滇东南薄竹山晚燕山期酸性岩浆热液成矿作用研究

【作者】 张亚辉；

【导师】 张世涛；

【作者基本信息】 昆明理工大学 ， 矿产普查与勘探， 2013， 博士

【摘要】 在前人研究成果之上,本文按照成矿系列划分的四要素,对不同类型、不同矿种的典型矿床进行了剖析,同时辅以岩石学、岩石地球化学、矿床地球化学、同位素年代学和包裹体岩相学的研究,来认识薄竹山矿集区内矿床的时空分布特征及矿床成因,以多金属矿床时空分布样式作为大地构造环境的标志和限定,为薄竹山矿集区的靶区优选提供理论依据。取得的认识与成果如下：1、本文从地层、构造、岩浆岩、成矿构造环境、地质事件等多方面探讨了成矿的控制因素：地层中成矿元素的高背景值为成矿提供了良好的基础；矿集区内褶皱的核部及区域性断裂构造带为深部物质上涌的提供通道及赋矿空间。着重对燕山晚期花岗岩的演化、成因、成岩时代及构造环境进行了研究,认为薄竹山复式花岗岩为深源陆壳沉积物经局部熔融形成,是燕山晚期不同阶段演化产物,且岩体为两期侵入,早期形成于挤压环境,晚期形成于板内伸展环境。在对矿床空间分布规律研究中,认为,矿床产出主要围绕岩体分布,自岩体向外,在岩体与围岩接触带上产出高温W、W-Sn、 Fe-W矿床,在距离岩体稍远与岩浆活动有关的断裂中产出中温Ag-Pb-Zn矿床,在距离岩体更远的地表浅部断裂中产出低温Sb (Pb、Zn)矿床。2、对研究区内不同矿床类型、不同矿种典型矿床进行了详细剖析,通过各典型矿床的区域成矿地质背景、矿床地质、矿床地球化学、同位素年代学、包裹体岩相学等特征研究,认为陆壳重熔花岗质岩浆是薄竹山矿集区形成的主要物质来源,古生代沉积的浅海陆棚—滨海相碎屑岩—碳酸盐岩地层则为成矿提供了少部分物质。中生代构造一岩浆岩带是矿床的集中分布区。矿床的时间分布规律表明薄竹山矿集区内矿床集中分布于燕山晚期。成矿流体总体特征表现为成矿流体主要来自富钾花岗质岩浆的分异作用,早期成矿流体具有高温、高盐度、低NaCl含量、含CH4、CO2的特征,是在陆陆碰撞体背景下形成的,具有浆控高温热液矿床的流体特征。同时,以官房矿床和白牛厂矿床为例,论述了不同矿床之间的差异性和内在联系,认为研究区矿床间的联系和差异主要是由于赋矿地层岩性及含矿性的差异,控矿构造和矿体形成机制的差异以及岩体成岩构造背景的不同,导致了矿床间的矿床类型及成因上的差异,此结论为进一步在该区进行成矿系列的划分提供了依据。3、将典型矿床研究成果与前人对华南及滇东南地区成矿构造演化研究成果相结合,提出薄竹山矿集区成矿主要集中在燕山期,其成矿构造演化过程分为两个阶段：燕山晚期早阶段和燕山晚期晚阶段。燕山晚期早阶段(-91Ma)形成与板块碰撞挤压作用有关的以官房矿床为代表的矽卡岩型钨多金属矿(床)点,燕山晚期晚阶段(68Ma-)形成与拉张作用有关的以白牛厂矿床为代表的热液脉型银、铅、锌多金属矿床。并认为晚阶段成矿与华南西部地区晚白垩世岩石圈伸展作用有关。4、在上述成矿地质背景指导下,结合区域地球化学、地球物理资料,将研究区划分了一个成矿亚系列(薄竹山与燕山期壳源花岗岩有关的钨、锡、银、铅、锌、铁、铜矿床成矿亚系列)、4个矿床式(以官房高温矽卡岩型钨矿床为代表的官房式、以白牛厂中温热液脉型银多金属矿床为代表的白牛厂式、以茅山洞锑矿低温热液脉型矿床为代表的茅山洞式)。5、通过成矿系列的研究最终总结了薄竹山矿集区岩浆成矿作用和成矿规律,认为滇东南薄竹山花岗岩体是主要成矿母岩,岩浆经过分离结晶致使成矿流体出溶,钨锡作为不相容元素在残留岩浆中富集。初始成矿流体具有高温、高盐度、低NaCl含量、含CH4的特征。当热液与碳酸盐围岩接触时,发生接触交代作用,形成矽卡岩同时导致钨锡矿发生沉淀；大规模矽卡岩化之后,在岩浆活动热驱动下,成矿流体继续向浅部运移,并与大气降水大量混合形成岩浆与大气降水的混合流体,伴随成矿体系温度的降低,发生了黄铁矿、黄铜矿、毒砂、银黝锑矿等硫化物沉淀；此时岩浆活动仍然强烈,在岩浆活动热驱动下,成矿流体继续岩断裂向更浅部运移,随着温度的进一步降低,在断裂有利部位发生辉锑矿、方铅矿、闪锌矿等沉淀,形成低温锑(铅、锌)矿体。经过整个岩浆成矿作用,从而形成了围绕岩体自内向外的由高温→中温→低温的金属一系列矿床。6、结合薄竹山矿集区的实际,确立了研究区区域成矿模式并进行成矿预测。确定对锡、钨、银、铅、锌、铁、铜等进行成矿预测和远景评价,提出了六个A+B类成矿预测区即：Ⅰ、官房矿床官房钨矿段；Ⅱ、大腰店—菖蒲塘—铁厂一带；Ⅲ、白牛厂矿区穿心洞—对门山—阿尾矿段南部、阿尾矿段北部及深部隐伏花岗岩体接触带；Ⅳ、白牛厂矿区外围小寨矿段；Ⅴ、岩羊坡—分水岭——衣格白地段；Ⅵ、小平坝矿区所作底—龙树边地段。其中,Ⅰ远景区主要寻找矽卡岩型白钨矿床；Ⅱ、Ⅴ远景区,其矿体主要产在花岗岩与碳酸盐岩接触带上,为寻找矽卡岩型钨、锡、铁矿床的有利地段,其找矿前景巨大；Ⅲ远景区为寻找热液脉型银铅锌矿有利靶区,找矿前景仅次于Ⅱ、Ⅴ远景区。更多还原

