Re¨COs geochronology of Cu and W¨CMo deposits in the Balkhash metallogenic belt, Kazakhstan and its geological significance

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• 作者：Xuanhua  ; Chen^a ;   ; ^b ;   ; ^{xhchen@cags.ac.cn} ; Wenjun  ; Qu^c ; Shuqin  ; Han^b ; Seitmuratova  ; Eleonora^d ; Nong  ; Yang^a ;   ; ^b ; Zhengle  ; Chen^a ;   ; ^b ; Fagang  ; Zeng^c ; Andao  ; Du^c ; Zhihong  ; Wang^b
• 关键词：Re&ndash ; Os geochronology ; Metallogenic age ; Porphyry Cu&ndash ; Mo deposit ; Greisen W&ndash ; Mo deposits ; Balkhash metallogenic belt ; Kazakhstan
• 刊名：Geoscience Frontiers
• 出版年：2010
• 出版时间：October 2010
• 年：2010
• 卷：1
• 期：1
• 页码：115-124
• 全文大小：1896 K

文摘

The Central Asian metallogenic domain (CAMD) is a multi-core metallogenic system controlled by boundary strike-slip fault systems. The Balkhash metallogenic belt in Kazakhstan, in which occur many large and super-large porphyritic Cu¨CMo deposits and some quartz vein- and greisen-type W¨CMo deposits, is a well-known porphyritic Cu¨CMo metallogenic belt in the CAMD. In this paper 11 molybdenite samples from the western segment of the Balkhash metallogenic belt are selected for Re¨COs compositional analyses and Re¨COs isotopic dating. Molybdenites from the Borly porphyry Cu deposit and the three quartz vein-greisen W¨CMo deposits¡ªEast Kounrad, Akshatau and Zhanet¡ªall have relatively high Re contents (2712?772?¦Ìg/g for Borly and 2.267?1.50?¦Ìg/g for the other three W¨CMo deposits), and lower common Os contents (0.670?.696?ng/g for Borly and 0.0051?.056?ng/g for the other three). The molybdenites from the Borly porphyry Cu¨CMo deposit and the East Kounrad, Zhanet, and Akshatau quartz vein- and greisen-type W¨CMo deposits give average model Re¨COs ages of 315.9?Ma, 298.0?Ma, 295.0?Ma, and 289.3?Ma respectively. Meanwhile, molybdenites from the East Kounrad, Zhanet, and Akshatau W¨CMo deposits give a Re¨COs isochron age of 297.9?Ma, with an MSWD value of 0.97. Re¨COs dating of the molybdenites indicates that Cu¨CW¨CMo metallogenesis in the western Balkhash metallogenic belt occurred during Late Carboniferous to Early Permian (315.9?89.3?Ma), while the porphyry Cu¨CMo deposits formed at ?16 Ma, and the quartz vein-greisen W¨CMo deposits formed at ?98 Ma. The Re¨COs model and isochron ages thus suggest that Late Carboniferous porphyry granitoid and pegmatite magmatism took place during the late Hercynian movement. Compared to the Junggar-East Tianshan porphyry Cu metallogenic belt in northwestern China, the formation of the Cu¨CMo metallogenesis in the Balkhash metallogenic belt occurred between that of the Tuwu-Yandong in East Tianshan and the Baogutu porphyry Cu deposits in West Junggar. Collectively, the large-scale Late Carboniferous porphyry Cu¨CMo metallogenesis in the Central Asian metallogenic domain is related to Hercynian tectono-magmatic activities.