T171 Paleoenvironmental Reconstruction of Hominin Sites: New Methods, New Data, and New Insights II

Monday, 2 November 2015
1:30 PM - 5:30 PM
Room 324

NEW INVESTIGATIONS ON HOMININ PALEOLANDSCAPES, PALEOENVIRONMENTS AND PALEOCLIMATES THROUGH SCIENTIFIC CORING AT OLDUVAI GORGE, TANZANIA

Paper number: T171-8
Program: Technical Sessions
Time: 3:10 PM – 3:25 PM

Authors

Abstract

Initial results of the successful Olduvai Gorge Coring Project represent the first attempt to extract a detailed paleoenvironmental core record from this critically important paleoanthropological site in northern Tanzania. Four high-quality cores were obtained in 2014 from 3 strategic Olduvai basin locations, targeting inferred positions of Paleolake Olduvai during Beds I, II, III and younger); the fourth core was inclined 23° for detailed paleomagnetic studies, one of few successful angled cores obtained in equatorial Africa. Almost 600m of core were retrieved (average recovery ~94%), sampling the well-preserved lacustrine and lake marginal sediments of the Olduvai sequence. The majority of important archaeological outcrop exposures are within five kilometers of a borehole, providing excellent opportunity to link the detailed paleoclimatic and paleoenvironmental record of the core to sites documenting biological changes in hominin species (Australopithecus boisei, Homo habilis, Homo erectus, and prehistoric Homo sapiens) and cultural behavior (from Oldowan to Acheulean to Middle Stone Age) over ~2 million years.

Downhole logging included natural gamma ray, magnetic susceptibility, and electromagnetic induction (conductivity and resistivity), and an international, multidisciplinary team is now analyzing the cores for lithofacies/stratigraphy, radiometric dating, paleomagnetism, tephrostratigraphy, mineralogy, C and O isotopes, biomarkers, and paleobiology (phytoliths, ostracodes, diatoms, and pollen).

Our study approach relates a known hominin site horizon at outcrop to specific core depths, applying marker tuffs and sequence stratigraphic boundaries as correlative tools. These techniques will provide precise tie-lines between the abundant Olduvai hominin occurrences (archeological and paleontological) to the high-resolution paleoclimatic and paleoenvironmental record in the core. E.g. Tuff IF is identified in all four cores, establishing the boundary between Olduvai Beds I and II and thus the equivalent core depth of HWK E Level 1. The completeness of the borehole record should establish the core as a key inland Pleistocene reference for East Africa and make a major contribution to understanding climatic, tectonic, environmental and biological forcing of human evolution.