Journal of South American Earth Sciences, Vol. 4, No. I/2, pp. 99-117, 1991 Printed in Great Britain

0895-9811/91 $3.00 + 0.00 © 1991 Pergamon Press pie

& Earth Sciences & Resources Institute

Stratigraphy and paleontology of Campanian and Eocene sediments, Cockburn Island,

Antarctic Peninsula R. A. ASKIN I, D. H. ELLIOT 2, J. D. STILWELL 3, and W. J. ZINSMEISTER 4

1 . . . . . . . 2 Department of Earth Sclences, Umvermty of Califorma, Rwermde, CA 92521 USA; Byrd Polar Research Center, The Ohio State University, Columbus, OH 43210 USA; 3Department of Geology, University of

Otago, Box 56, Dunedin, New Zealand; 4Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, IN 47906 USA

(received July 1990; accepted January 1991 )

Abs t rac t - -Approx ima te ly 150 meters of fine-grained Campanian sediments and over 100 meters of fine- to medium-grained Eocene sands underlie Pliocene basal ts and conglomerates on Cockburn Island, north- eas tern Antarct ic Peninsula. The Campanian beds are par t of the "Unnamed s t ra ta" of the Marambio Group and contain inver tebrate and palynomorph fossils tha t predate the adjacent Seymour Island L6pez de Berto- dano succession. Rich palynomorph floras suggest a middle Campanian age. Deposition was in low energy, shallow shelf environments. Invertebrate and palynomorph fossils, and lithology, all indicate correlation of the Eocene beds with the basal La Meseta Formation, members Telm I and lower Telm 2 of Seymour Island. The age of these beds is probably late early Eocene. The basal La Meseta sands are margina l mar ine to shallow shelf sediments tha t fill a broad valley probably incised during latest Paleocene-earliest Eocene as a resul t of toctonism and sea-level lowstands.

Resumen- -Aprox imadamen to 150 m de sedimentos campanianos de grano fino y mas de 100 m de arenas eocenas finas a medianas subyacen a basaltos pliocenos y conglomerados en la Isla Cockburn, ubicada en la porci6n nororiental de la Peninsula Ant~rtica. Las capas campanianas son parte de las "Unnamed s t r a t a ~ del Grupo Marambio, y contienen invertebrados y palinomorfos fSsiles mas antiguos que los de la sucesi6n de L6pez de Bertodano de la Isla Seymour adyacente. Las ricas floras palinomorfas sugieren una edad cam- paniana media. La sedimentaci6n tuvo lugar en un ambiente de plataforma somera y t ranqulla . Palino- morfos e invertebrados f6siles, al igual que la litologia indican una correlaci6n de las capas eocenas con la porci6n basal de la Formacibn La Meseta, miembros Telm 1 y parte inferior de Telm 2, de la Isla Seymour. La edad de estas capas es probablemente eocena temprana tard[a. Las arenas basales de La Meseta son sedi- mentos de plataforma somera a marinos marginales que rellenan un amplio valle, probablemente modelado durante el Paleoceno mas tardIo al Eoceno mas temprano, como resultado de tectonismo y condiciones eustAticas de nivel de mar bajo.

INTRODUCTION

CRETACEOUS and Tertiary sedimentary s t ra ta and basalt flows are exposed on Cockburn Island, which lies between Seymour and James Ross Islands in the northwestern Weddell Sea near the tip of the Ant- arctic Peninsula (Figs. 1 and 2). Lower Cretaceous (Barremian) to Eocene sediments (Table 1) were deposited in the J ames Ross Basin (Elliot, 1988; Larsen Basin of McDonald et al., 1988}. Lower Creta- ceous rocks occur in the northwest part of the basin, adjacent to the Antarctic Peninsula. Upper Cretace- ous beds crop out on James Ross and adjacent islands, and Tert iary strata are known only from Seymour and Cockburn Islands. Recent work on Seymour Is- land (in Feldmann and Woodburne, 1988} reported rich fossil faunas and floras, and established a stra- t ig raph ic f r amework for Campan ian to Eocene sequences. At least two major episodes of valley cut- ting on the early Tert iary continental shelf separate

Address all correspondence and repr int requests to: Dr. Rose- mary Askin, Dept. of Ear th Sciences, University of California, Riverside, CA 92521-0423 (Telephone: 714-787-3434; Fax: 714- 787-4324).

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Marambio Group (Upper Cretaceous-Lower Tertiary,I

[ ] Gustav Group 0 km 25 (Lower-Upper Cretaceous)

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Fig. 1. Location and geologic map for J ames Ross Island region.

99

100 R. A. ASKIN, D. H. ELLIOT, d. D. STILWELL, and W. J. ZINSMEISTER I6 T 56o' 5w K Seymour Island

Table 1. S t r a t i g r a p h y of the J a m e s Ross Ba s in .

Group Formation Age

La Meseta Early-late Eocene Cross Valley ?Late Paleocene "Wiman" Late Paleocene

Marambio Sobral Paleocene L6pez de Bertodano Late Campanian--early Paleoeene "Unnamed strata" Campanian Santa Marta Santonian-Campanian

Gustav Hidden L a k e ?Coniacian-Santonian Whiskey Bay Albian-Coniacian Kotiek Point Aptian-Albian Lagrelius Point ?Barremian-Aptian

Nordenskjold Kimmeridgian-Tithonian

(after Elliot, 1988; with '%Viman Formation" from Elliot and Hoffman, 1989)

Seymour Island

[ J Surficial deposits

La Meseta Formation

[ ~ Cross Valley Formation

Wiman Formation

~ J Sobral Formation

~ ] Lopez de Bertodano Formation Dike

Cockburn Island

James Ross Island Volcanic Group

La Meseta Formation

~ Cretaceous strata

Base of measured 1t" sections

T Tertiary

K Cretaceous

Fig. 2. Location and geologic map of Cockburn and S e y m o u r islands. Note tha t the distr ibut ion of Ter t iary beds on Cockburn Island is uncertain, except near the measured section.

Eocene, and late Paleocene, from older Paleocene- Cretaceous strata on Seymour Island. Similar rela- tions exist on Cockburn Island.

In addition, a thin package of upper Pliocene sediments (Pecten Conglomerate) is preserved on a prominent erosional bench in Pliocene basalts tha t overlie the older strata on Cockburn Island (Soot- Ryen, 1952; Zinsmeister and Webb, 1982; Webb and Andreasen, 1986). The Pliocene beds are not dis- cussed here.

In this paper we summarize the l i thostrat igra- phy, paleontology, and age interpretations of the Cre- taceous and Paleogene beds on Cockburn Island, and suggest correlations with Seymour Island.

Fig. 3. Cockburn Island, viewed from the nor thern end of the meseta on Seymour Island. J a m e s Ross Is land is in the background. Section localities are marked by a r rows (K = Cretaceous section, CI; T = Tert iary section A, 87/10).

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 101

P R E V I O U S WORK

Cockburn Island was first visited on January 6, 1843, during the voyage of Sir J ames Clark Ross around Antarctica. Ross and others landed on the island and collected a few samples, which were not described until late in the century (Prior, 1899). Their basalt , basal t ic glass, and calcareous glau- conitic sandstone samples could be from either out- crop or float, but the two granite samples must be glacial erratics.

The island was visited next by members of Otto Nordenskj61d's Swedish South Polar Expedition of 1901-1903 (NordenskjSld, 1905; reviewed by Zins- meister, 1988). During a brief visit between Novem- ber 21 and 25, 1902, they collected some "volcanic tuff" but did not recognize the presence of sedimen- tary strata that form most of the island. However, none of the group was a trained scientist and doubt- less the volcanic cone-like form of the island (Fig. 3) and volcanic debris blanketing the slopes contributed to the oversight. J. Gunnar Andersson, who had joined NordenskjSld on October 12, 1903, returned to the island on October 21-23 and collected fossils from the Cretaceous beds, the glauconitic sands at the base of the Tert iary sequence, and the Plio-Pleistocene Pecten Conglomerate. Buckman (1910) described the early Tert iary brachiopod fossils and Wilckens (1924) the other fossil groups.

More than 40 years passed before the next visit in 1946 by W. N. Croft of the Falklands Islands Depen- dencies Survey (now the British Antarctic Survey; Adie, 1958; Bibby, 1966). After establishment of the Argentine base on Seymour Island in 1969, several brief visits were made by members of the Instituto Antartico Argentino. Prior to our visit in January, 1987 (Elliot and Rieske, 1987; Stilwell and Zins- meister, 1987), the only landing by U.S. scientists was in 1982 (Zinsmeister and Webb, 1982).

