新疆阿舍勒盆地泥盆纪火成岩与构造- 岩浆演化

阿舍勒泥盆纪火山盆地是阿尔泰西南缘重要的矿集区，产出我国著名的火山成因块状硫化物型（VMS）矿床——阿舍勒铜矿。其内部发育的火山岩和侵入岩地球化学特征记录了阿舍勒盆地的构造- 岩浆演化和成岩、成矿作用过程，但其形成构造背景和成岩成矿机制一直存在争论。本文报道了阿舍勒矿集区萨尔朔克铜金多金属矿区深部英云闪长岩的LA- MC- ICP- MS锆石U- Pb 年龄（376. 7±1. 3 Ma）和岩石地球化学数据，结合前人在阿舍勒矿区火山岩、潜火山岩及其东侧哈巴河侵入岩体的岩石地球化学特征、同位素年代学研究成果和区域岩浆岩研究成果，笔者认为阿舍勒矿区泥盆纪火山岩和东侧哈巴河岩体可能是同一地质构造背景下同期不同阶段和不同构造部位的产物，形成于地幔软流圈高热流地幔柱上涌、板片断离背景下的活动陆缘拉张环境，与成矿作用时空关系密切的双峰式火山岩是不同深部、不同性质岩浆源在快速拉张背景下喷发、喷溢的产物。地幔柱上涌致使板片断离、沿基底断裂系快速拉张和幔源岩浆持续补给可能是形成“双峰式火成岩”和阿舍勒高镁火山岩建造的主要深部动力学机制。

Devonian igneous rocks and tectono- magmatic evolution in the Ashele basin, Xinjiang

The Ashele basin is an important ore concentration area in the southwestern margin of Altay. The famous Ashele Cu- Zn deposit of volcanic massive sulfide type (VMS) occurs in China. The geochemical characteristics of both volcanic and intrusive rocks in the Ashele basin record the tectonic magmatic evolution, diagenesis and mineralization processes in this basin. However, the tectonic background and mineralization mechanism of the Ashele basin has always been controversial. This paper reports the zircon U- Pb age (376.7±1.3 Ma) of tonalite in the core of the Saershuoke Cu polymetallic deposit in the Ashele ore concentration area. Based on the geochemical characteristics, isotopic geochronology and regional magmatic rocks including volcanic, subvolcanic and intrusive rocks in the Ashele area, the authors believe that the Devonian volcanic rocks and Habahe intrusive rocks in the Ashele area may have had different stages and ages in the same geological tectonic setting. The bimodal volcanic rocks, which are closely related to mineralization in time and space, are the products of eruption, overflow and intrusion of different deep magma sources with different properties under the background of rapid extension. Mantle plume upwelling resulted in plate fragmentation, rapid extension along the basement fault system and continuous supply of mantle- derived magma may be the main deep dynamic mechanism for the formation of bimodal igneous rocks and the Ashele high Mg volcanic rocks.