ABSTRACT

Paleocurrent, petrographic, and sedimentologic data from the Boggy and Thurman formations (early to middle Desmoinesian) in the Arkoma basin, Oklahoma, documents the recurrent uplift of the Ouachita fold belt. The Boggy is composed of sandstone-shale sequences which record progradation of coal-bearing, fluvially-dominated deltaic complexes from north to south. Folding and faulting in the Boggy suggests this unit was involved in thrusting during the uplift of the Ouachita fold belt and the closing of the Arkoma basin, prior to deposition of the Thurman. Paleocurrent indicators in the dominantly shallow marine facies of the overlying Thurman indicate some variability, but with a source to the southeast. The change in paleoslope and the presence of pebbles eroded from Ordovician to Devonian chert units in the Thurman documents the uplift of the Ouachita core area. Accompanying the uplift was a distinct change in the nature of the cyclothems, from longer, typically coal-bearing nonmarine cycles in the Boggy to shorter, marine clastic cycles in the Thurman. The cycles in the Boggy were probably controlled by glacial-eustatic changes in sea level or by avulsion within the delta system. Cycles in the Thurman were probably strongly influenced by episodic thrust loading in the Ouachitas during plate collision.