S T R A T I G R A P H Y

In this paper we use the stratigraphic framework of Ineson et al. (1986), modified in part by Olivero et aI. (1986) and summarized in Elliot (1988), in which the Marambio Group is subdivided into four units (Table 1): the Santa Marta Formation (oldest), "Un- named s t ra ta" [part of Bibby's (1966) Snow Hill Island Series], L5pez de Bertodano Formation, and Sobral Formation. The LSpez de Bertodano and Sebral Formations are currently restr icted to Sey- mour Island, sensu Rinaldi et al. (1978). Ineson et al. (1986) used the term "Unnamed strata" for the lower part of the Marambio Group because that part of the section was poorly known and they anticipated fur- ther fieldwork would lead to additional subdivision. This is the case for the oldest Marambio Group beds from northern James Ross Island, described as the Santa Marta Formation (Olivero et al.,1986). Re- maining "Unnamed strata" include predominantly fine-grained, relat ively well-bedded sediments ex-

posed at various locations on eastern and southern James Ross Island and Vega, Humps, Snow Hill, and Cockburn Islands (see Fig. 1). Pending further in- vestigation, it is possible that some of these s t ra ta may be a s s i g n e d to the LSpez de B e r t o d a n o Formation, such as the y o u n g e r (eastern) beds of northern Snow Hill Island, as suggested by Macellari (1984a), and some of the older beds may belong to the Santa Marta Formation. Pirrie et al. (in press) show that part of the Vega Island section may correlate with the LSpez de Bertodano Formation.

The age of the "Unnamed strata" may be mis- interpreted. The inadvisability of grouping all the post-Santa Marta "Unnamed strata" into the L6pez de Bertodano Formation, as has been done by many authors, is illustrated by Pirrie and Riding's Fig. 1 and Table 1 (1988). A latest Campanian-Maastrich- tian age for all but the uppermost part of the L6pez de Bertodano Formation - - which is correct for the type locality of the LSpez on Seymour Island - - is thus incorrectly inferred for all the sedimentary outcrops on eastern and southern James Ross Island, Vega Island, Humps Island, Snow Hill Island, and Cock- burn Island. As discussed below, this conclusion is invalid.

The Marambio Group is overlain by Paleogene sediments of the "Wiman," Cross Valley, and La Meseta Formations (see Fig. 2 and Table 1}. These formations are, as yet, known only from Seymour Is- land and, in the case of La Meseta, a small exposure on Cockburn Island.

La Meseta Format ion sediments crop ou t on northern Cockburn Island, and C r e t a c e o u s "Un- named strata" occur on the flanks of the rest of the island. All these sediments are poorly consolidated, except for an occasional calcite-cemented bed. Both formations are overlain by Pliocene basaltic lavas of the James Ross Island Volcanic Group. Basalt talus obscures much of the underlying sedimentary pack- ages, which are exposed in small gulleys eroding the steep (45 ° ) slopes. This study describes beds from the south and east (Seymour) side of Cockburn Island.

The steep contact between the Cretaceous and Tertiary strata on the east side of Cockburn Island is not exposed, although in a gulley just above the shore to the north of the basalt spine, the Tert iary beds lie unconformably on the older beds. Although initially suggested as a fault contact (Elliot and Rieske, 1987), the unexposed steep ea s t e rn con tac t s e p a r a t i n g Cretaceous and Tertiary beds may also be erosional, as observed on Seymour Island. In Cross Valley on Seymour Island, La Meseta beds lap onto the older Cross Valley Formation with present dips, away from the contact, as high as 20 ° (the original depositional dip may have been over-steepened either by later slumping of soft sediment or by growth faults). The contact itself must have a dip greater than 30 °. Near Cape Wiman the contact of La Meseta on older Sobral and Wiman beds is highly irregular, locally very steep and at one place is vertical. This contact also suggests valley or canyon cutting and, at least locally, significant and steep topographic relief. The

102 R.A. ASKIN, D. H. ELLIOT, J. D. STILWELL, and W. J. ZINSMEISTER

Cross Valley and lower La Meseta beds are recog- nized as valley fill deposits (Sadler, 1988), and it is likely that the Tertiary beds on Cockburn Island also represent sediments filling a valley incised into Cre- taceous beds. The anomalously high dips of the Tert iary beds on Cockburn Island are here regarded as largely primary and the unexposed steep contact on the east side of the island as a possible uncon- formity, probably a buttress unconformity against a paleocanyon wall.

Cretaceous ~Unnamed Strata"

The Cretaceous beds, approximately 150 meters thick, dip about 6 ° to the southeast, are poorly bedded to massive, medium grey (brownish weathering}, and fine grained. In the measured section (Fig. 4), a lower 30-meter- thick clayey silt unit g rades up into a slightly coarser-grained, more lithologically varied, fossiliferous unit about 40 meters thick. This second unit includes: silty, very fine sands with res is tant sandy interbeds; indurated, calcareous clayey silt- stone interbeds up to 1 meter thick in the lower part; thin si l ty clay interbeds; and a few horizons of calcareous concretions (up to 1.5 m diameter}. The beds contain a relatively well-preserved invertebrate fauna. The upper part of the second unit is very thinly bedded, with some flaser bedding. It is over- lain by approximately 50 meters of silty, very fine sands and, in places, displays very thin bedding and flaser bedding. It grades into an upper 25 meters of sandy silts.

La Meseta Formation

The Lower Tertiary beds, more poorly exposed than the Cretaceous, have a stratigraphic thickness exceeding 100 meters. A partial section of the lower part is illustrated in Fig. 5.

Glauconitic beds were observed only in the basal 22 meters of the measured section; all other examined outcrops are grossly similar to the overlying beds in that section.

The lower 22 meters of the measured section are predominant ly glauconitic sands and sandstones. The loose glauconitic sands occur as beds 10-20 cm thick and contain clay-rich layers. The more lithified sandstones are each less than 1 meter thick, with widely varying glauconite content and common clay- rich stringers. These sandstone beds are weakly stratified and the upper one is flaggy.

The beds lose most of the glauconite within a few meters above the basal 22 meters, and thereaf ter consist of medium- to fine-grained sands alternating with muddy beds (Fig. 6}. These beds continue to the overlying basalt contact. The sands, dominantly grey to greenish grey, form beds up to 20 cm thick and carry sparse concretions; clay wisps and laminae are common in the thicker beds. Cleaner, pale-colored

Fig. 4. Stratigraphic column for the Carnpanian beds, section CI.

sample meter no.

- 25

14o - 2 4

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- 2 0

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- 1 8

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• . : . : . : . : . . : . : . . . : . : f ine s a n d ( s t o n e )

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G~ a m m o n i t e s

b i v a l v e s

g a s t r o p o d s

<~ e c h i n o i d s

r o t u l a r i d s

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 103

meters sample n o ,

30

20

10

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_ - : - : -

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medium to fine grained sand(stone)

G glauconite

Fossils (molluscs, brachiopods, bryozoa)

sands with lesser amounts of clay occur sporadically and have similar thicknesses. The chocolate-brown muddy beds range up to 15 cm thick. In places, the mud layers and laminae are sl ightly l i thified and form shale-like flakes and splinters.

The lower glauconitic sandstones exhibit ripple drift cross-lamination (Fig. 7), but no other structures were observed. Sedimentary structures in the overly- ing thin- to medium-bedded s t ra ta are re la t ive ly uncommon. Ripple drift cross-lamination with mud drapes occurs in most thicker sands (Fig. 8) and fiaser bedding is also present (Fig. 9). Load casts and flame structures are present at the base of a few beds. Small-scale penecontemporaneous faulting is evident in a few sands.

These thin-bedded strata show broad scour and fill s t ructures that cut down several meters into underlying beds (Fig. 10). Individual beds pinch out on the flanks of the scour. Slumping of sediment in one scour has produced a recumbent fold (Fig. I l L Sediment filling scours is the same as that forming scour walls. Scours are stacked on each other (Fig. 12), which leads to widely divergent attitudes. The scour surfaces, where examined, are sharp and lack any lag deposit. The scours are interpreted as the resul t of s lumping or mass movemen t of wa te r - saturated sands and muds.

Based on lithology and fossil content, these beds bear a close resemblance to, and are interpreted as a more proximal correlative of, Members Telm 1 (in the Cross Valley area) and Telm 2 (Sadler, 1988} of the La Meseta Formation, Seymour Island.

