Geochemistry and petrogenesis of the granitoid rocks in Mahiroud volcano-plutonic complex; Southeast of Sarbisheh (Eastern of Iran)

Authors

1 M. Sc., of Geology, Faculty of Science, Lorestan University, Khorramabad, Iran

2 Assoc. Prof., Dept., of Geology, Faculty of Science, Lorestan University, Khorramabad, Iran

3 M. Sc., of Geology, Faculty of Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Abstract

The study granitoid pluton is a part of the Mahiroud (Cheshmeh Ostad) volcano-plutonic complex in the southeast of Sarbisheh (South Khorasan province). The composition of this pluton is mostly granodiorite-tonalite. Its main minerals include plagioclase, quartz, orthose and hornblende with granular texture. Based on mineral chemistry, amphiboles in these rocks have a calcic composition and are placed in the Mg-hornblende subgroup. These amphiboles crystallized under pressure conditions of 0.5 to 2 kbar, temperature between 700 - 725 ºC and high oxygen fugacity. Based on the geochemical results, this granitoid pluton is in the range of type I, metalunimous and calc-alkaline granites. Also, this puloton is been formed through mantle partial melting so that La and Dy increase with the increase of La/Sm and Dy/Yb ratios. These rocks were formed through partial melting and less than 5% of sediments have been subducted and fluid has entered the magma source. The spider diagram of trace elements normalized with the primary mantle shows relative enrichment with a gentle slope of LREE elements compared to HREE. This granitoid pluton is similar to subduction-related granites and is consistent with the calc-alkaline magmatic arc in the eastern of Iran which is the result of the subduction of the Neotethys oceanic plate (Sistan Ocean) under the eastern zone of Iran.

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History

  • Receive Date: 13 April 2024
  • Revise Date: 08 July 2024
  • Accept Date: 10 September 2024

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