Palynological investigations of Campanian to lower Oligocene ...
include bivalves, gastropods, echinoderm spines, and abundant wood. This work was supported by National Science Foundation grant DPP 80-20096.
References Andersson, J. C. 1906. on the geology of Graham Land. Bulletin of the Geological Institute of the University of Upsala, 7, 19-71. Elliot, D. H., Rinaldi, C. A., Zinsmeister, W. J., Trautman, T. A., Bryant, W. B., and del Valle, R. 1975. Geological investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 10(4),182-186.
Howarth, M. K. 1966. Ammonites from the Upper Cretaceous of the James Ross Island Group. Bulletin of the British Antarctic Survey, 10,
55-69. Olivero, E. G. 1981. Esquema de zonaciOn de ammonites del Cretácico Superior del Grupo de Islas James Ross, Antártida. VIII Congresso Geologico Argentino, San Luis, September 20-27, 1981. Acta, 311, 897-907. Rinaldi, C. A. 1982. The Upper Cretaceous in the James Ross Island Group. In C. Craddock(Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Rinaldi, C. A., Massabie, A., Morelli, J., Rosenman, H. L., and del Valle, R. 1978. GeologIa de la Isla Vicecomodoro Marambio. Contribuciones del instituto Antdrtico Argentino, 217, 1-37. Spath, L. F. 1953. The Upper Cretaceous cephalopod fauna of Graham Land. Falkland Islands Dependencies Survey, Scientific Reports, 3, 1-60.
Palynological investigations of Campanian to lower Oligocene sediments on Seymour Island, Antarctic Peninsula -; ROSEMARY
A.
A
ASKIN
B
Geology Department Colorado School of Mines Golden, Colorado 80401 R. F1\11lY F1I:MIN;
Department of Geological Sciences University of Colorado Boulder, Colorado 80309
/
C
Palynomorphs have been recovered from all of the first prepa rations of samples collected during the February-March 1982 expedition to Seymour Island. In all, 363 samples were collected, mainly from Seymour Island but also from Snow Hill Island (provided by B. Huber), Cape Lamb on Vega Island, The Naze on northeastern James Ross Island, and Cape Melville on King George Island. The stratigraphy of Seymour Island is summarized by Macellari and Huber (Antarctic Journal, this issue; Campanian to ? Paleocene, Lopez de Bertodano and Sobral Formations) and by Zinsmeister and DeVries (Antarctic Journal, this issue; ? Paleocene to lower Oligocene, Seymour Island Group). Apart from cemented resistant sandstone beds and concretions, most of the sedimentary sequence on Seymour Island is unconsolidated. Fine-grained sediments (mud and silt) are abundant in places particularly in the Sobral Formation. Much of the finegrained sediment is carbonaceous and highly suitable for palynological sampling. The best continuously exposed section of predominantly fine-grained sediment crops out in the central part of Seymour Island. This approximately 300-meter-thick section includes the Sobral Formation and is believed to include the Cretaceous70
4. 1 E
F
5Opm
Photomicrographs of fossil pollen from Seymour Island (bar is equivalent to 50 micrometers). A, M!crocachryidites antarcticus Cookson; B, Phyllocladidites mawsoniiCookson; C, Nothofagidites fleming!! (Couper) Potonie; D, Proteacidites parvus Cookson; E, Haloragacid!tes harris!! (Couper) Harris; F, Tricolpates sp. A, B, D, and E occur in the Sobral Formation and throughout the Seymour Island Group; C occurs in the Seymour Island Group; and F occurs In the Sobral Formation and the Cross Valley Formation. ANTARCTIC JOURNAL
Tertiary boundary. Over much of this section it was possible to collect at 1.5-meter intervals; for most of the remainder, we could collect at 3-meter intervals. Cretaceous strata (Lopez de Bertodano Formation) cropping out on the southwestern part of the island are characterized by low topographic relief (in comparison with the rest of the island), and much of the strata is covered with debris; therefore, continuous sampling for palynomorphs was not possible in the older sandy units. Sampling was carried out throughout the Cross Valley Formation, although horizons suitable for palynomorphs are rare in the predominantly coarse-grained lower part of the formation. A coal bed presumed to be included in the Cross Valley Formation (see Fleming and Askin, Antarctic Journal, this issue) was sampled, as was much of the La Meseta Formation, including a unit adjacent to the marsupial bone locality (see Woodburne, Antarctic Journal, this issue). Distinct palynomorph assemblages are recognized from samples provided by the 1974-75 expedition of Elliot and others (1975) and our recent collections (figure). Podocarpaceous pollen predominates in Sobral Formation sediments, with less common Nothofagidites spp. (fusca and brassi groups), some proteaceous species, and pteridophyte spores. In the Seymour Island Group, podocarpaceous species and Nothofagidztes spp. (fusca, brassi, and menziesii groups) are dominant; proteaceous pollen is often abundant but shows a noticeable decline in relative abundance in the upper part of the La Meseta Formation. A succession of other distinctive and previously undescribed angiosperm pollen, some of which appear to have restricted ranges, occurs throughout. A few of these species also occur in the Ross Sea region (Truswell personal communi-
Observations on the stratigraphy of the lower Tertiary Seymour Island Group, Seymour Island, Antarctic Peninsula WILLIAM J . ZINSMEISTER and THOMAS J.
