Correlating environmental changes during early Albian oceanic anoxic event 1B using benthic...

ELSEVIER Marine Micropaleontology 38 (1999) 7–28www.elsevier.com/locate/marmicro

Correlating environmental changes during early Albian oceanic anoxicevent 1B using benthic foraminiferal paleoecology

Jochen Erbacher a,Ł, Christoph Hemleben b, Brian T. Huber c, Molly Markey c

a Bundesanstalt fur Geowissenschaften und Rohstoffe, Referat Meeresgeologie, Stilleweg 2, 30655 Hannover, Germanyb Institut und Museum fur Geologie und Palaontologie, Universitat Tubingen, Sigwartstrasse 10, 72076 Tuebingen, Germany

c Department of Paleobiology, NHB-121, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560, USA

Received 18 February 1999; accepted 14 July 1999

Abstract

The nature and consequences of mid-Cretaceous oceanic anoxic events (OAEs) are the subject of ongoing debate, andrecent studies have shown that different scenarios are needed to explain each of these events. Nevertheless, similaritiesbetween the different OAEs can be observed. Here, we have reconstructed paleoenvironmental changes during the earlyAlbian OAE 1b using benthic foraminiferal distributions and lithologies in three sections from different basins andpaleowater depths. Eutrophic conditions, as indicated by the presence of infaunal as well as opportunistic genera such asGyroidinoides, Pseudobolivina, Pleurostomella and bolivinitids, prevailed before and during the OAE and led to dysoxicto anoxic conditions. Dysoxia was most intense in the bathyal sections but also occurred in the outer shelf wheremore heterogeneous patterns of foraminiferal distributions are believed to reflect fluctuations of the upper boundary ofan oxygen-minimum zone. A change from eutrophic to mesotrophic conditions caused the termination of OAE 1b andopportunistic benthic foraminifera (e.g. Pseudobolivina, Pleurostomella) were the first to subsequently repopulate thebathyal sea floor. Repopulation occurred rapidly in the shallow settings and gradually in the deeper sites, where a normal,diverse pre-event fauna was established a few tens of thousands of years after OAE 1b. 1999 Elsevier Science B.V. Allrights reserved.

Keywords: benthic foraminifera; oceanic anoxic events; Cretaceous; black shales; ODP Leg 171B; SE France Basin

1. Introduction

Since the pioneer work of Schlanger and Jenkyns(1976), the origin and spatial distribution ofmid-Cretaceous anoxic sediments, so-called oceanicanoxic events (OAEs), have remained open to per-sistent debate. Subsequent studies focused on theimpact of OAEs on the evolution and distribution

Ł Corresponding author. Tel.: C49-511-643-2795; Fax:C49-511-643-3663; E-mail: [email protected]

of organisms (e.g. Jarvis et al., 1988; Koutsoukoset al., 1990; Kuhnt and Wiedmann, 1995; Erbacherand Thurow, 1997), stable isotope shifts that wereparalleled by or followed OAEs (e.g. Gale et al.,1993; Hasegawa, 1997; Weissert et al., 1998), andvariations in organic matter (e.g. Stein et al., 1989;Crumiere et al., 1990; Erbacher et al., 1996). Mostof these investigations concentrated on carbonaceoussediments from the Cenomanian–Turonian bound-ary interval (OAE 2) resulting in a comprehensive,almost global picture of this event (e.g. Arthur et

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8 J. Erbacher et al. / Marine Micropaleontology 38 (1999) 7–28

al., 1990; Thurow et al., 1992; Sinninghe Damasteand Koster, 1998). In addition, pelagic Aptian toAlbian sections reveal a great number of black, car-bonaceous layers some of which are synchronous indifferent basins and have therefore been identifiedas oceanic anoxic events 1a (late-early Aptian), 1b(earliest Albian), 1c (early-late Albian), and 1d (lateAlbian) (Arthur et al., 1990; Erbacher and Thurow,1997). Each of these events seems to have its ownlithologic character, influence on the evolution ofdifferent groups of organisms, and geographical dis-tribution. However, it has been suggested that Ap-tian to Albian black shale horizons can be linkedto different positions of sea level (Breheret, 1994;Erbacher, 1994; Erbacher et al., 1996). These stud-ies distinguished between black shales formed asthe result of increased oceanic productivity (produc-tivity oceanic anoxic events, P-OAE; Erbacher etal., 1996) and black shales which are the result ofincreased sedimentation rates of terrestrial organicmatter (detrital oceanic anoxic events, D-OAE; Er-bacher et al., 1996). P-OAEs are believed to beconnected to transgressive periods, whereas D-OAEsapparently correlate with still-stands or falling sealevel. OAE 1a and 1c are the best studied intervals ofthe Aptian=Albian interval (e.g. Herbert and Fischer,1986; Coccioni et al., 1989, 1992; Erba and PremoliSilva, 1994; Jenkyns, 1995; Menegatti et al., 1998),but comparably little information exists on OAE 1band 1d (compare with Bralower et al., 1993).

The intention of this paper is to reconstruct andcorrelate the environmental changes during OAE 1b(Hedbergella planispira planktic foraminiferal zone,Fig. 1) by using benthic foraminiferal paleoecologyas a correlation tool.

One reason for the scarcity of investigations ofOAE 1b is its relatively poor biostratigraphic defini-tion. Often, ammonites are rare in pelagic deposits,and the latest Aptian–early Albian interval lacksage-diagnostic calcareous plankton taxa such as cal-careous nanoplankton and planktic foraminifers (seediscussion in Hart et al., 1996). However, smallerplanktic foraminifers (e.g. hedbergellids), radiolariaand dinoflagellates have proved to be of useful strati-graphic value (Erbacher, 1994; Vink, 1995; R.M.Leckie, pers. commun., 1998). Stable carbon isotopestratigraphy has recently become a powerful toolin correlating other mid-Cretaceous OAE sediments

(Gale et al., 1993; Jenkyns et al., 1994; Grotsch etal., 1998; Weissert et al., 1998), but to date this isnot well established for the late Aptian to Albianinterval (compare Erbacher, 1994; Erbacher et al.,1996; Grotsch et al., 1998). OAE 1b has been de-scribed from the Tethyan Southeast France Basin(Niveau Paquier, Figs. 2 and 3), Umbria–MarcheBasin (Livello Urbino, Italy), India and Deep SeaDrilling Project (DSDP) and Ocean Drilling Pro-gram (ODP) Sites from the Atlantic (Bralower etal., 1993; Erbacher, 1994). In the boreal realm, OAE1b probably correlates with the shaley, SchrammeniClaystones (Lower Saxony Basin, NW Germany).Ocean Drilling Program Leg 171B drilled the firstwell-dated interval of OAE 1b in the Atlantic (Ship-board Scientific Party, 1998; Fig. 4). In the followingdiscussion, we present the results from high-resolu-tion studies of OAE 1b sections from different pale-owater depths in the Southeast France Basin and thewestern tropical Atlantic (ODP Hole 171B–1049C).

2. Regional setting and lithology of investigatedsections

2.1. Southeast France Basin

Two of the studied sections are located in thenorthern part of the Southeast France Basin, whichrepresent the hemipelagic to pelagic part of a basinthat corresponded to the northern margin of the west-ern Tethys (Arnaud and Lemoine, 1993; Fig. 2A).Here, the Aptian to Albian stages are characterizedby a thick, monotonous succession of dark marls(Marnes Bleues). The late Aptian and early Albianpart of this unit reveals numerous black shale hori-zons (Breheret, 1994), most of which cannot yet becorrelated to other basins. In order to study NiveauPaquier (OAE 1b) along a depth transect, we inves-tigated one section in the deepest, upper bathyal partof the basin (Col de Palluel section) and one from thesoutherly outer shelf (Le Coulet section) (Fig. 2A).

The Niveau Paquier from the Col de Palluel sec-tion comprises a 1.30-m-thick succession of veryfinely laminated black ‘paper’ shales. The maximumtotal organic carbon (TOC) content measured withinthis horizon is up to 8%, with hydrogen index (HI)values up to >500 (Breheret et al., 1986). Breheret

J. Erbacher et al. / Marine Micropaleontology 38 (1999) 7–28 9

Fig. 1. Stratigraphic position of OAE 1b. Planktic foraminiferal zonation from Premoli Silva and Sliter (1994).


