T33G-03
Geodynamic Drivers of Vertical Crustal Motion: Integrating Paleoaltimetry with Basin Development in the Central Andean Plateau of Southern Peru
Wednesday, 16 December 2015: 14:10
304 (Moscone South)
Kurt E Sundell II1, Joel Edward Saylor1, Thomas J Lapen2, Dustin Patrick Villarreal1, Richard H Styron3, Brian K Horton4,5 and Jose Cardenas6, (1)University of Houston, Department of Earth and Atmospheric Sciences, Houston, TX, United States, (2)University of Houston, Houston, TX, United States, (3)Earth Analysis, Seattle, WA, United States, (4)University of Texas at Austin, Department of Geological Sciences and Institute for Geophysics, Austin, TX, United States, (5)Department of Geological Sciences and Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, TX, United States, (6)Departamento Académico de la Universidad Nacional de San Antonio Abad del Cusco, Cusco, Peru
Abstract:
Determining the spatial and temporal relationships between surface uplift, tectonic subsidence, and exhumation during periods of oblique crustal shortening is essential to discriminating geodynamic processes controlling formation of high topography in the central Andes. Although subsidence analysis is now a standard tool, paleoelevation estimation remains a challenging task, as estimates based on proxy data can be complicated by uncertainties in the relative controls of tectonics and climate. We therefore adopt an approach of combining established tools of subsidence analysis and detrital geochronology with emerging methods of volcanic glass paleoaltimetry, which enables us to explore a broad range of viable interpretations to understand the development of intermontane basins and their relationship to the development of the central Andean plateau. We investigated a suite of temporally overlapping and spatially separate Cenozoic basins spanning the east-west extent of the central Andean plateau in southern Peru. These basins contain an exceptional record of the vertical movements of this region. We calculate sediment accumulation and subsidence rates through decompaction of measured stratigraphic sections, and reconstruct past environmental conditions based on the stable isotopic composition of ancient waters preserved in hydrated volcanic glass. These data and published records of crustal shortening and exhumation show that although paleoaltimetry data in the study areas may be interpreted in various ways, they are best explained by multiple geodynamic processes driving (i) Eocene–early Miocene development of high topography in the Western Cordillera, then (ii) a pulsed middle Miocene–present building of the central Andean plateau from west to east, consistent with global climate changes as well as regional climate shifts driven by topographic development of the Andean orogen.
