A MOST COMPLETE AND CONTINUOUS EARLY PENNSYLVANIAN SEQUENCE STRATIGRAPHIC FRAMEWORK NEAR KIRBY, ARKANSAS, USA AND ITS IMPLICATION ON GLOBAL REMNANT BASIN TECTONICS AND DEEPWATER HYDROCARBON E&P ACTIVITIES

The Pennsylvanian deepwater strata in the Ouachita Mountains have been studied for over forty years. This latest research is focused on a most complete and continuous outcrop section of Early Pennsylvanian deepwater sequence that consists of 25 outcrops near Kirby, Arkansas, USA. Outcrops include 12 roadcuts in Highway 27 and 13 sections in the Baumgartner Quarry. All the measurements and interpretations on the outcrops have integrated of all the previous work including (1) regional tectonic and sequence stratigraphic framework of the Stanley Group, Jackfork Group, Johns Valley Shale and Atoka Formation in the Ouachita Basin, (2) deepwater outcrop characterization in DeGray Lake Spillway, Hollywood Quarry and Dirks Spillway which is applicable to reservoir analogs for deepwater and onshore gas exploration and production, (3) subsurface Jackfork Group gas/oil reservoir characterization using well log/cutting data, (4) reservoir quality study with emphasis on the cause and effect of friable and cemented Jackfork Group sandstones.

The entire Kirby section consists of at least three 3rd order sequence from the bottom of Jackfork Group to the top of Johns Valley Group, and over ten 4rd order sequence boundary caused by a combined effect from tectonic uplift, eustatic sea-level change, mixed sediment provenance and shifting of depositional fairways during the time of Early Pennsylvanian when Ouachita Basin was shifting from passive margin to a remnant oceanic basin.

A possible ancient analog to the Carboniferous deepwater Ouachita basin is the Triassic Songpan-Ganzi Complex (SGC) in southwest China, which is also one of the world’s largest ancient turbidite systems. Both of these basins are remnant ocean basins caused by continent-continent collision and their dimensions are comparable.

This research will provide an understanding of the regional evolution and basin architecture in early Pennsylvanian time. It covers a range of depositional environments from slope to basin, which is applicable to be various reservoir analogs for deepwater exploration and production. In addition, comparison of both the Ouachita Basin and Songpan-Ganzi Basin will reveal tectonic and sequence stratigraphic features of typical remnant basins before the foreland basin stage during plate-scale continental collision.