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Biotite geochemistry and its implication on the temporal and spatial difference of Cu and Mo mineralization at the Xiaokele porphyry Cu-Mo deposit, NE China
被引:8
作者:
Feng, Yuzhou
[1
,2
]
Deng, Changzhou
[1
]
Xiao, Bing
[2
]
Gong, Lin
[2
]
Yin, Runsheng
[1
]
Sun, Deyou
[3
]
机构:
[1] Chinese Acad Sci, Inst Geochem, State Key Lab Ore Deposit Geochem, Guiyang 550081, Peoples R China
[2] Chinese Acad Sci, Key Lab Mineral & Metallogeny, Guangzhou 510640, Peoples R China
[3] Jilin Univ, Coll Earth Sci, Changchun 130061, Peoples R China
基金:
美国国家科学基金会;
关键词:
Biotite;
Xiaokele Cu-Mo deposit;
Cu and Mo separation;
Halogen fugacity;
NE China;
COPPER-DEPOSIT;
HYDROTHERMAL SOLUTIONS;
CHEMICAL-COMPOSITION;
MOLYBDENUM SYSTEM;
CENTRAL PROVINCE;
VOLCANIC-ROCKS;
CALC-ALKALINE;
EVOLUTION;
CHEMISTRY;
FLUORINE;
D O I:
10.1016/j.oregeorev.2021.104508
中图分类号:
P5 [地质学];
学科分类号:
0709 ;
081803 ;
摘要:
The Late Jurassic large Xiaokele porphyry Cu-Mo deposit is newly discovered in the northern Great Xing'an Range, NE China. Both Cu and Mo mineralizations have occurred in the potassic stage and are present in the potassic zone, but only Mo (Cu negligible) mineralization has been developed in the phyllic stage and is present in the phyllic zone. The cause for such temporal and spatial difference of Cu and Mo mineralization at Xiaokele remains unclear. In this study, biotite major element compositions were studied to reveal the magmatichydrothermal processes, and the temporal and spatial difference of Cu and Mo mineralization at Xiaokele. Biotite geochemical data show that the magmatic biotites (Bi-I), and the potassic-stage (Bi-II) and phyllic-stage (Bi-III) hydrothermal biotite are Mg-biotites, and that mineralization at Xiaokele occurred under 52-86 MPa (equivalent to 1.95-3.32 km depth). Calculated oxygen fugacity of Bi-I, Bi-II, and Bi-III biotites are all above nickel-nickel oxide (NNO) oxygen buffer, suggesting that these biotites were formed under oxidizing conditions. The decreasing Cl and largely constant F content from Bi-I, Bi-II to Bi-III result in an increasing trend of IV(F/Cl), indicating different elemental behavior between F and Cl during the magmatic-hydrothermal fluid evolution. Given that Cl content is a key Cu-transporting ligand in porphyry type mineral systems, the decreasing Cl content in Bi-III indicates lower Cu transporting capacity in the phyllic stage, resulting in the negligible Cu mineralization in the phyllic zone. Since F is important for Mo transport in hydrothermal systems, we conclude that the constant F content reflects stable Mo transporting capacity in the fluids, resulting in significant Mo mineralization in both the potassic and phyllic zones. Our results show that biotite geochemistry can be used to explain the temporal and spatial distribution of Cu and Mo mineralization in porphyry Cu-Mo systems.
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