Re-Os pyrite geochronology of Zn-Pb mineralization in the giant Caixiashan deposit, NW China

The newly discovered Caixiashan Irish-type Zn-Pb deposit (similar to 131 Mt at 3.95 % Zn + Pb), located in the Eastern Tianshan of Xinjiang, is one of the largest Zn-Pb deposits in NW China. Massive colloform/framboidal textured syn-sedimentary pyrite yielded a Re-Os isochron age of 1019 +/- 70 Ma (...

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Bibliographic Details
Published in:Mineralium Deposita
Main Authors: Li, Dengfeng, Chen, Huayong, Hollings, Pete, Zhang, Li, Mi, Mei, Li, Jie, Fang, Jing, Wang, Chengming, Lu, Wanjian
Format: Report
Language:English
Published: SPRINGER 2016
Subjects:
Geochemistry & Geophysics
Mineralogy
Pyrite Re-Os
Irish-type Pb-Zn deposit
Caixiashan
Eastern Tianshan
BROOKS RANGE
TARIM BASIN
ZIRCON GEOCHRONOLOGY
NORTHWEST CHINA
VOLCANIC-ROCKS
BLACK SHALES
CENTRAL-ASIA
ORE FIELD
SYSTEMATICS
MOLYBDENITE
Brooks Range
Online Access:http://ir.gig.ac.cn/handle/344008/55112
https://doi.org/10.1007/s00126-016-0637-0
Description
Summary:The newly discovered Caixiashan Irish-type Zn-Pb deposit (similar to 131 Mt at 3.95 % Zn + Pb), located in the Eastern Tianshan of Xinjiang, is one of the largest Zn-Pb deposits in NW China. Massive colloform/framboidal textured syn-sedimentary pyrite yielded a Re-Os isochron age of 1019 +/- 70 Ma (MSWD = 3.5), which is interpreted to be the depositional age of the Kawabulake group that hosts the ore. The age of the main mineralization stage is constrained by two types of pyrite: the layered pyrite coexists with recrystallized calcite and dolomite and is locally replaced by sphalerite, whereas the euhedral pyrite occurs with galena that crosscuts the massive sphalerite. The layered pyrite yielded a Re-Os age of 859 +/- 79 Ma (MSWD = 6.7; initial Os-187/Os-188 ratio [I-Os] = 0.19 +/- 0.25) and the euhedral pyrite 837 +/- 39 Ma (MSWD = 6.5; [I-Os] = 0.16 +/- 0.09), which are interpreted to be the Zn and Pb mineralization ages, respectively. The low radiogenic initial Os values of the Zn-Pb mineralization suggest interaction between a hydrothermal fluid and a mafic or ultramafic source rock with a mantle Os signature with some contamination with Mesoproterozoic Kawabulake group. Based on our new Re-Os ages, we conclude that the giant Caixiashan Zn-Pb deposit formed in the early Neoproterozoic and it represents a newly identified mineralization epoch in the Eastern Tianshan of the Central Asia Orogenic Belt.

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