I N V E R T E B R A T E P A L E O N T O L O G Y

Cretaceous Fauna

Most of the invertebrate fossils occur in calcare- ous, fine sandstone beds, particularly in the second unit of the "Unnamed s t ra ta ," though some o c c u r

scattered throughout the rest of the section. They include the ammonites Diplomoceras lambi Spath, Gunnarites cf. antarcticus (Stuart Weller), Maorites sp., and PseudophyUites loryi (Kilian and Reboul); t h e

serpulid Rotularia cf.fallax (Wilckens); the bivalves Pinna cf. anderssoni Wilckens, the oyster Pycnodonte (Phygraea) cf. vesiculosa (sewerby), and Entolium sp., Panopea sp., Malletia sp., Lucina sp., Seymourtula antarctica (Wilckens); the gastropods "Cassidaria" sp., "Eunaticina" sp., and a pyramidellid?; excellently preserved specimens of the lobster Hoploparia stokesi (Weller) (discussed by Feldmann and Tshudy, 1989} in small concretions; crinoid fragments; corals; an

Fig. 5. Stratigraphic columns for the Eocene beds, composite section 87/10. Column A represents the lower 50 meters of the exposed section. Column B was measured about 100 meters south of column A; the lithology is the same as the upper part of column A and is likely to be slightly higher stratigraphicaUy, although the talus slopes and scour-and-fill structures make correlation of strata impossible.

104 R.A. ASKIN, D. H. ELLIOT, J. D. STILWELL, and W. J. ZINSMEISTER

Fig. 6. Alternating thin- to medium-bedded dark clay-rich silty sands and light, medium-grained sands, La Meseta Formation. Hammer at right for scale.

Fig. 7. Ripple cross-lamination in weakly lithified glauconitie sand, La Meseta Formation. Second resistant sand unit in column A, Fig. 5.

i r r egu l a r echinoid and spines; and fish scales. Bibby (1966) ea r l i e r repor ted Gunnarites antarcticus, Pinna sp., Pecten sp., and LahiUia sp. in these beds.

Al though the inve r t eb ra te fauna is sparse, it is c l e a r l y d i s t inc t f rom the f aunas of the L6pez de Ber todano Format ion on Seymour Island. The ab- sence of any of the age-res t r ic ted la tes t Campanian- Maas t r i ch t i an ammoni te s of Seymour Island, and the presence of Gunnarites cf. antarcticus, known f rom Snow Hi l l I s l a nd , s u g g e s t s t h a t t he s t r a t a on Cockburn Island are older than the Seymour Island

Cretaceous beds. The only species of Gunnarites on S e y m o u r Is land is G. bhavaniformis ( K i l i a n a n d Reboul), res t r ic ted to the lowermost beds (locali ty 1, Uni t 1; Macellari , 1986). The am m o n i t e D. lambi is also res t r ic ted to Campan ian lower beds on S e y m o u r Island, and occurs on Snow Hill and adjacent islands; younger specimens are now separa ted as D. rnaximus (Olivero and Z insme i s t e r , 1989). P. loryi r a n g e s through the Campan ian and Maas t r i ch t ian , and the presence of Hoploparia stokesi c a n n o t be used for precise b ios t ra t ig raphy because it is long r ang ing

Fig. 8. Cross-lamination, with weakly developed climbing rip- plea, in non-glauconitic sand; mud laminae and drapes are pre- sent in the ripple troughs and on the crests, La Meseta Formation. Upper part of column B, Fig. 5.

Fig. 9. Dark clay-rich silty sand and flaser-bedded medium- grained sand, La Meseta Formation. Upper part of column A, Fig. 5.

C a m p a n i a n and E o c e n e s t r a t i g r a p h y and p a l e o n t o l o g y on C o c k b u r n I s l and , A n t a r c t i c P e n i n s u l a 105

Fig. 10. Scour-and-fill structure in upper non-glauconitic part of La Meseta section. Thicker, cleaner, pale-colored sand beds are interspersed in alternating sands and muddy beds. The base of a scour is marked by dots. Arrow indicates location of slump fold illustrated in Fig. 11. Lower part of column B, Fig. 5.

Fig. 11. Recumbent fold formed by slumping of water-saturated, thin-bedded muddy strata, La Meseta Formation. Location indicated in Fig. 10 by arrow. Lower part of column B, Fig. 5.

Fig. 12. Stacked scour-and-fill structures, marked by white squares, in non-glauconitic strata, showing divergent attitudes of beds. Adjacent to location of column B, La Meseta Formation.

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Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 107

PALYNOLOGY morphs. Palynomorphs were less abundant in some sandier samples. Palynomorph preservation varies

General from good to fair. Spores and pollen are yellow to yellow orange and are not significantly darker in

Thirty nine (39) samples from Cockburn Island samples immediately underlying the basalt. The were studied for palynomorphs. These include 25 predominant organic matter is woody vitrinitic Cretaceous samples collected at 6-meter intervals in material. Inertinite (inert or oxidized organic mat- a section (CI) measured by F. C. Barbis, T. R. Kelley, tar) fluctuates in abundance, being notably the most and J. D. Stilwell on the south side of the island (see abundant maceral type in sample CI-9A, a resistant Figs. 2, 3, and 4), and 14 Tertiary samples (see Figs. sand and the most weathered of the sample set. 2, 3, and 5) collected by D. H. Elliot and D. E. Rieske Minor to rare dispersed plant cuticle occurs in some from a composite section (87/10) on the northeastern samples, including some moderately large (-500 pro) side of the island• cuticle fragments.

The samples were processed using standard paly- Marine palynomorph assemblages (listed in nologic techniques, including mild oxidation in warm Table 2) are dominated by Isabelidinium cretaceum nitric acid, heavy liquid separation (with ZnCI2), and (Cookson) Lentin and Williams and are typical of late short centrifugation. Recovered palynomorphs in- Senonian high (to mid) latitude assemblages (e.g., clude marine microphytoplankton (dinoflagellate Lentin and Williams, 1980). Precise correlation of cysts, acritarchs, other algae) and transported non- dinocyst zones within the Weddellian Province of marine palynomorphs (spores and pollen from land Zinsmeister (1979, 1982) is difficult, however, be- plants, rare freshwater algal remains and fungal cause of the disparity of species ranges from basin to spores), basin -- a problem noted by Dettmann and Thomson

(1987), Askin (1988), and Pirrie and Riding (1988) for Cretaceous Palynology samples from various localities in the James Ross

Basin. Most of the 25 Cretaceous samples yielded rich Samples from Cape Lamb on Vega Island, like

assemblages of marine and nonmarine palyno- those from Cockburn Island, are characterized bylsa-

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108 R.A. ASKIN, D. H. ELLIOT, J. D. STILWELL, and W. J. ZINSMEISTER

belidinium cretaceum, Cribroperidinium sp., Odonto- chitina pori[era Cookson, cf. Canninginopsis sp., Isa- belidinium pellucidum (Deflandre and Cookson) Len- tin and Williams (as I. cooksoniae), cf. Alterbidinium sp. and Operculodinium sp. This Vega assemblage was ini t ial ly interpreted (Askin, 1983) as late Campanian from correlation of palynomorphs to New Zealand assemblages, then middle to late Campanian (Askin, 1988) based on evidence from associated mollusc faunas (Macellari, 1984b) and foraminifera (Huber, 1988). An older Campanian age for the Vega palynomorph assemblage is more likely and is sup- ported by revision of ages of correlative New Zealand Piripauan-early Haumurian stages by Edwards et al. (1988). They placed the Piripauan-Haumurian boun- dary in the middle Campanian, though noting it may be as low as Santonian.

Species of Odontochitina with I. cretaceum may be useful biostratigraphic markers within the James Ross Basin where their presence appears to indicate a pre-Maastrichtian age. No Odontochitina have yet been observed in the continuous and relatively well- dated upper Campanian to Maastrichtian section on Seymour Island. In New Zealand, Odontochitina survived into the early Haumurian (late Campanian; Wilson, 1984a; Edwards et al., 1988). Likewise, in Australia (Helby et al., 1987) and the Falkland Pla~ teau (Goodman and Millioud, p. 40 in Ludwig et al., 1983), Odontochitina spp. are reported from Cam- panian and older rocks, h cretaceum ranges into the earliest Maastrichtian in Australia (Helby et al., 1987) and through the Campanian in New Zealand (Wilson, 1984a; Edwards et al., 1988). It has not been found above the Campanian on Seymour Island (Askin, 1988). Consistent co-occurrences on Cock- burn Island of 0. porifera (to 30 m below top of section) with common to abundant I. cretaceum are unambiguous evidence of a pre-Maastrichtian age for these Cretaceous sediments. Xenascus spp. are not as well documented in the James Ross basin, but these too have not been observed in the Maastrichtian (or upper Campanian) on Seymour Island and typically do not range into the Maastrichtian elsewhere.

