Petrography and Geochemistry of Sandstone of Upper Red Formation in Hasan-Abad area-SW Tehran

The combination of petrography and geochemistry data of sedimentary rocks can reveal the nature of source regions, the tectonic setting of sedimentary basins, and paleo-climate conditions. With this goal, the Oligocene Upper Red Formation clastic rocks with a thickness of 220 m outcrop in the southern region of Hasan Abad- Tehran were studied. Using thin sections and point counting of minerals and components and geochemical analysis of major and minor elements, the sequence were carefully investigated. This section is composed of repeating sequence of bright color Marl and Litharenite sandstone. Grain counts and geochemical evidence proved that most of these sandstones are volcanic-arenite. Maturity and sedimentary cycle index of these rock is equal to 1.722, which indicates the formation of deposits in the first cycle of sedimentation in active tectonic setting with relatively low maturity. Also, based on the results of the interpretation of geochemical data, felsic to intermediate source rock with a composition similar to continental crust is suggested for sandstone.