【作者】 曹晓峰；

【导师】 吕新彪；

【作者基本信息】 中国地质大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 库鲁克塔格地块位于塔里木盆地东北缘,西北邻接南天山褶皱系,东邻中天山地块及北山褶皱系,南部为塔里木盆地坳陷带,以孔雀河断裂和辛格尔断裂为其南北边界。该地块是新疆地区前寒武纪地质体出露相对较全,地层层序相对较完整的古老地块。其经历了复杂的构造演化阶段,由大面积前震旦系强烈变质、褶皱变形的基底岩系和变质、变形微弱的震旦系和显生宙盖层所组成,形成典型的双层结构。前震旦系主要由一套经历过中高级变质作用的千枚岩、片岩、片麻岩、花岗片麻岩、角闪片岩、斜长角闪岩、大理岩、变玄武岩、变安山岩、变流纹岩和对应的侵入岩所组成,在库鲁克塔格中部地区广泛发育。震旦系为粗碎屑岩、冰碛岩,其下部有数百米厚的中基性火山岩,与下伏岩层呈角度不整合接触：寒武纪为—套稳定的含磷硅质岩—碳酸盐岩系,奥陶系为半深海相青灰色中—薄层状浊积岩,志留纪为页岩—笔石页岩组合,泥盆系为红色碎屑岩系,石炭系为碳酸盐岩和碎屑岩组合,古生界各系之间为整合或假整合接触关系。该区区域性大断裂构造简单,兴地断裂是贯穿整个库鲁克塔格地块呈近东西向展布的一个长期活动的构造带,将库鲁克塔格一分为二,其经历了中元古以来的多期复杂构造演化。研究区是中亚造山带的重要组成部分,其工作程度较低,是新疆研究最薄弱的地区之一自2000年以来,兴地Ⅱ号铜镍矿床、大平梁铜钼矿床、穹塔格铜金矿床及大西沟铁磷矿床的发现及勘查,显示了该区良好的找矿前景。然而与中亚造山带其它地区如哈萨克斯坦、吉尔吉斯斯坦及俄罗斯等相比,仍未能发掘其在优越成矿条件下的巨大找矿潜力。因而,进一步深入开展成矿动力学背景研究、探究成矿作用和成矿规律,是该地区实现找矿突破需要解决的关键问题。本论文选取库鲁克塔格地块中新近普查发现的大平梁铜钼多金属矿床、兴地Ⅱ号铜镍矿床、大西沟铁磷矿床及穹塔格铜金矿床作为研究对象,在充分野外地质调查和岩相学研究基础上,进行了详细的锆石U-Pb年代学、岩石地球化学、同位素地球化学、流体地质学及矿床学等研究。以成矿系统观为指导,结合近年来区域地质构造背景研究新进展,对库鲁克塔格新发现的4个矿床形成的动力学背景、成矿条件、成矿机制进行了详细分析,恢复了成矿系统。并在分析区域成矿条件和成矿作用的基础上,结合区域地球化学特征及岩石建造含矿性,评价了库鲁克塔格不同矿种及矿床类型的成矿远景。本论文主要成果和结论如下：1.明晰了库鲁克塔格地区构造事件的时限和构造-建造特征在对前人资料的收集总结的基础上,结合本论文研究成果,得出库鲁克塔格地块经历了以下七个演化阶段：(1)古太古代陆核形成阶段(3.3-3.0Ga,如：辛格尔南斜长角闪岩3.3Ga的Sm-Nd等时线年龄及库鲁克塔格地区花岗岩中捕获的残留太古代的古老锆石年龄)；(2)新太古代-古元古代陆壳增生改造阶段(2.6-2.3Ga,表现为广泛分布的TTG花岗片麻岩类岩石及斜长角闪岩)；(3)古元古代中晚期陆壳改造阶段(2.1-1.8Ga,表现为连续的变质事件及中酸性岩浆活动及地层的强烈褶皱变形,该期岩浆活动形成的岩浆岩往往具有较老的Nd模式年龄,具有明显的改造特征)；(4)中元古代晚期-新元古代早期造山运动阶段(1.1-0.86Ga,伴随着造山运动出现新元古代地层的褶皱变形及中酸性岩浆侵入活动)；(5)新元古代中期后碰撞伸展阶段(830-800Ma,表现为富钾花岗岩及类埃达克岩的大规模出露和偏碱性基性超基性岩的侵入)；(6)新元古代中晚期陆内裂解阶段(770-600Ma,表现为拉斑质基性-超基性岩、基性脉岩、双峰式火山岩及深水沉积作用)；(7)显生宙造陆运动表现为沉积间断特征,在其东南边缘地区出现造山运动,如穹塔格地区寒武纪岛弧岩浆岩及志留纪碰撞花岗岩的出露。2.对三个阶段的典型矿床的成矿动力学背景和成矿年代提出了新的认识(1)大平梁矿区三个岩体的侵位时间依次为826Ma、816Ma和807Ma。野外地质特征显示早期两个岩体中斜长石具弱定向特征,晚期钾长花岗岩则无定向特征,揭示了该区从挤压向伸展的转换特点。地球化学研究表明斜长花岗岩、二长花岗岩及钾长花岗岩为高钾钙碱性至碱性系列演化,岩体整体呈准铝质、贫CaO、FeO*/MgO和HFSE,而富集K20。微量元素具有Nb、Ta、P、Zr和Ti的负异常,Ba、K、Sm和Sr的正异常。主微量元素均显示其形成于后碰撞环境。Sr-Nd-Pb同位素显示其来自于具有岛弧岩浆岩地球化学特征的下地壳。同一时期的大西沟铁磷矿床位于且干布拉克—团结村偏碱性超基性岩带,最新发表的锆石U-Pb年龄及Sm-Nd等时线年龄基本确定了该基性超基性岩带形成于800-820Ma,表明这些基性超基性岩体与800-830Ma的富钾岩浆岩的侵入时间一致,且其地球化学性质也显示了碱性特征,共同指示后碰撞环境。属首次在库鲁克塔格地区解离出的新元古代后碰撞环境。(2)本次获得了兴地Ⅰ号岩体的Sm-Nd等时线年龄为761±31Ma,结合最新发表关于兴地Ⅱ号及兴地Ⅳ岩体的年代学数据,基本确定了兴地基性超基性岩带形成于新元古代中期约760-735Ma,具多次侵入活动特点。野外地质特征表明,位于兴地基性超基性岩带的2个典型岩体中,兴地Ⅰ号和兴地Ⅱ号岩体中均出露有超基性岩相,两岩体中辉长岩相具有非常相似的地球化学特征。其主量元素均属于拉板质,岩体富集轻稀土和大离子亲石元素,相对亏损重稀土和高场强元素。然而,兴地Ⅰ号侵入岩演化程度更高,其不相容元素含量及锶初始比值更高,相容元素和εNd(t)值更低,且其围岩混染程度高。微量元素及同位素均显示该期岩浆活动形成于大陆裂谷环境,并具有富集地幔来源特征。(3)穹塔格矿区云英闪长岩形成于寒武纪,其锆石LA-ICP-MS U-Pb年龄为494±4Ma,。主量元素显示岩石为中酸性岩浆岩,岩体倾向于以钠质为主,属次铝质-准铝质岩石。岩石的稀土元素总量较低,为LREE富集型,具δEu弱负异常,微量元素表现为大离子亲石元素(LILE:Rb、Ba、K、Sr)相对富集,高场强元素(HFSE:Th、Nb、Ta、Zr、P等)相对亏损,这些特征均表明岩体具岛弧岩浆岩特征,与俯冲消减作用有关,与其东北部发现的奥陶纪碰撞型富钾花岗岩在演化史上相符。这是本区发现的唯一确定的形成于早古生代俯冲碰撞阶段的构造岩浆活动事件。3.系统研究了重要典型矿床的地质特征和成矿作用,确定了其成因类型(1)大平梁铜钼多金属矿床为矽卡岩型矿床,成矿物质及流体主要来自矿区内侵入岩。围岩对成矿物质及流体贡献不大,其主要提供成矿物质沉淀、富集的地球化学条件。其成矿过程为：在830-800Ma期间,库鲁克塔格地块发生构造体制转换,由挤压变为伸展,导致下地壳重融形成富钾埃达克岩和A2型花岗岩。