Detrital Mode and Geochemistry of the Shurijeh Formation (Late Jurassic‐Early Cretaceous) in the Central and Western Parts of the Intracontinental Kopet‐Dagh Basin, NE Iran: Implications for Provenance, Tectonic Setting and Weathering Processes

Abstract

Abstract:Petrographical and geochemical methods were combined to investigate the provenance, geodynamic and weathering history of the Shurijeh sandstones, Kopet‐Dagh Basin. The pointcounting method and XRF technique are used for modal and geochemical analyses. Based on petrographical examinations, it seems that the Shurijeh sandstones are mainly deposited in the craton interior and recycled orogen belts. In addition to petrographical investigation, geochemical analyses (major oxides and trace elements) of Late Jurassic‐Early Cretaceous rocks reveal that the sedimentation processes are performed in a passive continental margin. Such interpretation is supported with geodynamic and paleogeographical studies of the Kopeh‐Dagh basin during this time. The geochemical investigations suggested that the composition of probable source rocks mostly was acidic‐intermediate with minor mafic igneous rocks. Based on the above, Paleo‐Tethys remnants and their collision‐related granitoids, in the south and west of Mashhad, may have been the source area for these rocks. CIA values, which range from 63.8 to 94.9 in samples, are suggesting a moderate to relatively high degree of alteration (weathering) in the source area. Therefore, petrographical and paleogeographical studies of siliciclastic rocks can be used for the provenance, tectonic setting and paleoweathering studies in the source area.