Geochronological Constraints on Skarn Copper Metallogenesis of the Large-scale Sayak Ore Field, Kazakhstan, Central Asia
详细信息
- 责任者：Chen XuanHua(Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Wang ZhiHong
- 刊名：Acta Petrologica Sinica
- 出版年：2012
- 卷期：28(7)
- 关键词：铜矿 ; copper ores ; 中亚 ; Central Asia
- 页码：p.1981-1994
- 图表：illus.,4 tables,45 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Sayak ore field, composed of several separated skarn Cu and porphyry Cu-Mo deposits and Cu-Au-Mo lodes in the Sayak synclinorium, is the only one area with the occurrence of large-scale skarn Cu deposits in the Balkhash metallogenic belt, Kazakhstan, Central Asia. It consists of a metallogenic series with skarn and porphyry deposits as the two end members. Zircon SHRIMP U-Pb geochronology of the skarn-related granitoids presents three phases of pluton intrusions in the Middle to Late Hercynian at 335±2Ma (diorite), 308±10Ma (granodiorite), and 297±3Ma (monzonite), respectively. The first two phases of intrusions are consistent with the skarn Cu metallogenesis, suggesting the main and secondary skarn Cu metallogenic ages at 335±2Ma and 308±10Ma, before and after the regional main porphyry Cu metallogenesis, respectively. 40Ar/39Ar thermochronology of hornblede, biotite, and K-feldspar from granitoids gives the cooling ages at 286.6±6.7Ma, 306.6±2.9Ma, and 257±11Ma, respectively, constraining the skarn metallogenic time further more. Apatite fission track dating and thermal history modeling of granitoids gives low temperature cooling ages ranging from 85.4±4.5Ma to 66.9±4.1Ma, suggesting the uplifting and exhumation of the skarn Cu deposits together with the granitoids during the Late Cretaceous in the Sayak ore field. The geochronological data presented in this paper, together with metallogenic information from previous studies, reveal the entire thermo-history, from the intrusion of plutons and skarn metallogenesis in the abyssal system, and regional cooling, to the exhumation of the deposits, in the Sayak ore field.
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