2009 Portland GSA Annual Meeting (18-21 October 2009)
Paper No. 253-4
Presentation Time: 9:00 AM-6:00 PM

BASIN ANALYSIS OF AN EVOLVING FORELAND BASIN IN THE EASTERN CORDILLERA (ANGASTACO BASIN, NW ARGENTINA)

BYWATER-REYES, Sharon V., Department of Geology and Geophysics, University of Wyoming, Dept. 3006, 1000 E. University Ave, Laramie, WY 82071, sbywater@uwyo.edu, CARRAPA, Barbara, Department of Geology & Geophysics, University of Wyoming, 1000 East University Avenue, Laramie, WY 82071-3006, and MORTIMER, Estelle, School of Earth and Environment, University of Leeds, Earth Science Building, Leeds, LS2 9JT, United Kingdom

Basins of the southeastern margin of the Puna plateau (NW Argentina) preserve thick sequences of Cenozoic continental clastic deposits associated with Eastern Cordilleran mountain building. One of these basins, the Angastaco basin, contains > 6 km of Cenozoic Payogastilla Group strata. The Angastaco basin is the result of foreland basin development in the early Cenozoic; however flexural modeling has not been conducted. Middle Miocene deformation has folded and tilted the Eo-Oligocene Sierra de los Colorados, Miocene Angastaco Formation, upper Miocene Palo Pintado Formation and Pliocene San Felipe Formation. It is unclear how deformation has affected basin deposition and how the detrital record preserved in the Angastaco basin fits within a regional foreland. This study evaluates the foreland evolution of the Angastaco basin via basin analysis and sedimentology. Backstripping from the Angastaco basin and a basin now structurally separated from the Angastaco basin, the La Viña basin, reveals the geometry of an asymmetrical foreland basin. The tectonic component of accommodation in the Angastaco basin is 2.2 km from the period ~37.6 to ~3.3 Ma and the most rapid increase in accommodation corresponds to deposition of the Angastaco Formation at ~14 Ma. Tectonic accommodation steadily decreases from the time of deposition of the Palo Pintado Formation. The tectonic component of accommodation in the La Viña basin is 0.4 km for the same period with no significant change in rate. The best match from flexural modeling conducted using the modern topography as a load is an infinite plate with an effective elastic thickness of 25 km. This study documents the evolution of foreland basin depozones in the Angastaco basin region from a proximal foredeep to wedgetop during deposition of the upper Quebrada de los Colorados Formation and Angastaco Formation and to an intermontane basin during deposition of the Palo Pintado and San Felipe formations.

2009 Portland GSA Annual Meeting (18-21 October 2009)
General Information for this Meeting
Session No. 253--Booth# 269
Tectonics and Basins of Convergent Margins (Posters)
Oregon Convention Center: Hall A
9:00 AM-6:00 PM, Wednesday, 21 October 2009

Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 657
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