Petrology
Ashraf Torkian; Sara Damchin-Mashak; Zohreh Yarali; Maryam Souri
Abstract
The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite ...
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The studied area is located in N-Sonqor and in the Sanandaj-Sirjan zone. Field relationships and petrographic evidence show that volcanic rocks of the north of Bashirabad comprise of trachydacite to trachyandesite (and altered basaltic trachyandesite) and in the south of this area, it consists of andesite to trachyte. Their texture is mainly porphyry. Geochemical data {total abundance of (Na2O+K2O), enrichment of large lithophile ion elements and rare light earth elements) indicate that these rocks belong to the alkaline series. Spider diagrams show enrichment in LREE and depletion HREE, and parallel patterns in all volcanic samples confirm their common origin. According to modeling magmatic processes, fractional crystallization, assimilation and crustal contamination have played an important role in the magma forming the studied rocks. The discriminating diagrams the tectonic setting the Bashirabad volcanic rocks indicate their subduction-related volcanic arc that was formed in an active continental margin environment with local tensions.
G. Maleki; A. Saeedi; M.H. Emami; M. Kheirkhah
Abstract
In Sanandaj- Sirjan zone a vast outcrops of volcanic rocks, which founded as high terraces, are covered the Pre-Quaternany rocks. The volcanic rocks are appeared in different shapes and morphological features. Based on the Zagros geodynamical evolution, mentioned rocks assumed ...
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In Sanandaj- Sirjan zone a vast outcrops of volcanic rocks, which founded as high terraces, are covered the Pre-Quaternany rocks. The volcanic rocks are appeared in different shapes and morphological features. Based on the Zagros geodynamical evolution, mentioned rocks assumed to be Post – Collissional, that are formed in an extentional system with a NW-SE trend. Three studied complexes in this paper are Ahmad abad, Tahmures and Nadri. The structural investigation of three the sites are complementary data to the geochemical analysis. In this regards, structural investigation done in those 3 mentioned sites. Studied faults shows different trends and age. Mechanism of faults are normal, and their age are either Post- basalt or syn-basalt, that is, Contemporaneous with the last deposition of late-Miocene marls. The age of the oldest faults is late- Miocene, before basalt intrusion.