Analysis of Structural Controls on Basin Formation in a Deep-water Contractional Setting, Magallanes Foreland Basin, Patagonian Andes

Julie C. Fosdick
Stanford University, Geological & Environmental Sciences Stanford, California
[email protected]

Understanding the links between thrust belt and concurrent basin evolution has direct implications for successful exploration of deep-water hydrocarbon reservoirs, namely in reconstructing basin paleogeography, burial histories, and subsequent deformation and uplift. This study integrates new geologic mapping and 2D seismic-reflection data from the Magallanes retroarc foreland basin and Patagonian thrust belt. Additional temporal constraints from combined zircon U-Pb-He thermochronology characterize multiple stages of deformation, syntectonic sedimentation, and basin paleogeography. The Cretaceous-Tertiary Magallanes foreland basin, uplifted in the sub-Andean thrust belt, is an exceptional case study to evaluate the role of crustal shortening in deep-water contractional basins. Following Jurassic back-arc rifting, Late Cretaceous foreland basin deposition accumulated >6 km of deep-water (1000-2000 m water depth) sediments in a narrow foredeep. We document 35 km of shortening across the thrust belt that is partitioned into four stages of deformation beginning in Late Cretaceous time. The mode of deformation appears to change from thin-skinned deformation to high angle thrust faulting during middle Miocene time. Our palinspastic restorations shed light on the Cretaceous foreland paleogeography and document the spatial link between pre-existing Jurassic extensional structures and subsequent Cretaceous sedimentation patterns during foreland basin development.

AAPG Search and Discovery Article #90094 © 2009 AAPG Foundation Grants in Aid