其中富钾埃达克岩携带了大量的成矿物质。岩体富水且氧逸度高,表现为大量具格子双晶的微斜长石的存在。在演化晚期聚集了大量的富含成矿元素的流体,在与围岩大理岩接触时,发生交代形成早期矽卡岩及磁铁矿化,而后在晚阶段形成铜铝金硫化物矿化,形成大平梁矽卡岩型矿床。该矿床是我国发现的最早形成于后碰撞环境下与富钾埃达克质花岗岩有关的铜钼多金属矿化。(2)大西沟铁磷矿床含矿杂岩体由角闪斜长岩、辉石岩、角闪辉石岩、磷灰石角闪斜长岩、二辉橄榄岩等组成,铁磷矿体主要赋存在角闪斜长岩中。杂岩体明显分成暗色岩系(辉石岩类及橄榄岩类)和浅色岩系(斜长岩类),未见有过渡岩系。其成矿机制可能为后碰撞环境下,富集地幔来源的玄武质岩浆因富含磷、钛、碱和挥发份,在上升侵位时,随着温压下降,达到了体系的共结点,导致岩浆发生熔离,而铁磷矿往往与富硅及挥发份的(辉石)斜长岩相伴生。(3)兴地Ⅱ号铜镍矿床含矿杂岩体是一个同源岩浆经多次分异、侵入形成的基性超基性杂岩体,深部分异较强烈,其形成于新元古代裂解环境。矿体赋存在橄榄岩相带底部或者辉石岩相与橄榄岩相的交界部位。据矿石的显微结构及岩石地球化学特征可知,早期岩体发生了硫化物熔离作用,其熔离机制为分离结晶作用和围岩同化混染作用；而后期富水是铁成矿的关键性因素,岩浆结晶晚期往往在含水条件下导致氧逸度的升高形成大量的磁铁矿及含水矿物,如角闪石和黑云母等。(4)穹塔格铜金矿床形成于494Ma的岛弧俯冲环境。其形成过程为伴随着弧岩浆的侵入,上升侵位过程中同化围岩,岩体携带着成矿物质和流体。在成岩晚期,构造释压导致流体在岩体顶部(被剥蚀)及接触带附近发生热液交代及成矿物质的富集沉淀,形成了富含磁铁矿、黄铜矿及黄铁矿的硅化脉及硅质团块和方解石脉等。矿床形成后进一步受到构造挤压片理化作用,金属矿物沿片理方向定向分布,进一步叠加富集。该矿床可能是一个早期岩浆热液型矿化,之后受到了褶皱片理化构造作用叠加富集,属岩浆热液改造型矿床。该矿床是库鲁克塔格地区唯一在早古生代俯冲构造环境下发现的岩浆热液型矿床。4.恢复了新元古代新元古代-古生代各成岩成矿环境下的成矿系统,并结合成矿地质条件、岩石单元含矿性及区域地球化学特征进行了成矿远景评价新元古代-早古生代库鲁克塔格地区先后经历了后碰撞阶段(830-800Ma)、裂解阶段(774-735Ma)和俯冲碰撞阶段(约494Ma)等三个阶段。根据成矿系统论,一定的成矿环境下会形成特定的成矿系统。俯冲碰撞阶段一般会形成Cu-Pb-Zn-Mo-Fe-Au-W-Sn成矿系统,后碰撞转换环境一般会形成Cu-Mo-Fe-Au-Cr-V-Ti-Nb-Ta-REE成矿系统,而裂解环境下一般会形成Cu-Ni-Cr-Co-V-Ti-Pb-Zn成矿系统。库鲁克塔格地区新元古代至早古生代三大构造背景下,发生有三次成矿事件,分别为形成于后碰撞构造背景下与富钾花岗岩有关的矽卡岩型铜钼多金属矿床和与偏碱性基性超基性岩有关的铁磷矿床；形成于裂解构造背景下与拉斑质基性超基性岩有关的铜镍矿床及形成于俯冲构造背景下的与中酸性岩有关的铜金矿床。通过对其成矿地质条件,成矿作用及岩石建造的研究分别建立了：新元古代后碰撞阶段与富钾埃达克岩有关的铜钼金铁成矿系列和与偏碱性基性超基性岩有关的铁磷成矿系列；新元古代裂解阶段与拉斑质基性超基性岩有关的铜镍成矿系列；早古生代俯冲构造阶段与云英闪长岩有关的铜金成矿系列。最后综合成矿地质条件、岩石建造含矿性及区域地球化学调查成果,分析了库鲁克塔格地区与已知成矿系列相关的矿床类型和矿种的成矿远景。如：中西部地区KCS、HLGE、GSB、 NSSK及东部阿克布拉克等岩体具有铜钼金成矿远景；此外,已发现铜矿化的鲍温布拉克和永红山与1：20万奇异性化探异常相吻合,具有重要的找矿意义；沿着兴地断裂分布的隐伏-半隐伏及已经出露的偏碱性基性岩体具有铁磷矿找矿潜力；而兴地断裂南部的兴地Ⅰ号岩体深部具有非常好的铜镍成矿远景；穹塔格地区位于库鲁克塔格东南缘,受北山构造作用影响,其成矿与寒武纪中性的浅灰色云英闪长岩及安山玢岩等中性岩关系密切。区域1：5万地球化学异常显示：Hy-3与Hy-5异常具有较大的铜金找矿前景。更多还原

【Abstract】 Kuluketage block is located in the northeast of Tarim basin, with South-Tianshan orogen to the northwest, Middle-Tianshan block and Beishan orogen to the east, and Manjiaer depression basin to the south. Its north and south margins are controlled by the Xinger and Kongquehe faults. This block preserves the most complete Precambrian geologic units, which are composed of large area of extensively metamorphosed and deformed Pre-sinian basement rocks and weakly metamorphosed and deformed cover, leading to the typical bilayer structure. The Pre-sinian units comprise of a suite of medium to highly metamorphosed phyllite, schist, gneiss, hornblende schist, marble, metabasalt, metaandesite, metarhyolite and intrusive rocks. The Sinian units comprise of coarse clastic rocks and tillite with hundreds meters of medium-basic volcanic rocks and unconformably cover the Pre-sinian rocks. The Cambrian rocks are composed of a suit of phosphorous silicolites and carbonatites. The Ordovician units comprise of bathyalfacies cinerous medium to thin turbidites. The