GLOBAL, REGIONAL AND LOCAL CONTROLS ON ORGANIC MATTER PRODUCTION AND PRESERVATION: EVIDENCE FROM THE EAGLE FORD, MAVERICK BASIN, TX, USA

The Eagle Ford Group (Gr.) is a prolific source rock and active shale gas and liquid rich unconventional play encompassing the Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE-2). However, increasing evidence indicates a decoupling in the precise timing of the OAE-2 and the deposition of the most organic-rich sediment, reflecting that deposition of organic-rich sediment was modulated and ultimately dependent on local and regional processes (basin restriction, water stratification, bottom currents, sediment input) although favoured by global phenomena (atmospheric CO₂; large igneous provinces (LIPs), sea level change, orbital forcing etc..). Shell has been conducting research on road cuts along US Highway 90, and natural outcrops in the vicinity of Del Rio and Austin, Texas that provide excellent exposures of the Buda, Eagle Ford (locally known as Boquillas Fm) and the Austin Chalk Formations. In addition, Shell has drilled two cores, Shell IONA-1 and Shell INNES-1, behind these outcrops, recovering continuous core the entire stratigraphy of Eagle Ford and part of the encasing formations (Austin Chalk and Buda Limestone). This contribution provides an overview of the multi-disciplinary research conducted on these cores and the developed models into the main global, regional and local driving mechanisms of facies change within a robust chrono-stratigraphic framework. Furthermore, we present the Eagle Ford Gr. into a supra-regional context by comparing with correlative materials from the central KWIS (Portland-1 core, Colorado) and to the south in the Tropical Atlantic (ODP Leg 207, Demerara Rise) and Southern Ocean (ODP Leg 183, Kerguelen Plateau). This supra-regional understanding provides insights into oceanographic changes and the role of LIPs on the deposition of the Eagle Ford Gr.