Fig. 2. Location of the investigated OAE 1b sections and their paleogeographic position. (A) Paleogeographic reconstruction of thesoutheast France Basin with position of the investigated sections (modified after Arnaud and Lemoine, 1993). (B) Paleogeographicreconstruction of the Aptian Tethys and North Atlantic (modified after Blakey, 1998).


Fig. 2 (continued). (C) Location of ODP Holes 171B–1049C on the toe of the Blake Nose escarpment (modified after ShipboardScientific Party, 1998).

(1983) and Tribovillard and Gorin (1991) studied theNiveau Paquier in detail at a locality 20 km westof the Col de Palluel section with the same paleo-bathymetry. Therefore, we refer to these papers formore details concerning lithology, geochemistry andorganic facies. Ammonites are very frequent in mostof the black shale beds, with nearly monospecificassemblages consisting of the genus Leymeriella.Leymeriellids had a cosmopolitan to boreal paleo-geographic range. Therefore, their sudden mass oc-currence within the Niveau Paquier black shales hasbeen interpreted as a result of immigration of borealfaunas due to a relative rise of sea level (Breheretet al., 1986). Tiny planktic foraminifers of the genusHedbergella are abundant throughout the section.M. Caron (in Breheret et al., 1986) interpreted theabsence of larger taxa as a result of an expandedoxygen minimum zone (OMZ) which would havedestroyed the habitats of larger morphotypes that re-produced at deeper depths. However, recent evidencefrom stable isotope studies suggests that hedbergel-lids were deep-water dwellers (Norris and Wilson,1998). Thin, 0.5–3.0-cm-thick laminated carbonatebeds are intercalated within the black shales (Fig. 3),the lighter laminae of which consist of coccolithsand nanoconids and have been explained as resultingfrom seasonal nanoplankton blooms in oxygenatedsurface waters above an almost completely anoxicbasin (Tribovillard and Gorin, 1991).

The shallower Niveau Paquier at Le Coulet hasbeen described by Breheret (1991). There, the black-shale-rich interval reaches a thickness of 2 m withTOC and HI values very similar to those of thebathyal succession. In contrast to the bathyal section,black shales are interbedded with marly, bioturbatedlayers, that are very rich in glauconite (Fig. 5). Thefluctuations between glauconitic marls and blackshales are a result of O2 changes from anoxic todysoxic conditions (Breheret, 1991). Ammonites areless frequent than in the Col de Palluel section. Massabundances of Leymeriella are restricted to the lowerthird of the black shale interval.

2.2. Blake Nose escarpment, western North Atlantic

ODP Leg 171B drilled a depth transect of Pa-leogene to mid-Cretaceous strata along the BlakeNose escarpment, a salient of the Blake Plateau, offnorthern Florida (Fig. 2). Late Aptian to early Albiansediments were drilled in Holes 171B–1049A, B andC. Mid-Cretaceous sediments are only overlain by150 m of Upper Cretaceous to Eocene sedimentsand most probably have not suffered any deeperburial (Shipboard Scientific Party, 1998), which re-sults in good to excellent preservation of calcareousmicrofossils. The presence of OAE 1b in Site 1049represents the first well-dated recognition of thisblack shale horizon in the North Atlantic. The lam-


inated black shale interval has a thickness of 46cm. Distinct, light laminae, alternating with dark, or-ganic-rich laminae are composed of rhombic calcite(Shipboard Scientific Party, 1998; Fig. 4). Organicmatter contains type II kerogen, which indicates apredominantly marine origin of the organic matter.TOC values reach up to 11% (Shipboard ScientificParty, 1998). Our studies focus on OAE 1b fromHole 1049C.

The lithological similarity between the bathyalTethyan OAE 1b occurrences from Italy and Franceand from Blake Nose is striking, even if the thicknessof this interval is about three times higher in thesoutheast France Basin than at Blake Nose. Thisdifference in thickness most probably results fromhigher sedimentation rates during the early Albianin the southeast France Basin (approx. 3.0 cm=ka atCol de Palluel versus 0.6 cm=ka in Hole 1049C).Sedimentation rates for the southeast France Basinare rough calculations based on absolute ages fromGradstein et al. (1995) for the Aptian=Albian andAlbian=Cenomanian boundary. Rates for Blake Noseare taken from Shipboard Scientific Party (1998).

3. Material and methods

Eighty-one samples from three OAE 1b sectionshave been investigated. Samples from land sec-tions were treated with a detergent (REWOQUAD),whereas ODP samples were treated with a mixtureof H2O2 (15%) and chalk to avoid oxidation of pyri-tized fossils. Thereafter, samples were washed overa 63-µm sieve and dry-sieved into >125 µm and<125 µm fractions. To obtain a larger number ofspecimens, the relatively small (10 cm3 to 20 cm3)ODP samples were sieved into >100 µm and <100µm fractions. In addition, glauconite-rich samplesfrom Le Coulet section were split with a magneticseparator to separate magnetic glaucony grains fromlesser-magnetic carbonate grains and calcareous mi-crofossils. The larger fractions of all onshore sam-ples were split into fractions of equal size and,where possible, at least 300 benthic foraminiferswere picked, identified and counted. To calculatefaunal density, ODP samples were dried and weighedbefore and after washing. Because of the small sam-ple size, no splitting was necessary in most cases.

Consequently, faunal density is given in specimensper gram dried sediment. Samples from land sectionswere not weighed and the abundances are indicatedas counts relative to 1 g of >63 µm washed residue.Therefore, the abundances are relatively high dueto a non-representation of the fine fraction in theseland samples, and it should be noted that the countsdo not reflect faunal abundances per gram sediment.The preservation of benthic foraminifers from ODPSite 1049C is good to excellent. Specimens fromland sections show good to moderate preservation.Two samples from glaucony-rich levels of Le Couletsection are excluded from this study due to their poorpreservation. Species diversity is given as simple di-versity (number of species per sample). Tables ofbenthic foraminifer counts are shown on the internet:http:==www.bgr.de=B323=erbacher=.

To determine typical assemblages quantitativelyand qualitatively, Q-mode principal componentsanalyses (PCA) were carried out on the samplesfrom the French sections using the statistical soft-ware package SYSTAT 5.2. Accordingly, the benthicforaminiferal faunas were grouped into five assem-blages. This model explains 82% of the total vari-ance with communalities ranging from 0.99 to 0.22.However, as calculated faunas mostly consist of onlyone dominating taxa and hardly any overlap betweenfaunas of the deep and shallower sections appeared,the results of PCA in this case (in contrast to resultsin Erbacher et al., 1998) do not contribute to a betterunderstanding of faunal patterns and will thereforenot be discussed in greater detail herein.

Stable carbon isotope analyses were performedusing a Finnigan MAT 252 mass spectrometer withan on-line automated carbonate reaction Kiel deviceat Woods Hole Oceanographic Institution. Analyticalprecision based on repeated analyses of standards(NBS-19, Carrara marble, and B-1 marine carbonate)was better than 0.03‰. All analyses were performedon planktic foraminifers of the taxon Hedbergellatrocoidea.

4. Results

To describe the paleoecological changes acrossOAE 1b, we have chosen different parameters suchas abundance of benthic foraminifers and distribution

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Fig. 3. Benthic foraminiferal distribution patterns from a bathyal OAE 1b succession, Col de Palluel section, southeast France Basin. Counts are referring to benthicforaminifers > 125 µm in 1 g of washed residue > 63 µm. Scales are number of picked specimen. See text for the relationship between lithologic facies and bottom-waterventilation.


of selected taxa that have been demonstrated toreveal paleoecological significance (e.g. Koutsoukosand Hart, 1990; Koutsoukos et al., 1990; Kaihoand Hasegawa, 1994; Erbacher et al., 1998). Thesedata were compared to lithologic and stable carbonisotopic variations.

4.1. Bathyal Col de Palluel and Blake Nose sections

As mentioned above, the lithologic similarity be-tween the two compared bathyal sections is striking.The same is true for the patterns of distribution ofbenthic foraminiferal faunas which will be demon-strated below.

The abundance of benthic foraminifers in bothsections shows remarkable similarity (Figs. 3 and 4).The intervals preceding OAE 1b are characterizedby the highest abundance values in the investigatedinterval. The faunal densities in both cases declinerapidly from values around 230 individuals per gramdried sediments down to values around zero in dark,laminated facies (values from ODP Hole 1049C).A short interval of reoccurrence of benthic fora-minifera is present in both sections. Whether thisreoccurrence is caused by the same event in bothsections remains questionable. However, comparisonof average sedimentation rates and positions of thereoccurrence horizon suggests that both peaks arethe result of one event. In the Col de Palluel section,benthic foraminifers are absent until 10 cm abovethe OAE 1b black shales, whereas benthic foramin-ifers increase in abundance immediately above theblack shale at Site 1049. This may be an artifactof a higher sedimentation rate or postdepositionaloxidization of organic-rich sediments, as is the casefor many Mediterranean sapropels (Thomson et al.,1999). The interval following the repopulations inboth bathyal sections again shows very similar faunalpatterns and represents a slow increase of abundanceof benthic foraminifers.

