Petrography and Geochemistry of Arc section (Upper Paleocene-Lower Eocene) siliciclastic deposits, northwest of Birjand, evidence of provenance tectonic setting and Lithology

Authors

1 Assist. Prof., Dept., of Geology, Faculty of Sciences, University of Birjand, Birjand, Iran

2 M. Sc., student. Dept., of Geology, Faculty of Sciences, University of Birjand, Birjand, Iran

3 Assoc. Prof., Dept., of Geology, Faculty of Sciences, University of Birjand, Birjand, Iran

Abstract

The Arc Section in the northwest of Birjand is located in the eastern Iran structural zone. The petrography and geochemistry of siliciclastic deposits of this section have been studied in order to determine the lithology and tectonic setting of the source area. Petrographic evidence of sandstone samples, including types of monocrystalline and polycrystalline quartz with non undulose and undulose extinction, the abundance of sedimentary rock fragments and to a lesser extent metamorphic and volcanic lithics, as well as drawing results of the modal analysis of these samples on the tectonic provenance diagrams show that the studied sandstones are the result of recycled orogeny and post collision. Also, based on the geochemical analysis of the major elements of the shale samples, these sediments originate from igneous rocks and belong to the collision tectonic setting. The sistan suture zone is placed between two continental blocks of Lut and Afghan. According to most researchers, subduction of the oceanic crust has played a very important role in the tectonic evolution of this region. The recent studies show that due to the westward subduction of the Sistan Ocean in the Early to Middle Cretaceous, the upper mantle was pushed under the Lut block and the collision between the Lut and Afghan blocks along the Sistan collision zone probably occurred in the Upper Cretaceous. Combining above data and comparing it with the tectonic evolution of the region shows that the results of this study can be used to reconstruct the paleogeography of this area.

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History

  • Receive Date: 19 September 2022
  • Revise Date: 12 February 2023
  • Accept Date: 13 March 2023

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