【作者】 侯万荣；

【导师】 聂凤军；

【作者基本信息】 中国地质科学院 ， 矿物学、岩石学、矿床学， 2011， 博士

【摘要】 华北克拉通北缘地处华北克拉通和中亚造山带的结合部位,区内早前寒武纪地层出露广泛,深大断裂和韧性剪切带发育,岩浆活动频繁,具有良好的成矿地质条件,是中国重要的金成矿带之一。哈达门沟金矿床和金厂沟梁金矿床是位于其中的两个非常典型的大型金矿床。论文在前人工作的基础上,采用野外地质调查和室内研究相结合的方法,对两处典型金矿床开展重点解剖研究,初步查明成矿地质背景、矿床地质特征、成矿流体来源、成矿物质来源,确定成矿时代,阐明矿床形成机制。在此基础上,对两处矿床进行对比,分析成矿规律和控矿因素,探讨区域构造岩浆演化与金成矿作用的关系,丰富华北克拉通北缘金矿成矿理论,为区域金矿找矿提供依据。哈达门沟金矿床地处华北克拉通北缘阴山隆起带南缘乌拉山复背斜南翼,金矿体主要产于新太古界乌拉山群变质岩中,主要矿石类型包括含金石英脉、含金石英－钾长石脉、含金钾化蚀变岩等。区内大桦背岩体锆石SHRIMP U-Pb年龄为353±7Ma,为海西早期；沙德盖岩体锆石SHRIMP U-Pb年龄加权平均年龄为221.6±2.1Ma,西沙德盖岩体锆石LA-ICPMS U-Pb年龄为222.9±0.82Ma,均为印支期。岩石地球化学特征均表现为高硅、富碱、弱过铝质的特点,在Rb-(Y+Nb)和R1-R2图解中,大桦背岩体落入同碰撞－后碰撞伸展区,而沙德盖岩体投入晚造山－非造山范围。成矿流体主要为中低温(160～300℃)、中低盐度(5%-15%NaCleq),气相成分以H20和CO2为主,液相组分阴离子以CI-和S042-为主,阳离子以Na+、K+和ca2+为主。矿石834s变化于-21.7‰～5.4‰,极差为27.1‰,说明成矿物质来源的复杂性,平均值为-10.69‰,表现出亏损重硫的特点,硫继承了太古代地层中硫的同位素特点,并混有深部含矿流体的硫。矿石铅同位素组成、单阶段模式年龄、Th/U比值、μ值变化范围较大,表现出多源特点,在铅构造模式图上,投点比较分散,表明哈达门沟矿石铅来源的复杂性。氢-氧同位素表明,成矿流体来源于岩浆水和部分变质热液,后期有天水的混入。矿石辉铝矿Re-Os同位素加权平均年龄为(386.4±2.7)Ma,等时线年龄为(386.6±6.1)Ma,金矿床主要成矿时代为早泥盆世,后期有多期热液活动叠加。矿床形成于弧－陆碰撞后的伸展构造背景。金厂沟梁金矿床地处华北克拉通北缘阴山-燕山隆起带东段努鲁尔虎山隆起带,金矿体赋存在新太古界建平群小塔子沟组中。主要矿石类型为硫化物及富硫化物-石英脉型、富硫化物蚀变岩型。区内主要岩体锆石LA-ICP MS U-Pb同位素年龄为：金厂沟梁片麻状花岗岩加权平均年龄258.6±1.6Ma-261.61±0.94Ma,为二叠纪中晚期；西台子似斑状黑云母二长花岗岩锆石LA-ICP-MSU-Pb加权平均年龄226.8±0.87Ma,为三叠纪中晚期；对面沟似斑状花岗闪长岩锆石加权平均年龄140.86±0.71Ma～142.65±0.44Ma,细粒花岗闪长岩加权平均年龄138.7±1.2Ma,早白垩纪中期。这些岩体主、微量、稀土元素、钕、锶、铅同位素组成等地球化学特征相似,锆石年龄也表现出继承的特点,说明它们之间有成生联系。在Rb-(Y+Nb)和R1-R2图解中,片麻状二长花岗岩投点于同碰撞与火山弧花岗岩范围内,西台子似斑状二长花岗岩、对面沟细粒花岗闪长岩和似斑状花岗闪长岩均主要投入造山晚期-后造山范围。成矿流体表现为中高温(190-380℃),低盐度(0.18-8.81wt%NaCleq),气相成分以H20和CO2为主,液相组分以Cl-、SO42-、Na+、K+和Ca2+为主。矿石634S变化于-2.8%o～-0.6%o,极差为2.2‰6‰,平均值为－1.61‰,与长皋沟、二道沟金矿床硫同位素组成相似,均集中在0值附近,具有深源硫的特点。金厂沟梁、二道沟、常皋沟三个矿区铅同位素组成、单阶段模式年龄、Th/U比值、μ值等一系列参数均相似,变化范围小。在铅构造模式图上,铅同位素数据主要投在地幔铅演化曲线和下地壳铅演化曲线之间靠近地幔铅演化曲线的一侧,反映了铅的来源主要为地幔和下地壳,同时有少量造山带铅的混入。氢－氧同位素表明,成矿流体主要来自岩浆水,有部分天水混入。对与矿脉相互穿插的黑云粗安斑岩脉进行年龄测定,获得LA-ICP-MS年龄为131.7±1.1Ma,基本限定了成矿年龄。对面沟铜钼矿化辉钼矿Re-Os加权平均年龄131.45±0.93Ma,与金厂沟梁金矿床以及区内黑云粗安斑形成时代基本一致。对西矿区深部钼矿化石英脉辉钼矿Re-Os年龄测定,获得等时线年龄244.7±2.5Ma,加权平均年龄243.5士1.3Ma,说明本区存在三叠纪钼矿化。金矿床形成于中国东部大规模岩石圈伸展减薄的构造背景。通过对比研究,认为哈达门沟金矿床主要与华北克拉通北缘深大断裂的多期活动有关,成矿物质来源有太古代乌拉山群的贡献,但主要来自深部钾质流体,而金厂沟梁金矿成矿作用更多的与华北克拉通东部岩石圈减薄相联系,成矿物质主要来自对面沟岩体侵入的岩浆热液,他们虽然都产于华北克拉通北缘的太古代深变质岩中,但成矿机理是完全不同的。根据金矿床的区域成矿条件、成矿规律和控矿因素,认为两个典型矿床的深部和外围找矿潜力很大,哈达门沟金矿不仅在矿区深部找矿,在矿区东部和北部还有很大找矿远景,钾化、硅化、黄铁矿化等蚀变,地球化学异常区、区域性深断裂的次级断裂附近是重要的找矿标志。金厂沟梁金矿床应围绕对面沟岩体进行找矿,目前岩体的东半部有金矿产出,西半部还没有金矿发现,所以西半部也有找到金矿的可能。更多还原

【Abstract】 Northern margin of North China Craton is located at the convergence of North China Craton and central Asian orogenic belt, which is characterized by perfectly developed early precambrian strata, complex geological structures, frequent magmatic activities, rich gold ore resources and lots of gold deposits, has good mineral-forming condition and great prospection potential, thus formd an important gold metallogenic belt in China, In which Hadamengou gold deposit and Jinchanggouliang gold deposit are very typical large gold deposits. Based on the previous results, combining field geological investigation and laboratory study, in this paper, we gave a detailed analysis on the two typical gold