial sparite is of the same type as in the internal part of the builtup,&urr.s X and Y. Scale bar: 100 pm.

Planche II

a-e, Basin d’Abadla, niveau superieur

a, forzsi~lla saharicrrm, holotype. Les filaments calcitiques apparaissent sous forme de lignes claims dnns une matrice grise : ley filaments ferruginises sont noirs. La forme coudee est parfois visible sur les filaments clairs (fleche). Les laminations individuellcs clair/sombrc ont des limites diffuses. Partie sup. de l’echantillon ~1.1 h. 6chelle : 100 pm. b, vue gencralc de la region du type. Plusieurq doublets (a laminations h limites diffuse) \ont \upcrposCs ct continenncnt des filament% fcrruginiscs montrant souvcnt leur for-me coudee (lleche). Des depots ferrugineux secondaires horirontaux \oulignent lrs doublets. 6chcllc : 500 pm. c, partie inf. de l’dchantillon ~1.1 h ; doublets en microsparite Claire/ micrite sombre. formant des ondulations. &helle : 500 pm. d. partic moycnne de l’echantillon ~1.1 h ; les doublets ont dcs &pa&curs tres variables, avec parfois des ferruginisations intenses. Les vides sont dcs lacunes de croissance Clargies par alteration superticielle. 6chelle : 500 pm. e. oolitc, autre echan- tillon. Les laminations ont des Cpaisseurs variables, et sont recoup&x par des ligncs radialcs. l?chellc : 500 pm.

Bassin de Tiguentourine (Algerie)

f-h nivcau inf. ; i-k niveau \up. f, Pon.siw//n sahnricmcr. On distingue clairement les filaments rampants et inclines; photo dessinee fig. 2b. &helle : 100 pm. g, laminations a !? sahor-icrrm separees par des lami- nations micritiques sombres; les zones claires sont occupees par de la calcedoine. &helle : 500 pm. h, laminations micritiques recristallisees claires et sombres. rid&s. l%helle : 500 pm. i, LN et j. LP. laminations tres fines dans un Cdilice du niveau sup. Les laminations en sparite Ctroite fibro- radicc apparaissent nettement en LP. k, oolite d’un edifice du niveau sup. La sparite tibro-radiee est du m&me type que celle de la masse de l’edifice, fig. 8 et 9. fichelIe : 100 pm.

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46 PIERRE FREVTET ET AL.

Plate III

Basins of Sardinia

a, Toutinella sardiniarza~~ strobikrcru, tuft of erected filaments making superimposed shrubs. Scale bar: 500 pm. b, detail showing the regularly branched filaments, clearly separated one from the other. Scale bar: 100 ym. c, 7: radiate, millimetric elementary coliny, made of radiating filaments. well pre- served in the left part of the photo. Scale bar: 500 pm. d, outcrop with a large pluridecimetric mass of 7: rudiufu, in a mudstone layer bordered by two cinerites layers. Escalplano Basin. e, Dolomitic sam- ple photographed in a wall, Perdasdefogu Basin. I, stromatolitic domes; 2, planar laminations; 3, oolites bed. Scale bar: 5 cm. f, deformed oolite, same origin. The concentric zonation is still appar- ent: the contacts between oolites are rectilinear. Scale bar: 500 pm.

Lodtve Basin

g, negative photo, contact between a zone with small nodules (upper part) and a zone with clotted, vaguely laminated micrite. Scale bar: 5 mm. h, detail of a dome with radiating filaments. The very thin fila- ments appear on the form of a light line in a grey mass; the laminations have diffuse boundaries. Scale bar: 500 pm. i, other small nodule with clear laminations. The contact with the underlying nodule is strongly impregnated with iron products. Scale bar: 500 pm.

Planche III

Bassins de Sardaigne

a, Toutinelln sardiniann$ strobilacea, touffe de filaments dress&s en buissons superposCs. kchelle : 500 pm. b, d&ail montrant les filaments rCguli&ement ramit%, nettement &par& les uns des autres. l?chelle : 100 pm. E, 7: mdinta, ddifice ClCmentaire millCtrique, form6 de filaments rayonnants, assez bien visibles dans la partie g. &helle : 500 pm (1961). d, affleurement avec une grosse masse pluridC- cimetrique de T. mdiatu, dans un mudstone encadrC par deux cinCrites. Bassin d’Escalplano. e, Cchantillon (dolomitique) photograph% dans un petit mur, bassin de Perdasdefogu. I, d8mes stro- matolitiques ; 2, laminations planes ; 3, lit B oolites. l?chelle : 5 cm. f, oolite dCformCe, m&me origine. la ronation concentrique est encore visible, les contacts entre oolites sont rectilignes. fichelIe : 500 Km.