Silurian units comprise of shales and graptolite shales. The Devonian units comprise red clastic rocks and the Carboniferous units comprise of carbonatites and clastic rocks. All the Paleozoic groups are conformably or pseudo-conformably contacted. The Xingdi fault is the sole regional fault which divides the whole block into north and south parts. This fault is east-west trending and experienced multiple tectonic evolution since Mesoproterozoic.Kuluketage block is one of the most weakly studied area. It is an important part of the Middle-Asian orogen. Since2000, some important deposits are discovered, such as Xingdi No.Ⅱ Cu-Ni deposit, Dapingliang Cu-Mo deposit, Qiongtage Cu-Au deposit and Daxigou Fe-P deposit. This indicates the area is good prospecting of mineralization. However, compared to the other places in Middle-Asian orogen such as Kazakhstan, Kyrghyzstan and Russian, it is still needed to explore the ore-forming potention. Thus, further studies of the ore-forming theories, ore-forming mechanisms and metallogenesis are the crucial points for the breakthrough of minerals exploration. In this paper, the newly discovered Xingdi No.Ⅱ Cu-Ni deposit, Dapingliang Cu-Mo deposit, Qiongtage Cu-Au deposit and Daxigou Fe-P deposit are studied. Based on field work, detailed zircon U-Pb geochronology, geochemistry, isotope geochemistry and ore genesis studies were performed. With the thread of metallogenic system which are the combination of systematic and historical thinkings, the author synthesized the previous basic geology study and carried out the studies of the geodynamic background, ore-forming condition, ore-forming mechanism of the newly discovered four deposits to establish the metallogenic system. Then combining the geological condition, rock ore-bearing potential and regional geochemistry, the author made an assessment on the ore-forming potential. The main results and conclusions are summarized as follows:1.The magmatic events are systematically summarized.On the basis of the previous research achievements and the achievements of this paper, Kuluketage block experienced the following seven thermotectonic stages. They are:(1) Archean crust nucleus growing stage (3.6-3.3Ga, indicated by3.3Ga Sm-Nd age of Xinger plagio-amphibolite and the Archean inherited zircons in the granites);(2) crust growth and transformation stage (2.6-2.3Ga, indicated by widely distributed TTG granite gneiss and plagio-amphibolite);(3) crust transforming stage (2.1-1.8Ga, indicated by Paleo-to Meso-proterozoic continuous metamorphic events, medium to felsic magmatic activities and intensive strata folding and the magmatic rocks usually show very old Nd model age);(4) late Mesoproterozoic to early Neoproterozoic orogeny stage (1.1-0.86Ga, indicated by the folded strata and magmatic