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1.
The Xiaoxinancha Au–Cu deposit is located at the eastern segment of the Tianshan–Xingmeng orogenic belt in northeast China. The deposit includes porphyry Au–Cu orebodies, veined Au–Cu orebodies and veined Mo mineralizations. All of them occur within the diorite intrusion. The Late Permian diorite, Late Triassic granodiorite, Early Cretaceous granite and granite porphyry are developed in the ore area. The studies on geological features show that the porphyry Au–Cu mineralization is related to the Late Permian diorite intrusion. New geochronologic data for the Xiaoxinancha porphyry Au–Cu deposit yield Permian crystallization zircon U–Pb age of 257 ± 3 Ma for the diorite that hosts the Au–Cu mineralization. Six molybdenite samples from quartz + molybdenite veins imposed on the porphyry Au–Cu orebodies yield an isochron age of 110.3 ± 1.5 Ma. The ages of the molybdenites coeval to zircon ages of the granite within the errors suggest that the Mo mineralization was genetically related to the Early Cretaceous granite intrusion. The formation of the diorite and the related Au–Cu mineralization were caused by the partial melting of the subduction slab during the Late Palaeozoic palaeo‐Asia Ocean tectonic stage. The Re contents and Re–Os isotopic data indicate that the crustal resource is dominated for the Mo mineralization during the Cretaceous extensional setting caused by the roll‐back of the palaeo‐Pacific plate. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

2.
ABSTRACT

The Circum–Balkhash–Junggar area, including mostly Kazakhstan, NW China, Russia, Kyrgyzstan, Tajikistan, Uzbekistan, and Mongolia, occupies an important tectonic position of the Central Asian Orogenic Belt (CAOB) (Figure 1). Tectonically, this vast area records the complicated geodynamic processes, among which the most prominent stages are the formation of the U-shaped Kazakhstan Orocline and its interactions with adjacent Altai (Altay), Junggar (West Junggar, Junggar Basin, and East Junggar), and Tianshan orogenic collages in the Palaeozoic, bearing large-scale mineral deposits. The formation of the Late Palaeozoic mineral deposits is related to the tectonic evolution of the Devonian and Carboniferous–Permian volcano-magmatic arcs in the region. However, the link between the metallogeny and the evolution of the volcano-magmatic arcs is not well understood and existing geodynamic models have not explained satisfactorily the mechanism of the huge metallogenic belt. Therefore, this special issue focuses on the formation of the Late Palaeozoic porphyry Cu deposits and their link to the tectonic evolution of the Devonian and Carboniferous–Permian volcano-magmatic arcs with emphasis on comparative studies across the international borders.  相似文献   

3.
Uranium–Pb (zircon) ages are linked with geochemical data for porphyry intrusions associated with giant porphyry Cu–Au systems at Oyu Tolgoi to place those rocks within the petrochemical framework of Devonian and Carboniferous rocks of southern Mongolia. In this part of the Gurvansayhan terrane within the Central Asian Orogenic Belt, the transition from Devonian tholeiitic marine rocks to unconformably overlying Carboniferous calc-alkaline subaerial to shallow marine volcanic rocks reflects volcanic arc thickening and maturation. Radiogenic Nd and Pb isotopic compositions (εNd(t) range from + 3.1 to + 7.5 and 206Pb/204Pb values for feldspars range from 17.97 to 18.72), as well as low high-field strength element (HFSE) contents of most rocks (mafic rocks typically have < 1.5% TiO2) are consistent with magma derivation from depleted mantle in an intra-oceanic volcanic arc. The Late Devonian and Carboniferous felsic rocks are dominantly medium- to high-K calc-alkaline and characterized by a decrease in Sr/Y ratios through time, with the Carboniferous rocks being more felsic than those of Devonian age. Porphyry Cu–Au related intrusions were emplaced in the Late Devonian during the transition from tholeiitic to calc-alkaline arc magmatism. Uranium–Pb (zircon) geochronology indicates that the Late Devonian pre- to syn-mineral quartz monzodiorite intrusions associated with the porphyry Cu–Au deposits are ~ 372 Ma, whereas granodiorite intrusions that post-date major shortening and are associated with less well-developed porphyry Cu–Au mineralization are ~ 366 Ma. Trace element geochemistry of zircons in the Late Devonian intrusions associated with the porphyry Cu–Au systems contain distinct Th/U and Yb/Gd ratios, as well as Hf and Y concentrations that reflect mixing of magma of distinct compositions. These characteristics are missing in the unmineralized Carboniferous intrusions. High Sr/Y and evidence for magma mixing in syn- to late-mineral intrusions distinguish the Late Devonian rocks associated with giant Cu–Au deposits from younger magmatic suites in the district.  相似文献   