Although there are some differences in speciescomposition in both sections (e.g. agglutinated formsare very rare in samples from Blake Nose), the dis-tribution patterns of different taxa or morphologicalgroups are again very similar. Osangularia schloen-bachi is a common form in many samples. This taxonis abundant in the non-laminated intervals precedingOAE 1b and is one of the first taxa that reappears

after the OAE (Figs. 3 and 4). In addition, it isthe most abundant species in the short reoccurrenceevent within the black shales of both bathyal sec-tions. In both of these sections Gyroidinoides nitidusis very common in the samples preceding the OAE,but decreases rapidly in abundance as the sedimentbecomes laminated. This species is missing from thereoccurrence event, but reoccurs relatively late abovethe OAE.

The distribution pattern of gavelinellids (Gave-linella spp. group) differs only slightly between thetwo sections (Figs. 3 and 4). At Col de Palluel,gavelinellids are very abundant comparably far be-low the Niveau Paquier and almost disappear 30 cmbelow the OAE. A weak increase marks the sam-ples preceding the OAE. Gavelinella spp. is absentfrom all black shale samples and does not reappearuntil the establishment of a ‘normal’ and diversefauna, far above the OAE (Figs. 3 and 4). The samesituation appears in the Blake Nose section, wherethe Gavelinella group shows a peak abundance priorto the black shale and disappears during the blackshale event. However, the disappearance starts laterat Blake Nose compared to Col de Palluel.

Interestingly, the Fursenkoina viscida=Pleurosto-mella spp. morphogroup, which comprises the boli-vinitid F. viscida and different taxa of pleurostomel-lids (mostly Pleurostomella prima) in samples fromBlake Nose (Fig. 4), is not well-represented in sed-iments from the Col de Palluel section. The abun-dance of this morphogroup clearly increases towardsthe laminated facies, and the component taxa (espe-cially F. viscida) represent the dominant forms in the10 cm of indistinctly laminated facies that ultimatelyprecedes the OAE. The group includes the first taxa(especially P. prima) to repopulate the environmentafter the OAE. However, in contrast to other taxamentioned, the F. viscida=Pleurostomella spp. groupalmost disappears 20 cm above the OAE. Althoughcomparably rare, Pseudobolivina variabilis seems tohave occupied the same niche as the F. viscida=Pleu-rostomella spp. group in sediments from OAE 1b inthe southeast France Basin (Fig. 3). Like this mor-phogroup P. variabilis increases in abundance withinthe lowermost laminated interval and then reappearsduring the reoccurrence event. It is the first form torepopulate the sea floor above the black shales and al-most disappears soon thereafter. In samples from the

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Fig. 4. Benthic foraminiferal distribution patterns from a bathyal OAE 1b succession ODP Sections 171B–1049C, 12X-2 and 3, western North Atlantic. Scales are number of pickedspecimen. Stable carbon isotope curve was measured on selected specimens of planktic foraminifer Hedbergella trochoidea. See text for the relationship between lithologic faciesand bottom-water ventilation.


Col de Palluel section, pleurostomellids (mostly P.subfusiformis) are bigger and more thick-shelled thanpleurostomellids from Blake Nose. In addition, theirdistribution differs from Blake Nose as they clearlydecrease towards the OAE beyond the black shale.However, the Col de Palluel section also has pleu-rostomellids within the repopulation event and pleu-rostomellids are part of the fauna pioneering the en-vironment after OAE 1b.

Trochamminids (Trochammina spp. group) arenot present in sediments from Blake Nose but repre-sent a typical agglutinated morphogroup in the Colde Palluel section. The distribution of this groupis similar to Osangularia schloenbachi. However,trochamminids are among those forms that reappearfirst above the OAE then disappear for a short inter-val thereafter (Fig. 3).

4.2. Outer shelf Le Coulet section

As mentioned above, Le Coulet section in south-east France provides the opportunity to sample OAE1b in shallower water depth. In contrast to thebathyal sections, the distribution patterns of ben-thic foraminifers are much more heterogeneous inthis section (Fig. 5). With the exception of onlyone black shale sample, all samples show abundantfaunas and no clear correlation between foramini-fer abundance and oxic and dysoxic facies can bemade. As the marls and black shales contain somepercentage of sand-sized carbonate debris, this het-erogeneous pattern might be caused by reworking.However, shallow-water forms are very rare andthe distribution of paleoecologically significant taxashows better-defined trends. Osangularia schloen-bachi again proves to be a sensitive form to environ-mental changes during OAE 1b. The abundance of O.schloenbachi decreases dramaticaly towards the firstblack shales and a gradual decrease characterizes theinterval below the thick laminated shales. Again, ashort reoccurrence event, lithologically expressed asa non-laminated marly interval, rich in glauconite,marks a small peak in the abundance of O. schloen-bachi. As in the bathyal sections, sediments aboveOAE 1b are characterized by a gradual increase ofO. schloenbachi.

Gyroidinoides nitidus has proved to be of goodvalue for the paleoecologic interpretation of our

bathyal section (compare Erbacher et al., 1998), but isnot so important in the shallower section. Neverthe-less, a good correlation between lithology and distri-bution of this taxon was observed. As at the bathyalsections, G. nitidus decreases rapidly in abundancetowards the black shales, but in contrast, already reap-pears in the upper part of the Niveau Paquier.

Gavelinellids (Gavelinella spp. group) form alarge part of benthic foraminiferal faunas at LeCoulet, and their distribution pattern is very hetero-geneous. Most of the gavelinellids are comparablysmall and within the grain size spectra of glauconiteand carbonate grains. Again, reworking cannot beruled out as a factor being responsible for theirheterogeneous distribution pattern.

Dorothia levis and Globorotalites bartensteini arerare in the bathyal sections, but show interestingpatterns at Le Coulet. The abundance of D. levisincreases within the first thick black shale layer andshows a marked peak within the marly interval be-tween the two major black shale horizons. The formalmost disappears in the upper black shales and isabundant to dominant in the samples above OAE 1b.Globorotalites bartensteini is common in samplesbelow the Niveau Paquier. However, a continuousdecrease of this form characterizes the first marlyblack shales. The lower thick black shale horizonshows very high abundances of G. bartensteini. Theform disappears in the upper prominent black shalehorizon and is almost completely absent from alloverlying samples.

4.3. Stable carbon isotopes

The stable carbon isotope curve across OAE 1bfrom Blake Nose documents an increase of about1‰ (from 2.4 to 3.3‰) within the lower 20 cm ofthe investigated interval. Values decrease down to2.7‰ with the onset of distinctly laminated blackshales and show relatively stable values (from 2.7to 3.1‰) through the black shale horizon and theinterval following the shales.

5. Discussion

The paleoecology of benthic foraminifers andstable carbon isotope variations are powerful tools


for reconstructing ancient environments and doc-umenting paleoceanographic and paleoclimatologicchanges (e.g. Altenbach and Sarnthein, 1989; Kuhntet al., 1996a; Schmiedl and Mackensen, 1997; Weis-sert et al., 1998). Species morphologies as well asthe ecology of morphologically similar recent formshave been used to interpret the mode of life of fossilforaminifers and to reconstruct their environments(Koutsoukos and Hart, 1990). Here, we use the taxadescribed above to reconstruct and correlate environ-mental conditions during OAE 1b.

5.1. Bathyal sections

As can be seen in Figs. 3 and 4, the distribu-tion patterns of benthic foraminifers across the twobathyal successions of OAE 1b are very similar. Os-angularia schloenbachi may have been epifaunal dueto its morphology and distribution patterns and is acommon constituent of many Albian black shale fau-nas (compare Bernhard, 1986; Erbacher et al., 1998).The form seems to have tolerated dysoxic environ-ments but was less tolerant of eutrophic conditions(Erbacher et al., 1998).

In contrast, Gyroidinoides nitidus is a shallow in-faunal taxon that apparently thrived under eutrophicto mesotrophic conditions, but had very little toler-ance for oxygen-poor environments (Koutsoukos andHart, 1990; Coccioni and Galeotti, 1993).

