TITLE:
Mineral Chemistry in Volcanic Rocks of Ore Deposit Nochun and Sarcheshmeh Copper Mine, Iran
AUTHORS:
Mehdi Abdollahi Riseh, Mansur Vosughi Abedini, Mohammad Hashem Emami, Seysd Jamal Sheikh Zakariaii
KEYWORDS:
Petrography, Fractional Crystallization, Sarcheshmeh Copper Mine
JOURNAL NAME:
Open Journal of Geology,
Vol.7 No.3,
March
22,
2017
ABSTRACT: This paper studies on clinopyroxene, plagioclase of andesitic to dacite rocks of Nochun area to understand the geotectonic and geothermobarometry conditions. Eocene calc-alkaline volcanic rocks are exposed in Nochun that are near the Sarcheshmeh cooper mine. Volcanic rocks consist of andesitic to dacite rocks. Minerals in the volcanic rocks exhibit degrees of disequilibrium features. Plagioclase as dominant mineral in these rocks generally displays oscillatory zoning; sieves or dusty, cores are usually Ca-rich. Petrographic evidence and varying anorthite content (10% to 90%) of plagioclase and temperature estimates of clinopyroxene indicated fractional crystallization condition later than hydrothermal alteration and partial metasomatism occurred. The varying content indicates that the parent’s magma was generated from subalkaline composition and then hydrothermal alteration affected phenocryst minerals and matrix of andesitic to dacite rocks. The equilibration temperatures of clinopyroxene showed (800°C - 1200°C). Thus, in mafic minerals development of sieve textures in plagioclase, reaction rims, zoning and heterogeneity of plagioclase phenocrysts, the resorbed and embayed phenocrysts, unique composition of clinopyroxene phenocrysts; support fractional crystallization at deep reservoir and high pressure condition as an important process in the evolution of these rocks.