activities);(5) Neoproterozoic orogenic extensional stage (830-800Ma, with widely developed potassium-rich granite and adakite-like rocks, and alkaline mafic-ultramafic rocks);(6) Neoproterozoic intracontinental breakup stage (770-600Ma, with the tholeiitic mafic-ultramafic rocks and dykes, bimodal volcanic rocks and deep water sediments) and (7) Phanerozoic land building stage indicated by sedimentation interruption, but in the southeast margin, there are orogenic movements, such as Qiongtage cambrian arc magmatic activities and Ordovician collision magmatic activities.2.Proposed new geochronology data and discussed its ore-forming background(1) The three plutons in Dapingliang are intrusived at826Ma、816Ma and806Ma, respectively. Field geology shows that the first formed two plutons show weak oriention, while the last pluton shows typical granite structure, which indicates the tectonic transition from compression to extension. Geochemistry study shows that the plagiogranite, monzonitic granite and K-feldspar granite are high potassium calc-alkaline to alkaline, metaluminous, with CaO、 FeO*/MgO and HFSE depleted and K2O enriched. Trace elements show that the Nb, Ta, P, Zr and Ti have negative anomalies, while Ba, K, Sm and Sr have positive anomalies. These geochemistry features show that they are formed in the post orogenic setting. Sr-Nd-Pb isotopes indicate that the magmas are derived from the lower crust, which inherit the arc magma geochemistry. Daxigou Fe-P deposit is located in the Qieganbulake-Tuanjiecun alkalescent mafic-ultramafic rock belt. The latest published data show that this belt formed during the820-800Ma, within the same period of potassium-rich granite activities. The geochemistry of this mafic-ultramafic belt also shows alkalescent features, which indicates the mafic-ultramafic belt and the potassium-rich granite formed at the same tectonic setting.(2) In this paper,761±31Ma Sm-Nd isochrone age was obtained for Xingdi No.Ⅰ pluton. On the basis of published data of Xingdi No.II, No.IV, the Xingdi mafic-ultramafic belt formed at 760-735Ma. These plutons show multiple intrusion. Field geology shows that Xingdi No.IV pluton has the lowest basicity and the dominant phases are gabbro and diorite, while No.Ⅰ and NoⅡ have the ultramafic phase and they show very similar geochemistry. Both the two pluton are tholeiitic, enriched in light rare earth elements (LREE) and large iron lithosphile elements (LILE), and depleted in heavy rare earth elements (HREE) and high field strength elements (HFSE). However, the No.I experienced higher evolution, its incompatible elements and initial Sr isotope ratio are higher, the compatible elements andεNd(t) are lower, and it has more wall rock contamination. Geochemistry shows the plotons are formed in the rifting setting and their source is enriched.