Some bolivinitids (e.g. Fursenkoina) are con-sidered as opportunistic infaunal dwellers that areadapted to eutrophic–mesotrophic and=or dysoxicconditions (e.g. Koutsoukos and Hart, 1990; Bern-hard et al., 1997). However, studies of modern en-vironments and laboratory experiments have shownthat during dysoxic conditions and=or periods of ahigh nutrient flux bolivinids are able to ‘climb’ to thesediment surface (W. Kuhnt, pers. commun., 1998).

Little paleoecological work has been published onpleurostomellids. They have been described as shal-low infaunal deposit feeders by Koutsoukos and Hart(1990), but our data suggest that they were toler-ant of eutrophic, oxygen-depleted conditions. Kaihoand Hasegawa (1994) have also described Pleurosto-mella as indicative of dysoxic conditions during thelate Cenomanian of Japan. However, their observa-tion is contradicted by data from Coccioni and Gale-otti (1993), who defined Pleurostomella as an aerobic

species based on its distribution in late Albian marl–black shale rhythmites from central Italy.

Pseudobolivina is a typical opportunistic, pioneergenus that has been described as being among thevery first foraminifers to repopulate the sea floorafter OAE 2 (earliest Turonian) (Kuhnt, 1992; Coc-cioni et al., 1995). Flattened forms with a tendencyto become uniserial (as observed in samples fromCol de Palluel) are considered as typical componentsof oxygen-depleted deeper environments that tookadvantage of an increased food supply (‘Biofacies B’of Kuhnt and Kaminski, 1990).

Like O. schloenbachi, flat trochamminids havebeen described as having an epifaunal to semi-in-faunal mode of life (Koutsoukos and Hart, 1990;Nagy et al., 1995). This taxon was opportunisticand dominated dysoxic environments (Tyszka andKaminski, 1995).

The paleoecological utility of Gavelinella is ques-tionable, even though it has been shown that thick-shelled gavelinellids are usually common in aer-obic, oligotrophic–mesotrophic epifaunal environ-ments (Koutsoukos and Hart, 1990; Coccioni and Ga-leotti, 1993; Erbacher et al., 1998). However, Kout-soukos et al. (1990) described gavelinellids as typicalcomponents of dysoxic environments from the latestCenomanian to early Turonian of Brazil and England.

In general, thin-shelled, elongated taxa and=or taxawith a high surface-to-volume ratio (e.g. Fursenkoinaviscida, Pleurostomella, O. schloenbachi), as well asopportunistic agglutinated taxa (e.g. Pseudobolivina,Trochammina), were apparently adapted to dysoxicenvironments. However, this does not imply that theseforms are also indicative of general eutrophic oceanicconditions.

A comparison of benthic foraminiferal distributionand lithofacies results in the following interpretations.Directly below the bathyal black shales, ‘normal’,well-oxygenated conditions prevailed. This is indi-cated by high diversities and total abundances (Figs. 3and 4). A dominance of infaunal G. nitidus is believedto reflect an elevated food supply as principally in-fauna-dominated assemblages indicate increased or-ganic carbon flux (Corliss and Chen, 1988; Mack-ensen and Douglas, 1989). Dramatic environmentalchanges occurred in intervals ultimately precedingthe OAE when a severe depletion of oxygen, proba-bly induced by eutrophic conditions, was responsible


for a dominance of the F. viscida=Pleurostomella spp.group at Blake Nose and the appearance of P. vari-abilis in the French section, paralleled by the preser-vation of fissile lamination in both sections. The cleartolerance of Fursenkoina viscida to dysoxic facies insediments from Blake Nose (Fig. 4) is one of the ear-liest times in earth history where such an adaption,which is typical for modern environments, can be ob-served for bolivinitids (Murray, 1991). Gyroidinoidesnitidus continued to be dominant at this initiation ofdysoxic conditions, probably until the environmentbecame too anoxic for this taxon. The high abun-dance of Gavelinella in Hole 1049C in this phase issurprising, because gavelinellids have been describedas oligotrophic to mesotrophic forms. At Col de Pal-luel, P. variabilis seems to be resistant against severeoxygen depletion during the very beginning of OAE1b (Figs. 3 and 4).

In the lower third of OAE 1b, in both bathyalsections an oxygenation event apparently enabledO. schloenbachi, F. viscida and pleurostomellids torepopulate lost habitats. Whether this oxygenationevent also affected the sediment or only bottom wa-ters remains unclear because it has been shown thatinfaunal foraminifera are also able to live in epiben-thic habitats (Linke and Lutze, 1993). Above thisshort oxygenation event, anoxic conditions prevaileduntil the very top of OAE 1b when the first benthicsreappear at Blake Nose. We interpret the absence ofG. nitidus in this repopulation horizon, the presenceof opportunistic Pseudobolivina variabilis, as well asthe high abundance of Pleurostomella as a sign of areduced organic matter flux following the eutrophicevent. Moreover, it reflects a less extreme eutrophiccondition and shows that these species are the fastestto adapt to rapid environmental changes (compareKuhnt, 1992). At ODP Site 1049, the repopulation ofbenthic foraminifers happens gradually until approx.15 cm (approx. 25 ka) above the black shale whena normal ‘pre-event fauna’ can again be observed. Itis interesting, that repopulation at the Col de Palluelsection seems to happen at a comparable rate.

5.2. Outer shelf section

Due to the more inhomogeneous distribution pat-terns, interpretation of faunal changes are more diffi-cult in the shallow site at Le Coulet (Fig. 5).

Following Koutsoukos and Hart (1990), Dorothiais an infaunal deposit feeder which is able tolive in eutrophic to mesotrophic, dysoxic environ-ments. Coccioni and Galeotti (1993) documentedMarssonella oxycona, a form very similar to our D.levis in late Albian black shales from central Italy.

Globorotalites is thought to be an epifaunal, free-living deposit feeder (Koutsoukos and Hart, 1990),but not much is yet known about the paleoecology ofthis genus. However, the obvious correlation betweenblack shales and high abundances of G. bartensteiniindicates an affinity of this taxon for either eutrophicconditions and=or dysoxia (Fig. 5).

As in the bathyal sections, the onset of dysoxicconditions on the outer shelf is marked by a drasticdecrease of O. schloenbachi, followed by a shortpeak of G. nitidus, which might be correlative tothe bathyal distribution patterns and also a sign ofan increased flux of organic matter. Environmentalconditions apparently became too dysoxic for G. ni-tidus in the lower part of OAE 1b when it seems asthough G. bartensteini was the opportunistic speciesin this shallower setting and was able to profit fromeither higher fluxes of organic matter and=or dysoxicconditions. However, whether or not the subsequentdecrease of G. bartensteini (paralleled by an increaseof Dorothia levis) reflects a response to a continuousoxygen decrease remains equivocal. Nevertheless,the presence of pyrite nodules in these layers maysupport such an assumption. A short repopulationevent documents reoxygenation of the bottom wa-ters following the lower black shale layer. The layerfollowing this reoxygenation event is almost bar-ren of benthic foraminifers, indicating near-anoxicconditions. Whether the peaks of G. nitidus andGavelinella in the upper black shales are caused byresedimentation remains uncertain (see discussionabove). Assuming that this is the case, repopula-tion above the Niveau Paquier occurs immediately.This conclusion supports interpretations that repop-ulation of anoxic environments starts from shallowand oxic environments (Kuhnt, 1992) and thereforeis observed in shallow environments first. The over-all heterogeneous distribution pattern in the shallowsection is striking and might reflect fluctuations inthe intensity of oxygen depletion or variations offood supply and, to a much lesser extent, reworking.We believe that such fluctuations may have been

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Fig. 5. Benthic foraminiferal distribution patterns from an outer-shelf OAE 1b succession, Le Coulet section, southeast France Basin. Counts refer to >125 µm benthicforaminifers in 1.0 g of >63 µm washed residue. Scales represent number of picked specimens.


controlled by fluctuations of the upper boundary ofan OMZ. Another possibility would be changes offood supply due to changes of precipitation ratesand runoff. Fluctuations in the Pleistocene OMZoff Pakistan observed by Schulz et al. (1998) werecontrolled by monsoonal climate variabilities andsubsequent changes in biological productivity.