DEVRIES
Institute of Polar Studies Ohio State University Columbus, Ohio 43210
The 1981-82 geological program on the Tertiary of the Seymour Island Group represents a continuation of fieldwork initiated on Seymour Island by a joint U.S.-Argentina expedition during the austral summer of 1974-75 (Elliot et al. 1975). Results of the fieldwork this year have greatly enhanced our knowledge of the Tertiary succession on Seymour Island and the stratigraphic relationships between the Tertiary and the underlying Upper Cretaceous Marambio Group. The most significant events were recognition of approximately 300 meters of 1982 REVIEW
cation), but some may have been endemic to the Seymour Island region. Simple tricolpate species are common in Sobral Formation samples. In summary, a good, representative sampling for palynomorphs on Seymour Island has been obtained. These samples may provide both a palynostratigraphic zonation and information on the changing vegetation and paleoenvironmental conditions in the area. We thank fellow members of the expedition for companionship and enthusiastic support, and Captain Coste and the crew of USCGC Glacier for logistic support. This research is funded by National Science Foundation grant DPP 80-20095.
References Elliot, D. H., Rinaldi, C., Zinsmeister, W. J., Trautman, T. A., Bryant, W. A., and del Valle, R. 1975. Geological investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 10(4),182-186. Fleming, R. F., and Askin, R. A. 1982. Early Tertiary coal bed on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
Macellari, C., and Huber, B. T. 1982. Cretaceous stratigraphy of Seymour Island, East Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
Truswell, E. M. Personal communication, 1981. Woodburne, M. 0. 1982. Newly discovered land mammal from Antarctica. Antarctic Journal of the U.S., 17(5).
Zinsmeister, W. J., and DeVries, T. J . 1982. Observations on the stratigraphy of the lower Tertiary Seymour Island Group, Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
additional sediments in the lower part of the La Meseta Formation in Cross Valley and verification of the formation's unconformable relationship with the underlying Cretaceous. During the 1974-75 field season, Elliot and Trautman (1982) determined that the La Meseta Formation has a thickness of about 450 meters. Because of the faulted nature of the basal contacts of the sections they measured at the northern end of the island, it was suggested that the formation was probably thicker. Work this year around Cross Valley (figure 1) revealed approximately 300 meters of additional sandy siltstones referable to unit I of the La Meseta. These sediments are characterized by finely laminated to thinly bedded sandy siltstones with clayey sands. Several fossiliferous, coarser, sandy facies similar to the shell banks of unit II were encountered approximately 200 meters above the base. Lenticular beds near the western mouth of Cross Valley contained moderately abundant leaf impressions and fish scales, as well as marine mollusks. Fossilized logs, which are common in the overlying shell bank facies of unit II, were not observed in this newly discovered part of the La Meseta Formation. We were also able to demonstrate that the sequence across Cross Valley was nearly continuous, not cut by a series of large faults as previously thought (Elliot et al. 1975). Several small faults were observed, but none had any significant displacement. 71
References Andersson, J. C. 1906. on the geology of Graham Land. Bulletin of the Geological Institute of the University of Upsala, 7, 19-71. Elliot, D. H., Rinaldi, C. A., Zinsmeister, W. J., Trautman, T. A., Bryant, W. B., and del Valle, R. 1975. Geological investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 10(4),182-186.
