STRUCTURAL ORIGIN OF CLASTIC INTRUSIONS IN THE AND-2A ROCK CORE, SOUTHERN MCMURDO SOUND, ANTARCTICA

This project focuses on the tectonic evolution of the Transantarctic Mountains and the West Antarctic Rift System. The project involves analyzing structures in core obtained by the Antarctic Geological Drilling (ANDRILL) project. Specifically, by compiling various forms of descriptive data I hope to explore the structural origin of sedimentary intrusions found in the core. I am performing petrographic analysis on 13 prepared thin section samples of the core to 1) validate the structure is a sedimentary intrusion, 2) characterize the textures present, and 3) observe how the intrusion interacts with the host rock and other structures. After sedimentary textures within the intrusions are logged and understood, I will be performing a stereonet analysis using the orientations of the intrusions. This will allow for understanding of the stress regime that was in place when these features formed, and will allow for interpretation of their structural origin. I will also try to understand how these features interact with other structures such as faults, veins, and brecciation zones. Understanding the formation of these sedimentary intrusions will provide new insight into tectonic conditions during Cenozoic sediment deposition as well as the glacial history of the Victoria Land Basin. Sedimentary intrusions are thought to be formed in strata where there are high fluid pressures caused by vertical loading of the sediment pile. In addition, the process of sedimentary intrusion is believed to be aided by extensional stresses. Current understanding of the sedimentary intrusions suggests they may be formed due to 1) loading of the sediment caused by glaciers/ice sheets, or 2) regional extension. My study seeks to better understand how these mechanisms interact. I will use petrographic observation and stereonet analysis of sedimentary intrusions in the AND-2A rock core to draw conclusions that further elucidate specifics of extension in the Victoria Land Basin, and how isostatic and/or extensional stresses may have caused the formation of sedimentary intrusions within the strata sampled by the ANDRILL core.