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    广西富川岩鹰嘴W-Mo-Cu多金属矿区斑岩体LA-ICP-MS锆石U-Pb定年及其地质意义

    LA-ICP-MS zircon U-Pb dating of the granitic and granodioritic porphyries from the Yanyingzui W-Mo-Cu polymetalic ore district in Fuchuan area, Guangxi, and its geological implications

    • 摘要: 提要:岩鹰嘴W-Mo-Cu多金属矿床位于桂东北W-Mo多金属成矿带中部,矿体产于岩鹰嘴斑岩体内及其接触带矽卡岩中,成矿作用与斑岩体密切相关,但对于该矿床成矿斑岩形成时代至今仍没有精确的年龄数据。本文通过对与该矿床成矿有关的花岗斑岩和花岗闪长斑岩进行LA-ICP-MS锆石U-Pb同位素测年,获得其成岩年龄分别为(426.2±2.3)Ma和(426.9±2.3)Ma,说明岩鹰嘴斑岩体是加里东期区域构造-岩浆活动的产物。结合区域构造演化、区域成岩成矿时代对比和矿床地质特征,推测岩鹰嘴W-Mo-Cu多金属矿区成矿作用和岩浆活动可能发生于晚志留世,形成于华南加里东运动由挤压向伸展转换的构造背景下,并与桂东北地区加里东期W-Mo成矿作用产于同一时期、同一构造背景,间接表明在加里东期桂东北地区可能存在一定强度的W-Mo-Cu成矿作用。此外,NE向构造-岩浆带、斑岩体分布带及矿化区外围是寻找斑岩-矽卡岩型W-Mo-Cu多金属矿床、同系列矿床以及隐伏矿床的有利地区,今后应加强该区加里东期花岗岩、花岗斑岩出露区的找矿勘查工作。

       

      Abstract: Abstract:The Yangyingzui W-Mo-Cu polymetallic deposit is located in the middle segment of the northeast Guangxi metallogenic belt. Orebodies occur within the porphyry and skarn of the contact zone, and mineralization is closely related to the Yanyingzui porphyry. Up till now, however, there have been no precise data concerning the porphyry mineralization age of this ore deposit. The authors conducted the LA-ICP-MS zircon U-Pb chronologic study of the mineralized granite porphyry and granodiorite porphyry in the Yanyingzui W-Mo-Cu deposit and obtained ages of (426.2±2.3) Ma and (426.9±2.3) Ma, indicating that the porphyry is a product of tectonic-magmatic activity during the Caledonian. Combined with regional tectonic evolution, contrastive study of the timing for diagenesis and mineralization as well as geological characteristics of ores, it is suggested that the ore-forming and igneous activities of the Yangyingzui W-Mo-Cu polymetallic deposit occurred during Late Silurian, when the tectonic setting of the deposit was in the transition period from collision orogeny compression to extension. The Yangyingzui W-Mo-Cu polymetallic deposit has the same metallogenic age and same structural setting as the northeast Guangxi W-Mo mineralization belt, implying that the probable existence of an intense W-Mo-Cu mineralization during Caledonian period in northeast Guangxi. In addition, the NE-trending tectonomagmatic belt, the porphyry body zone and the periphery of the mineralization area are favorable areas in search for porphyry-skarn-type W-Mo-Cu polymetalic deposits, homologous series deposits and conceaned ore deposits, and hence more attention should be paid to the exploration and evaluation of the study area in the future.

       

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