4.
The Altaids are an orogenic collage of Neoproterozoic–Paleozoic rocks located in the center of Eurasia. This collage consists of only three oroclinally bent Neoproterozoic–Early Paleozoic magmatic arcs (Kipchak, Tuva–Mongol, and Mugodzhar–Rudny Altai), separated by sutures of their former backarc basins, which were stitched by new generations of overlapping magmatic arcs. In addition, the Altaids host accreted fragments of the Neoproterozoic to Early Paleozoic oceanic island chains and Neoproterozoic to Cenozoic plume-related magmatic rocks superimposed on the accreted fragments. All these assemblages host important, many world-class, Late Proterozoic to Early Mesozoic gold, copper–molybdenum, lead–zinc, nickel and other deposits of various types.In the Late Proterozoic, during breakup of the supercontinent Rodinia, the Kipchak and Tuva–Mongol magmatic arcs were rifted off Eastern Europe–Siberia and Laurentia to produce oceanic backarc basins. In the Late Ordovician, the Siberian craton began its clockwise rotation with respect to Eastern Europe and this coincides with the beginning of formation of the Mugodzhar–Rudny Altai arc behind the Kipchak arc. These earlier arcs produced mostly Cu–Pb–Zn VMS deposits, although some important intrusion-related orogenic Au deposits formed during arc–arc collision events in the Middle Cambrian and Late Ordovician.The clockwise rotation of Siberia continued through the Paleozoic until the Early Permian producing several episodes of oroclinal bending, strike–slip duplication and reorganization of the magmatic arcs to produce the overlapping Kazakh–Mongol and Zharma-Saur–Valerianov–Beltau-Kurama arcs that welded the extinct Kipchak and Tuva–Mongol arcs. This resulted in amalgamation of the western portion of the Altaid orogenic collage in the Late Paleozoic. Its eastern portion amalgamated only in the early Mesozoic and was overlapped by the Transbaikal magmatic arc, which developed in response to subduction of the oceanic crust of the Paleo-Pacific Ocean. Several world-class Cu–(Mo)-porphyry, Cu–Pb–Zn VMS and intrusion-related Au mineral camps, which formed in the Altaids at this stage, coincided with the episodes of plate reorganization and oroclinal bending of magmatic arcs. Major Pb–Zn and Cu sedimentary rock-hosted deposits of Kazakhstan and Central Asia formed in backarc rifts, which developed on the earlier amalgamated fragments. Major orogenic gold deposits are intrusion-related deposits, often occurring within black shale-bearing sutured backarc basins with oceanic crust.After amalgamation of the western Altaids, this part of the collage and adjacent cratons were affected by the Siberian superplume, which ascended at the Permian–Triassic transition. This plume-related magmatism produced various deposits, such as famous Ni–Cu–PGE deposits of Norilsk in the northwest of the Siberian craton.In the early Mesozoic, the eastern Altaids were oroclinally bent together with the overlapping Transbaikal magmatic arc in response to the northward migration and anti-clockwise rotation of the North China craton. The following collision of the eastern portion of the Altaid collage with the Siberian craton formed the Mongol–Okhotsk suture zone, which still links the accretionary wedges of central Mongolia and Circum-Pacific belts. In the late Mesozoic, a system of continent-scale conjugate northwest-trending and northeast-trending strike–slip faults developed in response to the southward propagation of the Siberian craton with subsequent post-mineral offset of some metallogenic belts for as much as 70–400 km, possibly in response to spreading in the Canadian basin. India–Asia collision rejuvenated some of these faults and generated a system of impact rifts.  相似文献   

5.
东天山铜金多金属矿床成矿系统和成矿地球动力学模型   总被引：47，自引：2，他引：47  
近年来，在东天山地区地质找矿不断取是突破，一系列大型，中型铜金矿床先后被发现。绝大多数铜金矿床在空间上密集分布于黄山－康古尔缝合－剪切带两侧的岛弧带内，时间上集中在石炭纪－二叠纪。金矿床包括造山型，石英脉型和浅成低温热液型，铜矿床包括斑岩型，夕卡岩型和热液脉型及铜镍硫化物型，金，铜和铜镍矿化各自成系统产出，为板块俯冲晚期和碰撞期大规模镁铁质－超镁铁质和中酸性－酸性花岗质岩浆侵位－喷发事件的产物。  相似文献   

