Petrogenesis of Volcanic Rocks in Alasht, Mazandaran, Iran
Petrogenesis of Volcanic Rocks in Alasht, Mazandaran, Iran作者机构：Department of Geology Faculty of Sciences North Tehran Branch Islamic Azad University Tehran Iran Faculty of Science Shahid Sherafat University of Farhangian Tehran Iran
出 版 物：《Open Journal of Geology》 (地质学期刊（英文）)
年 卷 期：2016年第6卷第3期
页 面：131-145页
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
主 题：Alasht Area Crustal Contamination Olivine Basalt Sub-Alkaline
摘 要：Area studied in this paper is located in the northwest of city of Alasht. The most important varieties of studied rocks are volcanic and semi-volcanic rocks of basic nature. These rocks, which form a distinguishable solid mass on 1:100,000 geological map, belong to Cretaceous period. According to results of petrographic study, rocks of this area include olivine basalt, dolerite, gabbro and microgabbro, and all have almost similar chemical compositions. According to chemistry-based naming process carried out through TAS method, these rocks are entirely basalt and basic and are all products of Sub-alkaline-Tholeiitic magma. According to Harker diagrams, a magmatic differentiation can be observed in all volcanic rocks;furthermore, basaltic magma erupted in this area has undergone an alteration and possibly a crustal contamination. The spider diagrams plotted in this paper show that basic rocks of Alasht area (basalts, andesite basalts, dolerites, gabbros and microgabbros) are all mostly similar to ocean island basalts (OIB). Once field study, sampling and microscopic study stages were complete, ten samples were selected for chemical analysis and were analyzed by XRF method.
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