The geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances

TitleThe geochemistry of glacial deposits in Taylor Valley, Antarctica: Comparison to upper continental crustal abundances
Publication TypeJournal Article
Year of Publication2019
AuthorsDowling, C, Welch, S, W Lyons, B
JournalApplied Geochemistry
Date Published05/2019
KeywordsAntarctica, geochemistry, glacial deposits, polar dry-based glaciers, Taylor Valley
Abstract

Wet-based glacial deposits have been used traditionally as an analog for upper continental crust (UCC) abundances. To provide more information on the validity of using glacial deposits from wet-based glaciers, samples deposited by the dry-based polar glaciers located in Taylor Valley, Antarctica, were collected. Stream channel sediments, comprised of igneous, metamorphic, and sedimentary rocks initially deposited as glacial tills by polar glaciers, were analyzed by XRF, ICP-MS, and SEM. Based on the Chemical Index of Alteration values and A–CN–K ternary diagram, there are low levels of chemical weathering in these tills. Additionally, major and trace element geochemical data are compared to the average UCC values. The observed discrepancies between the mean UCC and Antarctic samples develop from the existence of mafic components, most likely the McMurdo Volcanic Group and Ferrar Dolerite, being present in the Taylor Valley tills. Even though the mafic material typically comprises 3–7% of the till, the volcanic rocks have a significant influence on the tills’ bulk geochemistry. The existence of this mafic fraction in the dry-based glacial tills results from the reduced rate of weathering, as compared to wet-based glaciers. Geochemical analyses of the dry-based glacial tills in polar deserts, such as those found in Taylor Valley, may provide a better representative composition of the original material than wet-based glaciers and need to be incorporated into upper continental crust calculations.

URLhttps://www.sciencedirect.com/science/article/pii/S0883292719301246
DOI10.1016/j.apgeochem.2019.05.006
Short TitleApplied Geochemistry