6.
Duobaoshan is the largest porphyry-related Cu-Mo-Au orefield in northeastern(NE)Asia,and hosts a number of large-medium porphyry Cu(PCDs),epithermal Au and Fe-Cu skarn deposits.Formation ages of these deposits,from the oldest(Ordovician)to youngest(Jurassic),have spanned across over 300 Ma.No similar orefields of such size and geological complexity are found in NE Asia,which reflects its metallogenic uniqueness in forming and preserving porphyry-related deposits.In this study,we explore the actual number and timing of magmatic/mineralization phases,their respective magma genesis,fertility,and regional tectonic connection,together with the preservation of PCDs.We present new data on the magmatic/mineralization ages(LA-ICP-MS zircon U-Pb,pyrite and molybdenite Re-Os dating),whole-rock geochemistry,and zircon trace element compositions on four representative deposits in the Duobaoshan orefield,i.e.,Duobaoshan PCD,Tongshan PCD,Sankuanggou Fe-Cu skarn,and Zhengguang epithermal Au deposits,and compiled published ones from these and other mineral occurrences in the orefield.In terms of geochronology,we have newly summarized seven magmatic phases in the orefield:(1)Middle-Late Cambrian(506-491 Ma),(2)Early and Middle Ordovician(485-471 Ma and~462 Ma),(3)Late Ordovician(450-447 Ma),(4)Early Carboniferous and Late-Carboniferous to Early Permian(351-345 and 323-291 Ma),(5)Middle-Late Triassic(244-223 Ma),(6)Early-Middle and Late Jurassic(178-168 Ma and~150 Ma),and(7)Early Cretaceous(~112 Ma).Three of these seven major magmatic phases were coeval with ore formation,including(1)Early Ordovician(485-473 Ma)porphyry-type Cu-Mo-(Au),(2)Early-Middle Triassic(246-229 Ma)porphyry-related epithermal Au-(Cu-Mo),and(3)Early Jurassic(177-173 Ma)Fe-Cu skarn mineralization.Some deposits in the orefield,notably Tongshan and Zhengguang,were likely formed by more than one mineralization events.In terms of geochemistry,ore-causative granitoids in the orefield exhibit adakite-like or adakite-normal arc transitional signatures,but those forming the porphyry-/epithermal-type Cu-Mo-Au mineralization are largely confined to the former.The varying but high Sr/Y,Sm/Yb and La/Yb ratios suggest that the ore-forming magmas were mainly crustal sourced and formed at different depths(clinopyroxene-/amphibole-/garnet-stability fields).The adakite-like suites may have formed by partial melting of the thickened lower crust at 35-40 km(for the Early Ordovician arc)and>40 km(for the Middle-Late Triassic arc)depths.The Early Jurassic Fe-Cu skarn orecausative granitoids show an adakitic-normal arc transitional geochemical affinity.These granitoids were likely formed by partial melting of the juvenile lower crust(35-40 km depth),and subsequently modified by assimilation and fractional crystallization(AFC)processes.In light of the geological,geochronological and geochemical information,we proposed the following tectonometallogenic model for the Duobaoshan orefield.The Ordovician Duobaoshan may have been in a continental arc setting during the subduction of the Paleo-Asian Ocean,and formed the porphyry-related deposits at Duobaoshan,Tongshan and Zhengguang.Subduction may have ceased in the latest Ordovician,and the regional tectonics passed into long subsidence and extension till the latest Carboniferous.This extensional tectonic regime and the Silurian terrestrial-shallow marine sedimentation had likely buried and preserved the Ordovician Duobaoshan magmatic-hydrothermal system.The south-dipping Mongol-Okhotsk Ocean subduction from north of the orefield had generated the Middle-Late Triassic continental arc magmatism and the associated Tongshan PCD and Zhengguang epithermal Au mineralization(which superimposed on the Ordovician PCD system).The Middle Jurassic closure of Mongol-Okhotsk Ocean in the northwestern Amuria block(Erguna terrane),and the accompanying Siberia-Amuria collision,may have placed the Paleo-Pacific subduction system in NE China(including the orefield)under compression,and formed the granodiorite-tonalite and Fe-Cu skarn deposits at Sankuanggou and Xiaoduobaoshan.From the Middle Jurassic,the consecutive accretion of Paleo-Pacific arc terranes(e.g.,Sikhote-Alin and Nadanhada)onto the NE Asian continental margin may have gradually distant the Duobaoshan orefield from the subduction front,and consequently arc-type magmatism and the related mineralization faded.The minor Late Jurassic and Cretaceous unmineralized magmatism in the orefield may have triggered mainly by the far-field extension led by the post-collisional(Siberia-Amuria)gravitational collapse and/or Paleo-Pacific backarc-basin opening.  相似文献   

7.
The Eastern Junggar terrane of the Central Asian Orogenic Belt includes a Late Paleozoic assemblage of volcanic rocks of mixed oceanic and arc affinity, located in a structurally complex belt between the Siberian plate, the Kazakhstan block, and the Tianshan Range. The early history of these rocks is not well constrained, but the Junggar terrane was part of a Cordilleran-style accreted arc assemblage by the Late Carboniferous. Late Paleozoic volcanic rocks of the northern part of the east Junggar terrane are divided, from base to top, into the Early Devonian Tuoranggekuduke Formation (Fm.), Middle Devonian Beitashan Fm., Middle Devonian Yundukala Fm., Late Devonian Jiangzierkuduke Fm., Early Carboniferous Nanmingshui Fm. and Late Carboniferous Batamayineishan Fm. We present major element, trace element and Sr–Nd isotopic analyses of 64 (ultra)mafic to intermediate volcanic rock samples of these formations. All Devonian volcanic rocks exhibit remarkably negative Nb, Ta and Ti anomalies on the primitive mantle-normalized trace element diagrams, and are enriched in more highly incompatible elements relative to moderately incompatible ones. Furthermore, they have subchondritic Nb/Ta ratios, and their Zr/Nb and Sm/Nd ratios resemble those of MORBs, characteristics of arc-related volcanic rocks. The Early Devonian Tuoranggekuduke Fm., Middle Devonian Beitashan Fm., and Middle Devonian Yundukala Fm. are characterized by tholeiitic and calc-alkaline affinities. In contrast, the Late Devonian Jiangzierkuduke Fm. contains a large amount of tuff and sandstone, and its volcanic rocks have dominantly calc-alkaline affinities. We therefore propose that the Jiangzierkuduke Fm. formed in a mature island arc setting, and other Devonian Fms. formed in an immature island arc setting. The basalts from the Nanmingshui Fm. have geochemical signatures between N-MORB and island arcs, indicating that they formed in a back-arc setting. In contrast, the volcanic rocks from the Batamayineishan Fm. display geochemical characteristics of continental intraplate volcanic rocks formed in an extensional setting after collision. Thus, we propose a model that involves a volcanic arc formed by northward subduction of the ancient Junggar ocean and amalgamation of different terranes during the Late Paleozoic to interpret the formation of the Late Paleozoic volcanic rocks in the Eastern Junggar terrane, and the Altai and Junggar terranes fully amalgamated into a Cordilleran-type orogen during the end of Early Carboniferous to the Middle–Late Carboniferous.  相似文献   

