7-4 Bugs in the Mud: Examination of Benthic Foraminifera in the Pleistocene Cool-Water Carbonates of the Southern Tasman Ocean (ODP Leg 189, Sites 1171C and 1168A)

Session: Undergraduate Research, Part I (Posters)

Presenting Author:

Authors:

Abstract:

Leg 189 of the Ocean Drilling Project’s (ODP) collected core samples in the Southern Tasman Sea to better understand the formation of this seaway and its geological and paleoceonographic setting. Using Pleistocene sediments collected during this expedition (A white-light grey foraminifer-bearing nannofossil ooze), this study explores the community dynamics of the benthic foraminifer fossils from these sediments to add to the understanding of the Southern Tasman Sea. The hope for this study is to use the addition of faunal data to support paleoceonographic claims made in previous projects, provide additional information on gathered foraminiferal data through statistical methods, and detail our own conclusions on the site given the new information.

This low-resolution study was done by adding additional benthic foraminiferal data to the previous 1171C ((Located roughly 550 km south of Tasmania.) database and comparing those statistical and biological results to known results from Site 1168A of the same ODP Leg 189. (Located roughly 70km west of the central Tasmanian coast.) These samples, washed and sieved to the >125 size fraction for the purpose of picking and identifying foraminifer specimens, were obtained from the Gulf Coast Repository for use in this study. In total, the study includes four samples ranging from Site 1171C that are 15ky – 115ky in age and spaced roughly 20-30ky apart, in addition to the results of the previous study of Site 1168A fauna (Evans, et al., 2023). Given student time constraints, only one extra sample was added to the previous Site 1171C data.

With the addition of this sample’s data, we performed preliminary statistical analysis on the total collected foraminiferal population dynamics across the four sampling sites of Site 1171C and compared those findings to known Site 1168A statistical findings. Using publicly available data collected from site 1171C and 1168A sediments during the research cruise, we offer a detailed look at a portion of the benthic foraminiferal community and hopefully inspire more work in understanding its link to the paleoceonographic setting of the Southern Tasman Sea.

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.