CARBONIFEROUS PROVENANCE FOR THE SOUTHERN MARGIN OF LAURENTIA USING DETRITAL ZIRCON U-PB AGES FROM THE MID-PENNSYLVANIAN ATOKA SANDSTONE, OUACHITA MOUNTAINS, OK

Carboniferous sediments of the Ouachita trough are suggested to be derived from multiple provenances with a complex sediment dispersal system. Detrital zircon (DZ) U-Pb ages from the southern exposures of the Atoka Formation in the Ouachita Mountains are studied to recognize terranes contributing sediments to the trough. A total of 480 zircons from 4 sandstone samples were analyzed by LA-ICP-MS, with ages ranging from 367 ± 4.8 to 2995 ± 26 Ma. All samples are dominated by Grenville age zircons with subordinate Granite-Rhyolite and Mid-continent zircons, and minor Acadian, Taconic, Braziliano/Pan-African, Trans-Amazonian/Eburnian, and Archean zircons. Both Acadian and Taconic orogenic zircons are increasing in age towards the stratigraphic younging direction, which indicates the progressive unroofing of the provenance area. Minor influence from the peri-Gondwanan terranes is suggested by the absence of Braziliano/Pan- African zircons in the stratigraphic oldest sample and presence of the Trans- Amazonian/Eburnian zircons only in the stratigraphically oldest and youngest samples. 20 zircons per samples were analyzed for core-rim age pairs, core-rim dates from the same orogenic event are dominant. Core-rim dates of different orogenic events include Grenvillean core with Braziliano rim, midcontinent core with Acadian rim, Braziliano core with Taconic rim, and granite-rhyolite core with Grenvillean rim. In comparison to previous DZ age studies in the Ouachita trough, the Atoka sandstone from this study has a more diverse age range than the Mississippian Stanley tuff and the Ordovician/Silurian Blakely and Blaylock sandstones.

The relationship of the Ouachita orogeny with the Alleghanian orogeny for provenance is indicated by similarities in age populations of Acadian, Taconic, Grenville, Granite-Rhyolite, Mid-continent, and Superior craton zircons. In addition to the North American craton, derivation of sediments from southern terranes including the Suwannee basin and basement of Florida and Mexican terranes including the Oaxaca terrane, Mixteca terran, and Yuactan Peninsula is indicated by the Acadian/Taconic and peri-Gondwanan zircons.