High-Relief Slope Clinoform Development: Insights from Outcrop, Magallanes Basin, Chile

摘要

The Cretaceous–Paleogene Tres Pasos and Dorotea formations of the Magallanes Basin, Chile record the filling of a deep-water foreland setting. Slope clinoforms with at least 700–900 m relief (compacted) prograded southward along the foredeep axis, which was oriented parallel to the adjacent Patagonian Andes. Fluvial- and wave-influenced deltaic deposits of the Dorotea Formation represent the upper, flat portions of the sigmoidal slope profiles. The paleo-shelf edge is estimated where shelf sandstones pinch-out basinward. Mudstone, siltstone, and a notable paucity of sandstone characterize upper slope strata. Further down-slope, conduits are evidenced by sedimentary bodies associated with cross-stratified or normally graded sandy conglomerate and local mudstone rip-up clasts, interpreted to indicate that considerable sediment bypassed the slope. Turbiditic sandstones and mass-transport deposits of the Tres Pasos Formation characterize the lower to base of slope setting.