Himalayan Geology, Vol. 43 (2), 2022, pp. 417-428, Printed in India
Petrography and geochemistry of the Early Permian strata in the Kalmard Area, Central Iran Zone, Implications on provenance and tectonic setting
SAMIRA TAGHDISI NIKBAKHT1*, PAYMAN REZAEE2, YAGHUB NASIRI1, REZA MOUSSAVI-HARAMI3, MOHAMMAD KHANEHBAD3
1Department of Geology, Faculty of Sciences, University of Gonabad, Gonabad, Iran
2Department of Geology, Faculty of Science, University of Hormozgan, Iran
3Department of Geology, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran
*Email (Corresponding author): SamiraTaghdisi@gmail.com
Abstract: Petrographic and geochemical study of the Early Permian sandstones of the Khan Formation was conducted to infer provenance, tectonic setting, source rock and palaeoclimate conditions in Rahdar and Tangal-e-Shotoru sections, Kalmard area. These sandstones are mainly composed of monocrystalline quartz with straight to slightly undulose extinction, chert, carbonate fragments and potash feldspar that show high textural and compositional maturity. Modal analysis on 35 thin sections and 21 samples of sandstone have been analyzed for major and trace elements. Based on petrographic study, the sandstones of the Khan Formation are classified as quartz arenite and sublitharenite with high textural and mineralogical maturity. Plotting point counting data on (Qt-F-L) and (Qm-F-Lt) ternary diagrams, suggests craton interior provenance. In addition, based on geochemical diagrams, major and trace elements indicate that these sandstones deposited in a passive continental margin tectonic setting. According to petrographic and geochemical evidence, the sandstones of the Khan Formation derived from a mixture of felsic igneous, moderate-to high-grade metamorphic, and quartzose sedimentary rocks. High mineralogical maturity, high value of CIW′ suggest high chemical weathering under warm and relatively humid climates. Passive continental margin tectonic setting and warm and humid paleoclimatic condition is consistent with paleogeographic position of Central Iran along shoreline of the Neotethys Ocean during the Early Permian.
Keywords: Provenance, Geochemistry, Sandstone Petrography, Khan Formation, Kalmard Area.