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岩石学报 2010
Geochemical characters, metallogenic chronology and geological significance of the Yanxi copper deposit in eastern Tianshan, Xinjiang.
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Abstract:
Yanxi copper deposit is located in the west area of the Yandong-Tuwu porphyry copper belt, Harlik-Dananhu island arc. The Carboniferous Qieshan Group is the main ore-hosting stratum, which was intruded by the mineralized plagiogranite porphyry. The main lithology in the deposit contains andesite, diorite-porphyrite and plagiogranite porphyry. Both of the andesite and diorite-porphyrite are the ore-hosting rocks, which are island arc volcanic rocks and formed by the same magmatism. However, the mineralized plagiogranite porphyry is adakite rock and directly responsible with copper mineralization, which is probably different magmatism from the andesite and diorite-porphyrite. The Re-Os isochronal age of molybdenites in Yanxi deposit is 326±4.5Ma, which represents the main mineralized age of this deposit and corresponds to the 322.7±2.3Ma metallogenetic age of Tuwu-Yandong copper deposits. The metallogenetic age of Tuwu-Yandong copper belt is coeval or litter latter with its diagenetic age. The Yanxi copper deposit has the similar characteristics such as the mineralization and wall rock alteration with the porphyry Cu deposit, and it was formed by the same Middle Carboniferous magmaitism as other deposits in the Tuwu-Yandong copper belt. These deposits have the similar metallogenetic process, and their metallogenetic materials were come from the same magmatic source, all the evidences above refer that the deposits in Tuwu-Yandong copper belt maybe formed by the same magamatism and mineralized in different positions. The metallogeny of Yanxi deposit as well as Tuwu-Yandong copper belt was formed in island arc compressional environment in Jueluotage area eastern Tianshan, and concomitanced with outcome of the Harlik-Dananhu island arc, which is probably to related to the north underthrust of the Kangguer ocean plate along the Harlik-Dananhu island arc.