8.
东天山大南湖岛弧带石炭纪岩石地层与构造演化   总被引：5，自引：0，他引：5  
详细的地质解剖工作表明,东天山地区大南湖岛弧带石炭纪出露4套岩石地层组合,即早石炭世小热泉子组火山岩、晚石炭世底坎儿组碎屑岩和碳酸盐岩、晚石炭世企鹅山组火山岩、晚石炭世脐山组碎屑岩夹碳酸盐岩。根据其岩石组合、岩石地球化学、生物化石、同位素资料以及彼此的产出关系,认为这4套岩石地层组合的沉积环境分别为岛弧、残余海盆、岛弧和弧后盆地。结合区域资料重塑了大南湖岛弧带晚古生代的构造格架及演化模式。早、晚石炭世的4套岩石地层组合并置体现了东天山的复杂增生过程。  相似文献   

9.
中亚造山带东部岩浆热液矿床时空分布特征及其构造背景   总被引：1，自引：0，他引：1  
中亚造山带东部是古亚洲洋构造域、鄂霍茨克洋构造域和古太平洋构造域复合叠加区域,矿产资源丰富。本文收集2000—2014年公开发表文献中岩浆热液矿床约1 200个同位素年龄数据,整理出201个较为可靠的年龄数据,通过数字化编图,揭示成矿的时空分布特征及形成背景。结果显示:中亚造山带东部成矿作用始于寒武纪,出现6个重要成矿期:510~473、373~330、320~253、250~210、210~167、155~100 Ma。510~473 Ma(峰值507 Ma),矿床主要分布在大兴安岭—小兴安岭—张广才岭和北山地区,零星发育热液脉型和斑岩型铁铜金钨矿床,与古亚洲洋开始俯冲及微陆块碰撞拼合有关。373~330 Ma(峰值372Ma),矿床主要分布在南蒙古奥尤陶勒盖地区,发育超大型斑岩型铜金矿床,形成于古亚洲洋俯冲环境。320~253 Ma,矿床主要分布在大兴安岭南段,发育少量斑岩型铜矿床和造山型金矿床;其中,298 Ma在大兴安岭南段首次出现以钼为主的斑岩型矿床,指示该区板块俯冲增生向拼贴转变逐渐过渡。250~210 Ma(峰值244 Ma),在蒙古—鄂霍茨克造山带东侧额尔古纳—中蒙古地块主要形成斑岩型铜矿床,可能与蒙古—鄂霍茨克洋俯冲有关;以东地区,主要在大兴安岭南段和辽远地块形成斑岩型钼矿床,在张广才岭发育岩浆熔离型铜镍矿床,反映了古亚洲洋闭合后伸展环境。210~167 Ma(峰值170 Ma),在蒙古—鄂霍茨克造山带西侧乌兰巴托西北部发育造山型-斑岩型金矿床,其东侧额尔古纳地区形成斑岩型铜钼矿床,可能与蒙古—鄂霍茨克洋俯冲碰撞有关;在吉黑东部—张广才岭—小兴安岭—大兴安岭,发育斑岩型钼铜矿床和矽卡岩型铅锌钨金矿床组合,可能属于古太平洋板块向西俯冲成矿体系。155~100 Ma(峰值136 Ma),中亚造山带东部整体处于伸展环境;其中,155~120 Ma在额尔古纳地区主要发育浅成低温热液型银铅锌矿床和造山型金矿床,大兴安岭北段发育斑岩型钼矿床,可能反映了额尔古纳地区和大兴安岭北段受蒙古—鄂霍茨克洋碰撞后伸展环境控制,而在吉黑东部形成浅成低温热液型金矿床,大兴安岭南段发育热液脉型-矽卡岩型锡矿床,可能受古太平洋板块向北俯冲弧后伸展的控制;120~100 Ma沿着华北克拉通和佳蒙陆块边缘发育浅成低温热液型-斑岩型金钼矿床。本研究综合岩浆热液矿床时空分布和矿床类型,进一步揭示了古亚洲洋构造域控制中亚造山带东部古生代成矿作用持续到晚二叠世(到早三叠世),并在晚三叠世叠加古太平洋构造域成矿体系,而额尔古纳—中蒙古地块成矿作用在三叠纪开始主要受蒙古—鄂霍茨克洋构造域限定,并持续到早白垩世早期。  相似文献   