5.3. Carbon isotope variations

High values at around 3‰ from OAE 1b as doc-umented in Fig. 4 have also been reported fromthe Umbria–Marche Basin in central Italy (Erbacheret al., 1996). Weissert and Breheret (1991) doc-umented relatively low values between 2.2‰ and0.5‰ around OAE 1b from the Vocontian Basin.Grotsch et al. (1998) described a rise of δ13C val-ues at the Aptian–Albian boundary from a carbonateplatform section in Greece. There, values rise fromaround 1.2 to 2.8‰. Whether this rise is time equiva-lent to OAE 1b remains questionable due to the lackof black shales and a relatively poor biostratigraphyin this Greek section. However, these prior inves-tigations were based on whole rock samples and acomparison to our data is difficult.

An increase of stable carbon isotope ratios charac-terizes the 20 cm preceding the black shale horizon.The overall increase of δ13C values of 1.0‰ lies inthe range of other oceanic anoxic events (e.g. Galeet al., 1993; Jenkyns et al., 1994; Erbacher et al.,1996; Weissert et al., 1998), and it has been demon-strated that increases of such an amplitude mightbe interpreted as a result of changing fractionationpatterns in the global carbon reservoir (see discus-sion in Weissert et al., 1998). Moreover, increasedδ13C values can be regarded as an indicator for anincreased surface water productivity (Arthur et al.,1990; Jenkyns et al., 1994). A drop of carbon isotopevalues with the onset of black shale sedimentationmight be caused by a secondary decrease of carbonisotope values due to the presence of 13C-depletedorganic carbon in the sediment. This process couldexplain the slight relative increases of carbon isotopevalues in the repopulation horizon and the first cen-timeters following the OAE. The 0.3‰ decrease ofδ13C values above the event might again be the resultof a reduced surface water productivity followingOAE 1b.

5.4. Correlation of OAE 1b sections

Following the distribution of benthic foraminifersand the inferred ecological interpretation, we cor-related the three investigated sites on the basis ofvariations in food supply (organic carbon flux) andoxygen content (Fig. 6). Up to five intervals can bedistinguished and correlated between these sections(indicated as intervals I to V from base to top of thesections).

Interval I precedes OAE 1b. As indicated by apeak of infaunal G. nitidus, the presence of thinblack shale layers in the southeast France Basin andan increase of δ13C values at Blake Nose (Fig. 4),it is characterized by an increase of oceanic produc-tivity and subsequent Corg flux. A continuous carbonflux resulted in dysoxic to anoxic conditions dur-ing Interval II, again induced by an ongoing highoceanic productivity. This scenario resulted in a peakof opportunistic taxa at the beginning of OAE 1b andup to nearly anaerobic conditions in the bathyal sec-tions thereafter. However, oxygen depletion duringInterval II was less in shallower realms, as shownby the presence of abundant foraminiferal faunas. In-terval III marks a reoxygenation horizon in all threesections and is characterized by a return of severalbenthic foraminifers. Above this, Interval IV resem-bles a return to conditions experienced in Interval IIwith even stronger anaerobic conditions, which alsoaffected the shallower section for the first time. Be-sides the absence of almost any benthic foraminifers,this anoxia is indicated by very fissile paper shalesand the presence of pyrite nodules in all the sec-tions investigated. Above OAE 1b, Interval V showsa gradual return of the first opportunistic taxa, fol-lowed by a ‘normal’ fauna in the bathyal sections afew tens of thousands of years after the anoxic event.Repopulation happens faster in the shallower sectionat Le Coulet.

5.5. Problems and questions

Although the suitability of benthic foraminifersfor paleoecological reconstruction during OAEs haspreviously been demonstrated, a number of questionsremain. Here, we propose that the unusually detailedsimilarity and temporal development in foraminiferalchanges is due to the synchroneity of the event at

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Fig. 6. Correlation of three OAE 1b sections on the basis of benthic foraminiferal distribution patterns. Roman numbers I to V refer to depositional intervals as described inthe text. Scales in m. Legend as in Figs. 3–5. Total organic carbon (TOC) values are from Breheret (1997), French sections and Shipboard Scientific Party (1998), for Hole1049C.


least in the two basins studied. Elsewhere, the syn-chroneity of anoxic events between different basinsdocumented by stable carbon isotope excursions hasbeen demonstrated for the late Cenomanian=earlyTuronian OAE 2 (Gale et al., 1993). We believethat such a correlation between basins is possiblefor OAE 1b as well, in our case based on thedistribution of benthic foraminifera and changes ofenvironmental conditions, respectively. Leon Clarke(pers. commun., 1998) has demonstrated good corre-spondence of stable carbon isotope curves from theAptian=Albian interval in central Italian sections andSite 1049, Blake Nose.

Accurate correlation and estimation of the dura-tion of OAE 1b and the repopulation event (IntervalIII, Fig. 6) between the bathyal and shallow sec-tions remain difficult. One way to prove their timeequivalence would be to obtain an absolute age as-signment of the horizons in the different sectionswhich is, of course, impossible in the absence ofminerals that can be radiometrically dated. In ad-dition, sedimentation rates are difficult to calculate,because cyclostratigraphy and appropriate narrowspacing of well-dated horizons are lacking. High-resolution carbon isotope data in the French sectionswould contribute to a more sophisticated correlationof the sections investigated.

The distribution of benthic foraminifers is mainlycontrolled by the interplay of oxygen in the pore- andbottom-waters as well as by the flux of particulateorganic matter (Jorissen et al., 1995). Which of thetwo factors controls the presence or absence of cer-tain taxa is often difficult to pinpoint. Furthermore, ithas been shown that the adaptation of foraminifers tohabitats is dynamic for many modern taxa and varieswith environmental changes (Linke and Lutze, 1993).Therefore, while dealing with infaunal and epifau-nal habitats it has to be considered that these habitatsmight have changed mainly due to the availability offood and=or oxygen (Kuhnt et al., 1996b). However,we believe that this uncertainty does not undermineour main interpretation that infaunal-dominated fau-nas and faunas with a dominance of opportunistic taxaindicate eutrophic conditions. Whether these formslived infaunally during eutrophic conditions or not isof lesser relevance. In this case, the presence or ab-sence of lamination can be taken as a criterion for theoxygen content of pore- and bottom-waters.

With respect to habitat preferences, it is inter-esting to compare the distribution and repopulationpatterns between the two bathyal sections. Nichesthat are not covered by a species in Blake Nose(e.g. Pseudobolivina variabilis) are there populatedby another species (e.g. Fursenkoina viscida) andvice versa. The relatively high number of aggluti-nated forms and the comparably high sedimentationrate at Col de Palluel might be caused by the prox-imal position close to a deep-sea fan (Fries, 1984;Holbourn et al., 1999). As mentioned above, therepopulation of environments following the anoxicconditions happen at a comparable rate and are char-acterized by similar morphotypes. The first formsto reappear after the OAE are thin-shelled elon-gated forms at Blake Nose. Similar elongated, butagglutinated pseudobolivinids play the same role inthe more clastic-dominated environment at Col dePalluel. This underlines the role of morphologies,probably rather than test composition as principalfactor for habitat adaptation. A long delay of full re-population after the OAE, as observed in our bathyalsections seems to be typical. A similar delay in ben-thic repopulation after the Holocene S1 sapropel,where a fully restored benthic fauna does not occuruntil present, was observed by Schmiedl et al. (1998)in the Mediterranean.

6. Conclusions

We have reconstructed environmental changesduring OAE 1b on the base of benthic foraminif-eral distributions and lithologies in three sites. Al-though all the three sites are characterized by faunaland sedimentological differences, five ecological in-tervals can be described on the base of which wecorrelated the sections.

Mesotrophic to eutrophic conditions characterizethe interval preceding the OAE, which is indicatedby high abundances of shallow infaunal benthic for-aminifers and a rise of δ13C values. This first in-terval is succeeded by Interval II with abundantopportunistic infaunal and epifaunal species and in-distinctly to distinctly laminated black shales, indi-cating eutrophic, dysoxic to anoxic conditions. Arepopulation event, showing opportunistic infaunaland epifaunal benthic foraminifers can be observed


in all three sections and represents a reoxygena-tion event of the sea floor. This repopulation event,however, is followed by eutrophic, anoxic conditionswith very rare benthic foraminifers (Interval IV).Interval V commences immediately above OAE 1band is characterized by a gradual repopulation ofthe sea floor, starting with opportunistic taxa in thebathyal sections. Repopulation occurs rapidly in theshallow settings and gradually in the basin, wherea normal diverse pre-event fauna was established afew tens of thousands of years after OAE 1b. Thefactors controlling this set of intervals are believedto be an increased oceanic productivity paralleled orcaused by a relative sea-level rise and global warm-ing (e.g. Jenkyns, 1997), which led to an increasedflux of organic matter to the sea floor and subsequentbottom-water dysoxic to anoxic conditions. Factorsinterrupting and terminating the OAE scenario mightbe stagnation of the sea level paralleled by cooling,which is probably caused by a decrease of CO2 in theatmosphere due to the storage of large amounts ofcarbon in the black shales (compare with Erbacheret al., 1996; Jenkyns, 1997; Weissert et al., 1998;Kuypers et al., 1999).

