地质学
黄铁矿
地球化学
δ34S
热液循环
变质岩
绿泥石
石炭纪
再结晶(地质)
矿物学
流体包裹体
岩石学
石英
构造盆地
古生物学
地震学
作者
Narges Daneshvar,Mohammad Maànijou,David R. Lentz,Hossein Azizi,Christopher R.M. McFarlane,Teruyuki Maruoka
标识
DOI:10.1016/j.oregeorev.2021.104087
摘要
The Qolqoleh gold deposit is located in the northern part of the Sanandaj-Sirjan Zone (SaSZ), northwest Iran. The main host rocks include mylonitic granite and chlorite schist. Four generations of Au-bearing sulfides have been identified and are referred to as Py1 to Py4. LA-ICP-MS elemental maps and spot analyses of gold and other trace elements in Py1 to Py4 were performed to provide robust information about the ore-forming fluid and conditions of saturation. Element compositions in all generations of pyrite show heterogeneity in fluid compositions and reflect the role of a multistage hydrothermal system in their formation. The earliest hydrothermal event is related to magmatic fluids synchronous with magmatic fluids from a granitic pluton emplacement in Carboniferous time. Multistage magmatism and related heating caused reaction, replacement, and recrystallization (RRR) of original Py1, generating overgrowths of Py2 to Py4. The variation in the Au-As rim compositions shows that fluctuating temperatures occurred during overgrowths of pyrite. The ratios of Co/Ni for most Py1 to Py4 are higher than 1. This along with the high Te contents infer that the ore-forming fluids came from mainly a magmatic source with low redox conditions. The increase in Au and other elements in Py2 and Py4 shows enrichment through the coupled dissolution-reprecipitation reaction (CDRR) mechanism in response to greater non-metamorphic fluids. The bulk δ34S values range from 3.1 to 6.9‰. Two samples range from 13.8 to 14.3‰, which are compatible with a main magmatic source and to a minor metamorphic source for the ore-forming fluids. Subsequently, dextral movements caused brittle-ductile deformation and dislocation of mineralization and mylonitization. However, this study determines that the Qolqoleh deposit is a magmatic-related gold deposit.
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