Work

Fluid evolution of the Ermi porphyry Cu system, southern Jilin Province, northeastern China

Year: 2025

Type: article

Abstract: The Ermi Cu deposit of northeastern China, is a “reduced” porphyry-type Cu deposit associated with emplacement of dioritic to granitic intrusions of Late Cretaceous. Mineralization style at Ermi is characterized by sequenced sulfides, from early pyrrhotite–pyrite to chalcopyrite to late arsenopyrite, which is related to the sericite alteration. These sulfide phases suggest an intermediate to low sulfidation state of Ermi ore system. Their slightly heavier S isotopic compositions, combined with the systematic variation of H and O compositions of hydrothermal fluids, have a vector towards a magmatic origin of mineralizing fluids that were increasingly mixed with meteoric water. A detailed microthermometric study of fluid inclusions hosted in quartz of different fluid stages also indicates a cyclic dilution of meteoric water, with cooling down by 200 ℃ (from 385℃ to 185℃). The cooling of mineralizing fluids in the Ermi porphyry Cu system is considered to have a first-order control on the Cu precipitation by decreasing the solubility of Cu complex in fluids. The Cu mineralization formed at pressure of 205 ± 56 bars under hydrostatic conditions estimated using temperature and salinity of fluid inclusions of boiling assemblage, corresponding to a depth of emplacement of 2.1 ± 0.6 km beneath the paleowater table.

Source: Ore Geology Reviews

DOI: 10.1016/j.oregeorev.2025.106664

Authors: Guozhen Dong, Junkang Zhao, Jinggui Sun, Jilong Han

Institutions: Jilin University, Zijin Mining Group Co., Ltd. (China), China Geological Survey

Language: English

Topic: Geochemistry and Geochronology of Asian Mineral Deposits

Subfield: Economics and Econometrics

Field: Economics, Econometrics and Finance

Domain: Social Sciences

Open Access status: gold

Estimated APC paid: $3,310

Funders: National Natural Science Foundation of China, National Key Research and Development Program of China