Bassin de LodPve

g, photo negative, contact entre une zone g petits nodules (partie supgrieure) et une zone 1 micrite grume- leuse vaguement IaminCe. !%helle : 5 mm. h, d&ail d’un d8me avec filaments en disposition rayon- nante. Les filaments, tr&s fins, apparaissent sous forme d’un trait clair dans une masse grise; les lami- nations ont des limites diffuses. t%helle : 500 bm. i, autre petit nodule h laminations nettes. Le contxt avec le nodule sous-jacent est fortement imprCgn6 de produits ferrugineux. &hellc : 500 pm.

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PERMIAN NON MARINE ALGAE AND STROMATOLITES 41

Plate III

48 PIERRE FREYTET ET AL.

Plate IV

Bourbon I’Archambault Basin. Samples from Buxieres les Mines (silica, dolomite)

a, silicified sample, laminations with Bakerella aumanciana, interrupted by ex-micritic laminations (white). The dark zones consist in organic impurities. Scale bar: 500 pm. b, detail of the preceeding view: the hollow filaments are lined with a dark coating; locally, thinner filaments may be remains of Eflenhergrrella attenuate (arrow), badly preserved, with no cells apparent. Scale bar: 50 urn. c, dolomitized zone of the same sample: the laminations of dark dolomicrite/light dolosparite are vari- able in thickness, of the same order of size as the silicified laminations (photo a). The edificating algae are the same, but here nothing of them remains. Scale bar: 500 pm. d, e, f, Plaziatella colleniar-

formis, silicified sample. d, wrinkled laminations, variable in thickness. The filaments are light lines in a dark, siliceous, matrix. Scale bar: 500 pm. e, magnified detail with very thin, radiating filaments. Scale bar: 100 pm. f, magnified detail. Scale bar: SO pm.

Souvigny samples (calcite)

g, negative photo, section of a builtup. The laminations are very thin, and reveals two sizes of undulations: l-2 cm (waves) and 50-100 pm (wrinkles). Scale bar: 1 cm. b, thin section in the same sample.The laminations are very thin, regularly made of dark micrite/light microsparite, and affected by very small wrinkles. Scale bar: 500 pm. i, detail of the previous photo; under such magnification, the lami- nations are relatively discontinuous; the filaments are white lines with a radial disposition. Scale bar: 100 pm.

Planche IV

Bassin de Bourbon I’Archambault. &hantillons de Buxieres les Mines (silice, dolomite)

a, echantillon silicifice, laminations a Ba/tzew/la antncrnciunc~, s&par&es par des laminations ex-micri- tiques (en blanc). Les zones sombres sent des impure& organiques. ichelle : 500 pm. b, detail du precedent; les filaments creux sent hordes d’une ligne sombre; localement, des filaments plus fins peuvent etre des restes de Elfedwrgere//n nftenwta (tlttche). mal conserves (cellules non visibles). &helle : 50 pm. c, zone dolomitisee du m&me Cchantillon : les laminations de dolomicrite sombre/ dolosparite Claire ont des Cpaisseurs variables, du m&me ordre de grandeur que les laminations silici- tiees (fig. 1). Les algues constructrices sent les m&mes, mais ici il n’en reste rien. &helle : 500 pm. d, e, f, Phzintella collmiaeformis, Cchantillon silicifie. d, laminations tres rid&es, d’epaisaeur variable. Les filaments se voient sous forme de lignes claires dam une matrice sombre (siliceuse). &helle : 500 pm. e, detail grossi, montrant lcs filaments tri-s tins en disposition radiaire. &helle : 100 pm. f, detail grossi. &helle : 50 pm.

6chantillons de Souvigny (calcite)

g, photo negative, section d’un edifice. Les laminations sent t&s fines, et montrent deux tnilles d’ondula- tions : l-2 cm (vagues) et 50-100 pm (rides). &helle : 1 cm. h, lame mince du m&me Cchantillon. Les laminations sont tres tines, regulierement en micrite sombrel microsparite claim, et affectee de tres petites rides. fichelIe : 500 pm. i, detail de la photo precedeme; a ce grossisscment, les lamina- tions sent relativement discontinues; les filaments apparaissent SOW forme de lignes blanches en dis- position radiaire. &helle : 100 pm.