【Abstract】 From system theory perspective, Minerogenetic series is a guiding、directional theory for studying the interconnections between depositions,regional metallogeny in the sciences of mineral deposits and the geological prospecting work in the four-dimensional spacetime. Bozhushan ore field is inportant part of Diandongnan tin polymetal metallogenic belt. For now, it has discovered bainiuchang sivler polymetal very large depoist、guanfang tungsten polymetal large depoist and mineralization10point.this paper chooses bozhushan area to carry on research of metallogenetic series and mineralization, which based on adequately collect and nderstanding the former research results, in accordance with division four elements of metallogenetic series, by studying petrology、petrogeochemistry、geochemistry of mineral deposits、isotope chronology and fluid-inclusion petrography of defferent typical deposits, such as guanfang deposit and bainiuchang deposit, and through applying to the theory of metallogenetic series to understanding characters of the geological era and space in bozhushan ore field. this article uses the temporal-spatial distribution patterns of polymetallic deposits as signs and qualification of tectonic environment, provides theoretical evidence for the target region in the bozhushan ore field.The first, Discusses the controlling factors of various metallogenesis mineral deposits from strata、structure, and intrusion body、the ore-forming environment and geological: In the strata of ore-forming elements in the high background value of metallogenetic provides a good foundation; Fold cores and regional fracture tectonic belt provides deep material upwelling channels and space of ore.On the research about evolution,cause of formation, diagenetic age and tectonic environment of the late yanshanian ore-bearing granite,consider bozhushan compound granite deposits formed by the partial melting of deep source continental crust.lt is the late yanshanian different stages of evolution,for Two period of time intrusive rock mass,early formation about extruding environment,and late formation about intraplate extension environment.At the same time, At the same time, analysis the space distribution regularity of ore deposit, that ore deposit output main distribution of surrounding rock mass, Rock mass from inside to outside, in contact with the surrounding rock mass with high temperature output W, W-Sn, Fe-W deposits, a little farther from the rock mass fracture associated with magmatic activity in the output medium temperature Ag-Pb-Zn deposit, output in the distance beyond the earth’s surface shallow rock mass fracture Sb (Pb, Zn) deposits in low temperature.The secondly, this paper does comprehensive research on defferent types and minerals of deposit in the bozhushan ore field, explains the regional ore-forming geological background、Geologic characteristics of the deposits、geochemistry of mineral deposits、 isotope chronology and fluid-inclusion petrography of all kinds of types depositss in detail to discuss the differences and internal connection between deposits, suggests that granitoids of crust remelting types is sources of ore-forming metals in the bozhushan ore field. shallow marine shelf facies—clastic rock of littoral facies—carbonate formations of the Late Paleozoic renders ore-forming few material. tectonic magmatic belt of the Mesozoic is concentrated distribution area of deposits. spatial and temporal distribution of deposits shows deposits are concentrated in the late Yanshanian. the ore-forming fluids are evolved from high temperature, low NaCl, containing CH4content of H2O-CH4-NaCl magmatic fluid to middle temperature, law NaCl, H2O-CH4-CO2-NaCl hydrothermal system containing CH4、CO2, final change to low temperature、meteoric fluid containing CO2. Taking the deposit of Guanfang and Bainiuchang for example, expound the differences deposit between dissimilitude and internal relation, thinking the contact and diversity of deposits research area that is mainly due to the lithology of Ore formation and ore-bearing potential, different ore-controlling structure andformation mechanism of Orebody between the background