滇西保山地块金厂河矿集区铁铜金铅锌多金属矿床成矿系统

Metallogenic system of polymetallic Fe-Cu-Au-Pb-Zn deposits in Jinchanghe ore concentration district,Baoshan block,Southwest China

滇西保山地块是西南“三江”特提斯构造带的重要组成部分,其大地构造位置处于藏-滇-泰-马中间板块中段,是近年来科学研究和地质找矿的热点地区之一。受区域构造演化的影响,保山地块先后历经原、古、中、新特提斯演化,并发生了多期成岩成矿事件,在北部形成了以金厂河铁铜铅锌矿、核桃坪铅锌矿、陡崖铁铜多金属矿、黑牛凹金矿、黄家地金矿等为代表的金厂河铁铜金铅锌多金属矿集区。区内矿床在成矿空间上具有明显的分带性,单个矿床在垂向上、平面上均呈有规律地分布,其分带标志除了矿床类型外,还表现在有用矿物组合及元素分带。由下往上、由内向外均有Fe→Cu-Fe→Cu-Pb-Zn→Au矿种分带及“矽卡岩型→构造蚀变岩型→石英脉型”的矿床类型分带,成矿元素均从高温到中低温变化。成矿系统的分析表明,区内各代表性矿床中矿石的硫、铅同位素组成和变化范围较为一致性,矿床的形成具有相似的成矿流体,表明不同类型的矿化可能形成于早白垩世中特提斯洋的闭合过程。本文综合区内构造演化、典型矿床地质特征、各地质事件发生的先后关系,建立了金厂河矿集区铁铜金铅锌多金属矿床成矿模式,以期为该区深边部地质找矿提供科学依据。

The Baoshan block in western Yunnan is an important part of the Sanjiang Tethys tectonic belt in southwest China.Its tectonic position is located at the middle section of the Sibumasu plate,which has been one of the hotspots in geoscientific research and has been a geological prospecting target in recent years.Controlled by the regional tectonic evolution,the Baoshan block has experienced the evolution processes of the Proto-,Paleo-,Meso-and Neo-Tethys,and the multi-stages of diagenetic and metallogenic events have occurred.The Jinchanghe polymetallic iron-copper-gold-lead-zinc ore concentration district includes Jinchanghe iron-copper-lead-zinc deposit,Hetaoping lead-zinc deposit,Douya polymetallic iron-Copper deposit,Heiniuao gold deposit,and Huangjiadi gold deposit.The deposits in the region have obvious metallogenetic zonings in space,and even ore bodies of a single deposit are also regularly distributed in zonings in the vertical and horizontal directions.In addition to deposit types,the useful mineral assemblages and element associations appear in zones in space,and the metallogenic elements change from high temperature to low temperature.Usually,it is showed that the pattern of Fe→Cu-Fe→Cu-Pb-Zn→Au mineral zonings from bottom to top or from inside to outside and the pattern of the skarn type→tectonic altered rock type→quartz vein type mineral zonings from the center to the outside.The sulfur and lead isotopic compositions and their variation ranges of representative deposits are relatively consistent,and the ore-forming fluids have similar characteristics,showing that different types of mineralization may have formed in the closing process of the Meso-Tethys Ocean in the early Cretaceous.Based on the characteristics of typical deposits and the sequences of tectonic events in the study area,the metallogenic model for polymetallic iron-copper-gold-lead-zinc deposits in Jinchanghe ore concentration district is proposed to provide scientific basis for future geological prospecting in the area.