Sedimentology of Lower Pliocene to Upper Pleistocene Diamictons from IODP Site U1358, Wilkes Land Margin, and Implications for East Antarctic Ice Sheet Dynamics

During the early Pliocene a dynamic marine-based ice sheet retreated from the Wilkes Land margin with periodic ice advances beyond Last Glacial Maximum position. A change in sand provenance is indicative of a more stable Mertz Glacier system during the Late Pleistocene. East Antarctic Ice Sheet (EAI...

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Bibliographic Details
Published in:Antarctic Science
Main Authors: Orejola, Nadine, Passchier, Sandra
Format: Text
Language:unknown
Published: Montclair State University Digital Commons 2013
Subjects:
continental shelf
geochemistry
heavy minerals
particle size
provenance
Antarctic
Victoria Land
East Antarctic Ice Sheet
Wilkes Land
Mertz Glacier
Wilkes Subglacial Basin
Antarc*
Ice Sheet
Iceberg*
Online Access:https://digitalcommons.montclair.edu/earth-environ-studies-facpubs/529
https://doi.org/10.1017/S0954102013000527
Description
Summary:During the early Pliocene a dynamic marine-based ice sheet retreated from the Wilkes Land margin with periodic ice advances beyond Last Glacial Maximum position. A change in sand provenance is indicative of a more stable Mertz Glacier system during the Late Pleistocene. East Antarctic Ice Sheet (EAIS) dynamics were evaluated through the analysis of marine diamictons from Integrated Ocean Drilling Program (IODP) site U1358 on the Adélie Land continental shelf. The warmer than present conditions of the early Pliocene coupled with the site's proximity to the landward sloping Wilkes Subglacial Basin provided the rationale for the investigations at this site. Based on visual core descriptions, particle size distributions, and major and trace element ratios, we interpret the origin of lower Pliocene strata by intermittent glaciomarine sedimentation with open-marine conditions and extensive glacial advances to the outer shelf. Heavy mineral analyses show that sand-sized detritus in the lower Pliocene strata was sourced from local intermediate to high-grade metamorphic rocks near Mertz Glacier. In contrast, Pleistocene diamictons exhibit a larger contribution from a prehnite-pumpellyite greenschist facies suggesting supply via iceberg rafting from northern Victoria Land. From this sedimentological evidence, we postulate a shift from a dynamic EAIS margin in the early Pliocene to possible stabilization in the Pleistocene.

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