【作者】 王春光；

【导师】 孙丰月； 孙国胜；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2016， 博士

【摘要】 少郎河成矿带作为华北板块北缘加里东增生带的一部分,北以西拉木伦河为界,南以赤峰-开原断裂为界,位于东西向西拉木伦断裂带的中部位置,其多成矿域叠加、复合和转换的地理位置,使得该地区具有成矿背景复杂、成矿条件优越,成矿期次多、强度大、矿床类型多样的特点。少郎河成矿带北侧即为中国北方铅锌多金属矿床主要聚集地黄岗梁-甘珠尔庙-乌兰浩特成矿带,虽然在少郎河成矿带已发现一些具有代表性的铅锌多金属矿床(小营子、敖包山、硐子、荷尔勿苏),但对少郎河成矿带整体的研究工作仍局限在单个矿床的孤立研究,并且很多方面仍为空白。本文以研究区内典型矿床为依托,通过锆石U-Pb年代学、岩石地球化学、流体包裹体以及稳定同位素地球化学等方面的分析,对研究区开展系统的成矿作用研究。研究结果表明中生代以前研究区主要受到古亚洲洋构造成矿域的影响,处于一个由多个次生洋盆组合起来的微陆块环境;中生代以后,由于古亚洲洋自西向东“剪刀式”闭合,华北板块与西伯利亚板块发生碰撞拼贴,使得这一地区的构造活动频繁,处于陆陆碰撞与碰撞后伸展的构造环境;燕山期古太平洋板块向古亚洲大陆的斜向俯冲使得区域构造格局发生大的转变,构造-岩浆活动强烈,并同时伴随着较强的多金属成矿作用。少郎河成矿带内主要的矿床类型分为矽卡岩型(小营子铅锌矿、敖包山铅锌矿)和热液脉型(硐子铅锌矿、荷尔勿苏铅锌矿)两类。本文研究结果显示,硐子和小营子铅锌多金属矿床侵入岩锆石U-Pb年龄分别为424.5±4.1Ma、414.8±2Ma和404.3±7.8Ma;荷尔勿苏铅锌多金属矿床侵入岩年龄为268.1±2.6Ma。研究区加里东晚期为古亚洲洋向西伯利亚板块俯冲作用环境;华力西期为西伯利亚板块与华北板块碰撞对接整体挤压环境下火山弧岩浆作用的背景;燕山期为构造体制大转折时期,区域伸展减薄的构造环境伴随着大规模的铅锌成矿作用。成矿年代学表明,研究区铅锌多金属矿床的成矿年龄均在中生代侏罗纪:小营子铅锌矿床(161~171Ma)、敖包山铅锌矿(125~170Ma)、硐子铅锌矿(153Ma)、荷尔勿苏铅锌矿(135~154Ma)的成矿年龄反映了少郎河成矿带主要受中生代构造岩浆活动的影响,形成于中生代侏罗纪大规模爆发性成矿阶段,这与中国北方中生代的构造体制大转换和岩石圈减薄过程密切相关,西拉木伦河两侧多金属矿床的形成大多与该时期的岩浆侵入活动有一定的关系。矿床流体包裹体及碳、氢、氧、硫、铅同位素的研究表明,少郎河成矿带多金属矿床成矿流体主要为气液两相型,属于Na Cl-H2O体系,成矿温度为120°C~382°C,盐度为0.5~25.6%Na Cleqv,成矿深度为0.38~2.60km;成矿流体以岩浆水为主,大气降水不同程度的参与了成矿过程。小营子铅锌矿床的成矿流体主要来源于岩浆水,大气降水很少参与到成矿作用中,其分布状态受到了成矿温度的影响;硐子和荷尔勿苏铅锌矿床的成矿流体主要来源于大气降水和岩浆水两个部分组成的混合流体,其成矿受到大气降水和成矿温度两方面控制。成矿带各矿床金属硫化物中硫的来源比较单一,主要为深源岩浆硫;铅同位素显示成矿物质来源不仅由深源岩浆提供,还有一部分来自太古宙基底地层,具有壳幔混合的特征。成矿规律研究表明,少郎河成矿带多金属矿床受到地层、构造、岩浆岩等共同作用。断裂构造作为本区主要的控矿因素,不仅为成矿提供了流体运移的通道,也为矿床的最终富集提供了有利的赋矿空间。二叠系地层作为该区主要的赋矿层位,明显富集Pb、Zn等成矿元素,而碳酸盐地层和断裂构造分别控制了矽卡岩型和热液脉型铅锌矿床的分布。成矿带矿体多与中生代中酸性侵入体相伴生,表现出该区矿化作用与中生代中酸性岩浆的紧密联系。论文在充分收集和分析前人研究成果的基础上,对华北板块北缘增生带少郎河成矿带铅锌多金属矿床成矿地质条件、成矿物质来源以及矿床在时间和空间上的分布规律进行了分析总结,为该区域开展进一步的找矿勘探工作提供一定的理论依据,同时成矿作用及成矿规律的总结对于该区找矿模型的建立以及指导矿床预测工作也有重要意义。更多还原