Acknowledgements

We thank Wolfgang Kuhnt (Kiel), Paul A. Wilson(Cambridge), Jens O. Herrle (Tubingen) and the en-tire Shipboard Scientific Party of ODP Leg 171B forfruitful discussions and comments on earlier versionsof this paper. Raffaela B. Palliani and an anonymousreviewer provided us with valuable hints and com-ments. Dick Norris (Woods Hole) kindly providedcarbon isotope data. Statistical calculations were car-ried out by and discussed with Gerhard Schmiedl(Tubingen). Thanks also to Walter Hale and AxelWulbers (ODP-Core Repository, Bremen) for pro-viding ODP samples. Martina Schmidtke (Hannover)and Karen Klose (Tubingen) are thanked for tech-nical assistance. This research was supported by theDeutsche Forschungs Gemeinschaft (‘SFB 275, TPA4’ and ‘Schwerpunktprogramm ODP=DSDP’).

Appendix A. Taxonomic reference list

See Weidich (1990), Meyn and Vespermann (1994) and Hol-bourn and Kaminski (1997) for a fuller description and syn-onymy of the listed taxa (except as noted).

Ammobaculites spp.Ammodiscus cretaceus (Reuss) Tappan 1962Ammodiscus infimus Franke 1936Astacolus sp.

Buliminids:Neobulimina sp.Praebulimina elata Magniez-Jannin 1975 (this paper:

Plate 1, 10)

Citharina sp.Clavulinoides gaultinus (Morozova) Noth 1951Conorotalites bartensteini (Bettenstaedt) Loeblich and Tappan

1987Conorotalites sp.Discorbis sp.?Dorothia filiformis (Berthelin) Risch 1971Dorothia gradata (Berthelin) Risch 1971Dorothia levis Magniez-Jannin 1975Dorothia sp.

Falsogaudryinella sp.Frondicularia sp.Fursenkoina viscida (Khan) Revets 1996 (this paper: Plate 1, 1,

6 and 9)Gaudryina dividens Grabert 1959

Gavelinella spp. group:Following Michael (1966) and Weidich (1990) gavelinellids are

subdivided into three different morphogroups. These are:Gavelinella ammonoides (Reuss) Gavelinella intermedia (Ber-

thelin)Gavelinella berthelini (Keller)Globulina spp.=Lagena spp. group:Globulina prisca Reuss 1863Lagena globosa (Montagu) Bartenstein und Brand 1951Lagena sulcata (Walker and Jacob) Michael 1967

Glomospira spp. group:Glomospira charoides (Jones and Parker) Weidich 1990Glomospira irregularis (Grzybowski) Bartenstein 1954Glomospira gordialis (Jones and Parker) Bartenstein and Brand

1951

Gyroidinoides nitidus=Valvulineria spp. group:Gyroidinoides nitidus (Reuss) (in this paper: Plate 1, 1, 1 and

2); see Revets (1996) for a comprehensive description andsynonymy

Valvulineria infracretacea (Morozova) Weidich 1990Valvulineria parva Khan 1950

Haplophragmoides spp.Hemirobulina sp.Hippocrepina sp.


Hormosina sp.Hyperammina sp.

Laevidentalina spp. groupLaevidentalina deflexa (Reuss) Meyn and Vespermann 1994Laevidentalina linearis (Roemer) Meyn and Vespermann 1994X xiphoides (Reuss) Meyn and Vespermann 1994

Lenticulina muensteri (Roemer) Jendryka-Fuglewicz 1975Lenticulina pulchella (Reuss) Jendryka-Fuglewicz 1975Lenticulina saxocretacea Bartenstein 1954Lingulina loryi (Berthelin) Bartenstein, Bettenstaedt and Bolli

1966

Marginulina spp.=Marginulinopsis spp. group:Marginulina acuticosta Reuss 1863Marginulinopsis jonesi (Reuss) Bartenstein and Brand 1951Marginulinopsis robusta (Reuss) Bartenstein and Brand 1951

Nodosaria sp.Orbitulinopsis sp.Orthokarstenia shastaensis Dailey 1970Osangularia schloenbachi (Reuss 1863) Crittenden 1983 (this

paper: Plate 1, 1, 4 and 5)Planularia sp.

Pleurostomella spp. group:Pleurostomella prima Bettenstaedt and Spiegler 1982, see Bet-

tenstaedt and Spiegler (1982) for a full description.Pleurostomella subfiliformis Bettenstaedt and Spiegler 1982, see

Bettenstaedt and Spiegler (1982) for a full description.Psammosphaera sp.Pseudobolivina variabilis Vasicek 1947 (this paper: Plate 1, 1,

11) see Coccioni et al., 1995 for a fuller description.Pseudonodosaria humilis (Roemer) Neagu 1975Psilocitharella spp.=Brunsvigella spp. group:Psilocitharella kochii (Roemer) Meyn and Vespermann 1994Psilocitharella recta (Reuss) Meyn and Vespermann 1994Brunsvigella angustissima (Reuss) Meyn and Vespermann 1994

Plate 1

1 and 2. Gyroidinoides nitidus (Sample 1049A, 20X-2, 36–40cm, scale bar D 200 µm)

3. Trochammina sp. (Sample Pal Paq 31, scale bar D 150µm)

4 and 5. Osangularia schloenbachi (Sample 1049C, 12X-3,67–69 cm, scale bar D 250 µm)

6 and 9. Fursenkoina viscida (Sample 1049C, 12X-3, 84–86cm, scale bar D 100 µm)

7 and 8. Pleurostomella prima (7: Sample Pal Paq 31, scale barD 250 µm; 8: Sample 1049C, 12X-3, 47–48 cm, scalebar D 100 µm)

10. Praebulimina elata (Sample 1049C, 12X-3, 84–86 cm,scale bar D 100 µm)

11. Pseudobolivina variabilis (Sample Pal Paq 27, scalebar D 150 µm)

Pyramidulina spp. group:Pyramidulina sceptrum (Reuss) Meyn and Vespermann 1994Pyramidulina lamellosocostata (Reuss) Meyn and Vespermann

1994

Ramulina spp.Rhabdammina sp.Rheophax sp.Rhizammina sp.Saccammina sp.Saracenaria sp.Spiroplectinata annectens (Parker and Jones) Cushman 1937Spiroplectinella gandolfii (Carbonnier) Haig 1992Textularia sp.Tristix excavata (Reuss) Magniez-Jannin 1975Tritaxia pyramidata Reuss 1863Trochammina sp.Verneuilinoides neocomiensis (Mjatliuk) Kuznetsova 1974

References

Altenbach, A.V., Sarnthein, M., 1989. Productivity record inbenthic foraminifera. In: Berger, W.H., Smetacek, V.S., Wefer,G. (Eds.), Productivity of the Ocean: Present and Past. Wiley,Chichester, pp. 255–269.

Arnaud, H., Lemoine, M., 1993. Structure and Mesozoic–Cenozoic evolution of the South-East France Basin (SFB).Geol. Alpine, Ser. Spec. Colloq. Excursions 3, 3–58.

Arthur, M.A., Brumsack, H.-J., Jenkyns, H.C., Schlanger, S.O.,1990. Stratigraphy, geochemistry, and paleoceanography of or-ganic carbon-rich Cretaceous sequences. In: Ginsburg, R.N.,Beaudoin, B. (Eds.), Cretaceous Resources, Events andRhythms. Kluwer, Dordrecht, pp. 75–119.

Bernhard, J.M., 1986. Characteristic assemblages and morpholo-gies of benthic foraminifera from anoxic, organic-rich de-posits: Jurassic through Holocene. J. Foraminiferal Res. 1,207–215.

Bernhard, J.M., Sen Gupta, B.K., Borne, P.F., 1997. Benthicforaminiferal proxy to estimate dysoxic bottom-water oxygenconcentrations: Santa Barbara Basin, U.S. Pacific continentalmargin. J. Foraminiferal Res 27, 301–310.