(3) The tonalite in Qiongtage is formed at Cambrian with the zircon LA-ICP-MS U-Pb of494±4Ma. Major elements suggest the pluton is medium to felsic, sodium and metaluminous. The REE content is low, with enriched LREE and weak δEu anomaly. The LILE elements are enriched and the HFSE are depleted. All the features show the affinity to arc magma which is related to subduction. This tectonic setting agrees with regional tectonic evolution.3.Synthetic ore genesis studies were performed(1) Dapingliang Cu-Mo deposit is a typical skarn deposit. Ore-forming substances and fluid are mainly from the pluton, while the wall rock mainly provides the geochemical barriers for metals deposition. The ore-forming process is that during830-800Ma, tectonic transition from compression to extension happened in the Kuluketage block and in such tectonic setting the potassium-rich adakite and A2-type granite are formed by the lower crust melting. Among them, the potassium-rich adakite carried numerous metals and fluid. The pluton is in oxide state with huge of fluid indicated by universal distributed microcline in the pluton. The magmatic fluid interacts with the marble and formed the skarn rock accompanied by the deposition of magnetite. Then in the later fluid stage, the sulfides are deposited and forms the Dapingliang skarn deposit.(2) Daxigou pluton are composed of hornblende-plagioclasite, pyroxenite, hornblende-pyroxenite, apatite-hornblende-plagioclasite and iherzolite. The Fe-P ore bodies are hosted in the hornblende-plagioclasite. According to the petrology, the pluton is divided into dark series (pyroxenite and peridotite) and white series (plagioclasite). The ore-forming mechanism is described as that during the post-collision tectonic setting, the enriched mantle-originating basalt is rich in P, Ti, alkaline and volatile matters. During its ascending, the temperature and pressure decree and come to the eutectic point, which leads to the magma liquation. The P and Ti are usually accompany the silica and volatile matter rich end member, such as plagioclasite.(3) Xingdi No.II pluton undergoes multiple evolution and extensive differentiation in the deep. It is formed in the rifting setting. The ore bodies are hosted in the lower part of peridotite facie or the contact between the pyroxenite and peridote. According to the microscope observation and geochemistry study, the magma experienced sulfide liquation in the early stage and the liquation is caused by fractional crystallization and wall rock assimulation. While in the later stage, fluid-rich is the crucial point for ore deposition. In the later stage of magma crystallization, fluid usually increases the oxygen fugacity and causes the formation of magnetite and water-containing minerals such as hornblende and biotite. (4) Qiongtage Cu-Au