Petrography and geochemistry of late Devonian sandstones (Shishtu Formation): Middle East central Iran

Abstract

The petrography of sandstones integrated with geochemistry is important to infer the provenance, paleoclimate, and tectonic setting. An integrated petrographic and geochemical study of the late Devonian sandstones, Shishtu Formation in central Iran was performed to determine the provenance, tectonic setting, and weathering history. These sandstones are classified into quartz arenite, subarkose, and litharenite types. Sandstones consist of quartz, feldspars, and sedimentary rock fragments, and also provenance shows a recycled orogen and craton interior. Moreover, petrographic data indicate quartz-rich sedimentary (recycled), metamorphic, and plutonic parent rocks. Major and trace elements suggest a quartzose sedimentary provenance in a passive continental margin. As indicated by the chemical index of weathering (CIA), the sandstones underwent a moderate degree of chemical weathering. Diagenetic processes consist of cementation, compaction, and dolomitization. Dolomitization in the carbonate particles of sandstones in the upper part of organic Frasnian-Famennian shale indicates the potential for producing Mg fluid and shows that this unit differs from other shales in these strata.