Bettenstaedt, F., Spiegler, D., 1982. Pleurostomella (Foram.)in der Unterkreide Nordwestdeutschlands. Geol. Jahrb. A65,445–479.

Blakey, R., 1998. Sedimentation, tectonics and paleogeographyof the North Atlantic region. http:==vishnu.glg.nau.edu=rcb=nat.html

Bralower, T.J., Sliter, W.V., Arthur, M.A., Leckie, R.M., Allard,D., Schlanger, S.O., 1993. Dysoxic=anoxic episodes in theAptian–Albian (Early Cretaceous). Geophys. Monogr. 77, 5–37.

Breheret, J.G., 1983. Sur des niveaux de black shales dansl’Albien inferieur et moyen du domaine vocontien (Sud-Est dela France): etude de nannofacies et signification des paleoen-vironments. Bull. Mus. Hist. Natl. Paris 5C, 113–159.


Breheret, J.-G., 1991. Glauconitization episodes in marginal set-tings as echoes of mid-Cretaceous anoxic events in the Vocon-tian basin (SE France). In: Tyson, R.V., Pearson, T.H. (Eds.),Modern and Ancient Continental Shelf Anoxia. Geol. Soc.London Spec. Publ. 58, 415–425.

Breheret, J.-G., 1994. The Mid-Cretaceous organic-rich sedi-ments from the Vocontian Zone of the French Southeast Basin.In: Mascle, A. (Ed.), Hydrocarbon and Petroleum Geology ofFrance. Springer, Berlin, pp. 295–320.

Breheret, J.-G., 1997. L’Aptien et l’Albien de la Fosse voconti-enne (des bordures au bassin). Evolution de la sedimentationet enseignements sur les evenements anoxiques. Publ. Soc.Geol. Nord 25, 1–614.

Breheret, J.G., Caron, M., Delamette, M., 1986. Niveau richesen matiere organique dans l’Albien Vocontien; quelques car-acteres du paleoenvironment; essai d’interpretation genetiques.Doc. Bur. Rech. Geol. Min. 110, 141–191.

Coccioni, R., Galeotti, S., 1993. Orbitally induced cycles inbenthonic foraminiferal morphogroups and trophic structuredistribution from the Late ‘Amadeus Segment’ (Central Italy).J. Micropalaeontol. 12, 227–239.

Coccioni, R., Franchi, R., Nesci, O., Wezel, F.-C., Battisini, F.,Pallecchi, P., 1989. Stratigraphy and mineralogy of the Sellilevel (Early Aptian) at the base of the Marne a Fucoidi in theUmbro–Marchean Apennines (Italy). In: Wiedmann, J. (Ed.),Cretaceous of the Western Tethys. Proc. 3rd Int. CretaceousSymp., Schweizerbart, Tubingen, pp. 563–584.

Coccioni, R., Erba, E., Premoli Silva, I., 1992. Barremian–Aptian calcareous plankton biostratigraphy from the GorgoCerbara section (Marche, central Italy) and implications forplankton evolution. Cretaceous Res. 13, 517–537.

Coccioni, R., Galeotti, S., Gravili, M., 1995. Latest Albian–earliest Turonian deep-water agglutinated foraminifera in theBottacione section (Gubbio, Italy) — biostratigraphic andpalaeoecologic implications. Rev. Esp. Paleontol., no. home-naje al Dr. Guillermo Colom, pp. 135–152.

Corliss, B.H., Chen, C., 1988. Morphotype patterns of Norwe-gian Sea deep-sea benthic foraminifera and ecological impli-cations. Geology 16, 716–719.

Crumiere, J.-P., Crumiere-Airaud, C., Espitalie, J., Cotillon,P., 1990. Global and regional controls on potential source-rock deposition and preservation: the Cenomanian–Turonianoceanic anoxic event (CTOAE) on the European Tethyan mar-gin (southeastern France). Am. Assoc. Pet. Geol. Stud. Geol.30, 107–118.

Erba, E., Premoli Silva, I., 1994. Orbitally driven cycles in trace-fossil distribution from the Piobbico core (late Albian, centralItaly). In: de Boer, P.L., Smith, D.G. (Eds.), Orbital Forcingand Cyclic Sequences. Spec. Publ. Int. Assoc. Sedimentol. 19,211–225.

Erbacher, J., 1994. Entwicklung und Palaoozeanographie mit-telkretazischer Radiolarien der westlichen Tethys (Italien) unddes Nordatlantiks. Tubinger Mikropalaontol. Mitt. 12, 1–120.

Erbacher, J., Thurow, J., 1997. Influence of Oceanic AnoxicEvents on the evolution of mid-Cretaceous radiolaria in theNorth Atlantic and western Tethys. Mar. Micropalaeontol. 30,139–158.

Erbacher, J., Thurow, J., Littke, R., 1996. Evolution patterns ofradiolaria and organic matter variations — a new approach toidentify sea-level changes in mid-Cretaceous pelagic environ-ments. Geology 24, 499–502.

Erbacher, J., Gerth, W., Schmiedl, G., Hemleben, Ch., 1998.Benthic foraminiferal assemblages of late Aptian–early Albianblack shale intervals from the Vocontian Basin, SE France.Cretaceous Res. 19, 805–826.

Fries, G., 1984. Les gres de Rosans et slumpings aptiens asso-cies: restitution paleomorphologique. Bull. Soc. Geol. Fr. 26,693–702.

Gale, A.S., Jenkyns, H.C., Kennedy, W.J., Corfield, R.M., 1993.Chemostratigraphy versus biostratigraphy: data from aroundthe Cenomanian–Turonian boundary. J. Geol. Soc. London150, 29–32.

Gradstein, F.M., Agterberg, F.P., Ogg, J.G., Hardenbol, J., VanVeen, P., Thierry, J., Hang, Z., 1995. Jurassic and Cretaceoustime scale. Soc. Econ. Paleontol. Mineral., Spec. Publ. 54,95–126.

Grotsch, J., Billing, I., Vahrenkamp, V., 1998. Carbon-isotopestratigraphy in shallow-water carbonates: implications for Cre-taceous black-shale deposition. Sedimentology 45, 623–634.

Hart, M., Amedro, F., Owen, H., 1996. The Albian stage andsubstage boundaries. Bull. Inst. R. Sci. Nat. Belg. 66 (Suppl.),45–56.

Hasegawa, T., 1997. Cenomanian–Turonian carbon isotopeevents recorded in terrestrial organic matter from northernJapan. Palaeogeogr., Palaeoclimatol., Palaeoecol. 130, 251–273.

Herbert, T.D., Fischer, A.G., 1986. Milankovitch climatic originof mid-Cretaceous black shale rhythms in central Italy. Nature321, 739–743.

Holbourn, A.E.L., Kaminski, M.A., 1997. Lower Cretaceousdeep-water benthic foraminifera of the India Ocean. Grzy-bowski Found. Spec. Publ. 4, 1–172.

Holbourn, A.E.L., Kuhnt, W., El Albani, A., Ly, A., Gomez, R.,Herbin, J.P., 1999. Palaeoenvironments and palaeobiogeogra-phy of the Late Cretaceous Casamance transect (Senegal, NWAfrica): distribution patterns of benthic foraminifera, organiccarbon and terrigenous flux. Neues Jahrb. Geol. Palaontol.Abh. 212, 335–377.

Jarvis, I., Carson, G.A., Cooper, M.K.E., Hart, M.B., Leary, P.N.,Tocher, B.A., Horne, D., Rosenfeld, A., 1988. Microfossilassemblages and the Cenomanian–Turonian (late Cretaceous)oceanic anoxic event. Cretaceous Res. 9, 3–103.

Jenkyns, H.C., 1995. Carbon-isotope stratigraphy and paleo-ceanographic significance of the Lower Cretaceous shallow-water carbonates of Resolution Guyot, Mid-Pacific Mountains.Proc. ODP, Sci. Results 143, 99–104.

Jenkyns, H.C., 1997. Mesozoic anoxic events and palaeoclimate.Zbl. Geol. Palaontol. I, 7–9, 943–949.

Jenkyns, H.C., Gale, A.S., Corfield, R.M., 1994. Carbon- andoxygen-isotope stratigraphy of the English Chalk and ItalianScaglia and its paleoclimatic significance. Geol. Mag. 131,1–34.

Jorissen, F.J., De Stigter, H.C., Widmark, J.G.V., 1995. A con-


ceptual model explaining benthic foraminiferal microhabitats.Mar. Micropaleontol. 26, 3–15.

