Reworked late Neogene Austrochlamys anderssoni (Mollusca: Bivalvia) from northern James Ross Island, Antarctica

Abstract We report on the discovery of a new outcrop of fossiliferous Neogene sediments on northern James Ross Island, northern Antarctic Peninsula. Approximately 100 specimens of the pectinid bivalve Austrochlamys anderssoni (Hennig, 1911) were collected from the permafrost active layer. This bival...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Pirrie, D., Jonkers, H.A., Smellie, J.L., Crame, J.A., McArthur, J.M.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2011
Subjects:
Geology
Ecology, Evolution, Behavior and Systematics
Oceanography
Antarctic
Antarctic Peninsula
Ross Island
Hobbs
Cockburn
Cockburn Island
Antarc*
Antarctic Science
Antarctica
James Ross Island
permafrost
Online Access:http://dx.doi.org/10.1017/s0954102010000842
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102010000842
Description
Summary:Abstract We report on the discovery of a new outcrop of fossiliferous Neogene sediments on northern James Ross Island, northern Antarctic Peninsula. Approximately 100 specimens of the pectinid bivalve Austrochlamys anderssoni (Hennig, 1911) were collected from the permafrost active layer. This bivalve species has a late Miocene to late Pliocene range and has previously been reported from both the glaciomarine Hobbs Glacier Formation and the interglacial Cockburn Island Formation in the James Ross Island area. The localized presence of abundant A. anderssoni within the permafrost suggests that the fossils have been frost heaved from an outcrop of either the Cockburn Island or the Hobbs Glacier formations, originally deposited on northern James Ross Island. The overall shell form, general absence of associated Antarctic Peninsula-derived clasts in the host sediment, and the measured 87 Sr/ 86 Sr isotope ratio of the shells (0.709050) which is indistinguishable from that for pectinid bivalves from the Cockburn Island Formation on Cockburn Island (0.709047) suggest that the shells were derived from a unit similar in age to the Cockburn Island Formation. This suggests that the Cockburn Island Formation was originally more laterally extensive than was previously known.

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