deposits, preliminary identified regional ore-forming geological background, geological features of deposits, source and evolution of ore-forming fluid and ore-forming material source, determined metallogenic epoch, illustrated ore-forming mechanism. Further synthetically analyzing regional metallogenic geological setting, ore-control factors and metallogenic law by contrasting study on the two deposits, discussing on the relationship of regional tectonics setting, magmatism evolution and gold metallogeny, deepening cognition on gold mineralization law in the northern margin of North China Craton, enriching metallogenic theory and providing guidance for regional prospecting.Hadamengou large gold deposit in Inner Mongolia is one of the important deposit, located in southern margin of Wulashan anticlinorium of Yinshan uplift(west part of the Inner Mongolian earth axis) on the north margin of North China Craton. The gold orebodies mainly lies in the metamorphic rock of Wulashan Group, Archaeozoic erathem., main ore type include gold-bearing quartz vein type, gold-bearing quartz-potassic feldspar vein type, gold-bearing altered rock type. In the gold mineralization district, zircon SHRIMP U-Pb age of the Dahuabei granite is 353±7Ma, Early Hercynian. Zircon SHRIMP U-Pb weighted average age of the Shadegai granite is 221.6±2.1Ma, zircon LA-ICP MS U-Pb weighted average age of Xishadegai granite is 222.9±0.82Ma, both were formed in the Indosinian. Lithogeochemical characteristics show that those granites are characterized by high silicon, alkali-rich, weakly peraluminous. In the Rb-(Y+Nb)diagram and R1-R2 diagram, the geochemical data of Dahuabei Intrusive rock plotted into syn-collision and post-collision range, the geochemical data of Shadegai Intrusive rock plotted into post-oro genic range, ore-forming fluid is characterized by intermediate-low temperature (160～300℃), mid-low salinity (5%～15% NaCleq).The gas component of fluid inclusions is dominated by H2O and CO2, The main anions in the liquid composition are Cl- and SO42-, and the cations are Na+, K+ and Ca2+.The sulfur isotope composition of the oreδ34S vary from -21.7‰to 5.4‰, the change range is 27.1‰, average value is -10.6‰, depleted 34S, indicated the sources of ore-forming material are complexity, sulfur isotope composition inherited archean strata, mixed with sulfur in deep-sourced ore-bearing Fluid. Lead isotopic compositions of the ore, single-stage model age, Th/U ratios,μvalue vary in a large range, indicated multiple sources characteristics. In plumbotectonic model diagram by Zartman and Doe, the lead isotopic compositions of ore mineral plotted scattered, this demonstrates that the ore lead came from the mixed lead. Hydrogen and oxygen isotopes show that the ore-forming fluid was derived from magmatic and small metamorphic water, Late mixed with meteoric water, molybdenite Re-Os weighted mean age is (386.4±2.7)Ma and isochron age is (386.6±6.1)Ma of the orestone, which show the main metallogenic epoch is early devonian, later multi-phase hydrothermal activity probably superimposed on