Stratigraphic architecture of two deep-water depositional systems: The Tres Pasos Formation, Chilean Patagonia, and the Stevens Sandstone, Elk Hills, California

Outcrop data collected in Tres Pasos Formation, Magallanes basin, southernmost Chile, indicate that the formation represents the deposit of a mass-transport dominated slope depositional system characterized by a lower sand-rich unit up to 200 m thick deposited at or near the base-of-slope. This sandstone is characterized by a 70 km down depositional-dip facies evolution from a channelized system to slide evacuation infills to a sheet sandstone system partially ponded in a growth fault. Fine-grained strata underlying the sandstone at its distal end are growth faulted and intruded by a swarm of coarse-grained clastic dikes interpreted as downward-injected from the base of the Tres Pasos Formation along extensional faults and/or joint sets.; Lower slope sandstone beds are overlain by a middle part consisting of mass-transport complexes and fine-grained turbidite strata punctuated by a variety of turbidite sandstone bodies up to approximately 20 m thick. Sandstone bodies in the middle part of the Tres Pasos Formation can be subdivided into channelized units overlying and interacting with mass transport complexes, channelized units overlying concordant strata, and non-channelized units overlying concordant strata. Seismic-scale exposures of the lower sandstone unit and the middle part of the formation allow for detailed documentation of complex relationships between slope failure and coarse-grained turbidite sedimentation. A 300+ m thick coarse-grained to pebbly turbidite sandstone unit partially replaces the middle part of the Tres Pasos Formation in the southern study area, representing the deposits of a channelized turbidity current system. The upper part of the formation, interpreted as upper slope deposits, consists of concordant strata with thin channel form turbidite sandstone bodies and slide evacuation scarps.; Well core and three-dimensional seismic data from section 7R of Elk Hills oilfield indicate that the Stevens Sandstone consists of coarsening- and then fining-upward cycles interpreted as channelized lobe deposits in its lower portion overlain by a heterogeneous section characterized by traction-structured sandstones and debris-flow deposits. A separate Stevens channel system with a westerly source overlies these deposits with angular unconformity.