Howarth, M. K. 1966. Ammonites from the Upper Cretaceous of the James Ross Island Group. Bulletin of the British Antarctic Survey, 10,
55-69. Olivero, E. G. 1981. Esquema de zonaciOn de ammonites del Cretácico Superior del Grupo de Islas James Ross, Antártida. VIII Congresso Geologico Argentino, San Luis, September 20-27, 1981. Acta, 311, 897-907. Rinaldi, C. A. 1982. The Upper Cretaceous in the James Ross Island Group. In C. Craddock(Ed.), Antarctic geoscience. Madison: University of Wisconsin Press. Rinaldi, C. A., Massabie, A., Morelli, J., Rosenman, H. L., and del Valle, R. 1978. GeologIa de la Isla Vicecomodoro Marambio. Contribuciones del instituto Antdrtico Argentino, 217, 1-37. Spath, L. F. 1953. The Upper Cretaceous cephalopod fauna of Graham Land. Falkland Islands Dependencies Survey, Scientific Reports, 3, 1-60.
Palynological investigations of Campanian to lower Oligocene sediments on Seymour Island, Antarctic Peninsula -; ROSEMARY
A.
A
ASKIN
B
Geology Department Colorado School of Mines Golden, Colorado 80401 R. F1\11lY F1I:MIN;
Department of Geological Sciences University of Colorado Boulder, Colorado 80309
/
C
Palynomorphs have been recovered from all of the first prepa rations of samples collected during the February-March 1982 expedition to Seymour Island. In all, 363 samples were collected, mainly from Seymour Island but also from Snow Hill Island (provided by B. Huber), Cape Lamb on Vega Island, The Naze on northeastern James Ross Island, and Cape Melville on King George Island. The stratigraphy of Seymour Island is summarized by Macellari and Huber (Antarctic Journal, this issue; Campanian to ? Paleocene, Lopez de Bertodano and Sobral Formations) and by Zinsmeister and DeVries (Antarctic Journal, this issue; ? Paleocene to lower Oligocene, Seymour Island Group). Apart from cemented resistant sandstone beds and concretions, most of the sedimentary sequence on Seymour Island is unconsolidated. Fine-grained sediments (mud and silt) are abundant in places particularly in the Sobral Formation. Much of the finegrained sediment is carbonaceous and highly suitable for palynological sampling. The best continuously exposed section of predominantly fine-grained sediment crops out in the central part of Seymour Island. This approximately 300-meter-thick section includes the Sobral Formation and is believed to include the Cretaceous70
4. 1 E
F
5Opm
Photomicrographs of fossil pollen from Seymour Island (bar is equivalent to 50 micrometers). A, M!crocachryidites antarcticus Cookson; B, Phyllocladidites mawsoniiCookson; C, Nothofagidites fleming!! (Couper) Potonie; D, Proteacidites parvus Cookson; E, Haloragacid!tes harris!! (Couper) Harris; F, Tricolpates sp. A, B, D, and E occur in the Sobral Formation and throughout the Seymour Island Group; C occurs in the Seymour Island Group; and F occurs In the Sobral Formation and the Cross Valley Formation. ANTARCTIC JOURNAL
Tertiary boundary. Over much of this section it was possible to collect at 1.5-meter intervals; for most of the remainder, we could collect at 3-meter intervals. Cretaceous strata (Lopez de Bertodano Formation) cropping out on the southwestern part of the island are characterized by low topographic relief (in comparison with the rest of the island), and much of the strata is covered with debris; therefore, continuous sampling for palynomorphs was not possible in the older sandy units. Sampling was carried out throughout the Cross Valley Formation, although horizons suitable for palynomorphs are rare in the predominantly coarse-grained lower part of the formation. A coal bed presumed to be included in the Cross Valley Formation (see Fleming and Askin, Antarctic Journal, this issue) was sampled, as was much of the La Meseta Formation, including a unit adjacent to the marsupial bone locality (see Woodburne, Antarctic Journal, this issue). Distinct palynomorph assemblages are recognized from samples provided by the 1974-75 expedition of Elliot and others (1975) and our recent collections (figure). Podocarpaceous pollen predominates in Sobral Formation sediments, with less common Nothofagidites spp. (fusca and brassi groups), some proteaceous species, and pteridophyte spores. In the Seymour Island Group, podocarpaceous species and Nothofagidztes spp. (fusca, brassi, and menziesii groups) are dominant; proteaceous pollen is often abundant but shows a noticeable decline in relative abundance in the upper part of the La Meseta Formation. A succession of other distinctive and previously undescribed angiosperm pollen, some of which appear to have restricted ranges, occurs throughout. A few of these species also occur in the Ross Sea region (Truswell personal communi-
Observations on the stratigraphy of the lower Tertiary Seymour Island Group, Seymour Island, Antarctic Peninsula WILLIAM J . ZINSMEISTER and THOMAS J.
