DETRITAL ZIRCON CORE-RIM DATES AND CL IMAGE ANALYSIS FROM DEEPWATER ATOKA SANDSTONES (MIDDLE PENNSYLVANIAN) FROM BOKTUKOLA SYNCLINE, SOUTHEAST OKLAHOMA, USA

Deepwater Atoka Formation (DWA) exposed in the Boktukola Syncline is the southernmost exposure of the Ouachita foredeep deposition in Oklahoma. Four sandstones from this 1,400-m-thick section were processed for detrital zircon (DZ) LA-ICP-MS dating of core and rim pairs and CL image analysis for a total 68 DZ grains. DZ ages range from core date of 2,747 (+/-26) Ma to rim date of 370.9 (+/- 7.3) Ma. Both core and rim date spectra are dominated by Mesoproterozoic and older (core 86%; rim 80%). Subrounded to well-rounded DZ textures are most prevalent overall (79% DZ) with this being the case for Mesoproterozoic and older grains (81% DZ) and Neoproterozoic and younger grains (67% DZ). Based on CL image characteristics, Mesoproterozoic and older grain rims are subequal metamorphic (55%) and magmatic (45%) and cores are mostly metamorphic, whereas Neoproterozoic and younger grain rims are mostly magmatic (89%).

The DWA samples and DZ selected for this study provide insight into the provenance for sedimentation in this part of the Ouachita foredeep. The proximate source is most likely recycled sedimentary containing DZ ranging in age from Archean to Devonian with a dominance of Mesoproterozoic and older grains. Of these older grains, DZ core and rim ages are in range of the Grenville/Sunsás orogenies (56% overall DZ age spectra). Insights into possible basement inliers come from analysis of DZ grains with subangular to very angular textures (a subset of 21% of grains with core-rim dates). Paleoproterozoic magmatic core and rim DZ is limited (7% of subset). Grenville/Sunsás cores and rims are mixed metamorphic and magmatic (43% of subset). DZ grains with Neoproterozoic to Taconic rim ages are mixed metamorphic and magmatic, and core ages ranging from Paleoproterozoic to Neoproterozoic (21% subset). DZ with Acadian age rims are all magmatic, and have cores ranging from Taconic to Acadian ages (29% of subset).