Environmental Interpretation of Marine Isotope Stage M2 (3.12-3.264 Ma) through the use of Antarctic diatoms in the Weddell Sea
Abstract
Over the last 5 million years, the global benthic foraminiferal δ18O record shows a +1.5‰ shift reflected by colder temperatures and increase ice cover. The Marine Isotope Stage (MIS) M2 (3.312-3.264 Ma) is a global glaciation event that corresponds to a +0.5‰ shift. This 50 thousand year (kyr) event, associated with a 20 to 60 m sea level drop, precedes Arctic glaciation and is associated with the onset of the glacial-interglacial cycles of the Quaternary. The samples used in this study are from ODP Site 697 from 3.6-3.2 Ma. We examined the diatom community of 15 samples for their use as paleoenvironmental proxies. All samples are dominated by Chaetocerous resting spores, reaching an average relative abundance of 27%. Diatom assemblages through our 400 kyr sample interval are generally characterized by open ocean related species, but the presence of sea ice related species increases in the younger material. Preliminary results show the MIS M2 event at Site 697 is marked by a reduction in productivity associated with the proliferation of sea ice, indicated by the highest relative abundance of Thalssiosira antarctica (9.9%, 3.25 Ma). Also, we find evidence to support the southern migration of the Antarctic Polar Front around 3.6 Ma, through diatom mats generated by the species Thalassiothrix antarctica. Greater sampling resolution of diatoms from this interval coupled with statistical analysis will allow for more detailed environmental interpretations.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMED13E0795C
- Keywords:
-
- 0810 Post-secondary education;
- EDUCATIONDE: 0850 Geoscience education research;
- EDUCATIONDE: 0855 Diversity;
- EDUCATION