HR: 11:35h
AN: T12D-06    [Abstracts]
TI: Deposition and Deformation in the El Cajon Basin, NW Argentina: a record of climate change, plateau growth and foreland fragmentation
AU: * Schoenbohm, L M
EM: schoenbohm.1@osu.edu
AF: Ohio State University, School of Earth Sciences, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210, United States
AU: Mortimer, E
EM: estelle_mortimer@yahoo.com
AF: University of Leeds, School of Earth and Environment, 912b ES, Leeds, LS2 9JT, United Kingdom
AU: Strecker, M
EM: strecker@rz.uni-potsdam.de
AF: University of Potsdam, Institute for Geological Sciences, Karl-Liebknecht-Str. 24, Golm, D- 14476, Germany
AU: McPherson, H
EM: mcpherson.84@osu.edu
AF: Ohio State University, School of Earth Sciences, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210, United States
AU: Pratt, J
EM: pratt.114@osu.edu
AF: Ohio State University, School of Earth Sciences, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210, United States
AB: The series of intermontane basins located along the southern margin of the Puna Plateau in NW Argentina are uniquely positioned to record a variety of surface, structural and geodynamic processes. Deformed strata in the basins document foreland fragmentation and out of sequence reverse faulting in a thick-skinned setting with pre- existing crustal heterogeneity. The basins also show evidence for closed or restricted outlets and times of filling, which could have led to incorporation into the morphologic plateau. However, the basins have been re-integrated, perhaps multiple times, reflecting both climate and tectonic controls. Finally, the deposition of the Punaschotter conglomerate in late Pliocene or Quaternary time could reflect local tectonic control or regional climate change. In this study we focus on the El Cajon basin, which contains ~1500 m of Miocene through Quaternary sedimentary strata. These strata have been deformed by reverse faulting to the west (Sierra Chango Real) and uplift of a basement cored anticline (Sierra de Quilmes) to the east, and are cut by several mostly east-vergent faults within the basin. Growth strata document syn-depositional deformation. We present new structural mapping and U-Pb dating of 13 intercalated tuffs from the tertiary stratigraphy. These data, in addition to three existing ages, allow detailed determination of the rate of deposition over time, the timing and extent of a lacustrine interval within the basin, the depositional age of the Punaschotter conglomerate, and a maximum age constraint on the onset of basin incision. Combined with our structural analysis, and with data from the other marginal basins, we can assemble a regional picture of basin fragmentation and tectonic and climatic controls on deposition and deformation around the margin of the Puna Plateau.
DE: 8002 Continental neotectonics (8107)
DE: 8169 Sedimentary basin processes
DE: 8175 Tectonics and landscape evolution
DE: 8177 Tectonics and climatic interactions
DE: 9360 South America
SC: Tectonophysics [T]
MN: 2007 Fall Meeting