The Neogene Chaco foreland basin, Bolivia: Its evolution as related to Andean tectonics

Introduction The up to 200 m wide Chaco foreland basin was initiated during the Late Oligocene, and evolved during the Late Miocene due to eastward migration of the deformation front as a result of active stages of crustal shortening and uplift of the adjacent Interandean and the Subandean Zone (Sempere et al., 1990; Husson and Moretti, 2002). The up to 7.5 krn-thick, eastward-wedging Neogene stratigraphy is complicated by the existence of multiple basinwide unconformities with diffused relief and anticlines separated by synclines. This paper investigates the relationship of Andean thrust-belt tectonism and foreland basin system development to understanding the depositional response of the Chaco foreland basin to Andean loading and shortening using seismic and sedimentologic data set. Five isopach maps were established to determine the depositional pattern, temporal-spatial thickness distribution , and migration of the depocenter.