Rare O. operculata (Wetzel) Deflandre and Cook- son (with I. cretaceum and I. pellucidum) have now (contrary to Askin, 1988) been found in a sample from northern Snow Hill Island. This sample (K209), from the cliffs close to Nordenskjfld's hut, occurs in rocks stratigraphically below the Seymour Island L6pez de Bertodano beds and is palynologically more similar to the "Naze assemblage" (Askin, 1988) from north- eastern James Ross Island than to the Cockburn Island flora. Cranwell (1969) also figured an O. oper- culata specimen from the "Seymour Island area" (most likely from Snow Hill Island; for Nordenskj/ild's Cretaceous samples, see Zinsmeister, 1988).

When compared to the samples studied by Dett- mann and Thomson (1987), the Cockburn Island assemblages most closely resemble their sample D3030.3 from "back of Brandy Bay" (Santa Marta Formation), northern James Ross Island. Similari- ties include the presence of I. cretaceum, 0. porifera,

Xenascus and Chatangie l la- type (see Appendix} dinocysts. They assigned this sample a Santonian] Campanian age based on dinocyst and ammonite evidence.

I. cretaceum was also found in Dettmann and Thomson's (1987) sample D3122.3 from Cape Lamb, Vega Island. Their assemblage lacks O. porifera but, in addition to I. cretaceum, contains I. pe l lucidum, Chatangiella cf. campbellensis (Wilson} Lentin and Williams, Palaeocystodinium granula tum (Wilson} Lentin and Williams, and diverse angiosperm pollen, and was assigned a Maastrichtian age.

Pirrie and Riding (1988) suggested a late Cam- panian to early Maastrichtian age for dinocyst assem- blages from Humps Island (see Fig.l) containing O. porifera and I. cretaceum, with I. pellucidum, I. koro- jonense (Cookson and Eisenack) Lentin and Williams, and Ceratiopsis diebelii (Alberti) Vozzhennikova.

It could be argued that the presence of sometimes rare Odontochitina spp. depends on subtle facies dif- ferences. However, based on the biostratigraphically useful series of lsabelidinium-ManumieIla species on Seymour Island (Askin, 1988), the presence of I. cretaceum, instead of Manumiel la "sp.3," strongly argues for a Campanian rather than Maastrichtian age for both the Vega Island sample of Dettmann and Thomson (1987) and the Humps Island samples of Pirrie and Riding (1988), as well as those from Cock- burn Island. Relationships between these sequences remain unclear, as each contains a slightly different flora. Pirrie and Riding (1988) stated that the Humps Island strata, based on facies analys is and con- sideration ofpaleogeography, may best be interpreted as the offshore equivalent of the Santa Mar ta Formation, and not the direct age equivalent of the basal Seymour Island strata (as suggested by their dinocyst interpretation). The revision suggested here for the age of the tIumps Island strata (Campanian, and older than the Seymour Is land L6pez de Bertodano beds) supports that suggestion and is consistent with a previous ammonite correlation sug- gesting an early-middle Campanian age for the Humps Island beds (Howarth, 1966).

Using the New Zealand dinocyst zonation of Wilson (1984a), the Cockburn Island assemblage correlates with part (upper) of the Odontochit ina porifera Zone, from the association of O. porifera, I. cretaceum, Alterbidinium acutulum (Wilson) Lentin and Williams, and Leberidocysta chlamydata (Cook- son and Eisenack) Stover and Evitt. Palynomorphs of the O. porifera Zone occur in Piripauan-lower Hau- murian rocks (Santonian to approximately Cam- panian/Maastrichtian boundary; Edwards et al., 1988). Other species of stratigraphic interest include Vozzhennikovia cf. spinulosa Wilson and Batiaca- sphaera sp. 1. V. spinulosa occurs in upper Piripauan- Haumurian rocks (Campanian-Maastrichtian; Wil- son, 1984a,b) and "Leiosphaeridia" ovata (cf. Batiaca- sphaera sp.1) was described from the Haumurian (Maastrichtian) of Campbell Island and Campbell Plateau (Wilson, 1967, 1972, 1975).

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 109

The Cockburn Island assemblages are clearly equivalent to part of the Santonian to Maastrichtian Isabelidinium Superzone of the Australian dinocyst zonation of Helby et al. (1987), but considerable dis- parity of species ranges between these areas prevents precise correlation with either the I. cretaceum Zone (Santonian), Nelsoniella aceras Zone (late Santonian- early Campanian), Xenikoon austraIis Zone (early Campanian), or lower part (middle Campanian} of the I. korojonense Zone.

Despite problems with disparity of ranges, the marine palynomorphs suggest that the Cretaceous "Unnamed strata" of Cockburn Island are of Campan- ian age, probably middle Campanian, although possibly as old as early Campanian. They are older than zone 1 (Askin, 1988) of Seymour Island.

Nonmarine palynomorphs of the Cretaceous beds are always dominated by the conifer pollen Phyllo- cIadidites mawsonii Cookson (see Table 2). Other conifer pollen, angiosperm Nothofagidites (southern beech) pollen, and fern spores Laevigatosporites spp. are relatively common. The assemblage is correlated to the Phyllocladidites mawsonii (PM) Assemblage of South Island, New Zealand (Raine 1984), and pro- bably to Zone PM2 (lower/middle Campanian to Maastrichtian). Tubulifloridites lilliei (Couper) Far- abee and Canright, which defines the base of Zone PM2, occurs rarely on Cockburn Island. The presence of other species such as Gambierina rudata Stover and Cranwellipollis palisadus (Couper) Martin and Harris supports a PM2 correlation. In Australia, G. rudata appears in the upper part (lower Campanian) of the Nothofagidites senectus Zone; it ranges through the "Tricolporites" lilliei Zone (base equivalent to the base I. korojonense dinocyst Zone; Helby et al. 1987), while T. lilliei and C. palisadus appear at the base of the T. lilliei Zone. Specimens similar to the Cockburn Grapnelispora sp. occur in Campanian-Maastrichtian rocks in New Zealand and Australia (see Askin, 1990). In general, first appearances of spore and pollen species are not good biostratigraphic markers in the Weddellian Province, owing to their often long dispersal time (e.g., Dettmann, 1986; Askin, 1989).

Tertiary Palynology

Palynomorphs are relatively common in 3 (87/10- 8, 14, 1} of the 14 Tertiary samples examined, and are sparse to rare (as is total organic matter) in the other 11 samples - - which is not unexpected in these sandy samples. Palynomorphs are yellow in color and pre- servation is generally fair to poor. The preserved plant tissue (vitrinite and cuticle} and palynomorphs (particularly the nonmarine forms) are frequently corroded, sometimes severely, as a result of bio- degradation and/or oxidation (the lat ter during transport and deposition, or outcrop weathering}. Inertinite is relatively common to abundant. Some palynomorphs are broken or abraded. As noted above, shelly fossils in these beds are also poorly preserved. Except for Nothofagidites pollen, small- sized land-derived palynomorphs are lacking in some

sandy samples. A possible explanation is that fine sedimentary particles (including palynomorphs) were removed during transport, and Nothofagidites grains were subsequently blown in. Nothofagus trees are wind-pollinating and can produce copious amounts of pollen. Wind-carried podocarpaceous conifer pollen is also relatively abundant.

Both marine and nonmarine palynomorph assem- blages in these Tertiary samples are of low diversity. For the land-derived spores and pollen, this may be due to poor preservation and selective removal during transport. Poor preservation may only partly affect the marine assemblages because chorate dinocysts with complex delicate processes are among the better- preserved palynomorphs. The absolute scarcity of palynomorphs is another contributing factor for low diversity.

Marine and nonmarine palynomorph taxa iden- tified in the 14 Tertiary samples are listed in Table 3. Only presence/absence is indicated for all but two (87/10-8, -1) because, unlike the Cretaceous samples, palynomorphs are often unidentifiable and too sparse in most samples for meaningful counts.