【Abstract】 Shaolang River metallogenic belt, as a part of the northern margin of North China plate of the Caledonian fold belt, is situated at the central position of Xar Moron caledonian fold belt that is EW-trending. Its north boundary and south boundary are Xar Moron river and Chifeng-Chaoyang Fault, respectively. The area has the characteristics of complicated, superior metallogenic conditions, mutiple mineralization periods, intensive mineralization and complex and various deposit types due to multiple metallogenic provinces overlying, combining and transforming. North of the Shaolang River metallogenic belt is Huanggangliang-ganzhuermiao-Wulanhaote metallogenic belt where the Pb-Zn polymetallic deposit focused in North China. Though there are some representative Pb-Zn polymetallic deposits(Xiaoyingzi, Aobaoshan, Dongzi, Heerwusu) found, yet study in Shaolang River metallogenic belt was unsystematic and still there are new works expected to be explored. This paper carried out systematic chronology, petrogeochemistry and the other analysis on basis of typical deposits. Studies suggested that the area was mainly influenced by Paleo-Asian Ocean tectonics metallogenic province before Mesozoic and was under a micro continental environment consisting of a number of secondary ocean basins. After Mesozoic, the North China plate and Siberia plate collided and jointed after the closure of the Paleo-Asian ocean, leading to the area with frequent tectonic activities and under a continent/continent collision and post-collisional crustal extension tectonic environment. Paleo-Pacific plate subducted towards Pal-Asia, resulting in regional tectonic framework occurring a great change during Yanshanian, and tectonic-magmatic activities were intensive along with strong polymetallic mineralization generating at that time.Main deposits of Shaolang River metallogenic belt according to its tectonic setting and mineralization characteristics are divided into two types including skarn type(Xiaoyingzi and Aobaoshan) and hydrothermal vein type deposits(Dongzi and Heerwusu). Petrogeochemistry datas revealed that ore-hosting rock ages of Dongzi and Xiaoyingzi Pb-Zn polymetallic deposit were 424.5±4.1Ma, 414.8±2Ma and 404.3±7.8Ma, respectively. While age of the Heerwusu rock was 268.1±2.6Ma. During late Caledonian subduction occurred from Paleo-Asian Ocean to Siberia Plate and during Variscan, Siberia Plate and North China Plate collided, the whole environment belongs to volcanic arc magmatism environment under compressional condition and Yanshanian was the period that tectonic regime changed greatly, regional extension and thinning took place with mass Pb-Zn mineralization generating. Metallogenetic chronology suggested metallogenic ages of Pb-Zn polymetallic deposits in study area belonged to Mesozoic Jurassic: Xiaoyingzi Pb-Zn deposits of 161~171Ma, Aobaoshan Pb-Zn deposit of 125~170Ma, Dongzi Pb-Zn deposit of 153 Ma, Heerwusu Pb-Zn deposit of 135~154Ma, reflecting Shaolang River metallogenic belt was affected by Mesozoic tectonic- magmatic activities, and formed during the time Mesozoic Jurassic thet massive mineralizations broking out. This was closely related to the tectonic regime changing and the rock thinning in North China. Most polymetallic deposits of both sides in Xar Moron River were connected with the magma intrusion activities to some degree.Fluid inclusion and C, H, O, S, Pb isotopes researches revealed that Shaolang River metallogenic belt polymetallic deposit were mainly gas-liquid two-phase types, and belonged to NaCl-H2 O system, at tempertures of 120°C~382°C, salinity of 0.5~25.6%NaCleqv, depth of 0.38~2.60 km. Ore-forming fluid was mainly composed of magmatic water, and inconclusive meteoric waters participated in the mineralizations as well. Ore-forming fluid of Xiaoyingzi Pb-Zn deposit was derived mainly from magmatic water, few meteoric waters participated in the mineralization. The distribution condition was merely influenced by mineralization temperature. Ore-forming fluid of Dongzi and Heerwusu Pb-Zn deposits were derived mainly from waters mixed by magmatic water and meteoric waters and mineralization were controlled by both meteoric waters and mineralization temperature. Source of S of metal sulfide was single, basically coming from deep source magmatic sulfur. Pb isotope analysis showed that source of mineralization materials were not only provided by deep source magmatic sulfur, but a part of the archean basement strata with characteristics of mixed crust-mantle.Metallogenic regularity research suggested that Shaolang River metallogenic belt polymetallic deposit was affected by strata, tectonics and magmatite. As the main ore-controlling factor, the fault tectonics provied channels for mineralization as well as favorable room for the final concentration of the deposit. As the main ore-bearing layer, the Permian strata obviously enriched in metallogenic elements such as Pb, Zn, while the carbonate and fault controlled the distribution position of scarn type and hydrothermal vein type respectively. Metallogenic belt ore body was usually accompanied by Mesozoic intermediate-acidic intrusive rocks, suggesting Pb-Zn polymetallic mineralization had genetic connection with intermediate-acidic magma.This paper based on full collection and analysis results of previous studies, combined with this study on the ore-forming geological conditions and the source of ore-forming materials in the northern margin of the North China plate hyperplasia with Shaolang River metallogenic lead-zinc polymetallic deposit. At the same time, the regularities of distribution of the deposit in time and space are analyzed and summarized, for further exploration work providing certain theoretical basis in this region. Besides, summary of the mineralization and metallogenic regularity for the establishment of prospecting model, has important significance for guide of the deposit prediction.更多还原