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Plate IV

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50 PIERREFREYTETETAL.

Planche V

Blanzy-Le Creusot Basin

a, negative photo of a thin section; section of the area of the type of Bmurinellu hlar~zynnu (general draw- ingfigure 40). I, layer of the basal domes (detail plate V d); 2, zone of small, irregular columns; 3. small column of the type, lateral zone (detail plate 1/h); 4, central zone (detail plate V e,fi: 5. upper- most zone with small dark columns (detail plate V c). Scale bar: 5 mm. b, Broutineh blnrz;ymc~. very thin filaments appearing as white lines in a micrite with light/dark laminations; the lateral continuity is low under such magnification, Scale bar: 100 pm. c, detail of the small, dark columns of the upper- most area. Scale bar: 500 urn. d, detail of the small basal domes with laminations and peloides. Scale bar: 500 pm. e and f, detail of the central of the folded type-column, with laminations made of narrow, radial sparite crystals. e, PPL; f, XPL. Scale bar: 500 pm. g, dolomitired sample of Les Pagnes. The laminations are alternatively made of dolomicrite and of dolosparite. Lines of dark inclusions appear in the layers of dolosparite. The irregularity of laminations suggests a fabric similar to those figured in p/ate VI a and h (dark, micritic laminations micritiques and light laminations with peletoides). Scale bar: 500 pm.

Planche V

Bassin de Blanzy-Le Creusot

a, photo negative de lame mince, coupe de la region du type de R~ontirzrll~ h/on:~rru (dessin general fig. 4a). I, couche des domes basaux (detail pl. V d) ; 2, zone des colonettes irreguliercs : 3, colonette du type, zone IatCrale (detail pl. V b) : 4, zone centrale (detail pl. V e,f ); 5, zone sommitale a petite!, colonettes sombres (detail pl. V c). fichelIe : 5 mm. b, Broutidh hlrrn:rancr. filaments tres tins sous forme de lignes blanches dam une micrite B laminations clair/ sombre, a faible continuite laterale h ce Erossissement. Echelle : 100 urn. c, detail des petites colonettes sombres de la region sommitale. &hclle : 500 pm. d, d&ail des petits domes basaux a laminations et peloides. &helle : 500 pm. e et f. detail de la partic centrale de la colonette coudee du type, avec laminations en cristaux etroits de spa- rite radiaire. e, lumiere naturelle ; f. lumiere polarisdc. fichelie : 500 pm. g. Cchantillon des Pagnes, dolomitise. Lcs laminations sont alternativement en dolomicrite et en dolosparitc. Des lignes d’inclu- sions sombres se situcnt a I’interieur des couches de dolosparite. L’irregularitc des laminations fait penser a une diposition analogue h celles figurees pi. VI a et b, laminations micritiqucs sombres et laminations claires a peletoides. !%helle : 500 pm.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 51

Plate V

52 PIERRE FREYTET ET AL.

Plate VI

Blanzy-Le Creusot Basin, Sample of Les CorvCes, drawing,figure 4b

a. Very irregular, dark, micritic laminations and light, peletoidal laminations in a large column. Scale bar: 500 pm. b, adjacent microcolumns in a small, irregular column, with dark, micritic laminations and

light laminations with peletoides. Scale bar: 500 Km. Couy drilling. c, negative photo, small column made of lenticular laminations with Hanskerpelk~~ scriprc~ and floors with P. col/enine~~n,~i.\. In the

left lower part, detailed oncolite of photo g. Scale bar: 5 mm. d. detail of lenticular laminations rich in short filaments of H. scripta (I) and micritic, more extented laminations with filaments weakly appar-

ent of F1 colleniaeformis (2). Scale bar: 500 pm. e. From a tuft of fl c~pto-oorzitrefonnis (I), develop-

ment of a rounded tuft of H. scripra with adjacent, rounded. basal “cell” (2) and erected, branched ti- aments (3). Scale bar: 500 Km. f. detail of the small column of P. cr~pto?oo?zincr.~i.s with

laminations of two order of size, 30-100 pm and 5-10 pm. Scale bar: 100 pm. g, oncolite with irregu-

lar laminations. The large filaments of H. scrip&/ are barely visible. Scale bar: 500 pm. h, strongly

dolomitised oolite, also impregnated with iron oxides underlining the concentrical fabric. Scale bar: 500 urn.

