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Two mineralization events in the Laozuoshan Au deposit, north‐east China: Evidence from Re–Os geochronology and trace element geochemistry
Author(s) -
Shi Kaituo,
Wang Keyong,
Ulrich Thomas,
Ma Xueli,
Sun Qingfei,
Wang Rui
Publication year - 2021
Publication title -
geological journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.721
H-Index - 54
eISSN - 1099-1034
pISSN - 0072-1050
DOI - 10.1002/gj.4036
Subject(s) - skarn , arsenopyrite , isochron , geology , geochemistry , mineralization (soil science) , trace element , geochronology , quartz , mineralogy , fluid inclusions , chalcopyrite , copper , chemistry , paleontology , organic chemistry , soil science , soil water
The Laozuoshan deposit, located in the central Jiamusi Block of north‐east China, is characterized by two types of mineralization, including principal skarn‐type Au mineralization occurring along the contact zone between granite and migmatite, and minor auriferous quartz‐arsenopyrite veins hosting in plagiogranite and granite. Re–Os dating of auriferous pyrrhotite and arsenopyrite were performed to determine the metallogenic ages of the Laozuoshan gold deposit. Analyses of arsenopyrite from quartz vein‐type ores yield a weighted average model age of 89.0 ± 3.1 Ma (mean standard weighted deviationMSWD = 9.3), which is within uncertainty in agreement with the 187 Re/ 188 Os versus 187 Os/ 188 Os isochron age of 93.2 ± 2.6 Ma (MSWD = 1.3) and the 187 Re versus 187 Os isochron age of 97 ± 14 Ma (MSWD = 7.4). Pyrrhotite samples from skarn‐type ores have model ages from 82.6 Ma to 424.8 Ma, indicating an unclosed Re–Os isotope system. However, the skarn‐type Au mineralization likely occurred during the Permian following the emplacement of the Laozuoshan granite. Results of laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) trace element analysis show that element contents in sulphides from different types of ores are systematically different. Au, Ag, Bi, Pb, Co, and Ni are significantly enriched in skarn‐type arsenopyrite. These data suggest that the Laozuoshan deposit formed from two gold mineralization events. Combined with previous studies, we suggest that the skarn‐type Au mineralization was associated with the subduction of the Panthalassic oceanic plate, whereas the rollback of the Palaeo‐Pacific Plate was responsible for the quartz vein‐type Au mineralization in the Laozuoshan deposit. The multiple mineralization events have important implications for regional exploration.