Controls on Sediment Supply and Stratigraphic Response in the Mio-Pliocene Bermejo Foreland Basin, Central Andes

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Studies of sedimentary basins are beginning to integrate solid-earth phenomena and surficial processes. In foreland basins, conceptujal and quantitative models have reached the point at which areful tests are needed of predictions. The PIs will use the Bermejo basin, in the foreland of the Andes in western Argentina, as a testing ground. Mio-Pliocene strata of the Bermejo basin are well known on the basis of several complementary data sets. A central objective is to measure the volume of sediment preserved in the Bermejo basin in successive 1 to 2 million year intervals. The volume history will be compared to the history of source areas and to the distribution of facies in the basin. This information will provide new insight into the constancy of sediment supply to a foreland basin on a short time scale and to the impact that variable sediment supply might have on the character of the strata. The PIs will better constrain the history of deformation by gathering additional chronological data, for strata which show cross-cutting relations to thrust faults and for strata in a piggyback basin which is likely to be controlled by thrust activity. Comparison of the thrust history to the history of volume of sediments through time will demonstrate the response of erosion and sediment flux to thrust-indiced topography. This information will be utuilized in the next generation of conceptual and quantitative models of erosion of mountain belts and stratigraphy in foreland basins.