Record of Late Miocene glacial deposits on Isla Marambio (Seymour Island), Antarctic Peninsula

Abstract We report and describe two new small diamictite outcrops on Isla Marambio (Seymour Island), Antarctic Peninsula. These rocks rest on an erosional unconformity on top of the Eocene La Meseta Formation and are unconformably covered by glaciomarine rocks of the ?Pliocene–Pleistocene Weddell Se...

Full description

Bibliographic Details
Published in:Antarctic Science
Main Authors: Marenssi, Sergio A., Casadío, Silvio, Santillana, Sergio N.
Format: Article in Journal/Newspaper
Language:English
Published: Cambridge University Press (CUP) 2009
Subjects:
Online Access:http://dx.doi.org/10.1017/s0954102009990629
https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0954102009990629
Description
Summary:Abstract We report and describe two new small diamictite outcrops on Isla Marambio (Seymour Island), Antarctic Peninsula. These rocks rest on an erosional unconformity on top of the Eocene La Meseta Formation and are unconformably covered by glaciomarine rocks of the ?Pliocene–Pleistocene Weddell Sea Formation. The lithology, fossil content and isotopic ages obtained strongly suggest that the rocks belong to the Hobbs Glacier Formation and support a Late Miocene age for this unit. Additionally, the dated basalt clast provides the oldest age (12.4 Ma) for the James Ross Island Volcanic Group recorded up to now. The here described diamictite cannot be confidently correlated with a glaciomarine unit previously assigned to the Late Eocene–Lower Oligocene taken as proof that initial expansion of ice on Antarctica encompassed the entire continent synchronously in the earliest Oligocene. However, it is now evident that there are likely to be more, short but important, stratigraphic sequences of key regional and Antarctic wide interest preserved on the plateau of Isla Marambio.