Planche VI

Bassin de Blanzy-Le Creusot, tchantillon des CorvCes, dessinC fig. 4b

a, laminations micritiques sombres t&s irrCguli?res et laminations claires h pcletoides dans une grande colonette. fichelIe : 500 pm. b. microcolonettes adjacentes dans une petite colonette i&guli&re, avec

laminations micritiques sombres et laminations claires B peletoides. &helle : 500 pm.

Sondage de Couy

c, photo negative. colonette form&e de laminations lenticulaires ?I H. scrip& et planchers g E colhi~~efior-

mix. Vers le bas, ZI g., << oncolite D dCtaillCe photo 7. fichelIe : 5 mm. d, d&ail des laminations lenticu- laires riches en filaments courts de H. scripm (I) et des lamination\ plus &endues, micritiques. a Ma-

merits peu nets dc P. co/lrrzi@~rmis (2). fichelIe : 500 Km. e, B partir d’une touffe de f?

c~proxoniaeformis (I), dCveloppement d’une touffe arrondie de H. scripfu avec x cellules x basales

arrondies/juxtaposies (2) et lilamcnts dress&slramitiCs (3). &helle : 500 pm. f, detail de la colonette d e

P. crvproroo/ziarfi,rmi.s avec des laminations de deux ordres de grandeur, 30)IO0 pm et 5-10 pm.

fichelIe : 100 pm. g, N oncolite x h laminations irrtgulitirey. Les gros filaments de H. scrip/cl sent peu visible% l&hclle : 500 pm. b. oolite. fortement dolomitisCe et imprCgnCe d’oxyde? de fer. soulignant

la structure concentrique. &hclle : 500 pm.

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PERMIANNONMARINEALGAEANDSTROMATOLITES 53

54 PIERRE FREYTET ET AL.

Plate VII

Couy drilling

a. part of lensoid laminations with long filaments of H. scriptcz included in sparite (I) separated by dat-k.

micritic laminations with short filaments more or less well preserved (2); (3), micritic laminations

with filaments weakly apparent of /? collerzic@&~~is. Scale bar: 500 pm. b, part of lenticular lamina- tions with short filaments of H. scriptcr included in sparite (I) or micrite (2). separated by micritic

laminations with filaments of R culhia&vmis barely visible (3). Scale bar: 500 pm.

Toulon Basin

c, dolosparite with traces of peletoides. Scale bar: 100 pm. d, oolites included in wide, millimetric lamina- tions. The oolites have concentric layers which are regular (left), or wrinkled (right). Scale bar: 100 pm.

Orohic Alps, Lombardy (Italy)

e and f, the main encrustation, with very thin laminations and dark inclusions of organic matter that draws irregular erected bands.: e, PPL, f, XPL. Scale bar: SO0 pm. g, detail of the pioneer encrustation, with

domes and mushrooms, micritic at the base (I) and recrystallised in sparite in the upper part (2). The main encrustation (3) is more regular, and made of radial palisadic sparite. Scale bar: 500 pm.

Plancbe VII

Sondage de Couy

a, parties de laminations lenticulaires a longs filaments de H. scripts inclus dam de la sparite (I) separees

par des laminations micritiques sombres a filaments courts plus ou mains bien conserves (2) ;

(3), laminations micritiques 1 filaments peu nets de FI co/hic@mis. &helle : 500 pm. b, parties de laminations lenticulaires a filaments courts de H. scriptcr inclus duns de la sparite (I) ou de la micrite

(2). separees par des laminations micritiques h filaments de P. collerlicwformis peu visibles (3). 6chelle : 500 pm.

Provence, bassin de Toulon

c, doloaparite h traces de peletoidcs. fichelIe : 100 pm. d, oolites dam de grandes laminations millime- triques. Les oolites ont des couches concentriques regulieres (a gauche), ou ridees (a droite). i?chclle :

100 pm.

Alpes de Lomhardie (Italie)

e et f, encroutement principal h tres fines laminations et inclusions sombre< de matiere organique en bandes irregulieres dressees ; e, lumierc naturelle. f, lumiere polarisee. &helle : 500 pm. g, detail de

I’encroutement pionnier a domes et champignons, micritiques a la base (I) et recristallises en sparite

vers le haut (2). L’encroutement principal (3) est plus regulier, fait de sparite radiaire palissadique. &helle : 500 pm.

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PERMIAN NONMARINEALGAEANDSTROMATOLITES 5.5

Plate VII