PETROGRAPHY AND DETRITAL ZIRCON GEOCHRONOLOGY OF CRETACEOUS DEPOSITS: IMPLICATIONS FOR PROVENANCE ANALYSIS IN WESTERN MISSISSIPPI EMBAYMENT

The Mississippi Embayment (MSE) is a wedged shaped southward-plunging basin ~100,000 sq miles in the Gulf Coastal Plain that extends from southern Illinois and fans out into parts of AL, AR, KY, LA, MS, MO, TN and TX. It is filled with Cretaceous (~145.5 Ma to 65.5 Ma) to recent sediments. Cretaceous deposits in the Western Mississippi Embayment (WMSE) are significant for establishing sediment accumulation and dispersal patterns during and after the reactivation of the late Proterozoic and early Paleozoic Reelfoot rift system at the end of the Mesozoic era. We report U-Pb ages of detrital zircons in unlithified sands from Cretaceous deposits in the WMSE to track their provenance and understand weathering patterns and sediment sources. Preliminary observations of these unlithified sands reveal dominant quartz content with minor magnetite and rutile in the heavy fraction. The morphology of zircons are sub-rounded to well-rounded with some euhedral crystals, displaying colors ranging from clear to pale yellow. The presence of both rounded and euhedral crystals suggests a journey involving both mechanical wear and tear during transport and potential preservation from local sources. Additionally, the zircons exhibit a range of shapes from tabular to prismatic, and are ranging in size from 100µm - 500µm, further suggesting contributions from multiple sources, potentially located at varying distances from the depositional site. Hence, we hypothesize that a significant portion of this material originates from the Ouachita Mountains and other distal sources primarily from the central to western Laurentian cratonic basement.