甘肃寨上超大型钨、金(锑)多金属矿床成因研究

甘肃寨上超大型钨、金(锑)多金属矿床位于西秦岭岷-礼成矿带西段,属于复合矿床,具有显著的多期次、多物源和多成因特点。年代学结果表明,矿区至少存在早期钨矿化(220 Ma)和晚期金矿化(140~120 Ma)两期成矿作用。钨矿为破碎蚀变岩型,矿质主要来源于岩浆热液,在时空和成因上与同时代富钨的闪长玢岩脉(220~210 Ma)关系密切,属于岩浆成矿系统的铜-钨-钼中高温成矿系列;金成矿作用的物质来源主要是泥盆纪地层,矿化与闪长玢岩脉没有时空关联,成矿时代为燕山期(140~120 Ma),与西秦岭地区燕山期构造岩浆活动具有一致性。金矿类型介于卡林型金矿床和造山型金矿床的过渡类型,属锑-汞-铅-锌中低温成矿系列。笔者认为,寨上超大型多金属矿床成因是中生代陆内造山体制下与构造-岩浆活动有关的成矿系统之2个成矿系列叠加的结果,尚有巨大的找矿潜力。

Genesis of the Super-large Tungsten,Gold(Antimony)Polymetallic Deposit in Zhaishang,Gansu Province

The super-large tungsten,gold(antimony)polymetallic deposit in zhaishang,Gansu province is located in the western part of the Min-Li metallogenic belt,West Qinling.It belongs to the compound deposit characterized by the multiple stages,multi-source and multi-genesis.The chronological results show that it has experienced two metallogenic stages:the early stage(220Ma)of tungsten mineraliazation and the late stage(140~120Ma)of gold mineralization.The W deposit belongs to the broken alteration rock type of the Cu-W-Mo intermediate-high temperature metallogenic series.The ore-forming material is from hydrothermal fluid,which is closely associated with the magmatism of the w-rich diorite porphyrite(220~210 Ma)in terms of time and space.The Au-forming material mainly derived from the Devonian strata,its mineralization has no direct relation with diorite porphyrite in terms of time and space.The mineralization occurred during the Yanshanian period(140~120Ma),which was in consistent with the Yanshanian tectonic-magmatic activities in West Qinling.The Au deposit belongs to transitional deposit between the carlin deposit and the orogenic deposit,being the Sb-Hg-Pb-Zn intermediate-low metallogenic series.The authors propose that Zhaishang super-large polymetallic deposit is superimposed metallogenic series related to the tectonic-magmatic activities in the mesozoic metallogenic system and has huge prospecting potential.