The marine palynomorph assemblages through- out the Tertiary section are characterized by two species of chorate dinocysts: the large flamboyant Areosphaeridium sp. cf. A. diktyoplokus (Klumpp) Eaton, and the small Enigmadinium cylindriflori- ferurn Wrenn and Hart. The peridinioid dinocysts Deflandrea spp., including D. antarctica Wilson, are relatively common in some samples, as are some poorly preserved indeterminate forms. The non- marine component includes Nothofagidites spp., podocarpaceous conifer pollen, and few other taxa (Table 3).

These Tertiary samples closely resemble those from the lower part (members Telm 1 and 2) of the La Meseta Formation on Seymour Island [Wrenn and Hart, 1988 (3 samples in section 17); Askin, 1988 ("zone 7"); and unpublished data] in their abundance of A. sp. cf. A. diktyoplokus, E. cyclindrifloriferum, and Nothofagidites spp., and their poor represen- tation of most other marine and nonmarine taxa. Wrenn (1982; Wrenn and Hart, 1988} assigned a late early Eocene age to the lower part of the La Meseta Formation that he studied [the basal 250 m was then unknown, and he examined samples from the over- lying beds ("Interval A" which included section 17)]. It is likely that the underlying La Meseta beds on Seymour Island and their correlatives on Cockburn Island are late early Eocene (or older}, based in part on the presence of A. sp. cf. A. diktyoplokus. A. dik- tyoplokus first appears in the late early Eocene else- where (e.g., Williams and Bujak, 1985}; however, a slightly older age for the southern form is possible because Haskell and Wilson (1975} found it in the Paleocene of the South Tasman Rise, and possible fragments occur in the Paleocene Cross Valley For- mation and uppermost Sobral Formation on Seymour Island (Askin, unpublished data).

Diatom evidence (Harwood, 1988) indicates a late early Eocene age for part of the lower La Meseta

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Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 111

Formation on Seymour Island. Harwood's material was one sample (S13-19) from a small, shelly outlier of the La Meseta Formation overlying the top of the Cross Valley Formation. Therefore, the precise stra- tigraphic position of his La Meseta sample is un- known, although it is stratigraphically higher than the basal La Meseta beds.

P A L E OENVIRONMENTS

Cretaceous

The fine-grained Campanian strata on Cockburn Island were deposited in a low energy, shallow shelf environment. The bivalve fauna includes infaunal and epffaunal suspension feeders that suggest quiet conditions, as in younger Seymour Island L6pez de Bertodano sediments (Macellari, 1988). Palyno- morph assemblages have high relative abundances of terrestrially derived palynomorphs and plant debris including, in some intervals, common and large fragments of plant cuticle; this and the composition of the dinocyst floras, indicate shallow marine, near- shore conditions. Peridinioid dinocysts (particularly I. cretaceum group) are abundant, and the gony- aulacacean ratio (of Harland, 1973) is relatively low (mean 2.5, up to 5.5 in CI-17), an indicator of nearshore environments. Dinocyst diversity is low (below 25 species/sample), and relative dominance (Goodman, 1979) is moderate to high, also indicating nearshore conditions. There is no significant varia- tion in palynomorph pa ramete r s , nor a clear relationship with lithologic units, although minor variations (suggesting fluctuating conditions in dis- tance to shoreline, water depth, local microenviron- ments, salinity, etc.) are evident.

Tertiary

For the Eocene Cockburn Island strata, the low diversity-high dominance dinocyst assemblages are compatible with shallow, inshore conditions (e.g., Goodman, 1979) - - i.e., low salinity or estuarine/ brackish. Low (<2) gonyaulacacean ratios are also typical of such an environment. This is consistent with previous interpretations for the correlative Seymour Island basal La Meseta beds. For example, Zullo et al. (1988) found Solidobalanus (in Telm 2, loc. 1), which are associated with subtidal and inner shelf faunal assemblages in moderate- to high-energy environments and exhibit preservation typical of burial of living specimens. Sadler (1988) notes that the Seymour basal sediments (Telm 1) are marginal facies including shallow, subtidal to possibly inter- tidal faunal elements, and that Telm 2 is prograding valley fill. A similar depositional environment exis- ted for the Tertiary beds on Cockburn Island. It is possible that the basal glauconitic sands represent transgressive system tract deposits (Van Wagoner et al., 1988; Loutit et al., 1988), overlain by a prograding

highstand complex filling the wide Cockburn- Seymour paleovalley.

While the long, complex processes of A. cf. dik- tyopIokus are typically associated with more "open marine" conditions, it is possible that the presumed added buoyancy provided by these processes were adaptations for a hypopycnal system where lower density river water flows out over sea-water.

The presence of Beaupreaidites elegansiformis Cookson (sample 87/10-1, three specimens observed), although not age diagnostic, is important for its paleoclimatic implications. A humid, mild and equable climate was inferred for latest Maastrichtian Seymour Island samples containing this and other presumed "warmth-loving" (frost-sensitive) species (Askin, 1989). Aside from this single indication of mild climate in the upper part of the section, the rest of the terrestrial palynoflora is more typical of cool temperate beech (mainly fusca type) and conifer- dominated rainforest. On the South Shetland Islands to the north, the discontinuous Upper Cretaceous (Coniacian) through Miocene sequences (e.g. Birken- majer and Zastawniak, 1989) have yielded evidence of cold phases during the Tertiary, including an early Eocene "Krakow Glaciation" based on glaeiomarine sediments overlain by basaltic lavas dated as 49.4 + 5 Ma (Birkenmajer et al., 1986). This cold phase was correlated with the pre-La Meseta Formation hiatus and erosional event, but it would have to be followed by rapid and substantial warming to presumed mild, frost-free conditions suitable for B. elegansiformis. Glaciation in the early Eocene is also not easily reconcilable with other evidence (e.g., Shackleton and Kennett, 1975; Stott et al., 1990) that indicates this was a time of maximum warmth for the Cenozoic.

GEOLOGIC HISTORY

In Late Cretaceous time, during deposition of the lower to middle Marambio Group, siliciclastic sedi- ments derived from the Antarctic Peninsula cor- dillera filled the James Ross Basin. The "Unnamed strata," deposited after (and contemporaneous with?) the Santonian-Campanian Santa Marta Formation of James Ross Island and before the late Campanian to Maastrichtian (and Danian) L6pez de Bertodano Formation of Seymour Island, are exposed in several localities, including Cockburn Island.

The Campanian "Unnamed strata" on Cockburn Island dip at about 6 ° to the southeast, implying a trend conformable with beds on Snow Hill and Sey- mour Islands which dip at about 10 ° to the southeast. The Cockburn beds appear to form an older part of the Seymour Island homoclinal Marambio Group succes- sion. Tilting of these beds occurred in post-Sobral time, and probably post-Cross Valley time m that is, latest Paleocene to earliest Eocene. Tilting and uplift may have brought the beds above sea level, although deposition was marine by the start of La Meseta time. The broad depositional trough of the La Meseta Formation, which was eroded down several hundred

112 R.A. ASKIN, D. H. ELLIOT, J. D. STILWELL, and W. J. ZINSMEISTER

mete r s into Sobral and uppermost L6pez de Ber to- dano beds on Seymour Island, had steep and i r regu la r marg ins where more res i s tan t beds formed the valley (canyon?) wall. Cockburn Island, to the northwest , r ep resen t s a more proximal par t of tha t t rough where even g rea te r cu t t ing into Cretaceous beds may have occurred. Downcut t ing to form incised valleys is com- monly associated with low sea level s tands brought about by regional uplift or eusta t ic fall in sea level. The la rge p r e - La M e s e t a e r o s i o n a l ep i sode was appa ren t ly caused in par t by tectonism, and in par t might have occurred dur ing the several short t e rm pulses of low sea level near the Thane t ian /Ypres ian b o u n d a r y (Haq et al., 1987), p r e s u m i n g an e a r l y Eocene age for the basal La Meseta beds.

C O N C L U S I O N S

1. The Cockburn Island Cretaceous beds are inter- media te in s t r a t i g r a p h i c pos i t ion be tween the San ta Mar t a Format ion (Santonian-Campanian) of no r the rn J a m e s Ross Island and the Ldpez de Ber todano F o r m a t i o n ( la te C a m p a n i a n , Maas- t r ich t ian , and Danian) of Seymour Island. These Cockburn Island beds are included in the "Un- named s t r a t a" of the Marambio Group.

2. The Cockburn Island Cretaceous beds are Cam- panian , probably middle Campanian , bu t possibly as old as ea r ly Campanian . Corre la t ion and age as s ignment are based mainly on d inof lage l l a t e cysts, and in par t on mar ine inver tebra tes .

