【作者】 薛明轩；

【导师】 孙丰月；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 黑龙江省位处兴蒙造山带东段，内生金矿成矿条件良好，但目前区内仅发现矿产地34处，矿床数量和规模与成矿条件极不匹配。本次工作以分析总结区域地质和地球物理资料为基础，结合与成矿有关岩浆岩的锆石年代学、岩石学和地球化学资料，认为黑龙江省内生金矿成矿地球动力学背景是古亚洲和环太平洋两大构造域的演化及其叠加、转换，受构造域转换及太平洋板块俯冲作用的影响，岩石圈经历了强烈的挤压增厚，进而发生了大规模的拆沉、伸展、减薄，引发了大规模构造岩浆活动和成矿作用，查明区域动力学演化与成矿耦合关系为：(1)海西晚期(260~250Ma)晚二叠世末古亚洲洋闭合额尔古纳-佳木斯地块与华北板块陆-陆碰撞，该体制下可形成老柞山、英城子等造山型金矿，且存在地壳连续成矿模式。(2)早燕山期(190~170Ma)中生代早-中侏罗世进入环太平洋构造域，太平洋板块强烈俯冲，区内大地构造体制发生根本变化，西太平洋大陆边缘由被动陆缘转化为活动陆缘，控制了霍吉河、鹿鸣等一系列规模巨大的细网脉型钼矿床、矽卡岩型钼多金属矿床和大安河矽卡岩型金矿，原认为属晚三叠世的花岗岩绝大多数为该期侵位。(3)晚燕山期(120~100Ma)早白垩世太平洋板块俯冲后岩石圈大规模拆沉、伸展、减薄，该体制下可形成东安、三道湾子等浅成低温热液型、砂宝斯等中低温热液脉型金矿床，成矿作用最强。本文系统地对晚古生代碰撞体制下形成的造山型金矿（老柞山、英城子）、中生代早-中侏罗世岩石圈挤压加厚体制下形成的矽卡岩型金矿床（大安河）、早白垩世岩石圈伸展减薄体制下形成的浅成低温热液型（三道湾子、东安和四平山）以及中低温热液脉型金矿床（砂宝斯）等各类典型矿床开展野外地质调研、成矿流体学以及成矿年代学等方面的研究，确定了主要的矿床成因类型，建立了内生金矿的成矿模式及成矿系列。并获得创新成果如下：(1)本次通过矿区有关侵入岩中锆石SHRIMP U-Pb定年以及首次在黑龙江选取与金属矿物密切共生的热液独居石进行SHRIMP U-Pb定年以及矿石中辉钼矿Re-Os测年等，明确厘定出老柞山金矿存在两期成矿。早成矿期成矿岩体片麻状花岗岩年龄256±3.1Ma，早成矿期辉钼矿Re-Os等时线年龄为256±1.3Ma，由此确定早成矿期的成矿年龄为海西晚期的256Ma，成矿与古亚洲洋闭合陆-陆碰撞体制有关；并准确确定晚成矿期成矿前闪长岩年龄106.8±1.0Ma、晚成矿期成矿后霏细岩年龄100.9±1.6Ma，晚成矿期热液成因独居石SHRIMP U-Pb法年龄为105.3±3.2Ma，从而确定晚成矿期的成矿年龄为燕山晚期的105Ma，成矿与早白垩世的岩石圈拆沉、伸展、减薄体制有关。热液成因的独居石在热液矿床中普遍发育，可应用于矿床直接定年，其前景广阔，值得大力推广。(2)浅成低温热液低硫化型金矿是省内规模最大、分布最广泛的一类金矿床，其标型蚀变矿物冰长石的形成时间可代表成矿年龄，而冰长石在东安、团结沟、金厂等大型矿床中普通发育。本论文首次选取东安金矿矿化蚀变过程中形成的冰长石进行Ar-Ar法测年，获得了105.14±0.7Ma的成矿年龄，其与东安成矿岩体石英斑岩的8个锆石206Pb/238U年龄平均值109.6±1.7Ma十分接近。该方法的成功应用，对研究区内规模大、分布广的浅成低温热液低硫化型金矿（如东安、团结沟、金厂等）的成矿年龄具有重要的参考价值。(3)前人多认为砂宝斯金矿等赋存于砂岩中的金矿为蚀变砂岩型、中低温热液型或造山型金矿床。本次研究认为：区内发育的早白垩世(133±5Ma和142.79±2.11Ma)闪长玢岩、闪长岩、煌斑岩、辉绿玢岩、流纹斑岩、花岗斑岩等双峰式岩脉，与金矿空间关系密切，是成矿前侵入岩，属伸展体制下产物；主要控矿构造为伸展状态下形成的、明显切层的一系列正断层，而非前人认为的逆冲推覆构造控矿，也不是有人认为的层间构造控矿；结合砂宝斯金矿成矿流体特点，确认矿床为受正断层控制的中低温热液脉型金矿床，成矿时代应与区内早白垩世(120-100Ma)大规模成矿的时代一致，矿化类型与老柞山第二期金矿化类型一致；最后，认为该类矿床存在浅部中低温热液脉型金矿和深部斑岩-矽卡岩金矿二套成矿系统，深部的斑岩-矽卡岩型金矿应是今后找矿勘探工作的重点方向。(4)通过对世界上极富的三道湾子金矿成矿动力学背景和地质特征研究，首次明确提出三道湾子金矿为幔源物质成矿。三道湾子金矿是与碱性岩有关的浅成低温热液低硫化型Au-Ag-Te矿床，矿石中发现的大量碲金硫化物为主要载金矿物，碲为深源来源，大量发育的碲化物是幔源成矿的重要矿物学标志，在早白垩世研究区岩石圈强烈伸展减薄的背景下，金与碲以地幔射气的方式迁移至地壳内并富集成矿；三道湾子与成矿关系密切的碱性岩也富含Te，而碱性岩通常来自上地幔；三道湾子矿石硫和铅同位素研究也表明硫和铅主要来自地幔。在前人资料基础上，系统地分析了黑龙江省区域金矿控矿条件，并总结了黑龙江省金矿的时空分布规律；尤其是通过对小兴安岭北西向上地幔凹陷、北西向深部重力异常低值带（可能为深部中酸性岩体引起）、北西向线性构造（重力异常）以及黑龙江追踪断裂的识别，进一步明确了小兴安岭北西向浅成低温热液型、中低温热液脉型金成矿带的存在。最后，针对内生金矿找矿指出今后应关注的关键问题是：(1)地球动力学背景是矿床形成的最根本的控制因素，是找矿选区的基础和必要条件，据此确定目标矿床类型最为重要；(2)区内主要类型金矿床为浅成低温热液型和造山型。前者形成深度浅，剥蚀(包括差异剥蚀)及保存情况的研究可有效指导找矿，目前黑龙江省发现的该类矿床均为LS型金矿，HS型金矿及LS型银铅锌矿在区内有良好的找矿前景，应引起高度重视；后者形成深度大，准确确定不同地壳层次造山型金矿成矿深度，可为区域找矿和深部资源预测提供可靠依据。(3)利用矿床类型特征和矿化富集规律，选用有效的勘查方法，是发现和勘查矿床的关键；利用矿体的群带规律、横向对应规律、等距分布规律、分段富集规律、侧伏规律等可有效地进行成矿预测。更多还原

【Abstract】 Heilongjiang province is located in the eastern part of Hinggan-Mongoliaorogenic belt. But there are only34gold deposits in it, which do not match well with goodmetallogenic conditions of the region. Based on regional geology and geophysical data,combining material from zircon geochronology, petrology and geochemistry, it was thoughtthat endogenetic gold geodynamic settings of Heilongjiang province belongs to evolution,transition and superposition between Paleo-Asia tectonical domain and circum-Pacific one.Under the transition and subduction of Pacific oceanic plate, the lithosphere underwent strongcompression and thickening. Then a large scale of detachment, extending and thinninghappened, which resulted in a large scale of structural-magmatic activities and mineralization.The coupling relationship between regional geodynamic evolution and metallogenesis areconcluded as follows:(1) In the late Permian in the late hercynian (260-250Ma),Songnei-Jiamusi block collided with North China plate during closing of Paleo-Asia ocean inLate Permian. Orogenic gold deposits such as Laozuoshan and Yingchengzi etc. depositsdeveloped and crustal continuum model occurred.