Microfossils in Mercer Subglacial Lake

Amy Leventer, Department of Geology, Colgate University, 13 Oak Dr, Hamilton, NY 13346 David Harwood, Department of Earth and Atmospheric Sciences, University of Nebraska, 1400 R St, Lincoln, NE 68588 SALSA Science Team,

Microfossils from sediment cores collected from Mercer Subglacial Lake (SLM) are used to help reconstruct the history of the overlying West Antarctic Ice Sheet. During the Subglacial Antarctic Lakes Scientific Access (SALSA) project, SLM, a 15-m deep lake under 1092 m of glacial ice, was accessed via clean hot-water drilling. The team collected 10 short sediment cores 0.45 m maximum length, with a modified Uwitek multicorer, and two free-fall gravity cores, 0.97 and 1.78 m length. Primary objectives of the SALSA project were to understand the geologic and biologic history of SLM, as recorded in the lake sediments and to determine the primary source of carbon for microbial communities in SLM. While relatively sparse, well-preserved microfossils present in the sediments include diatoms, silicoflagellates, ebridians, sponge spicules and cysts of unknown affinity. Age diagnostic marine diatoms are primarily Oligocene, Pyxilla reticulata and Pseudotriceratium radiosoreticulatum, and latest Miocene, Thalassiosira oliverana var. sparsa, Thalassiosira torokina, Actinocyclus fryxellae, and Fragilariopsis praecurta, indicating the presence of open marine waters at those times. No taxa diagnostic of Pliocene or Pleistocene age were observed, as has been reported in other sub ice shelf and sub ice sheet samples, though many long-ranged diatom species were observed. Clues to paleoenvironment include the presence of the silicoflagellate, Dictyocha fibula, a relatively warm water form, the occurrence of fragments of large epiphytic diatoms, transported from shallow water, and a combination of excellent preservation of valves and the presence of numerous colonies of diatoms, suggesting short transport distances.  Yet to be identified are cysts, approximately 25 microns in diameter. Ongoing research will focus on establishing the stratigraphic framework of these initial observations. 

Additional Abstract Information

Presenter: Meaghan Kendall

Institution: Colgate University

Type: Poster

Subject: Geography/Geology

Status: Approved

Time and Location

Session: Poster 7
Date/Time: Tue 3:30pm-4:30pm
Session Number: 5073