POSSIBLE SYNDEPOSITIONAL FAULT CONTROL ON LATE MISSISSIPPIAN STRATA IN THE ARKOMA BASIN: THE UNSTABLE OUTER RAMP OF THE FAYETTEVILLE SHALE

Reactivation of inherited structures, and particularly their effect on stratal and sedimentologic features, may serve as the harbinger of foreland basin development. Onset of rapid subsidence during deposition of the middle Atoka Formation (Early-Middle Pennsylvanian) is commonly viewed as the initiation of foreland basin tectonics in the Arkoma Basin. However, recent work documents Early (Morrowan) to Middle Pennsylvanian (Atokan), east to west migration of flexural extensional subsidence that reactivated inherited Neoproterozoic-Cambrian structures. This documents early stages of Arkoma Basin development and supports a commensurate spatial trend in thrust sheet stacking and loading along the southern margin of the basin. Potentially pushing back foreland basin tectonic activity earlier, some research interprets Late Mississippian (Chesterian) syndepositional fault movement along inherited structures from observed thickness changes in the Fayetteville Shale of the eastern Arkoma Basin. However, intraformational, time-correlative trends are lacking in this work and proposed fault orientations are uncertain. We document stratal and sedimentologic features within the Fayetteville Shale along the eastern basin margin to investigate the potential effects of syndepositional fault movement. We trace regional flooding surfaces and unconformities/correlative conformities in well logs, and incorporate previous work on outcrop and core data, to apply a depositional model to strata of the Fayetteville Shale’s starved outer ramp, and map sedimentary packages within the unit. Preliminary results demonstrate stratal thickness patterns, particularly during transgressive episodes, follow known normal fault orientations. Furthermore, we identify a possible zone of concentrated slumping parallel to, and directly west of, the northeast-trending Reelfoot rift structure, which bounds the Mississippi River embayment. We explore the possible drivers of the observed stratigraphic features in the Fayetteville Shale and the potential record of early foreland basin development and reactivation of inherited structures along the southern margin of Laurentia during the late Paleozoic.