Preliminary Wavelet Analysis of Circum-Antarctic Odp Well Logs and Split-Core XRF Scans From Odp Site 697 Cores Infers Obliquity Signal

Abstract

Global geological evidence from marine and terrestrial systems has demonstrated that prior to the onset of vast northern hemisphere glaciation in the Pleistocene, early Pliocene atmospheric CO 2 levels were near 400 p.p.m.v., and global mean temperatures were approximately 3°C warmer than present (Raymo et al., 1996; Pagani et al., 2010). These conditions offer a powerful analogue in the paleoclimate record that can be used to inform modern anthropogenic warming and sea level rise. Well-dated marine lithostratigraphic constraints from the Ross Sea by the ANDRILL program have linked 40-kyr fluctuations in the ice sheet extent and sediment record to orbitally-driven cycles in solar insolation (changes in Earth's obliquity; Naish et al., 2009). This project utilizes Ocean Drilling Program (ODP) cores from Expedition 113 in the Weddell Sea and Integrated Ocean Drilling Program (IODP) and ODP geophysical down-hole well logs from Expeditions 119 and 188 from Prydz Bay, Expedition 178 from the Bellingshausen Sea, and Expedition 318 offshore Wilkes Land to study the connection between nearshore diatomite-diamicton sequences (ANDRILL) and distal circum-Antarctic continental shelf sediments. While the ANDRILL program was able to study glacial cycles by directly identifying lithological facies diagnostic of either glacial advance or retreat, this project uses sediment cores (XRF) and borehole measurements (gamma ray and resistivity) in its analysis. LOCALITIES This study considers four circum-Antarctic marine ODP/ IODP locations: the Weddell Sea, Prydz Bay, the Bellingshausen Sea, and offshore Wilkes Land (see O'Connell, this volume for location map). Expedition 113 Site 697 is located northeast of the Antarctic Peninsula in the northwestern Weddell Sea, close to where the Weddell Gyre joins the Antarctic Circumpolar Current, both of which flow clockwise.