Paper No. 219-6
Presentation Time: 2:50 PM
RECONSTRUCTING MIOCENE ECOLOGIES IN THE TURKANA BASIN: INSIGHTS FROM PLANT WAX N-ALKANES
TWEEDY, Ruth1, UNO, Kevin2, SASLAW, Mae3, HENKES, Gregory3, BECK, Catherine4, FEIBEL, Craig5, LUKENS, William E.6, STINCHCOMB, Gary E.7, LIUTKUS-PIERCE, Cynthia8, MILLER, Ellen9, MINYA, Aggrey10, SHEDROFF, Sara11, GREEN, Daniel R.2, HOUSE, Ashley12 and BAPANA, Sneha13, (1)Earth & Planetary Science, Harvard University, Cambridge, MA 02138, (2)Human Evolutionary Biology, Harvard University, 601 West 115th Street, Cambridge, MA 02138, (3)Department of Geosciences, Stony Brook University, Stony Brook, NY 11794, (4)Dept of Geosciences, Hamilton College, Clinton, NY 13323, (5)Earth and Planetary Sciencies and Anthropology, Rutgers University, New Brunswick, NJ 08901, (6)Department of Geology and Environmental Science, James Madison University, Harrisonburg, VA 22807-1004, (7)Department of Earth Sciences, University of Memphis, Memphis, TN 38152, (8)Geological and Environmental Sciences, Appalachian State University, 572 Rivers Street, Boone, NC 28608, (9)Department of Anthropology, Wake Forest University, Winston-Salem, NC 27106, (10)Turkana University College, Nairobi, Kenya, (11)Geosciences Department, Hamilton College, 198 College Hill Road, Clinton, NY 13323, (12)Columbia University, 116th and Broadway, New York, NY 100227, (13)Barnard College, 3009 Broadway, New York, NY 10027
This study advances understanding of the Turkana Basin's Miocene ecology through the analysis of plant wax n-alkanes – molecular remains of past vegetation. These biomarkers are analyzed for chain length distributions and their carbon (δ13C) and hydrogen (δD) isotopic signatures to elucidate past plant communities and hydrology.
We present δ13C and δD measurements from three key paleontological localities within the basin: Buluk (~16-17 Ma), Loperot (~17 Ma), and Locherangan (~17.5 Ma). Collectively, these sites have produced important cercopithecoid (e.g., Noropithecus bulukensis) and hominoid (e.g., Afropithecus turkanensis, Limnopithecus legetet, and Rangwapithecus gordoni) fossils. The close temporal relationship of these sites allows us to compare habitat ecology at the onset of the Middle Miocene Climatic Optimum within a narrow time frame.
All three sites yield δ13C data indicating ecosystems characterized wholly by C3 plant biomass – traditionally interpreted as woody vegetation. These pure C3 ecosystem reconstructions corroborate tooth enamel data from these sites which suggest C3 diets, but the Buluk dataset provides a counterpoint to previously published paleosol carbonate δ13C data which demonstrated mixed C3/C4 environments.
Exceptional biomarker preservation at Buluk and Locherangan enables plant wax δD reconstructions of soil water availability. Results are forthcoming and will yield the first plant wax estimates of paleo-precipitation δD from the Turkana Basin, notably during the early Miocene.
These new biomarker records from Buluk, Loperot, and Locherangan offer insight into the region's paleoenvironmental conditions during the onset of the Miocene Climatic Optimum.
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