deposit formed at494Ma in the arc-subduction setting. During the intrusion of the magma, it assimilates the wall rock and extracting the metals from the wall rock. During the late stage, tectonic pressure release causes the fluid alteration and metals deposition in the top of the pluton and on the contact zone with wall rock. Magnetite, chalcopyrite and pyrite are developed in the quartz or/and calcite veins. After the ore formation, tectonic compression foliation makes the sulfide rearranged to coincide with the foliation and the ore gets further enriched. Thus, this deposit may be a magmatic hydrothermal transformed deposit.4.Recovered the Neoproterozoic-Paleozoic metallogenic system and then combining the ore-forming condition, rock ore-bearing potential and regional geochemistry, the author made an assessment on the ore-forming potential.During Neoproterozoic-Paleozoic, the Kuluketage block experienced post-orogenic stage (830-800Ma), rifting stage (774-735Ma) and subduction stage (ca.494Ma). According to the theory of metallogenic system, particular tectonic setting will have specific metallogenic system. The subduction stage will form the Cu-Pb-Zn-Mo-Fe-Au-W-Sn metallogenic system, the post-orogenic stage will form the Cu-Mo-Fe-Au-Cr-V-Ti-Nb-Ta-REE metallogenic system and the rifting stage will form Cu-Ni-Cr-Co-V-Ti-Pb-Zn metallogenic system. In the Kuluketage block, these tree stages are corresponding to the three ore-forming events. Those are potassium granite-related skarn Cu-Mo deposit and alkalescent mafic-ultramafic rock-related Fe-P deposit formed in the post-orogenic setting, tholeiitic mafic-ultramafic rock-related Cu-Ni sulfide deposit formed in the rifting setting and medium to felsic arc magmatic-related hydrothermal Cu-Au deposit formed in the subducting setting.Synthesizing the ore-forming condition, rock ore-bearing potential and regional geochemistry, the author suggests that KCS, HLGE, GSB and NSSK plutons in the west, and Akebulake pluton in the east have good Cu-Mo mineralization potential. Other more, the Baowenbulake and Yonghongshan Cu mineralization occurrences are corresponding well to the1:2million regional geochemistry anomalies. They have important Cu exploration potential. The uncovered alkalescent mafic-ultramafic rocks distributed along the Xingdi fault have the Fe-P mineralization potential. After study, there is impossible to find industrial Cu-Ni ore body in the shallow part of Xingdi No.Ⅰ pluton, but in the deep, there is very well Cu-Ni exploration potential. The Qiongtage area is a relative separated place, where mineralization is related to Cambrian tonalite. Combining with the regional geology and1:0.5million regional geochemistry anomalies, the area of Hy-3and Hy-5geochemistry anomalies have good mineral prospecting potential.更多还原