REVISITING AND RECONSTRUCTING MISSING STRATA IN THE ARKOMA FORELAND BASIN SYSTEM: A THERMAL RECORD OF ERODED OVERBURDEN

Studies of basin development often are limited to preserved sedimentary rock, which can miss critical portions of the depositional record if the area has experienced significant erosion. The string of late Paleozoic pro-foreland basins along the eastern and southern Laurentian margins experienced kilometers of late- to post-orogenic exhumation, and previous research has attempted to reconstruct these missing strata. In the Arkoma foreland basin system, which includes pre- and syn-orogenic sedimentary rock exposed in the Ouachita orogen/Arkoma Basin of western Arkansas and eastern Oklahoma, research suggests up to 4 km or greater of removed strata. We present preliminary research that revisits questions of magnitude and spatial patterns of exhumation in this foreland basin system. We do so through analysis of new and previously published vitrinite reflectance (VR_o) data, and new, parallel work in time-temperature modeling. Surface VR_o data yield a map of calculated maximum burial temperature. Pre-orogenic Ordovician to Lower Mississippian strata of the Broken Bow and Benton uplifts exhibit highest burial temperatures, but flanking Upper Mississippian and Pennsylvanian syn-tectonic strata to the north, in the basin, and in the southernmost Ouachita Mountains exhibit lower burial temperatures. New surface VR_o data expand coverage in the northern Arkoma Basin, better characterizing the north to south trend of increasing thermal maturity. Reconstructed paleo-geothermal gradients from well VR_o data and maximum burial temperature maps produce an estimation of removed sedimentary material. Maximum burial estimates are considered within the context of previous Arkoma foreland basin system research, which includes the complicating element of regional-scale migration of hydrothermal fluids. However, recent thermochronometric data and time-temperature modeling, also presented in this session, provide constraints on the timing of thermal events and bear on the relation of hydrothermal activity and burial history. We explore possible models of this thermal history, and reconstruct the missing strata of the Arkoma foreland basin system to provide a unique window into a rock record that no longer exists and whose characteristics are only available by proxy.