the early stages. The deposit formed in intracontinental extensional tectonic setting after arc-continental collision.Jinchanggouliang gold deposit in Inner Mongolia is another important deposit, located in Nuluerhushan uplift belt of mid-east part of Yinshan-Yanshan uplift(the Inner Mongolian earth axis) on the northern margin of North China Craton. The ore bodies are mainly hold within the the metamorphic rock of Xiaotazhigou Formation of Neoarchean Jianping group. The main type of ore include sulfide type, sulfide-rich quartz vein type and sulfide-rich altered rock type. In the gold mineralization district, the zircon LA-ICP MS U-Pb weighted mean age of Jinchanggouliang gneissic granite is 258.6±1.6Ma-261.61±0.94Ma, mid-late permian. The zircon LA-ICP MS U-Pb weighted mean age of Xitaizi porphyraceous biotite admellite is 226.8±0.87Ma, middle-late triassic. The zircon LA-ICP MS U-Pb weighted mean age of Duimiangou porphyraceous granodiorite is 140.86±0.71Ma～142.65±0.44Ma and weighted mean age of fine grained granodiorite 138.7±1.2Ma, early cretaceous. The major elements, trace elements, rare earth elements and Neodymium-Strontium-Lead isotope composition of these Intrusive rocks are similar, their zircon U-Pb isotope ages displayed inherited zircon age features, which indicated that these intrusive rocks had some correlations in metarial source. In the Rb-(Y+Nb)diagram and R1-R2 diagram, the geochemical data of Jinchanggouliang gneissic adamellite plotted into syn-collision and post-collision transitional environment, the geochemical data of Xitaizi porphyraceous biotite admellite, Duimiangou porphyraceous granodiorite and fine grained granodiorite plotted into post-orogenic stage extensional environment. Ore-forming fluid is characterized by medium-high temperature (190-380℃), low salinity(0.18～8.81 wt%NaCleq). The gas component of fluid inclusions is dominated by H2O and CO2, The main anions in the liquid composition are Cl-and SO42-, and the cations are Na+, K+ and Ca2+. The sulfur isotope composition of the oreδ34S vary from-2.8‰to-0.6‰, the change range is 2.2‰, average value is-1.61‰, similar to the sulfur isotope composition of ores in the Changgaogou and Erdao gold deposit, the averageδ34S values are all concentrated near 0 value, indicating that the magmatic sulfur source is dominant. A series of parameters such as Lead isotopic compositions of the ore, single-stage model age, Th/U ratios, p. values etc. are similar in Jinchanggouliang gold deposit, Erdaogou gold deposit and Changgaogou gold deposit, parameters variable range are very small. In plumbotectonic model diagram by Zartman and Doe, the lead isotopic compositions of ore mineral plotted between upper mantle curve and lowercrust curve, near the upper mantle curve, this indicated that source of Pb main derived from mantle and lowercrust, simultaneously a little orogenic belt Pb mixed. Hydrogen and oxygen isotopes show that the ore-forming fluid was mainly derived from magmatic water, Late mixed with some meteoric water. The zircon LA-ICP MS U-Pb weighted mean age of the biotite