Geology of the Wilkes Land Sub-basin and stability of the East Antarctic ice sheet; insights from rock magnetism at IODP Site U1361

Author(s): Tauxe, Lisa; Sugisaki, Saiko; Jimenez-Espejo, Francisco J.; Cook, Carys P.; van de Flierdt, Tina; Iwai, Masao; Escutia, Carlota
Author Affiliation(s): Primary:
University of California at San Diego, La Jolla, CA, United States
University of Tokyo, Japan
Japan Agency for Marine-Earth Science and Technology, Japan
University of Florida, United States
Imperial College London, United Kingdom
Kochi University, Japan
Instituto Andaluz de Ciencias Tierra, Spain
Volume Title: AGU 2014 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2014; American Geophysical Union 2014 fall meeting, San Francisco, CA, Dec. 15-19, 2014. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English. 3 refs.
Summary: IODP Expedition 318 drilled Site U1361 on the continental rise offshore of the Wilkes sub-glacial basin. The goal was to reconstruct the stability of the East Antarctic Ice Sheet (EAIS) during Neogene warm periods. Teasing out the paleoenvironmental implications is essential for understanding the evolution of the EAIS. Anisotropy of magnetic susceptibility (AMS) is sensitive to differential compaction and other rock magnetic parameters like isothermal remanence and anhysteretic remanence are very sensitive to changes in the terrestrial source region. In general, highly anisotropic layers correspond with laminated clay-rich units, while more isotropic layers are bioturbated and have less clay. Layers enriched in diatoms are associated with the latter, which also have higher Ba/Al ratios indicating higher productivity. Higher anisotropy layers have lower porosity and moisture contents and have fine grained magnetic mineralogy dominated by magnetic. Higher anisotropy layers are dominated by maghemite, supporting the suggestion by Cook et al. (2013) of different source regions during low and high productivity times. They tied the two facies to the coastal outcrops of the Lower Paleozoic granitic terranes and the Ferrar Large Igneous Province in the more inland Wilkes Subglacial Basin respectively. Here we present evidence for a third geological unit, one eroded at the boundaries between the high and low clay zones with a "hard" (hematite) dominated magnetic mineralogy. This unit likely outcrops in the Wilkes sub-glacial basin and could be hydrothermally altered Beacon sandstone similar to that detected by Craw and Findlay (1984) in Taylor Valley or the equivalent to the Elatina Formation in the Adelaide Geosyncline in Southern Australia (Schmidt and Williams, 2013).
Year of Publication: 2014
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Anisotropy; Antarctic ice sheet; Antarctica; Cenozoic; East Antarctic ice sheet; Expedition 318; IODP Site U1361; Integrated Ocean Drilling Program; Magnetic properties; Magnetic susceptibility; Magnetostratigraphy; Neogene; Paleomagnetism; Southern Ocean; Tertiary; Wilkes Land
Coordinates: S642434 S642434 E1435312 E1435312
Record ID: 2015116821
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