TY - JOUR
T1 - Plio-Pleistocene facies environments from the KBS Member, Koobi Fora Formation
T2 - implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana Basin (northwest Kenya)
AU - Lepre, Christopher J.
AU - Quinn, Rhonda L.
AU - Joordens, Josephine C.A.
AU - Swisher, Carl C.
AU - Feibel, Craig S.
N1 - Funding Information:
We would like to thank the National Science Foundation, Netherlands Organisation for Scientific Research (NWO), Catharine van Tussenbroek Foundation, Prins Bernhard Cultuurfonds, and the Center for Human Evolutionary Studies (CHES, Rutgers University) for financial support. Our gratitude is extended to Mr. Kamoya Kimeu, Mr. Muthoka Kivingo, Mr. Ndolo Muthoka, and the Koobi Fora Research Project for logistical support in the field. Andrew Cohen, Jim Russell, and several anonymous reviewers markedly improved earlier drafts of this paper. We also thank Beth A. Christensen and Mark Maslin for their solicitations and work with organizing the 2004 American Geophysical Union sessions on African Continental Paleoclimate and Hominid Evolution and this special issue of the Journal of Human Evolution. Editorial comments of Susan Antón are greatly appreciated. Finally, we thank the National Museums of Kenya for facilitating our research endeavors in the Koobi Fora Region.
PY - 2007/11
Y1 - 2007/11
N2 - Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession (∼20,000 years) and obliquity (∼40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of monsoonal rainfall variations that derive from orbital insolation and/or glacial forcing.
AB - Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession (∼20,000 years) and obliquity (∼40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of monsoonal rainfall variations that derive from orbital insolation and/or glacial forcing.
KW - Depositional environments
KW - East Africa
KW - Hominin evolution
KW - Lacustrine sedimentation
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U2 - 10.1016/j.jhevol.2007.01.015
DO - 10.1016/j.jhevol.2007.01.015
M3 - Article
C2 - 17919684
AN - SCOPUS:35648996401
SN - 0047-2484
VL - 53
SP - 504
EP - 514
JO - Journal of Human Evolution
JF - Journal of Human Evolution
IS - 5
ER -