Downslope Characterization of Channel Fill and Stratigraphic Architecture along an Ancient Basin Margin, Tres Pasos Formation, southern Chile

Abstract

Slope channel deposits of the Cretaceous Tres Pasos Formation, exposed in southern Chile, record the interplay of formative sedimentary processes along an ancient basin margin. An 8 km-long outcrop belt, known as Alvarez Ridge, provides the opportunity to characterize and interpret processes along depositional dip. Twenty distinct channel fills are identified at Alvarez Ridge; sedimentary observations are investigated using traditional sedimentological techniques, GPS methods, and 3-D architectural modeling. Notable changes in channel fill architecture are not observed along depositional dip, although this is expected, given the estimated length of the slope system (>40 km). The dimensions of the entire channel system (up to 288 m thick) vary along depositional dip; this is attributed to changes in differential compaction and autogenic channel migration patterns along the paleoslope. Documentation of these deposits also informs sandstone body connectivity at multiple scales, which can aid with reservoir prediction in analogous, petroliferous systems.