(2) In the early Yanshanian (190-170Ma),this region came into circum Pacific tectonic domain, strong subduction of Pacific plate andregional geotectonic settings changed basically. The continental margin of western Pacificocean transferred into active one, which controlled a series of large-scale veinlet-network-type Mo deposits such as Huojihe and Luming, skarn-type Mo polymetal deposits andDa’anhe skarn-type gold deposit. The granites that were thought to the late Triassic mostlyintruded in this era.(3) In late Yanshanian (120-100Ma), a large scale of detachment,extending and thinning of lithosphere happened after subduction of Pacific plate in the earlyCretaceous. Epithermal gold deposits like Dong’an, Sandaowanzi ones and Meso-epithermal vein type ones like Shabaosi deposit developed.The author researches typical gold deposits such as the orogenic gold deposits(Laozuoshan, Yingchengzi) under late Paleozoic collision, Skarn type gold deposits (Da’anhe)under the Mesozoic to the early-middle Jurassic compression and thickening of lithosphere,epithermal gold deposits (Sandaowanzi, Dong’an and Sipingshan) and meso-epithemalvein-type gold deposits (Shabaosi) under the early Cretaceous extensional thinning oflithosphere by the methods of field survey, fluid inclusion researches and metallogenicgeochronologies. Then the author determines major genetic type of deposits and buildsendogenetic gold metallogenic models and series in the studying area. The creativeachievements have been got as follows:(1) According to SHRIMP U-Pb dating of zircons inintrusive rocks and hydrothermal monazites related to metal minerals and Re-Os dating ofmolybdenites in ores, it was the first time to consider that there are two stages ofmetallogenesis in Laozuoshan gold deposit. And the author determined that the age ofmetallogenic gneiss granite is256±3.1Ma, and the Re-Os isochron age is256±1.3Ma in theearly metallogenic stage. So it was thought that the early metallogenic stage is256Ma in thelate Hercynian, which is related with continental-continental collision during closing ofPaleo-Asian Ocean. The author also determined that the age of pre-mineralization diorite is106±1.0Ma, the age of post-mineraliztion felsite is100.9±1.6Ma, and the hydrothermalmonazites SHRIMP U-Pb age is105.3±3.2Ma. So it was considered that the late metallogenicstage is105Ma in late Yanshanian, which is related with the detachment, extending andthinning of the lithosphere in the early Cretaceous. Hydrothermal monazites developcommonly in hydrothermal deposit, so they can be used to date directly the metallogenic ageof mineral deposits. Then the monazite dating has a better prospect and is worth to popularizewidely.(2) LS-type of epithermal gold deposits is the most extensive and largest type of golddeposit in Heilongjiang province. The age of typomorphic adularia can representmetallogenic age, while adularias develop well in Dong’an, Tuanjiegou, Jinchang golddeposits. It was the first time to date Ar-Ar age of Adularia formed during mineralization andalteration process in Dong’an gold deposit as105.14±0.7Ma, which is consistent with the109.6±1.7Ma of eight zircon206Pb/238U age from metallogenic quartz porphyry. The successof adularia dating has important reference value to date the metallogenic ages of theepithermal gold deposits like Dong’an, Tuanjiegou and Jinchang.