3. R e l a t i onsh ip s of C a m p a n i a n Cockburn I s land " U n n a m e d s t ra ta" and "Unnamed s t r a t a " else- where in the J a m e s Ross Basin (on Ula Point, The Naze , H a m i l t o n Po in t , H u m p s I s l and , Vega Island) r ema in uncer ta in and awai t fu r the r map- ping and b ios t ra t igraphic study.

4. It is r ecommended that , until s t ra t igraphic rela- t ionships are f i rmly es tabl ished, none of these outcrops of "Unnamed s t ra ta" should be assigned to the LSpez de Ber todano Format ion as defined and dated for Seymour Island.

5. The Cockburn Island Campanian beds were depo- sited in low energy, shallow shelf environments .

6. The Lower Te r t i a ry beds on Cockburn Island are cor re la ted with members Telm 1 and lower Telm 2 of the La Meseta Format ion of Seymour Island, based on lithologic and paleontologic similari t ies.

7. An la te ea r ly Eocene age is suggested for these basal La Meseta Format ion beds, based mainly on previous dinoflagel la te cyst and diatom evidence.

8. The basal La Meseta sediments on Cockburn and Seymour Islands were deposited in a broad t rough or va l l ey e roded seve ra l h u n d r e d me te r s into Cre taceous and Paleocene sediments . This in- cised t rough was probably cut in the la tes t Paleo- cene to ear l ies t Eocene, dur ing t i l t ing and uplift of the Peninsula , accompanied by sea-level low- stands. The valley fill sediments are marg ina l mar ine to shallow shelf deposits.

Acknowledgements--We appreciate valuable reviews of this manuscript by Stephen R. Jacobson {Chevron Oil Field Research Co.), Peter M. Sadler (University of California, Riverside), and Graeme J. Wilson (DSIR Geology and Geophysics, New Zealand), as well as discussion on the dinocysts by Warren S. Drugg (Chevron Oil Field Research Col. James B. Riding (British Geological Sur- vey) kindly provided an unpublished manuscript (Pirrie, Crame and Riding, in press) and discussion. We thank Fred C. Barbis, Tim R. Kelley, and David E. Rieske for assistance with field work, Marnie Crook for palynological preparations, Linda Jankov for photographic assistance (palynology), and John Nagy for drafting. Tables 2 and 3 use Checklist II (F. Jay Phillips) software. Support for field work was provided by U.S. National Science Foundation Grants DPP 83-14186 (Askin), DPP 85-19080 (Elliot), DPP 84- 16783 (Zinsmeister), and subsequent laboratory work was sup- ported by DPP 87-16484 (Askin).

A P P E N D I X N o t e s on S e l e c t e d D i n o f l a g e l l a t e C y s t S p e c i e s

1. The dinocyst species included in Table 2, Cribro- per id in ium sp., Cyclopsiella sp., cf. Canningino- psis sp., "Dinocyst N.Gen.X," Operculodinium sp., and Phelodin ium sp., are the same as those illus- t ra ted in Askin (1988).

2. The "Isabel idinium cretaceum group" in Table 2 includes typical I. cretaceum and m o re robus t , r ec tangula r forms i l lus t ra ted by D e t t m a n n and Thomson (1987) as I. sp. cf. I. bakeri and by Askin (1988) as [. sp. cf. I. cretaceum.

3. The Cretaceous samples inc lude m e m b e r s of a complex of peridinioid dinocysts (e.g., Fig. 131) with var iously developed pen tapa r t i t e parac ingu- lum, del taform to the ta fo rm in t e r ca l a ry archeo- pyle, absence of large epicys ta l shou lde r s , and

Fig. 13. Photomicrographs of selected dinoflagellate cysts and an acritarch (d) from Campanian "Unnamed strata" of Cock- burn Island. Magnification X500 for b, e-l; X750 for a, o; ×1000 for c, d, m, n. Sample and slide number, National Museum of Natural History {Washington, DC) collection number (prefix USNM), and England Finder references are provided for each specimen. a) Batiacasphaera sp.l, CL05/1, USNM 448139, J21 b) Batiacasphaera sp.2, C l- 10/1, USNM 448140, L40/2 c)Fromea chytra (Drugg) Stover and Evitt, CI-20/1, USNM 448141, H42/1 d)HorologiaeUa apiculata Cookson and Eisenack, CL20/1, USNM 448142, F47/1 e, h) Xenascus sp. e, Cl 21/1, USNM 448143, F39/3; h, CI-23/1, USNM 448144, C32 f, g)Isabel~d~nium cretaceum (Cookson) Lentin and Williams. f, CI-20/l, USNM 448145, U44; g, CI-05/l, USNM 448146, H43/2 i)Isabelidinium pellucidum (Defiandre and Cookson) Lentin and Williams, CI-23/1, USNM 448147, F17/4 j) Vozzhennikovia sp. cf. V. spinulosa Wilson, CI-19/1, USNM 448148, G25 k)Odontochit~na por~fera Cookson, CI-10/1, USNM 448149, Q43 I)Isabelidinium greenense Marshall, CI-08/1, USNM 448150, F17/4 m, n)cf. Mierodinium/Druggidinium sp. m, Cl-10/l, USNM 448151, K41/1; n, CI-04/I, USNM 448152, H16/3 o)Leberidocysta chlamydata (Cookson and Eisenack) Stover and Evitt, CI-05/l, USNM 448153, K12

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 113

F D

t-~

0 *-3

T z

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 115

.

.

faintly to distinctly sculptured (granulate to fine- ly spinulate) periphragm. Dettmann and Thom- son (1987) illustrated similar forms as Chatan- gieUa cf. campbellensis (from D3122.3) and C. serratula (D3030.3). Askin (1988) assigned them to "cf. Alterbidinium sp.," noting that there is a continuous morphologic gradation to acingulate forms then assigned to I. cooksoniae, which are now referred to I. pellucidum. Most of this com- plex falls into the broadly defined and extremely variable species Isabelidinium greenense Mar- shall recently described (Marshall, 1990) from the Campanian of the Gippsland Basin, southeastern Australia. Batiacasphaera sp.1 (Fig. 13a) may be conspecific with Leiosphaeridia ovata Wilson from Campbell Island (Wilson, 1967) and southeast Campbell Plateau, DSDP Site 275 (Wilson, 1975). The Cockburn form, however, has a thick foveolate outer wall, which sometimes has a granulate sur- face texture, and a thin inner wall is occasionally discernible. The thick spongeous wall of less well-preserved specimens can appear "densely granulate, verrucate or reticulate" as described for L. ovata type material by Wilson (1967). The apical archeopyle margin of the Cockburn speci- mens is sometimes angular rather than circular, with a sulcal notch. Cf. Microdinium/Druggidinium sp. has discern- ible paratabulation of Pr,4',4a,6" on the epicyst only of some specimens (Fig. 13re,n). The apical archeopyle involves apicals and anterior inter- calaries, and the operculum is free, though it is

Fig. 14. Photomicrographs of selected spore (a), angiosperm pollen (b-f, i) and dinoflagellate cysts (g, h, j-I) from Campanian ~Unnamed strata" (a-e) and Eocene La Meseta Formation (f-l) of Cockburn Island. Magnification X500 for a, g, I; x 750 for h,j; × 1000 for b-f, i, k. a) Grapnelispora sp., Cl-18/1, USNM 448154, Q28 b) Cranwellipollis palisadus (Couper) Martin and Harris, CI- 05/1, USNM 448155, H26

c) Gambierina rudato Stover, CI-24/1, USNM 448156, F27/3 d) Stellidiopollis annulatus Dettmann and Hedlund, CI-04/1, USNM 448157, J22/4 e) Tubulifloridites lilliei (Couper) Farabee and Canright, CI- 04/1, USNM 448158, E24/1 f) Proteacidites pseudomoides Stover, 87/10-14/1, USNM 448159, K29/2

g) Deflandrea antarctica Wilson, 87/10-12/1, USNM 448160, N32/1 h) Phelodinium boldii Wrenn and Hart, 87/10-4/1, USNM 448161, M34/4

i) Beaupreaidites elegansiformis Cookson, 87/10-1/1, USNM 448162, K30 j) Spinidinium essoi Cookson and Eisenack, 87/10-13/1, USNM 448163, Q13/4 k) Enigmadinium cyclindrifloriferum Wrenn and Hart, part of a clump, 87/10-1/1, USNM 448164, R22/1 I) Areosphaeridium sp. cf. A. diktyoplokus (Klumpp) Eaten, 87/10-12/1, USNM 448165, T33/3

.

