【作者】 江彪；

【导师】 邓军；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2014， 博士

【摘要】 “三江”地处青藏高原东、北缘，由并流的怒江、澜沧江、金沙江而得名，地域跨云南西部、西藏东部、四川西部，再向西到青海南部，形状呈弧形带状。兰坪—思茅盆地位于“三江”南段，夹持于西部的澜沧江缝合带和东部的金沙江缝合带之间，向北趋于歼灭，向南呈扫帚状散开，北窄南宽。区内新生代逆冲推覆构造十分发育，碳酸盐岩容矿的铅锌矿床大量产出。前人对这些矿床的成因还存在争议，思茅盆地内发育的碳酸盐岩容矿的铅锌矿床更是少有研究。兰坪—思茅盆地碳酸盐岩容矿铅锌矿床的深入研究对于整个“三江”贱金属成矿带，乃至沉积岩容矿型铅锌矿床成矿理论的丰富和完善都具有重要意义。本文通过对兰坪—思茅盆地典型沉积岩容矿型铅锌矿床兰坪盆地白秧坪矿集区各Pb-Zn矿床、金顶Pb-Zn矿床、河西—三山Pb-Zn矿床、菜籽地Pb-Zn矿床、老君山Pb-Zn矿床以及思茅盆地萝卜山Pb-Zn矿床、厂硐Pb-Zn矿床和易田Pb-Zn矿床进行大量野外和系统室内实验测试工作，查明了三江南段碳酸盐岩容矿铅锌矿床基本地质特征，明确了盆地内新生代逆冲推覆构造系统及其伴生的次级构造对铅锌矿床和矿体的控制形式；探究了矿石组构和矿物组合类型；确定了成矿流体性质和成矿物质来源；提出了兰坪—思茅盆地沉积岩容矿型铅锌矿床成因上可归于类MVT型铅锌矿床，并构成三江类MVT型铅锌矿床巨型成矿带的南延部分的观点；建立了兰坪—思茅盆地沉积岩容矿铅锌矿床成矿模型，总结了该类型矿床区域找矿思路和方向。兰坪—思茅盆地沉积岩容矿型铅锌矿床为后生矿床，构造控矿作用明显，同逆冲期形成的主逆冲断层及其次生断裂和平推断层、推覆形成的盐丘底辟穹窿构造、新生代区域走滑作用使先存的逆冲断层再张开、区域逆冲后的短暂应力松弛或区域伸展作用形成的张性断裂及相关溶洞垮塌构造，都是重要的控矿构造，此外，由于成矿流体交代围岩作用，个别矿床也出现顺层发育的层状或似层状矿化。赋矿围岩主要为碳酸盐岩和钙质胶结砂岩，矿石组成主要为方铅矿、闪锌矿和方解石三种矿物的各种组合，呈脉状、交代碳酸盐岩或交代角砾胶结物、胶结围岩角砾等矿化样式出现，一些矿床也发育重晶石、天青石、萤石等热液矿物，硫化物除方铅矿和闪锌矿外，也发育少量黄铁矿、黝铜矿、硫砷铅矿等。流体包裹体研究表明，成矿温度范围主体变化于110～210℃，峰值集中在110～150℃之间，盐度范围变化于3.7～24.17wt%(NaCleq)，平均为17.28wt%(NaCleq)，呈现低温高盐度的盆地卤水特征；热液成矿期单矿物主微量稀土元素研究结果显示成矿流体经历温度渐降的演化过程，总体呈现还原性流体性质和中低温成矿特点。C-O同位素研究表明，碳质主要源自地层碳酸盐岩溶解，部分矿床有沉积有机物脱羟基的贡献，成矿流体主体为盆地卤水，此外也有大气降水的加入。S同位素组成显示硫可能有多个来源，主要来自硫酸盐的热化学还原作用，或者有机质的热分解，部分矿床细菌还原硫作用显著；Sr同位素和Pb同位素示踪结果显示成矿物质全部来自沉积地层或有盆地基底物质贡献，成矿与岩浆作用无关；成矿年代学研究结果显示区域成矿作用发生在41～29Ma，对应于印度-欧亚大陆晚碰撞转换阶段。综上建立兰坪—思茅盆地沉积岩容矿型Pb-Zn系列矿床成矿模型：兰坪—思茅盆地沉积岩容矿型Pb-Zn矿床是盆地卤水活动的结果，印度-欧亚大陆碰撞在大陆内部形成富盆地卤水的挤压/走滑盆地，下渗的盆地卤水在深部被加热向上运移，并由盆地两侧隆起向地形低洼处横向排泄，流体运移过程中沿途萃取各沉积地层中的成矿元素，最终在有利成矿部位沉淀就位。更多还原

