HR: 0800h
AN: U21A-0706    [Abstracts]
TI: Connecting Local Environmental Sequences to Global Climate Patterns: Evidence From the Hominin-Bearing Hadar Formation, Ethiopia.
AU: * Campisano, C J
EM: cjcampi@rci.rutgers.edu
AF: Department of Anthropology, Rutgers University, New Brunswick, NJ 08901-1414 United States
AU: Feibel, C S
EM: feibel@rci.rutgers.edu
AF: Department of Anthropology, Rutgers University, New Brunswick, NJ 08901-1414 United States
AU: Feibel, C S
EM: feibel@rci.rutgers.edu
AF: Department of Geological Sciences, Rutgers University, Piscataway, NJ 08854-8066 United States
AB: Central to the debate surrounding global climate change and Plio-Pleistocene hominin evolution is the degree to which large-scale climate patterns influence low-latitude continental ecosystems and how these global influences can be distinguished from regional tectono-volcanic events and local environmental effects. These isolated factors must then be compared to trends or events in the hominin fossil or archaeological record. The Pliocene Hadar Formation preserves a high-resolution record of hominin paleoenvironments from roughly 3.5 to 2.3 Ma. The chronostratigraphic framework at Hadar, often divisible into sub-50,000 year intervals, provides temporal resolution relevant to evolutionary change within hominins and other taxa. Combined with a high sedimentation rate and abundant faunal remains, this tightly controlled stratigraphic framework allows Hadar to be compared to detailed climate proxies such as marine core isotope, dust, and sapropel records. Preliminary analyses from Hadar suggest that these comparisons can be used to distinguish local versus regional and global environmental change, determine the overall sensitivity of the Hadar system and its fauna to such change, and how this level of sensitively compares to other East African localities. Consistent cycling observed both between and within fluvial and lacustrine depositional environments prior to 2.9 Ma at Hadar appears to be dominantly climatic in nature. However, a significant change in depositional facies after 2.9 Ma to sequences dominated by conglomerate cut-and-fill cycles indicates a strong tectonic signature related to regional developments in the Main Ethiopian Rift (MER). While specific events seen in marine proxy records may have parallels in the Hadar environmental archive, their overall patterns of high versus low variability may be even more relevant. For example, periods of relatively high amplitude climate oscillations between 3.15 and 2.95 Ma may be linked to noted morphological changes within the Hadar australopithecine lineage. Similarly, high-resolution records such as those preserved at Hadar can be used to test theories of hominin evolution such as habitat-specific versus variability selection.
DE: 9305 Africa
DE: 9604 Cenozoic
DE: 8110 Continental tectonics--general (0905)
DE: 3344 Paleoclimatology
DE: 1620 Climate dynamics (3309)
SC: Union [U]
MN: 2004 AGU Fall Meeting