T309 Understanding African Environmental History through Continental Scientific Drilling: Past Successes and Future Opportunities

Wednesday, 25 October 2017
8:00 AM - 12:00 PM
Room 307/308

ENVIRONMENTAL DYNAMICS ON AN EARLY PLEISTOCENE LAKE MARGIN: THE WTK13 CORE AT KAITIO, WEST TURKANA, KENYA

Paper number: T309-11
Program: Technical Sessions
Time: 10:45 AM – 11:00 AM

Authors

Abstract

Records of environmental history from the Turkana Basin of Kenya are of particular interest in contextualizing the setting for early human evolution, the associated African savanna community and this portion of the East African Rift System. The WTK13 core, collected as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP), provides new insights into patterns of environmental development in this basin through the interval from 1.37 to 1.87 Ma. Age control on the core, which spans a portion of the Nachukui Formation, is established from numerous tephra in upper levels, and the top of the Olduvai Subchron lower down.

The WTK13 core recovered a dominantly fine-grained sequence with a complex pattern of facies alternations reflecting primary depositional character (laminites, diatomites, ostracodites) and pedogenic overprinting (vertisols). Investigations integrating lithostratigraphy, mineralogy and facies analysis have established a broad pattern of changes through the core. A diverse array of environmentally sensitive proxies (pollen, plant waxes, diatoms, phytoliths, ostracods) are developing a much more detailed perspective on short-term environmental dynamics.

The WTK13 sequence is interpreted to reflect a predominantly low-gradient lake margin setting, where sedimentation in a shallow lacustrine environment is frequently overprinted by exposure and pedogenesis. Parallel records from the Shungura Formation in Ethiopia reflect strong fluvial dominance, while the Koobi Fora Formation east of present-day Lake Turkana preserves a strong deltaic influence at this time. All record strong orbital climate signals (particularly precession), but the West Turkana record appears to be the most sensitive to high-frequency environmental dynamics.

Close proximity of the WTK13 core to the NK3 hominin site (Turkana Boy) will allow the establishment of a detailed environmental history for that unique fossil specimen, while the half-million-year record of the core expands our understanding of landscape diversity and habitats available through this important evolutionary window in the Turkana Basin.

This work reflects contributions from all members of the Hominin Sites and Paleolakes Drilling Project (HSPDP) and the Turkana Cyclostratigraphy Project (TCP) field and laboratory teams.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-303947

© Copyright 2017 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.