【Abstract】 The area of " Three Rivers" named by the flow of Nujiang, Lancang and JinshaRiver, including western Yunnan, eastern Tibet, western Sichuan, and southernQinghai, is located on the eastern and northern margin with a curved shape. Lanping-Simao Basin, located on the southern section of " three rivers" area and held by theJinsha in the west and the Lancang River suture zone in the east, tends to annihilate inthe north and a broom-like spread in the south. The Cenozoic tectonic overthrust iswell developed and lots of carbonate-hosted lead-zinc ore deposites yield out inLanping-Simao basin. The futher study on carbonate-hosted lead-zinc ore depositesyield out in Lanping-Simao basin is of great significance for the entire " three rivers"with base metal mineralization, as well as enriching and improvingsedimentary-rock-hosted lead-zinc ore-type forming theory since the causes of thosedeposits is still controversial and that type of deposite in Simao basin is rarely studiedbefore.A lot of extensive fieldwork and systemic laboratory experiments testing andanalysis have been done on these typical sedimentary-rock-hosted lead-zinc depositsincluding each Pb-Zn deposit in Baiyangping ore district, Jinding Pb-Zn deposit,Hexi–Sanshan Pb-Zn deposit, Caizidi Pb-Zn deposit, Laojunshan Pb-Zn deposit inLanping basin and Luoboshan Pb-Zn deposit, Changdong Pb-Zn deposit, Yitian Pb-Zndeposit in Simao Basin to identify the basic geological characteristics ofsedimentary-rock-hosted lead-zinc deposits in southern section of Sanjiang area,clarify the form of control to the lead-zinc deposits and ore bodies by the Cenozoicoverthrust tectonic and its associated secondary structure system in the basin, explorethe fabric and ore mineral assemblages type; determine the property of theore-forming fluids and mineral sources into; propose that the sedimentary-rock-hostedlead-zinc deposits in Lanping-Simao basin can be attributed to the MVT Pb-Zn typedeposits and Simao Basin is the southern extension of the Sanjiang MVT-like orezone, establish the model of MVT-like deposit in Lanping-Simao Basin, summedup the prospecting ideas and indicate the direction of this type of deposit.The sedimentary-rock-hosted Pb-Zn deposit in Lanping-Simao basin isepigenetic deposit, significantly controled by structure such as the main thrust faultand its secondary fracture and strike-slip fault formed in a thrust stage, salt domestructure result from napping, reopened preexisting thrust fault during the Cenozoicregional strike-slip stage, tension fracture and karst cave collapse structures formed during transient stress relaxation stage or regional tension after regional thrust, inaddition, layered or quasi-lamellar mineralization appeares in individual depositbecause of the metasomatic interaction between ore fluid and surrounding rock. Thehost rocks are mainly of carbonate rock and calcareous sandstone and The orescontain galena, sphalerite, and calcite alone or their assemblages in terms of replacingcarbonates and cements of breccias, and cementing breccias.Barite, celestite, andfluorite occur in some deposits. In addition to galena and sphalerite, pyrite,tetrahedrite, baumhauerite etc also appears.Fluid inclusion studies indicate that theore-forming temperature ranges from110～210℃with a peak at110～150℃.Salinity ranges from3.7～24.17wt%(NaCleq) with a average of17.28wt%(NaCleq).The ore forming fluid is brine in the basin of low temperature and high salinity. Singlemineral trace and rare earth elements research results of hydrothermal mineralizationperiod show that the evolution process of ore-forming fluid undergoes graduallydecreased temperature.The ore-forming fluid is of reducibility and middle-lowtemperature. C-O isotope studies show that carbon mainly comes from dissolution ofcarbonate rocks in the formation as well as sedimentary organic matterdehydroxylation contribution in some deposits. The ore-forming fluid mainly comesfrom basin brine in addition to precipitation.S isotopic compositions show that sulfurmay have multiple sources. Sulfur mainly comes from thermochemical sulfatereduction effect or organic matter decomposition. Bacteria reduced sulfur contributeobviously to the ore-forming in partial deposits.Sr isotope and Pb isotope tracerstudies show that ore-forming material, has nothing to do with magmatism, totallycomes from sedimentary strata or basin basement. Study on the metallogenicchronology shows regional mineralization occurred in the41～29Ma, correspondingto the transition stage of late India-Eurasia collision.A consolidated model of sedimentary-rock-hosted type Pb-Zn metallogenicseries in Lanping-Simao Basin is established: sedimentary-rock-hosted type Pb-Zndeposits in Lanping-Simao Basin are the results of the activities of brine. A strike-slipbasin rich of brine is formed in the interior of the continent becase of the India-Eurasia collision, brine infiltrates into the deep and then heated to uplift, migratingfrom both sides of the basin to lateral low-lying terrain. Fluid migrate along varioussedimentary strata and extract ore-forming elements, precipitating to mineralization infavorable position finally.更多还原