DEVRIES
Institute of Polar Studies Ohio State University Columbus, Ohio 43210
The 1981-82 geological program on the Tertiary of the Seymour Island Group represents a continuation of fieldwork initiated on Seymour Island by a joint U.S.-Argentina expedition during the austral summer of 1974-75 (Elliot et al. 1975). Results of the fieldwork this year have greatly enhanced our knowledge of the Tertiary succession on Seymour Island and the stratigraphic relationships between the Tertiary and the underlying Upper Cretaceous Marambio Group. The most significant events were recognition of approximately 300 meters of 1982 REVIEW
cation), but some may have been endemic to the Seymour Island region. Simple tricolpate species are common in Sobral Formation samples. In summary, a good, representative sampling for palynomorphs on Seymour Island has been obtained. These samples may provide both a palynostratigraphic zonation and information on the changing vegetation and paleoenvironmental conditions in the area. We thank fellow members of the expedition for companionship and enthusiastic support, and Captain Coste and the crew of USCGC Glacier for logistic support. This research is funded by National Science Foundation grant DPP 80-20095.
References Elliot, D. H., Rinaldi, C., Zinsmeister, W. J., Trautman, T. A., Bryant, W. A., and del Valle, R. 1975. Geological investigations on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 10(4),182-186. Fleming, R. F., and Askin, R. A. 1982. Early Tertiary coal bed on Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
Macellari, C., and Huber, B. T. 1982. Cretaceous stratigraphy of Seymour Island, East Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
Truswell, E. M. Personal communication, 1981. Woodburne, M. 0. 1982. Newly discovered land mammal from Antarctica. Antarctic Journal of the U.S., 17(5).
Zinsmeister, W. J., and DeVries, T. J . 1982. Observations on the stratigraphy of the lower Tertiary Seymour Island Group, Seymour Island, Antarctic Peninsula. Antarctic Journal of the U.S., 17(5).
additional sediments in the lower part of the La Meseta Formation in Cross Valley and verification of the formation's unconformable relationship with the underlying Cretaceous. During the 1974-75 field season, Elliot and Trautman (1982) determined that the La Meseta Formation has a thickness of about 450 meters. Because of the faulted nature of the basal contacts of the sections they measured at the northern end of the island, it was suggested that the formation was probably thicker. Work this year around Cross Valley (figure 1) revealed approximately 300 meters of additional sandy siltstones referable to unit I of the La Meseta. These sediments are characterized by finely laminated to thinly bedded sandy siltstones with clayey sands. Several fossiliferous, coarser, sandy facies similar to the shell banks of unit II were encountered approximately 200 meters above the base. Lenticular beds near the western mouth of Cross Valley contained moderately abundant leaf impressions and fish scales, as well as marine mollusks. Fossilized logs, which are common in the overlying shell bank facies of unit II, were not observed in this newly discovered part of the La Meseta Formation. We were also able to demonstrate that the sequence across Cross Valley was nearly continuous, not cut by a series of large faults as previously thought (Elliot et al. 1975). Several small faults were observed, but none had any significant displacement. 71