Kaiho, K., Hasegawa, T., 1994. End-Cenomanian benthic fo-raminiferal extinctions and oceanic dysoxic events in thenorthwestern Pacific Ocean. Palaeogeogr., Palaeoclimatol.,Palaeoecol. 111, 29–43.

Koutsoukos, E.A.M., Hart, M.B., 1990. Cretaceous foraminif-eral morphogroup distribution patterns, palaeocommunitiesand trophic structures: a case study from the Sergipe Basin,Brazil. Trans. R. Soc. Edinburgh: Earth Sci. 81, 221–246.

Koutsoukos, E.A.M., Leary, P.M., Hart, M.B., 1990. Lat-est Cenomanian–earliest Turonian low-oxygen tolerant ben-thonic foraminifera: a case-study from the Sergipe basin (NEBrazil) and the western Anglo–Paris basin (southern England).Palaeogeogr., Palaeoclimatol., Palaeoecol. 77, 145–177.

Kuhnt, W., 1992. Abyssal recolonization by benthic foraminiferaafter the Cenomanian=Turonian boundary anoxic event in theNorth Atlantic. Mar. Micropaleontol. 19, 257–274.

Kuhnt, W., Kaminski, M.A., 1990. Paleoecology of Late Creta-ceous to Paleocene deep-water agglutinated foraminifera fromthe North Atlantic and western Tethys. In: Hemleben, Ch.,Kaminski, M.A., Kuhnt, W., Scott, D.B. (Eds.), Paleoecology,Biostratigraphy, Paleoceanography and Taxonomy of Aggluti-nated Foraminifera. NATO Advanced Sci. Ser., Ser. C, Math.Phys. Sci. 327, Kluwer, Dordrecht, pp. 433–505.

Kuhnt, W., Wiedmann, J., 1995. Cenomanian–Turonian sourcerocks: paleobiogeographic and paleoenvironmental aspects. In:Huc, A.-Y. (Ed.), Paleogeography, Paleoclimate and SourceRocks. Am. Assoc. Pet. Geol. Stud. Geol. 40, 213–231.

Kuhnt, W., Moullade, M., Kaminski, M.A., 1996a. Cretaceouspalaeoceanographic events and abyssal agglutinated foraminif-era. In: Moguilevsky, A., Whatley, R. (Eds.), Microfossils anOceanic Environments. Aberystwyth Press, Aberystwyth, pp.63–75.

Kuhnt, W., Moullade, M., Kaminski, M.A., 1996b. Ecologicalstructuring and evolution of deep sea agglutinated foraminifera— a review. Rev. Micropaleontol. 39, 271–281.

Kuypers, M.M., Pancost, R.D., Sinninghe Damste, J.S., 1999.A large and abrupt fall in atmospheric CO2 concentrationsduring Cretaceous times. Nature 399, 342–345.

Linke, P., Lutze, G.F., 1993. Microhabitat preferences of benthicforaminifera — a static concept or a dynamic adaptation tooptimize food acquisition. Mar. Micropaleontol. 20, 215–234.

Mackensen, A., Douglas, R.G., 1989. Down-core distributionof live and dead deep-water benthic foraminifera in box coresfrom the Wedell Sea and the California continental borderland.Deep-Sea Res. 36, 879–900.

Menegatti, A.P., Weissert, H., Brown, R.S., Tyson, R.V., Farri-mond, P., Strasser, A., Caron, M., 1998. High-resolution δ13Cstratigraphy through the early Aptian ‘Livello Selli’ of theAlpine Tethys. Paleoceanography 13, 530–545.

Meyn, H., Vespermann, J., 1994. Taxonomische Revisionvon Foraminiferen der Unterkreide SE-Niedersachsens nachRomer (1839, 1841, 1842), Koch (1851) und Reuss (1863).Senckenbergiana Lethaea 74, 49–272.

Michael, E., 1966. Die Evolution der Gavelinelliden (Foram.)

der NW-deutschen Unterkreide. Senckenbergiana Lethaea 47,411–460.

Murray, J.W., 1991. Ecology and Palaeoecology of Benthic Fo-raminifera. Longman, Harlow.

Nagy, J., Gradstein, F.M., Kaminski, M.A., Holbourn, A.E.,1995. Foraminiferal morphogroups, paleoenvironments andnew taxa from Jurassic to Cretaceous strata of Thakkola,Nepal. Gryzybowski Found. Spec. Publ. 3, 181–209.

Norris, R.D., Wilson, P.A., 1998. Low-latitude sea-surface tem-peratures for the mid-Cretaceous and the evolution of plankticforaminifera. Geology 26, 823–826.

Premoli Silva, I., Sliter, W.V., 1994. Cretaceous planktonic fo-raminiferal biostratigraphy and evolutionary trends from theBottacione section, Gubbio, Italy. Paleontogr. Ital. 81, 2–90.

Revets, S.A., 1996. The generic revision of five families ofrotaliine foraminifera, II. The Anomalinidae, Alabaminidae,Cancrisidae and Gavelinidae. Cushman Found. ForaminiferalRes. Spec. Publ. 32, 57–113.

Schlanger, S.O., Jenkyns, H.C., 1976. Cretaceous anoxic events:causes and consequences. Geol. Mijnbouw 55, 79–184.

Schmiedl, G., Mackensen, A., 1997. Late Quaternary paleo-productivity and deep water circulation in the eastern SouthAtlantic Ocean: evidence from benthic foraminifera. Palaeo-geogr., Palaeoclimatol., Palaeoecol. 130, 43–80.

Schmiedl, G., Hemleben, C., Keller, J., Segl, M., 1998. Impactof climatic changes on the benthic foraminiferal fauna in theIonian Sea during the last 330,000 years. Paleoceanography13, 447–458.

Schulz, H., von Rad, U., Erlenkeuser, H., 1998. Correlationbetween Arabian Sea and Greenland climate oscillations ofthe past 110,000 years. Nature 393, 54–57.

Shipboard Scientific Party, 1998. Site 1049. Proc. ODP, Init. Rep.171B, 47–92.

Sinninghe Damaste, J.S., Koster, J., 1998. A euxinic south-ern North Atlantic Ocean during the Cenomanian=Turonianoceanic anoxic event. Earth Planet. Sci. Lett. 158, 165–173.

Stein, R., Rullkotter, J., Welte, D.H., 1989. Changes in pale-oenvironments in the Atlantic Ocean during Cretaceous times:results from black shale studies. Geol. Rundsch. 78, 883–901.

Thomson, J., Mercone, D., de Lange, G.J., van Santvoort, P.J.M.,1999. Review of recent advances in the interpretation of east-ern Mediterranean sapropel S1 from geochemical evidence.Mar. Geol. 153, 77–89.

Thurow, J., Brumsack, H.-J., Rullkotter, J., Meyers, P., 1992. TheCenomanian=Turonian boundary event in the Indian Ocean —a key to understand the global picture. Geophys. Monogr. 70,253–273.

Tribovillard, N.-P., Gorin, G.E., 1991. Organic facies of theEarly Albian Niveau Paquier, a key black shale horizon of theMarnes Bleues Formation in the Vocontian Trough (SubalpineRanges, SE France). Palaeogeogr., Palaeoclimatol., Palaeoecol.85, 227–237.

Tyszka, J., Kaminski, M.A., 1995. Factors controlling the dis-tribution of agglutinated foraminifera in Aalenian–Bajociandysoxic facies (Pienny Klippen Belt, Poland). GrzybowskiFound. Spec. Publ. 3, 271–291.

Vink, A., 1995. Biostratigraphy and Palaeoenvironmental Mod-


elling of the Latest Aptian to Middle Albian in the VocontianBasin (SE France); a Palynological Approach with Emphasison Dinoflagellate Cysts. Master Thesis, University of Utrecht,Utrecht, 44 pp.

Weidich, K.F., 1990. Die kalkalpine Unterkreide und ihreForaminiferenfauna. Zitteliana 17, 3–312.

Weissert, H., Breheret, J.-G., 1991. A carbonate carbon-isotope

record from Aptian–Albian sediments of the Vocontian trough(SE France). Bull. Soc. Geol. Fr. 162, 1133–1140.

Weissert, H., Lini, A., Follmi, K.B., Kuhn, O., 1998. Correlationof Early Cretaceous carbon isotope stratigraphy and platformdrowning events: a possible link? Palaeogeogr., Palaeoclima-tol., Palaeoecol. 137, 189–203.

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