Geochemistry of Dorojen volcanic rocks (SW Ardestan) with the special use of mineral chemistry of Propylitic alteration zones
Dorojin area in the Southwest of Ardestan city is part of the Urmia-Dokhtar magmatic zone. In the area of study, the intrusion of the Early Miocene granodiorite into the Middle-late Eocene sedimentary-volcanic complex caused the formation of hydrothermal propylitic alteration zones with green color....
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | fas |
| Published: |
University of Isfahan
2021-11-01
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| Series: | پترولوژی |
| Subjects: | |
| Online Access: | https://ijp.ui.ac.ir/article_26395_3e6af4651d45d0ef75bef15525b3a8e2.pdf |
| Summary: | Dorojin area in the Southwest of Ardestan city is part of the Urmia-Dokhtar magmatic zone. In the area of study, the intrusion of the Early Miocene granodiorite into the Middle-late Eocene sedimentary-volcanic complex caused the formation of hydrothermal propylitic alteration zones with green color. The vlcanics range in composition from basalt-andesite, trachyandesite, andesite, to rhyolite. These rocks under study are characterized by LREE and LILE enrichment compared to HFSE, calc-alkaline nature, and meta-aluminous composition related to the subduction zone. The most abundant mineral in the alteration zones is epidote formed by saussuritization of plagioclase. Average Pstacite [Fe3+/(Fe3++Al)×100] composition is 22% (PS22). Comb and radial textures are its remarkable textural features. Calcite is the second most abundant mineral in alteration zones. The nodules tourmaline is chemically dravite and alkaline. They have FeO/ (FeO+MgO)<0.6 and lower Al amount, high Mg, and low X site vacancy. Dravite composition and the Mg abundant reflect their alteration origin. Hence, they are regarded as hydrothermal tourmalines. Titanite with CaO<25wt%, Al2O3<2wt% as well as Al2O3+TiO2 versus CaO, and Al/Fe on variation diagrams are indication of hydrothermal alteration. Ore mineral potential in the region points to the effect of hydrothermal fluids. |
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| ISSN: | 2228-5210 2322-2182 |