10.
《International Geology Review》2012,54(15):1837-1851
The Taipingchuan Cu–Mo deposit is a recently discovered large porphyry deposit located in the north of the Derbugan metallogenic belt of northeastern China. The geochronological data of the deposit yielded a Late Triassic zircon U–Pb age of 202 ± 6 Ma from a granodiorite porphyry that hosts the Cu–Mo mineralization. Measured Re–Os isotopes of seven disseminated molybdenite samples yielded an isochron age of 200 ± 5 Ma with mean square of weighted deviates of 2.7, while those of seven veinlet molybdenite samples also produced an isochron age of 200.1 ± 2.5 Ma and mean square of weighted deviates of 3.3. These isochron ages show that a Cu–Mo mineralization event occurred at ca. 200 Ma. Based on regional tectonic evolution, we propose that the Late Triassic Cu–Mo mineralization of the host porphyry in the Derbugan metallogenic belt was mainly associated with the subduction of the Mongol–Okhotsk Ocean slab under the Ergun block, contrary to previous suggestion that it was related to the subduction of the Mesozoic Palaeo-Pacific plate.  相似文献   

11.
The paper reviews and integrates geological, geochronological, geochemical and isotope data from 21 intra-oceanic arcs (IOA) of the Paleo-Asian Ocean (PAO), which have been identified in the Central Asian Orogenic belt, the world largest accretionary orogeny. The data We discuss structural position of intra-oceanic arc volcanic rocks in association with back-arc terranes and accretionary complexes, major periods of intra-oceanic arc magmatism and related juvenile crustal growth, lithologies of island-arc terranes, geochemical features and typical ranges of Nd isotope values of volcanic rocks. Four groups of IOAs have been recognized: Neoproterozoic – early Cambrian, early Paleozoic, Middle Paleozoic and late Paleozoic. The Neoproterozoic – early Cambrian or Siberian Group includes eleven intra-oceanic arcs of eastern and western Tuva-Sayan (southern Siberia, Russia), northern and southwestern Mongolia and Russian Altai. The Early Paleozoic or Kazakhstan Group includes Selety-Urumbai, Bozshakol-Chingiz and Baydaulet-Aqastau arc terranes of the Kazakh Orocline. The Middle Paleozoic or Southern Group includes six arc terranes in the Tienshan orogen, Chinese Altai, East-Kazakhstan-West Junggar and southern Mongoia. Only one Late Paleozoic intra-oceanic arc has been reliably identified in the CAOB: Bogda in the Chinese Tienshan, probably due to PAO shrinking and termination. The lithologies of the modern and fossil arcs are similar, although the fossil arcs contain more calc-alkaline varieties suggesting either their more evolved character or different conditions of magma generation. Of special importance is identification of back-arc basins in old accretionary orogens, because boninites may be absent in both modern and fossil IOAs. The three typical scenarios of back-arc formation - active margin rifting, intra-oceanic arc rifting and fore-arc rifting were reconstructed in fossil intra-oceanic arcs. Some arcs might be tectonically eroded and/or directly subducted into the deep mantle. Therefore, the structural and compositional records of fossil intra-oceanic arcs in intracontinental orogens allow us to make only minimal estimations of their geometric length, life span, and crust thickness.  相似文献   

12.
The northwestern corner of New South Wales consists of the paratectonic Late Proterozoic to Early Cambrian Adelaide Fold Belt and older rocks, which represent basement inliers in this fold belt. The rest of the state is built by the composite Late Proterozoic to Triassic Tasman Fold Belt System or Tasmanides.In New South Wales the Tasman Fold Belt System includes three fold belts: (1) the Late Proterozoic to Early Palaeozoic Kanmantoo Fold Belt; (2) the Early to Middle Palaeozoic Lachlan Fold Belt; and (3) the Early Palaeozoic to Triassic New England Fold Belt. The Late Palaeozoic to Triassic Sydney—Bowen Basin represents the foredeep of the New England Fold Belt.The Tasmanides developed in an active plate margin setting through the interaction of East Gondwanaland with the Ur-(Precambrian) and Palaeo-Pacific plates. The Tasmanides are characterized by a polyphase terrane accretion history: during the Late Proterozoic to Triassic the Tasmanides experienced three major episodes of terrane dispersal (Late Proterozoic—Cambrian, Silurian—Devonian, and Late Carboniferous—Permian) and six terrane accretionary events (Cambrian—Ordovician, Late Ordovician—Early Silurian, Middle Devonian, Carboniferous, Middle-Late Permian, and Triassic). The individual fold belts resulted from one or more accretionary events.The Kanmantoo Fold Belt has a very restricted range of mineralization and is characterized by stratabound copper deposits, whereas the Lachlan and New England Fold Belts have a great variety of metallogenic environments associated with both accretionary and dispersive tectonic episodes.The earliest deposits in the Lachlan Fold Belt are stratabound Cu and Mn deposits of Cambro-Ordovician age. In the Ordovician Cu deposits were formed in a volcanic are. In the Silurian porphyry Cu---Au deposits were formed during the late stages of development of the same volcanic are. Post-accretionary porphyry Cu---Au deposits were emplaced in the Early Devonian on the sites of the accreted volcanic arc. In the Middle to Late Silurian and Early Devonian a large number of base metal deposits originated as a result of rifting and felsic volcanism. In the Silurian and Early Devonian numerous Sn---W, Mo and base metal—Au granitoid related deposits were formed. A younger group of Mo---W and Sn deposits resulted from Early—Middle Carboniferous granitic plutonism in the eastern part of the Lachlan Fold Belt. In the Middle Devonian epithermal Au was associated with rifting and bimodal volcanism in the extreme eastern part of the Lachlan Fold Belt.In the New England Fold Belt pre-accretionary deposits comprise stratabound Cu and Mn deposits (pre-Early Devonian): stratabound Cu and Mn and ?exhalite Au deposits (Late Devonian to Early Carboniferous); and stratabound Cu, exhalite Au, and quartz—magnetite (?Late Carboniferous). S-type magmatism in the Late Carboniferous—Early Permian was responsible for vein Sn and possibly Au---As---Ag---Sb deposits. Volcanogenic base metals, when compared with the Lachlan Fold Belt, are only poorly represented, and were formed in the Early Permian. The metallogenesis of the New England Fold Belt is dominated by granitoid-related mineralization of Middle Permian to Triassic age, including Sn---W, Mo---W, and Au---Ag---As Sb deposits. Also in the Middle Permian epithermal Au---Ag mineralization was developed. During the above period of post-orogenic magmatism sizeable metahydrothermal Sb---Au(---W) and Au deposits were emplaced in major fracture and shear zones in central and eastern New England. The occurrence of antimony provides an additional distinguishing factor between the New England and Lachlan Fold Belts. In the New England Fold Belt antimony deposits are abundant whereas they are rare in the Lachlan Fold Belt. This may suggest fundamental crustal differences.  相似文献   