of structure of Rock diagenesis, lead to the ore deposit types and the causes of differences between the deposit, to provided the foundation for dividing the metallogenetic series in this area.on this basis, this paper combines with the results of the previous study for metallo-geotectonic evolution in the southest yunnan and southest china, put forward The metallogenic time to focus on Late Yanshan period,and divides the metallo-geotectonic evolution in two stages:the early and late stage of Late Yanshan period.in the study area formed tungsten multi metal deposit represented asguanfang deposit, associated with magmatic fluids in the early stage. in the study area formed the Skarn tungsten multi metal deposit represented as guanfang deposit, associated with the collision and compression between continental plates in the late stage of Late Yanshan period.the hydrothermal Silver,lead, zinc multi metal deposit represented as bainiuchang deposit,associated with the transtension between continental plates in the late stage of Late Yanshan period. The formation of deposits in late stages of late Yanshan period may be associated with lithospheric thinning in western south china. The deposit distributions represents a rule of around granite,and distributes the high-temperature hydrothermal deposit→the mid-temperature hydrothermal deposit→the low-temperature hydrothermal deposit outward from granite. These features appear to mineralization has a close relationship with the Mesozoic granitic magmatic activity in the study area.It’s based on that unity of the metallogenic time and timing evolutionary、the relationship between the development of regional geological structure and the evolution history of regional mineralization, Combines dates of geology、geochemistry and geophysics in the study area, one metallogenic subseries relating to magmatic activities can be classified as follow:the W、Sn、Ag、Pb、Zn、Fe、Cu metallogenic subseries relating to Crust source of granite. According to defferent and composition relations of the mineralization age of ore deposits、tectonic conditions、the genesis of ore deposits、deposit types, divide the metallogenic subseries into three types of mineral deposits:guanfang type、 bainiuchang type and maoshandong type.on the base of Regional Ore-forming Geological Conditions、Analysis of Spatial and Temporal Distribution between、Isotopic age dating of the study area and ore-forming fluids features, the paple summarizes mesozoic Magmatism and metallogeny in bozhushan ore field in bozhushan ore field. The paper suggests that The Bozhushan granite in southeast Yunnan is parent rock of the deposit.Tungsten and tin that are inconsistent elements were enriched in remaining magma when the fluid were dissolved from magma by the magma crystallizing and fracturing.The metallogenic fluid containing light NaCl and CH4is hyperthermal and high salinity. Tungsten and tin were precipitated when metasomatism were happened between granite and carbonate rocks. After extensive skarnization common pyrite, chalcopyrite, arsenopyrite and silver antimony fahlore and so on were formed by migrating deeply of the metallogenic fluid and mixing with meteoric water with accompanied by falling of metallogenic system temperature.Then stibnite, galena and blende that made in low temperature environment were separate out in break that advantageous to mineralization with migrating deeper of the metallogenic fluid to break fall of lower temperature.From this time on hyperthermal→medium temperature→hypothermal metallic ore deposit were formed from rock mass to periphery.At last,align with the realities of bozhushan ore field, the bozhushan ore field is being evaluated and metallogenic predicted,at the same time, proposes six prediction region:Ⅰ、 guanfang Ore Section,Guanfang Scheelite Ore Deposit; Ⅱ、a belt of dayaodian—changputang—tiechang; Ⅲ、the southern part of Ore Section,bainiuchang Ore Deposit、the northern part of awei Ore Section and the contact zone of the deep concealed granites;Ⅳ、 xiaozhai Ore Section, outside of bainiuchang Ore Deposit; Ⅴ、yanyangpo—fenshuiling—yigebai area; Ⅵ、 suozuodi—longshubian section of xiaopingba mine.更多还原