.

often adherent. The hypocyst is considerably larger than the epicyst. The sculpture is finely rugulate. Vozzhennikovia sp. cf. V. spinulosa Wilson differs slightly from the type material from New Zealand (Wilson, 1984b) in its smaller, granulate sculp- tural elements (up to 1 pm high), larger size (110 pm) and less pronounced apical horn. Following Goodman and Ford (1983), the desig- nation Areosphaeridium sp. cf. A. diktyplokus is used for these southern forms with ragged incom- plete margins on the process terminations. The entire margin typical of northern A. diktyoplokus was not observed on any of the well-preserved Cockburn Island specimens.

R E F E R E N C E S

Adie, R. J., 1958. Geological investigations in the Falkland Islands Dependencies since 1940. Polar Record 9 (58), 3-16.

Askin, R. A., 1983. Campanian palynomorphs from James Ross and Vega Islands, Antarctic Peninsula. Antarctic Journal of the United States 18, 63-65.

Askin, R. A., 1988. Campanian to Paleocene palynological suc- cession of Seymour and adjacent islands, northeastern Antarctic Peninsula. In: Geology and Paleontology of Seymour Island, Ant- arctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of America, Memoir 169, 131-153.

Askin, R. A., 1989. Endemism and heterochroneity in the Late Cretaceous (Campanian) to Paleocene palynofloras of Seymour Island, Antarctica: Implications for origins, dispersal and palaeo- climates of southern floras. In: Origins and Evolution of the Ant- arctic Biota (edited by J. A. Crame). Geological Society of London, Special Publication 47,107-119.

Askin, R. A., 1990. Cryptogam spores from the upper Campanian and Maastrichtian of Seymour Island, Antarctica. Micropaleon- tology 36 (2), 141-156.

Bibby, J. S., 1966. The stratigraphy of part of north-east Graham Land and the James Ross Island Group. British Antarctic Survey, Scientific Reports 53, 1-37.

Birkenmajer, K., and Zastawniak, E., 1989. Late Cretaceous-early Tertiary floras of King George Island, West Antarctica: Their stratigraphic distribution and palaeoclimatic significance. In: Ori~ gins and Euolution of the Antarctic Biota (edited by J. A. Crame). Geological Society of London, Special Publication 47,227-240.

Birkenmajer, K., Delitala, M. C., Narebski, W., Nicoletti, M., and Petrucciani, C., 1986. Geochronology of Tertiary island-arc vol- canics and glacigene deposits, King George Island, South Shetland Islands (West Antarctica). Bulletin of the Polish Academy of Sciences, Earth Sciences 34, 139-155.

Buckman, S. S., 1910. Antarctic fossil brachiopoda collected by the Swedish south polar expedition. Wissenschaftliche Ergebnisse der Schwedischen Sudpolar Expedition 1901-1903 3 {7), 1--40.

Cranwell, L. M., 1969. Palynological intimations of some pre- Oligocene Antarctic climates. In: Palaeoecology of Africa (edited by E. M. van Zinderen Bakker), pp. 1-19. S. Balkema, Cape Town, Republic of South Africa.

116 R.A. ASKIN, D. H. ELLIOT, J. D. STILWELL, and W.J . ZINSMEISTER

Dettmann, M. E., 1986. Significance of the Cretaceous-Tertiary spore genus Cyatheacidites in tracing the origin and migration of Lophosoria (Filicopsida). Special Papers in Palaeontalogy 35, 63- 94.

Dettmann, M. E., and Thomson, M. R. A., 1987. Cretaceous paly- nomorphs from the James Ros~ Island area, Antarctica -- A pilot study. Bulletin of the British A ntarctic Survey 77, 13-59.

Edwards, A. R., Hornibrook, N. de B., Raine, J. I., Scott, G. H., Stevens, G. R., Strong, C. P., and Wilson, G. J., 1988. A New Zea- land Cretaceous-Cenozoic geological time scale. New Zealand Geological Survey Record 35, 135-149.

Howarth, M. D., 1966. Ammonites from the Upper Cretaceous of the James Ross Island Group. Bulletin of the British Antarctic Survey 10, 55-69.

Huher, B. T., 1988. Upper Campanian-Paleocene foraminifera from the James Ross Island region, Antarctic Peninsula. In: Geo- logy and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Soci- ety of America, Memoir 169, 163-252.

Ineson, J. R., Crame, J. A., and Thomson, M. R. A., 1986. Litho- stratigraphy of the Cretaceous strata of west James Ross Island, Antarctica. Cretaceous Research 7,141-159.

Elliot, D. H., 1988. Tectonic setting and evolution of the James Ross Island basin, northern Antarctic Peninsula. In: Geology and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of Ameri- ca, Memoir 169, 541-555.

Elliot, D. H., and Hoffman, S., 1989. Geologic studies on Seymour Island. Antarctic Journal of the United States 24 (5), 3-5.

Elliot, D. H., and Rieske, D. E., 1987. Field investigations of the Tertiary strata on Seymour and Cockburn islands. Antarctic Jour- nalofthe United States 22 (5), 6-8.

Feldmann, R. M., and Tshudy, D. M., 1989. Evolutionary patterns in macrurous decapod crustaceans from Cretaceous to early Ceno- zoic rocks of the James Ross Island region, Antarctica. In: Origins and Evolution of the Antarctic Biota (edited by J. A. Crame). Geological Society Special Publication 47, 183-195.

Feldmann, R. M., and Woodburne, M. O. (editors), 1988. Geology and Paleontology of Seymour Island, Antarctic Peninsula. Geologi- cal Society of America, Memoir 169,566 p.

Goodman, D. K., 1979. Dinoflagellate "communities" from the lower Eocene Nanjemoy Formation of Maryland, USA. Palynology 3,169-190.

Goodman, D. K., and Ford, L. R., Jr., 1983. Preliminary dino- flagellate biostratigraphy for the middle Eocene to lower Oligocene from the southwest Atlantic Ocean. Initial Reports of Deep Sea Drilling Project 71,859-877.

Haq, B. U., Hardenbol, J., and Vail, P. R., 1987. Chronology of fluc- tuating sea levels since the Triassic. Science 235,1156-1167.

Lentin, J. K., and Williams, G. L., 1980. DinoflageUate Provincia- lism with Emphasis on Campanian Peridiniaceans. American Association of Stratigraphic Palynologists, Contribution Series 7, 47 p.

Loutit, T. S., Hardenbol, J., and Vail, P. R., 1988. Condensed sec- tions: The key to age determination and correlation of continental margin sequences. In: Sea-Level Changes - - An Integrated Ap- proach (edited by C. K. Wilgus, H. Posamentier, C. A. Ross, and C. G. St.C. Kendall). Society of Economic Paleontologists and Minera- logists, Special Publication 42,183-213

Ludwig, W. J., Krasheninnikov, V. A., et al. (Shipboard Scientific Party), 1983. Site 511. Initial Reports of the Deep Sea Drilling Project 71 (1), 21-109.

McDonald, D. I. M., Barker, P. F., Garrett, S. W., lneson, J. R., Pirrie, D., Storey, B. C., Whitham, A. G., Kinghorn, R. R. F., and Marshall, J. E. A., 1988. A preliminary assessment of the hydro- carbon potential of the Larsen Basin, Antarctica. Marine andPet- roleum Geology 5, 34-53.

Macellari, C. E., 1984a. Revision of serpulids of the genus Rotu- /aria (Annelida) at Seymour Island (Antarctic Peninsula) and their value in stratigraphy. Journal of Paleontology 58, 1098-1116.

Macellari, C. E., 1984b. Late Cretaceous Stratigraphy, Sedimen- talogy and Macropaleontalogy of Seymour Island, Antarctic Penin- sula. Unpublished thesis, The Ohio State University, Columbus, OH, USA, 599 p.

Macellari, C. E., 1986. Late Campanian-Maastrichtian Ammonite Fauna from Seymour Island (Antarctic Peninsula). Journal of Paleontology Memoir 18, 55 p.

Harland, R., 1973. Dinoflagellate cysts and acritarchs from the Bearpaw Formation (upper Campanian) of southern Alberta, Cana- da. Palaeontology 16,665-706.

Harwood, D. M., 1988. Upper Cretaceous and Lower Paleocene diatom and silicoflagellate biostratigraphy of Seymour Island, eastern Antarctic Peninsula. In: Geology and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of America, Memoir 169, 55-129.