trachyandesite porphyry dyke is 258.6±1.6Ma～261.61±0.94Ma, which is mutual interpenetrated with Jinchanggouliang gold ore veins, thus the age basically constrained Jinchanggouliang gold metallogenic age. Duimiangou copper-molybdenum mineralization area, Molybdenite Re-Os weighted mean age is 131.45±0.93Ma, essentially consistent with Jinchanggouliang gold ore-forming age. molybdenum mineralization quartz veins in the deep position of western mining area of Jinchanggouliang gold deposit, Molybdenite Re-Os weighted mean age is 243.5±1.3Ma and isochron age 244.7±2.5Ma, show that existing triassic molybdenum mineralization in this area. The Early Cretaceous was a period of intensive intracontinental rifting, crustal stretching and lithospheric thinning in Eastern China and adjacent areas. By regional contrast, Jinchanggouliang gold deposit formed in lithosphere extension-thinning tectonic setting.By comparative study, the mineralization of Hadamengou gold deposit is main related to deep-seated faults which undergone multistage activities, in the northern margin of North China Craton. Ore-forming materials partly come from metamorphic rocks of Archean Wulashan group and mainly from deep potassium-bearing magmatic hydrothermal fluid. Jinchanggouliang gold metallogeny main related to the lithosphere thinning in eastern China, metallogenic materials originated from ore-bearing magmatic hydrothermal fluid of Duimiangou intrusive rocks. Both deposits hosted in high grade metamorphic rocks of northern margin of North China Craton, but their mineralization mechanism are different.on the basis of geological setting of ore-forming processes, geological characteristic and ore-controlling factors, deduced that prospecting potential is tremendous in deep and peripheral area of the two typical deposits, In Hadamengou gold deposit area, gold prospecting not limited the deep of exited orebodies, there is a great prospecting potential in the north and east of the Hadamengou gold mineralization area. Potassic alteration, sillcification alteration, pyrite and other alteration, pegmatite veins, intermediate-acid intrusive rocks, geochemical anomalies, sub-regional deep fault rupture is an important prospecting symbols. In the Jinchanggouliang gold mineralization area, gold prospecting should surround the Duimiangou intrusive rocks. At present, there had found a series of gold-molybdenimum deposit(occurences) in the east of Duimiangou intrusive rocks such as Jinchanggouliang, Erdaogou, Changgaogou gold deposits, Duimiangou copper-molybdenum deposit and other gold occurrences, but not found in the west of Duimiangou intrusive rocks. Therefore, the west of Duimiangou plutons is a potential area for gold-molybdenum porospecting. Regional prospecting should pay attention to Archean metamorphic bedrocks outcrop area, regional tectonic uplift belts such as Nuluerhushan uplift belt, Kalaqinqi uplift belt and Mingshan uplift beli etc., intermediate-acid dykes and intermediate-acid intrusive rocks distribution extensively, geochemical anomalies and intense tectonic active area.更多还原