Hydrothermal monazite trumps rutile: Applying U-Pb geochronology to evaluate complex mineralization ages of the Katbasu Au-Cu deposit, Western Tianshan, Northwest China

Zheng, Jiahao1,2,3; Shen, Ping2; Feng, Wanyi1

2022-05-27

10.2138/am-2022-8080

AMERICAN MINERALOGIST   影响因子和分区

0003-004X

1945-3027

The Tianshan orogenic belt hosts several world-class gold deposits and is one of the largest gold provinces on Earth. The Katbasu Au-Cu deposit in the Chinese Western Tianshan is hosted in a granite intrusion. Previous researchers have shown that the main gold ores formed much later than the ore-hosting granite. However, the formation age of Cu mineralization and its possible link to Au mineralization remain poorly understood. This paper reports detailed mineralogical studies, combined with zircon U-Pb, in situ hydrothermal monazite as well as rutile U-Pb ages to constrain the timing of Cu mineralization and its possible link to Au mineralization. The two main ore types in the Katbasu deposit include Cu-Au ores with pyrite-chalcopyrite veins that crosscut the granite and Au ores with massive pyrite and quartz as the main minerals. The Cu-Au ores are spatially associated with diorite that intruded the granite, and they are overprinted by massive gold ores. Detailed mineralogical studies show that chalcopyrite is the main Cu-bearing mineral in the Cu-Au ores, and it is closely associated with some native gold, monazite, and rutile. Secondary ion mass spectrometer (SIMS) U-Pb dating of zircon grains from the ore-hosting granite and mafic enclave yielded concordant ages of 354.1 +/- 1.6 and 355.8 +/- 1.7 Ma, respectively. The diorite that intruded the granite has a zircon U-Pb age of 352.0 +/- 3.2 Ma. The trace element compositions of the monazite suggest they were formed by hydrothermal fluids rather than inherited from the ore-hosting granite. Hydrothermal monazite coexisting with chalcopyrite and native gold yielded a concordant age of 348.7 +/- 2.3 Ma, and the W-rich hydrothermal rutile grains associated with the chalcopyrite yielded a U-Pb age of 345 +/- 27 Ma, indicating an early Cu-Au mineralization event prior to the major Au mineralization (ca. 323-311 Ma). The formation time of early Cu-Au mineralization is consistent with the emplacement age of the diorite and may be of magmatic-hydrothermal origin, whereas the main Au has no genetic associations with magmatic rocks in the ore district and may belong to the orogenic type. Monazite geochronology provided a more reliable age constraint than rutile in the Katbasu Au-Cu deposit, and we suggest hydrothermal monazite has advantages over rutile in dating the complex mineralization ages of gold deposits.

Hydrothermal monazite rutile geochronology Katbasu Au-Cu deposit Western Tianshan

SCI ; EI

英语

通讯

National Key Research and Development Program of China[2018YFC0603801] ; National Natural Science Foundation of China[42002052,41903042] ; China Postdoctoral Science Foundation["2016LH0003","2017M610984"]

Geochemistry & Geophysics ; Mineralogy

Geochemistry & Geophysics ; Mineralogy

WOS:000802910800020

MINERALOGICAL SOC AMER

20222312197960

Binary alloys ; Copper ; Copper alloys ; Copper compounds ; Copper deposits ; Deposits ; Gold deposits ; Granite ; Lead alloys ; Mica ; Mineralogy ; Monazite ; Oxide minerals ; Phosphate minerals ; Pyrites ; Titanium dioxide ; Trace elements ; Zircon

Geology:481.1 ; Geophysics:481.3 ; Mineralogy:482 ; Minerals:482.2 ; Gems:482.2.1 ; Heavy Metal Mines:504.3 ; Copper:544.1 ; Copper Alloys:544.2 ; Lead and Alloys:546.1 ; Precious Metals:547.1 ; Inorganic Compounds:804.2

GEOSCIENCES

Web of Science

1.Fuzhou Univ, Zijin Sch Geol & Min, Fuzhou 350108, Peoples R China
2.Chinese Acad Sci, Inst Geol & Geophys, Key Lab Mineral Resources, Beijing 100029, Peoples R China
3.Southern Univ Sci & Technol, Dept Earth & Space Sci, Shenzhen 518055, Peoples R China

Zheng, Jiahao,Shen, Ping,Feng, Wanyi. Hydrothermal monazite trumps rutile: Applying U-Pb geochronology to evaluate complex mineralization ages of the Katbasu Au-Cu deposit, Western Tianshan, Northwest China[J]. AMERICAN MINERALOGIST,2022,107(6):1201-1215.

Zheng, Jiahao,Shen, Ping,&Feng, Wanyi.(2022).Hydrothermal monazite trumps rutile: Applying U-Pb geochronology to evaluate complex mineralization ages of the Katbasu Au-Cu deposit, Western Tianshan, Northwest China.AMERICAN MINERALOGIST,107(6),1201-1215.

Zheng, Jiahao,et al."Hydrothermal monazite trumps rutile: Applying U-Pb geochronology to evaluate complex mineralization ages of the Katbasu Au-Cu deposit, Western Tianshan, Northwest China".AMERICAN MINERALOGIST 107.6(2022):1201-1215.