Haskell, T. R., and Wilson, G. J., 1975. Palynology of Sites 280-284, DSDP Leg 29, off southeastern Australia and western New Zea- land. Initial Reports of the Deep Sea Drilling Project 29,723-741.

Helby, R., Morgan, R., and Partridge, A. D., 1987. A palynological zonation of the Australian Mesozoic. Association of Australastan Palaeontologists, Memoir 4, 1-94.

Macellari, C. E., 1988. Stratigraphy, sedimentelogy and paleo- ecology of Upper Cretaceous/Paleocene shelf-deltaic sediments of Seymour Island (Antarctic Peninsula). In: Geology and Paleonto- logy of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of America, Memoir 169, 25-53.

Marshall, N. G., 1990. Campanian dinoflagellates from south- eastern Australia. Aleheringa 14, 1--38.

Nordenskj61d, O., 1905. Antarctica, or Two Years Amongst the Ice of the South Pole [English Edition]. Macmillan, New York, NY, USA, 6O8 p.

Olivero, E., and Zinsmeister, W. J., 1989. Large heteromorph am- monites from the Upper Cretaceous of Seymour Island, Antarctica. Journal of Paleontology 63 (5), 626-636.

Olivero, E., Scasso, R. A., and Rinaldi, C. A., 1986. Revision of the Marambio Group, James Ross Island, Antarctica. Instituta Ant- drtico A rgentino, Contribuciones 351,1-29.

Campanian and Eocene stratigraphy and paleontology on Cockburn Island, Antarctic Peninsula 117

Owen, E. F., 1980. Tertiary and Cretaceous brachiopods from Sey- mour, Cockburn, and James Ross Islands, Antarctica. Bulletin of the British Museum (Natural History), Geology 33, 123-145.

Pirrie, D., and Riding, J. B., 1988. Sodimentelogy, palynology and structure of Humps Island, northern Antarctic Peninsula. Bulletin of the British Antarctic Survey 80, 1-19.

Pirrie, D., Crame, J. A., and Riding, J. B., in press. Late Cretaceous stratigraphy and sedimentelogy of Cape Lamb, Vega Island, Ant- arctica. Cretaceous Research, in press.

Prior, G. T., 1899. Petrographical notes on the rock specimens collected in Antarctic regions during the voyage of H.M.S. Erebus and Terror under Sir James Clark ROss, in 1839-43. Mineralogical Magazine 12, 69-91.

Raine, J. I., 1984. Outline of a Palynological Zonation of Cretaceous to Paleogene Terrestrial Sediments in West Coast Region, South Island, New Zealand. New Zealand Geological Survey, Report 109, 82 p.

Rinaldi, C. A., Massabie, A., Morelli, J., Rosenmall, H. L. and del Valle, L., 1978. Geologia de la Isla Vicecomodoro Marambio. Insti- tuto An~rtico Argentino, Contribuciones 217, 1-37.

Sadler, P. M., 1988. Geometry and stratification of uppermost Cretaceous and Paleogene units on Seymour Island, northern Ant- arctic Peninsula. In: Geology and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Wood- burne). Geological Society of America, Memoir 169,303-320.

B. Saunders, and K. Perch-Nielsen), pp. 847-964. Cambridge Uni- versity Press, Cambridge, England, UK.

Wilson, G. J., 1967. Microplankten from the Garden Cove Forma- tion, Campbell Island. New Zealand Journal of Botany 5 (2), 223- 240.

Wilson, G. J., 1972. Age of the Garden Cove Formation, Campbell Island. New Zealand Journal of Geology and Geophysics 15, 184- 185.

Wilson, G. J., 1975. Palynology of deep-sea cores from DSDP Site 275, southeast Campbell Plateau. Initial Reports of the Deep Sea Drilling Project 29, 1031-1035.

Wilson, G. J., 1983. Late Cretaceous Dinoflagellate Assemblages from the Kaiwara District, North Canterbury. New Zealand Geo- logical Survey, Report PAL 64, 9 p.

Wilson, G. J., 1984a. New Zealand Late Jurassic to Eocene dino- flagellate biostratigraphy - - Summary. Newsletters on Strati- graphy 13, 104-117.

Wilson, G. J., 1984b. Some new dinoflagellate species from the New Zealand Haumurian and Piripauan Stages (Santenian-Maas- trichtian, Late Cretaceous). New Zealand Journal of Botany 22, 549-556.

Wrenn, J. H., 1982. Dinocyst Bmstratigraphy of Seymour Island, Palmer Peninsula, Antarctica. Unpublished thesis, Louisiana State University, Baton Rouge, LA, USA, 464 p.

Shackleten, N. J., and Kennett, J. P., 1975. Paleotemperature his- tory of the Cenozoic and the initiation of Antarctic glaciation: Oxygen and carbon isotope analyses in DSDP sites 277, 279, and 281. Initial Reports of the Deep Sea Drilling Project 29,743-807.

Soot-Ryen, T., 1952. Laternula eUiptiea (King and Broderip 1831) from the Pecten-conglomerate, Cockburn Island. Arkiv fiir Zoo- logic 4,163-164.

Stilwell, J. D., and Zinsmeister, W. J., 1987. Late Cretaceous fos- sils from Cockburn Island collected during the 1986-1987 expe- dition to the Antarctic Peninsula. Antarctic Journal of the United States 22 (5), 5-6.

Stett, L. D., Kennett, J. P., Shackleton, N. J., and Corfield, R. M., 1990. The evolution of Antarctic surface waters during the Paleo- gene: Inferences from the stable isotopic composition of planktonic foraminifers, ODP Leb 113. Proceedings of the Ocean Drilling Pro- gram, Scientific Results 113,849-863.

Van Wagoner, J. C., Posamentier, H. W., Mitchum, R. M., Vail, P. R., Sarg, J. F., Loutit, T. S., and Hardenbol, J., 1988. An overview of the fundamentals of sequence stratigraphy and key definitions. In: Sea-Level Changes - - An Integrated Approach (edited by C. K. Wilgus, H. Posamentier, C. A. Ross, and C. G. St.C. Kendall). Society of Economic Paleontologists and Mineralogists, Special Publication 42, 39-45.

Webb, P. N., and Andreasen, J. E., 1986. Potassium/argon dating of volcanic material associated with the Pliocene Pecten Conglo- merate (Cockburn Island) and Scallop Hill Formation (McMurdo Sound). AntarcticJournalofthe United States 21 (5), 59.

Wilckens, O., 1924. Die tertiiire fauna der Cockburn-lnsel (Westantarktika). Results of the Swedish Antarctic Expedition 1901-1903 1 (5), 1-18.

Wrenn, J. H., and Hart, G. F., 1988. Paleogene dinoflagellate cyst biostratigraphy of Seymour Island, Antarctica. In: Geology and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of Ameri- ca, Memoir 169,321-447.

Zinsmeister, W. J., 1979. Biogeographic significance of the late Mesozoic and early Tertiary molluscan faunas of Seymour Island (Antarctic Peninsula) to the final breakup of Gondwanaland. In: Historical Biogeography, Plate Tectonics and the Changing Envi- ronment (edited by J. Gray and A. J. Boucot), pp. 349-355. Oregon State University Press, Corvallis, OR, USA.

Zinsmeister, W. J., 1982. Late Cretaceous-early Tertiary mol- luscan biogeography of the southern Circum-Pacific. Journal of Paleontology 56, 84-102.

Zinsmeister, W. J., 1988. Early geological exploration of Soymour Island, Antarctica. In: Geology and Paleontology of Seymour Island, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of America, Memoir 169, 1-19.

Zinsmeister, W. J., and Stilwell, J. D., 1990. First record of the family Ringiculidae (Gastropoda) in the middle Tertiary of Ant- arctica. Journal of Paleontology 64 (3), 373-376.

Zinsmeister, W. J., and Webb, P. N., 1982. Cretaceous-Tertiary geology and paleontology of Coekburn Island. Antarctic Journal of the UnitedStates 17 (5), 41-42.

Zullo, V. A., Feldmann, R. M., and Wiedman, L. A., 1988. Balano- morph Cirripedia from the Eocene La Meseta Formation, Seymour Island, Antarctica. In: Geology and Paleontology of Seymour Is- land, Antarctic Peninsula (edited by R. M. Feldmann and M. O. Woodburne). Geological Society of America, Memoir 169,459-464.

Williams, G. L., and Bujak, J. P., 1985. Mesozoic and Cenozoic dinofiagellates. In: Plankton Stratigraphy (edited by H. M. Bolli, J.