Orbital-scale variability in biogenic silica accumulation in the Indian ocean sector of the southern ocean during the early pleistocene ...

• Main Author: Muench, Bastian
• Format: Thesis
• Language: English
• Published: University of Delaware 2023
• Subjects: Southern Ocean; Indian; Ice Sheet
• Online Access: https://dx.doi.org/10.58088/sg8t-zn28; https://udspace.udel.edu/handle/19716/33441

The early Pleistocene (0.7 – 2.5 million years ago, Ma) is characterized by d18O and inferred global ice volume variability dominantly at the 41 kyr obliquity periodicity. Despite being hypothesized to substantially influence global ice sheet variability, precessional-scale orbital forcing is barely present in the global d18O record. To further investigate proposed mechanisms responsible for this apparent mismatch and, in particular, to test whether the percent opal record indicates the presence of an interhemispheric d18O cancellation mechanism as proposed by Raymo et al. (2006) during the early Pleistocene, I generated an orbital-scale record of biogenic opal deposition from Ocean Drilling Program Site 745B in the Indian Ocean sector of the Southern Ocean between 1.6 – 2.47 Ma. A robust age model was constructed for this and an unpublished portion of the record between 1.07 and 1.6 Ma by orbitally tuning variations in magnetic susceptibility to variations in the global d18O stack LR04 (Lisiecki & ...