A Glimpse of Provenance Through the Diagenetic Haze in Smackover Sandstones of the Gulf Coast: ABSTRACT

Late Jurassic Smackover sandstones deposited in the four interior salt basins of the Gulf Coast have been extensively altered, yet their provenance signature has not been grossly modified on QFL and QmFLt plots. Recalculating framework compositions to account for diagenesis suggests that Smackover sandstones were derived from the Ouachita fold and thrust belt and the interior portion of the North American craton. Differences in framework composition between the four basins result from both diagenesis and provenance. Detrital quartz and rock fragments have been lime modified by diagenesis. The south Texas and Mississippi basin sandstones contain more polycrystalline quartz than the other two basins. Rock fragments in the three eastern basins consist primarily of SRFs and low-grade MRFs; south Texas sandstones contain mostly gneiss and schist. Feldspar composition is controlled by the pore fluid chemistry. The South Texas and Mississippi basins contain potassium-rich K-spar whereas the east Texas and Louisiana basins contain mostly albite. A uniform 6% loss (whole rock) of feldspar can be recognized petrographically in all four basins but this loss does not significantly shift the provenance fields on QFL and QmFLt plots. Mississippi basin sandstones plot primarily in the craton interior provenance field supporting derivation of these sandsmore » from the ancestral Mississippi river, East Texas sandstones are also dominated by a cratonic provenance area. Louisiana sandstones plot in the recycled orogen field and were primarily derived from a local source in the Ouachita fold belt. The provenance of south Texas sands was the interior zone of the Ouachitas, as indicated by the presence of high-grade metamorphic rock fragments and Rb-Sr dates of detrital muscovite.« less