SHRIMP U-Pb and Ar-Ar geochronology of major porphyry and skarn Cu deposits in the Balkhash Metallogenic Belt, Central Asia, and geological implications

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• 作者：Xuanhua Chen ; Eleonora Seitmuratova ; Zhihong Wang ; Zhengle Chen ; Shuqin Han ; Yong Li ; Yi Yang ; Baoying Ye ; Wei Shi
• 关键词：Porphyry copper deposit ; Skarn copper deposit ; SHRIMP zircon U&ndash ; Pb dating ; 40Ar/39Ar dating ; Balkhash metallogenic belt ; Kazakhstan
• 刊名：Journal of Asian Earth Sciences
• 出版年：5 January, 2014
• 年：2014
• 卷：79
• 期：Complete
• 页码：723-740
• 全文大小：2522 K

文摘

The Balkhash Metallogenic Belt (BMB) in Kazakhstan, Central Asia, with the occurrence of the super-large Kounrad and Aktogai, the large Borly porphyry Cu-Mo deposits, and the large Sayak skarn polymetallic ore-field, is one of the central regions of the Paleozoic Central Asian metallogenic domain and orogenic belt. In this study, newly obtained SHRIMP zircon U-Pb ages of nine samples and ⁴⁰Ar/³⁹Ar ages of six mineral samples (inclding hornblende, biotite and K-feldspar) give more detailed constraints on the timing of the granitic intrusions and their metallogeny. Porphyritic monzonite granite and tonalite porphyry from the Kounrad deposit yield U-Pb zircon SHRIMP ages of 327.3 卤 2.1 Ma and 308.7 卤 2.2 Ma, respectively. Quartz diorite and porphyritic granodiorite from the Aktogai deposit yield U-Pb SHRIMP ages of 335.7 卤 1.3 Ma and 327.5 卤 1.9 Ma, respectively. Porphyritic granodiorite and granodiorite from the Borly deposit yield U-Pb SHRIMP ages of 316.3 卤 0.8 Ma and 305 卤 3 Ma, respectively. Diorite, granodiorite, and monzonite from the Sayak ore-field yield U-Pb SHRIMP ages of 335 卤 2 Ma, 308 卤 10 Ma, and 297 卤 3 Ma, respectively. Hornblende, biotite, and K-feldspar from the Aktogai deposit yield ⁴⁰Ar/³⁹Ar cooling ages of 310.6 Ma, 271.5 Ma, and 274.9 Ma, respectively. Hornblende, biotite, and K-feldspar from the Sayak ore-field yield ⁴⁰Ar/³⁹Ar cooling ages of 287.3 卤 2.8 Ma, 307.9 卤 1.8 Ma, and 249.8 卤 1.6 Ma, respectively. The new ages constrain the timing of Late Paleozoic felsic magmatism to 鈭?36 to 鈭?97 Ma. Skarn mineralization in the Sayak ore-field formed at 鈭?35 and 鈭?08 Ma. Porphyry Cu-Mo mineralization in the Kounrad deposit and the Aktogai deposit formed at 鈭?27 Ma, and in the Borly deposit at 鈭?16 Ma. The Late Paleozoic regional cooling in the temperature range of 鈭?00 掳C to 鈭?50 掳C occurred from 鈭?07 to 鈭?57 Ma.