Ice Sheet Dynamics of the Past 17 Myr in Southern McMurdo Sound, Antarctica: A Heavy Mineral Analysis

• Main Author: Hauptvogel, Daniel William
• Format: Text
• Language: unknown
• Published: Montclair State University Digital Commons 2010
• Subjects: Earth Sciences; Environmental Sciences; Antarctic; The Antarctic; Ross Sea; West Antarctic Ice Sheet; McMurdo Sound; East Antarctic Ice Sheet; Ross Ice Shelf; Transantarctic Mountains; Antarc*; Antarctica; Ice Sheet; Ice Shelf; Sea ice
• Online Access: https://digitalcommons.montclair.edu/etd/880; https://digitalcommons.montclair.edu/context/etd/article/1882/viewcontent/Hauptvogel_Thesis_2010_Redacted.pdf

The ANtarctic Geologie DRILLing program (ANDRILL) drilled a sediment core from a sea ice platform in the Ross Sea in southern McMurdo Sound (SMS), Antarctica, in late 2007. The core site is located just to the east of the Transantarctic Mountains (TAM) along the western margin of a half graben and is a site of heavy sedimentation from the TAM, the East Antarctic Ice Sheet (EAIS), the McMurdo Volcanic Group (MVG), and the West Antarctic Ice Sheet (WAIS) and Ross Ice Shelf. The upper 650 m of the core were analyzed for heavy minerals in order to interpret ice sheet drainage patterns and dynamics of the past 17 Myr. Grain mounts of the fíne sand sized (63-250 pm) heavy mineral fraction of 23 intervals were created and approximately 300 grains were identified per slide. The data represents a major change in sediment provenance and indicates the Middle Miocene Climate Transition (MMCT), which was a cooling period 13.8-14.2 Ma. The period before the MMCT is represented by a invariant assemblage of heavy minerals in the interval 300 - 650 mbsf (15-17 Ma), especially static 350 - 550 mbsf, with a provenance of the Koettlitz and Ferrar Glaciers. This suggests a distal ice sheet relative to the SMS core site that is not providing any influence. Between 240 and 300 (13.8 - 15 Ma) mbsf, a change in provenance from local TAM to MVG and southern TAM occurred and mineral assemblages representing these source rocks are more abundant in the upper 240 m. This suggests a cooler environment in which the WAIS is expanding and forces transport and deposition of sediment by the EAIS from further south. This correlates well with clast provenance, wholerock geochemical data, and stratigraphic interpretations performed by other SMS team members.