Chert formation at IODP Site U1521 as a proxy for variations in marine geochemistry at the onset of the Miocene Climate Optimum

• Main Author: McElmeel, Finlay T.
• Other Authors: Dodd, Justin, Department of Geology and Environmental Geosciences
• Format: Thesis
• Language: English
• Published: Northern Illinois University 2021
• Subjects: Geology; Antarctica; Ross Sea; Geochemistry; Climate Change; Antarctic; Levy; Ross Ice Shelf; The Antarctic; Antarc*; Ice Shelf
• Online Access: https://commons.lib.niu.edu/handle/10843/24318

The goal of International Ocean Discovery Program (IODP) Expedition 374 in the Ross Sea, Antarctica was to collect marine sediment drill cores that would demonstrate the changes in the Antarctic Ice Sheets mass balance during times of Earth history when global temperatures and atmospheric CO2 were higher than today. Intervals such as the Miocene Climatic Optimum (MCO; ~17-14.5 million years ago) provide insights into what a future world could look like (Shevenell et al., 2004; Levy et al., 2016). Ice-proximal records from the near-Antarctic coast, such as those collected during IODP Exp 374, may hold critical information to understanding far-reaching impacts of the Antarctic Ice Sheets on global environmental changes. Depositional reconstructions of past glacial and open marine conditions in the region provide environmental constraints used to model changes in the Antarctic Ice Sheets. In my study, I will explore the presence of glacial deposits (till delta features), which prograde onto stratified glaciomarine sediment in several locations in the region during the Early to Middle Miocene (17.6-16.9 million years ago), immediately preceding the MCO. The samples presented here were collected from IODP Exp 374 Site U1521, from a depth of 287.21 to 344.92 meters below the sea floor (mbsf) and made up of a dark grey, massive to stratified diatom-bearing and clast-poor sandy diamictite as well as grey chert nodules interbedded with dark grey, silica cemented, faintly irregularly laminated mudstones (McKay et al., 2019). This study supports the basic shipboard lithological data, but there is distinct variability in the silica-carbonate content of the chert and upper diamictite layers. These data provide additional evidence for a significant change in depositional environment as a result of fluctuations in the in the Ross Ice Shelf that predate the MCO. B.S. (Bachelor of Science)