T169 Oceans and Climates through Earth History: From Proxy Reconstructions to Model Assessments (Posters)

Tuesday, 11 October 2022
9:00 AM - 1:00 PM
Exhibit Hall F

MIDDLE PLEISTOCENE DIATOM PALEOECOLOGY OF LAKE MALAWI, EAST AFRICA

Paper number: T169-26
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

Here we present a ~180 ka record of diatom paleoecology developed from part of the 2005 Lake Malawi deep scientific drill core. Our new record is composed of ~450 samples, ranging in age from ~220-400 ka, which extends the previously published diatom dataset from Lake Malawi. This proxy record incorporates a new age model based upon 39 luminescence ages that for the first time provide absolute ages for this interval. The diatom assemblage is Aulacoseira dominated, indicating high nutrient and high silica conditions. There are isolated intervals of dominance by Thalassiosira and Cyclotelloid diatoms, indicating low nutrient, saline, and alkaline conditions. Though this is a deep-water site, ~590 m water depth today, benthic diatoms form a significant part of the assemblage throughout. The changes in the concentration of benthic diatoms indicate changes in transport within the lake. While many dominant taxa are undescribed and thus do not have known nutrient preferences at the species level, changes in Aulacoseira valve size indicate changes in mixing strength. This new diatom record complements existing proxy records for this core and provides greater insight into seasonality and internal lake dynamics.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-383016

© Copyright 2022 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.