The Changshagou gold deposit, Eastern Tianshan, NW China: orogenic gold mineralization overprinting a porphyry gold occurrence
- 29 November 2021
- journal article
- Published by Geological Society of London in Geological Society, London, Special Publications
- Vol. 516 (1), 85-108
- https://doi.org/10.1144/sp516-2020-248
Abstract
The temporal–spatial relationships of porphyry and orogenic gold mineralization in the Eastern Tianshan Orogenic Belt are ambiguous. The newly discovered Changshagou deposit in this belt contains both porphyry and orogenic gold mineralization, which are characterized by polymetallic–sulfide veinlets and quartz–pyrite veins, respectively. Fluid inclusions in the porphyry mineralization episode were trapped at 290–340°C with salinities of 3.0–8.0 wt% NaCl equiv . The homogenization temperatures and salinities in the orogenic mineralization episode range from 240 to 300°C and from 1.0 to 5.0 wt% NaCl equiv . Coexisting V- and L-type fluid inclusions with similar homogenization temperatures are indicative of fluid immiscibility. The δ 18 O w and δ D w values are in the ranges 7.6–9.1 and −70.9 to −84.0‰ in the porphyry mineralization episode, and 6.4–7.1 and −65.7 to −72.1‰ in the orogenic mineralization episode, overlapping magmatic and metamorphic ranges, respectively. The pyrite δ 34 S values range from 3.5 to 4.9‰, falling into the magmatic range. Pyrite in porphyry and orogenic mineralization episodes yield Re–Os isotope ages of 269.1 ± 2.9 and 257.4 ± 2.4 Ma. The porphyry and orogenic gold mineralizations are genetically associated with the quartz syenite porphyry and Kanggur strike-slip shear activity, respectively.Funding Information
- Key Technologies Research and Development Program (2017YFC0601202)
- National Natural Science Foundation of China (41803013)
- Fundamental Research Funds for the Central Universities (QZ05201905, 2652019050)
- Key Laboratory of Deep-Earth Dynamics of Ministry of Natural Resource, Institute of Geology, Chinese Academy of Geological Sciences (J1901-16)
- State Key Laboratory for Mineral Deposits Research (2021-LAMD-K10)
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