Petrography and Provenance of Sandstones from the Aghajari Formation, Folded Zagros Zone, Southwestern Iran

Abstract

The Late Miocene- Pliocene Aghajari Formation is exposed throughout the Folded Zagros Zone and consists of fluvial sediments. Detailed petrographic studies of sandstone samples from the Aghajari formation contain abundant quartz and lithic grains with subordinate feldspars, accessory amounts of micas. The feldspar content mostly ranges from 0 to 5 %. The abundance of lithic grains shows a wide range of variation (5.9 to 69.8 %). Although the lithics are mainly sedimentary, but fragments of metamorphic rocks are observed. Micas, including both muscovite and biotite, are generally less than 5 % of the total detrital grains. On the basis of the framework composition (point counting), the sandstones are classified as lithic arenite and sublitharenite. The modal analysis data of 75 collected (medium size and well sorted) samples, imply a recycled orogen (quartzose and transitional recycled) tectonic provenance. Moreover, petrographic point count data indicate the sources of quartzs are low-grade and middle to high-grade metamorphic rocks. Also quartz-rich (sedimentary) and granitic/gneissic are parent rocks for the Aghajari Formation sandstones.