THE PROVENANCE OF GLACIAL TILL DEPOSITED IN ONG VALLEY, CENTRAL TRANSANTARCTIC MOUNTAINS DETERMINED BY LA-ICP-MS OF DETRITAL ZIRCON

In Antarctica, the provenance of glacial till can be used to identify unknown geologic terrains. Combined with cosmogenic nuclide exposure dates, provenance data can be used to indicate if glacial flow patterns have changed over time. In this study, we analyzed detrital zircon from three distinct glacial tills deposited in Ong Valley, central Transantarctic Mountains (157.5°E, 83.25°S) that we refer to as “oldest,” “middle,” and “youngest.” For our analysis, we rely specifically on detrital zircon because it can record age information of crustal units that contributed to the sediment load due to its low solubility in almost all melt and fluid compositions and durability during transport. The U/Pb age of zircon is the chemical signature we will use to determine the source.

To date, a total of 479 zircon grains have been extracted from bulk sedimentary samples. Cathodoluminescence imaging of the grains shows a diversity of zoning, from broad to weak internal zoning to simple oscillatory zone internal structures. LA–ICP–MS data is being reduced using Glitter software for U/Pb analysis, and preliminary results indicate that the range of U/Pb ages stretch from 400 Ma to 3.2 Ga. Initial analyses also suggest that the U/Pb ages of the detrital zircon cluster around three peaks at 570 Ma, 1.4 Ga and 2.6 Ga.

The analysis of detrital zircon from Ong Valley has not been completed before and offers us an opportunity to share unique information that will substantiate the findings of other geologists and glaciologists. Our analyses will provide us with the information necessary to compare previous periods of glacial change, supporting the international effort strongly focused on understanding the glacial change we are experiencing today. Similarly, we’re excited to expand the geographic contribution of combined cosmogenic nuclide exposure dates and provenance data beyond the few Antarctic regions where it has been applied.