Stratigraphy and vertebrate paleoecology of Upper Cretaceous–?lowest Paleogene strata on Vega Island, Antarctica

Roberts, Eric M., Lamanna, Matthew C., Clarke, Julia A., Meng, Jin, Gorscak, Eric, Sertich, Joseph J.W., O'Connor, Patrick M., Claeson, Kerin M., and MacPhee, Ross D.E. (2014) Stratigraphy and vertebrate paleoecology of Upper Cretaceous–?lowest Paleogene strata on Vega Island, Antarctica. Palaeogeography, Palaeoclimatology, Palaeoecology, 402. pp. 55-72.

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The Upper Cretaceous (Maastrichtian) Sandwich Bluff Member of the López de Bertodano Formation is well exposed on Vega Island in the James Ross Basin off the northeastern coast of the Antarctic Peninsula. Although this unit is one of the richest sources of end-Cretaceous vertebrate fossils in Antarctica, it is also one of the least sedimentologically and stratigraphically characterized units in the basin. New facies and stratigraphic analyses of the Sandwich Bluff Member and the underlying Cape Lamb Member of the Snow Hill Island Formation were performed in tandem with intensive prospecting for fossil vertebrates and stratigraphic assessment of historic paleontological localities on Vega Island. This effort has led to a revised stratigraphy for the Sandwich Bluff Member and the precise stratigraphic placement of important terrestrial and marine vertebrate fossil localities.

Facies analysis reveals a fining and shallowing upward trend through the section that culminates in a newly recognized sequence boundary near the top of the Sandwich Bluff Member, followed by the deposition of a previously unrecognized, 6 m-thick, matrix-supported pebble–cobble conglomerate of probable alluvial origin. Immediately overlying this unit, well-developed Thalassinoides burrow networks in fine-grained transgressive sandstones and siltstones indicate a rapid return to marine conditions. A similar stratigraphic pattern is well documented at the top of the López de Bertodano Formation and the base of the overlying (Paleocene) Sobral Formation on Seymour Island in the southern part of the basin. Although no fossils were recovered to constrain the age of the upper 10–15 m of the succession on Vega Island that preserves the newly recognized upper sequence boundary, strata below this level can be confidently placed within the Manumiella bertodano interval zone, which extends to a short distance below the K–Pg boundary on Seymour Island. Hence, based on sequence stratigraphic and lithostratigraphic evidence, the uppermost 10–15 m of the succession on Vega Island may encompass the Cretaceous–Paleogene boundary together with a few meters of the Paleocene Sobral Formation.

Item ID: 33737
Item Type: Article (Research - C1)
ISSN: 1872-616X
Keywords: vertebrates, stratigraphy, Antarctica, paleoecology, Cretaceous, Vega Island
Funders: National Science Foundation (NSF)
Projects and Grants: NSF grant ANT-0636639, NSF grant ANT-1142052, NSF grant ANT-1142129, NSF grant ANT-1142104, NSF grant ANT-1141820
Date Deposited: 18 Jun 2014 09:34
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040310 Sedimentology @ 40%
04 EARTH SCIENCES > 0403 Geology > 040311 Stratigraphy (incl Biostratigraphy and Sequence Stratigraphy) @ 30%
04 EARTH SCIENCES > 0403 Geology > 040308 Palaeontology (incl Palynology) @ 30%
SEO Codes: 96 ENVIRONMENT > 9603 Climate and Climate Change > 960306 Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) @ 20%
97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 80%
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