13.
The Tianshan–Xingmeng molybdenum belt is part of a larger E–W-trending metallogenic belt in northern China. Most of these molybdenum deposits occur as porphyry or porphyry-skarn type, but there are also some vein-type deposits. Following systematic Re-Os dating of molybdenite from four deposits and comparisons with two previously dated deposits, we conclude that molybdenum mineralization in the Tianshan–Xingmeng Orogenic Belt resulted from hydrothermal activity linked to the emplacement of granitoid stocks. Three pulses of granitoid magmatism and Mo mineralization have been recognized in this study, corresponding to tectonic events in the Tianshan–Xingmeng Orogenic Belt. We identify five distinct stages of Mo mineralization events in the Tianshan–Xingmeng Orogenic Belt: 320–250 Ma, 250–200 Ma, 190–155 Ma, 155–140 Ma, and 140–120 Ma. Late Palaeozoic (320–250 Ma) Mo mineralization was closely related to closure of the Palaeo-Asian Ocean and collision between the Siberia and Tarim cratons. Triassic (250–200 Ma) Mo mineralization occurred in a post-collisional tectonic setting. The Early–Middle Jurassic (190–155 Ma) Mo mineralization was related to subduction of the Palaeo-Pacific Ocean on the eastern Asian continental margin, whereas in the Erguna block, the Mo mineralization events were associated with the subduction of the Mongol–Okhotsk Ocean. From 155 to 120 Ma, large-scale continental extension occurred in the Tianshan–Xingmeng Orogenic Belt and surrounding regions. However, the Late Jurassic (150–140 Ma) Mo mineralization events in these areas evolved in a post-orogenic extensional environment of the Mongol–Okhotsk Ocean subduction system. The Early Cretaceous (140–120 Ma) Mo mineralization occurred under the combined effects of the closure of the Mongol–Okhotsk Ocean and subduction of the Palaeo-Pacific Ocean.  相似文献   

14.
The Oyu Tolgoi cluster of seven porphyry Cu-Au-Mo deposits in southern Mongolia,define a narrow,linear,12 km long,almost continuously mineralised trend,which contains in excess of 42 Mt of Cu and1850 t of Au,and is among the largest high grade porphyry Cu-Au deposits in the world.These deposits lie within the Gurvansayhan island-arc terrane,a fault bounded segment of the broader Silurian to Carboniferous Kazakh-Mongol arc,located towards the southern margin of the Central Asian Orogenic Belt,a collage of magmatic arcs that were periodically active from the late Neoproterozoic to PermoTriassic,extending from the Urals Mountains to the Pacific Ocean.Mineralisation at Oyu Tolgoi is associated with multiple,overlapping,intrusions of late Devonian(~372 to 370 Ma) quartzmonzodiorite intruding Devonian(or older) juvenile,probably intra-oceanic arc-related,basaltic lavas and lesser volcaniclastic rocks,unconformably overlain by late Devonian(~370 Ma) basaltic to dacitic pyroclastic and volcano sedimentary rocks.These quartz-monzodiorite intrusions range from earlymineral porphyritic dykes,to larger,linear,syn-,late- and post-mineral dykes and stocks.Ore was deposited within syn-mineral quartz-monzodiorites,but is dominantly hosted by augite basalts and to a lesser degree by overlying dacitic pyroclastic rocks.Following ore deposition,an allochthonous plate of older Devonian(or pre-Devonian) rocks was overthrust and a post-ore biotite granodiorite intruded at~365 Ma.Mineralisation is characterised by varying,telescoped stages of intrusion and alteration.Early A-type quartz veined dykes were followed by Cu-Au mineralisation associated with potassic alteration,mainly K-feldspar in quartz-monzodiorite and biotite-magnetite in basaltic hosts.Downward reflux of cooled,late-magmatic hydrothermal fluid resulted in intense quartz-sericite retrograde alteration in the upper parts of the main syn-mineral intrusions,and an equivalent chlorite-muscovite/illite-hematite assemblage in basaltic host rocks.Uplift,facilitated by syn-mineral longitudinal faulting,brought sections of the porphyry deposit to shallower depths,to be overprinted and upgraded by late stage,shallower,advanced argillic alteration and high sulphidation mineralisation.Key controls on the location,size and grade of the deposit cluster include(i) a long-lived,narrow faulted corridor;(ii) multiple pulses of overlapping intrusion within the same structure;and(iii) enclosing reactive,mafic dominated wall rocks,focussing ore.  相似文献   