(3) The predecessors considered that Shabaosi gold deposit that is located among sandstone belongs to alterationrock-type, epithermal-mesothermal or orogenic gold deposits. The author thought that theearly Cretaceous (133±5Ma and142.79±2.11Ma) bimodal diorite porphyrite, diorite,lamprophyre, gabbroporphyrite, rhyolite porphyry and granite porphyry were related spatiallywith gold mineralization. They are pre-mineralization intrusive rocks formed underextensional regime. Major ore-controlling structures are normal faults formed in extensionaland strata-cutting conditions rather than thrust faults or interbeded ones thought by thepredecessors. Combing with the characteristics of fluid inclusions of Shabaosi gold deposit, itwas thought that the deposit belongs to meso-epithermal vein-type deposit controlled bynormal faults, and the metallogenic age of it is consistent with the early Cretaceous(120-100Ma) large scale mineralization, whose mineralized type match well with the secondstage of mineralization in Laozuoshan gold deposit. Then the author proposed that there aretwo series of metallogenic systems which consist of the shallow LS-type epithermal goldmineralization and deep porphyry-skarn-type mineralization. And the deepporphyry-skarn-type mineralization may be the further prospecting target.(4) According tostudy on the geodynamic settings and geological characteristics of Sandaowanzi gold depositthat is one of richest deposit of the world, it was the first time to propose that the origin offluid is primary mantle-derived fluids. Sandaowanzi gold deposit belongs to LS-typeepithermal Au-Ag-Te deposit. There are lots of Au-Te-bearing sulfides in ores. Te isdeep-source element, and lots of Te-bearing sulfides are important mineral symbols ofmantle-derived metallogenesis. Au and Te migrate and enriched up to the crust because ofmantle degassing while early lithosphere extending and thinning. The alkaline rocks, whichare often derived from upper mantle, related to Sandaowanzi gold deposit also contain Te.And the S and Pb isotopic compositions from this deposit also show that the sources of S andPb are derived from the upper mantle.Based on the previous researches, the author analyzed the gold metallogenic conditionsin Heilongjiang province and summarized the spatio-temporal regularities of gold deposits init. Especially discriminating NW-striked upper mantle depression, NW-striked low valuezone of gravity anomalies (possibly resulted from deep acid-intermediate rock bodies),NW-striked linear structures (from explaination of gravity anomalies) in Xiao Hinggan Lingand Heilongjiang tracing-tension-joint fault, the author ascertained that there is a NW-striked epithermal and meso-epithermal vein-type gold metallogenic belt in Xiao Hinggan Ling.Finally, in order to prospect endogenetic gold deposit, the following key problems must beconsidered further:(1) The geodynamic settings are the basic ore-controlling factors for oredeposits forming, which are the basic and necessary conditions for ore prospecting.According to these conditions, ascertaining genetic type of gold deposit in prospective area isthe most important mission.(2) The major genetic types of gold deposits are epithermal andorogenic ones. The former one has shallow metallogenic depth, so studying on denudation(including different denudation) and conservation may help instruct prospecting. And the typeof epithermal gold deposit in Heilongjiang province mostly belong to the LS-type golddeposit, so the HS-type gold and LS-type Ag deposit may have good prospecting potentials.The latter one has deep metallogenic depth, exactly calculating the metallogenic depth ofdifferent levels of orogenic gold deposits can provide reliable data for regional oreprospecting and deep mineral prospecting.(3) Choosing effective exploration methods basedon the basic geological characteristics of gold deposit and mineralized enrichment regularitiesis the key for found and exploration of them. And occurrence regularities of ore bodies likecluster, lateral corresponding, isometry distribution, segment enrichment, and pitch can beused effectively for ore prospecting.更多还原