15.
近二十年来,蒙古南戈壁成矿带在寻找大宗金属矿产方面取得丰硕成果,发现了欧玉陶勒盖和查干苏布尔加等与古亚洲洋晚泥盆世岛弧演化有关的大型斑岩型矿床。研究表明:1)欧玉陶勒盖—查干苏布尔加地区在法门期弧岩浆与矿化作用之后,经历了短暂的抬升和剥蚀过程,随后被石炭纪火山-沉积岩所覆盖。两个矿床皆被埋藏于法门期(D_3)—杜内期(C_1)不整合面之下;2)矿床现今出露于石炭纪—二叠纪岩体包围的"天窗"中,矿体能否保存与其上覆岩层遭受的剥蚀程度有关;3)近EW向展布的蒙古南戈壁成矿带在欧玉陶勒盖—查干苏布尔加地区受三叠纪—早白垩世准巴彦断裂左旋走滑运动的影响,局部转变为NE走向,向东可延伸至中国境内东乌旗一带。因此,在中国内蒙古东乌旗地区开展的找矿勘查工作应重点关注法门期(D_3)—杜内期(C_1)不整合之下的晚泥盆世侵入体及其围岩,并在成矿远景区进行相应的区域构造解析研究。  相似文献   

16.
ABSTRACT

The Guichi ore-cluster district in the Lower Yangtze River Metallogenic Belt hosts extensive Cu–Au–Mo polymetallic deposits including the Tongshan Cu–Mo, Paodaoling Au, Matou Cu–Mo, Anzishan Cu–Mo, Guilinzheng Mo and Zhaceqiao Au deposits, mostly associated with the late Mesozoic magmatic rocks, which has been drawn to attention of study and exploration. However, the metallogenic relationship between magmatic rocks and the Cu–Au-polymetallic deposits is not well constrained. In this study, we report new zircon U–Pb ages, Hf isotopic, and geochemical data for the ore-bearing intrusions of Guichi region. LA-ICP-MS U–Pb ages for the Anzishan quartz diorite porphyrite is 143.9 ± 1.0 Ma. Integrated with previous geochronological data, these late Mesozoic magmatic rocks can be subdivided into two stages of magmatic activities. The first stage (150–132 Ma) is characterized by high-K calc-alkaline intrusions closely associated with Cu–Au polymetallic ore deposits. Whereas, the second stage (130–125 Ma) produced granites and syenites and is mainly characterized by shoshonite series that are related to Mo–Cu mineralization. The first stage of magmatic rocks is considered to be formed by partial melting of subducted Palaeo-Pacific Plate, assimilated with Yangtze lower crust and remelting Meso-Neoproterozoic crust/sediments. The second stage of magmatism is originated from partial melting of Mesoproterozoic-Neoproterozoic crust, mixed with juvenile crustal materials. The depression cross to the uplift zone of the Jiangnan Ancient Continent forms a gradual transition relation, and the hydrothermal mineralization composite with two stages have certain characteristics along the regional fault (Gaotan Fault). Guichi region results from two episodes of magmatism probably related to tectonic transition from subduction of Palaeo-Pacific Plate to back-arc extensional setting between 150 and 125 Ma, which lead to the Mesozoic large-scale polymetallic mineralization events in southeast China.  相似文献   

17.
大兴安岭北部主要金属矿床成矿系列和区域矿床成矿谱系   总被引：10，自引：4，他引：6  
武广  王国瑞  刘军  周振华  李铁刚  吴昊 《矿床地质》2014,33(6):1127-1150
文章以大兴安岭北部内生金属矿床、海相火山岩型硫铁矿矿床和砂金矿床为研究对象,按照矿床成矿系列的学术思想将其划分为7个矿床成矿系列,即:多宝山地区与加里东期中酸性火山_侵入活动有关的铜、钼矿床成矿系列,呼玛地区与华力西期辉长岩和花岗岩有关的铁、钛、金矿床成矿系列,伊尔施_黑河地区与华力西期花岗岩和海相火山岩有关的铁、铜、锌、硫铁矿矿床成矿系列,牙克石地区与华力西期海相中基性火山岩有关的铁、锌、硫铁矿矿床成矿系列,得尔布干地区与印支期_燕山期中酸性火山_侵入活动有关的铅、锌、银、铜、钼、金矿床成矿系列,伊尔施_呼玛地区与燕山期中酸性火山_侵入活动有关的金、铁、锌、铜、钼、钨矿床成矿系列和黑龙江流域与第四纪冲积沉积作用有关的砂金矿床成矿系列。大兴安岭北部区域矿床成矿谱系表明,从奥陶纪到新生代该区不同构造单元经历了7个主要的构造演化及成矿时期,依次出现奥陶纪岛弧环境的斑岩型矿床、泥盆纪陆块边缘拉张环境的岩浆型和热液脉型矿床、泥盆纪—石炭纪俯冲_碰撞环境的海相火山岩型和矽卡岩型矿床、石炭纪弧后盆地环境的海相火山岩型矿床、晚三叠世—早白垩世俯冲_碰撞_后碰撞环境的斑岩型、热液脉型、浅成低温热液型和矽卡岩型矿床、早侏罗世—早白垩世俯冲环境的斑岩型、热液脉型、浅成低温热液型和矽卡岩型矿床和新生代地壳差异运动带砂金矿床。大兴安岭北部优势矿种为铜、钼、金、银、铅、锌,主攻矿床类型为斑岩型、热液脉型、低硫化浅成低温热液型、冲积型和海相火山岩型。  相似文献   

18.
Abstract. Based on field investigation of large number of ore deposits including some latest discoveries and multidiscipline comprehensive research, we demonstrated the general features of metallic deposits and we suggest that Paleozoic archipelago-type collisional orogen at North Xinjiang, northwestern China show intimate similarity with the metallogenesis of Southeast Asia Cenozoic archipelago. We briefly described the characteristics of major porphyry-type, skarn-type Cu deposits and typical high-sulfidation type (HS-type) and low-sulfidation type (LS-type) epithermal Au deposits as well as some latest discoveries. Systematic isotopic age-dating on the Tuwu-Yandong superlarge porphyry Cu deposits revealed that they formed in Late Devonian to Early Carboniferous in an accretionary arc setting. The tectonic settings of epithermal Au deposits and its linkage with porphyry Cu deposits are further discussed. The formation condition for porphyry Cu deposits is more strict than epithermal Au deposits. The distribution width for porphyry Cu deposits in the orogenic belts is more limited than epithermal Au deposits. The discovery and prospecting progress of the Kalatage HS-type Cu-Au deposit were reported. The significance in further exploration was suggested.  相似文献   

19.
《China Geology》2021,4(4):630-643
The Nan Suture and Sukhothai Arc Terrane are products of the eastward subduction of the Paleotethyan Ocean during the Late Carboniferous to Triassic. However, their footprints in northwestern Laos are poorly constrained. New geochronological and geochemical data presented in this study demonstrate a Late Permian origin for the andesitic rocks in the B.Xiengnou area rather than Late Triassic. The breccia-bearing andesitic tuff in the B.On ultramafic complex yield a zircon U-Pb age of 260 ± 1.4 Ma, geochemically displaying a MORB-like signature. The andesitic tuff in the B.Kiophoulan-B.Houayhak belt gave the U-Pb age of 254 ± 1.3 Ma, with arc-like geochemical affinity. By combining geochronological and geochemical data from the Nan Suture and Sukhothai Arc Terrane, the authors suggest that the andesitic rocks in the B.On ultramafic complex formed in a back-arc basin background, which connected the Jinghong and Nan back-arc basin during the Permian; while the andesitic tuff in the B.Kiophoulan-B.Houayhak belt erupted in the Sukhothai continental arc setting.©2021 China Geology Editorial Office.  相似文献   

20.
新疆西天山吐拉苏地区发育的与中酸性火山-次火山岩有关的浅成低温热液-斑岩型金多金属成矿系统,是在晚古生代北天山洋向南部伊犁-中天山板块之下俯冲消减的活动大陆边缘背景下形成的。赋矿的大哈拉军山组火山岩及相关的次火山岩形成于晚泥盆世-早石炭世,岩石总体显示钾质-高钾质、准铝质-过铝质的钙碱性-高钾钙碱性特征,其轻稀土富集、Eu负异常显著、大离子亲石元素富集和高场强元素亏损等,均显示出俯冲带岛弧岩浆作用的特点。阿希(低硫型)和京希-伊尔曼得(高硫型)浅成低温热液金矿床以及塔北、吐拉苏铅锌矿床,受大哈拉军山组火山岩中的断裂破碎带以及具高孔隙度和渗透率的岩性控制;塔吾尔别克斑岩型金矿化主要受斑岩体及火山岩中的断裂和裂隙系统控制,并很可能存在浅成低温热液型金矿化的套合或叠加。硫、铅、碳、氧同位素特征显示,成矿物质主要来自岩浆所分泌的热液和/或赋矿的火山-次火山岩。根据成矿系统形成后的保存和变化情况,认为在吐拉苏盆地内剥蚀程度较低的地区,浅成低温热液型金铅锌矿床具备良好的保存条件,同时在其深部还应注意寻找斑岩型或矽卡岩型铜金矿床。  相似文献   

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