Cobalt mineralization in the Altai–Sayan orogen: age and correlation with magmatism

The paper discusses the spatiotemporal and genetic relationships of hydrothermal Co mineralization in the Altai–Sayan orogen with mafic, alkaline mafic, and granitoid magmatism on the basis of isotopic, geochemical, and geochronological investigations. Four stages of Co mineralization have been distinguished for this region: Early Devonian (D₁), Late Devonian–Early Carboniferous (D₃–C₁), Permo-Triassic (P₂–T), and Early Cretaceous (K₁). They correspond to periods of large-scale mafic magmatism. Isotopic (Pb, Sr, He) and geochemical studies have shown that Co mineralization is genetically related to mafic and granitoid magmatism. Also, these studies have confirmed that Co deposits are formed with the participation of mantle fluids and are related to chambers of mafic and alkaline mafic melts. Besides, it has been found that ore originated both from magmatic sources and host rocks. A pulsed facies endogenic zonation has been established for Co deposits, Co-bearing ore clusters, and zones with high-temperature Co–As and low-temperature Ni–Co–As mineralization. It has been first established that ores at hydrothermal Co deposits are rich in Pt and Pd.     

墨西哥中新生代岩浆活动规律及成矿研究

墨西哥中新生代岩浆作用与太平洋板块向东俯冲消减作用及晚白垩-始新世的拉腊米期造山运动有关,岩浆作用控制了矿床的分布规律。文章通过综合分析大量墨西哥中新生代岩浆岩和矿床资料,讨论了岩浆活动规律及构造活动和成矿作用的关系。墨西哥主要有5个岩浆活动时期,分别为晚古生代岩浆作用、早-中侏罗世岩浆作用、白垩世岩浆作用、古近纪岩浆作用、中新世岩浆作用。墨西哥的成矿作用主要与拉腊米期岩浆活动有关(约80 Ma—40 Ma),中新生代的矿床明显分成晚侏罗世(J3)、早白垩世(K1)、晚白垩世(K2)、古新世(E1)、始新世(E2)、渐新世(E3)、中新世(N1)等地质时期。古太平洋板块、法拉隆板块和科科斯板块等三大板块俯冲消减形成3个俯冲成矿系列,即从沿海到内陆依次发育有IOCG型铁铜金成矿带→斑岩型铜钼金成矿带→浅成低温热液型银金多金属成矿带,分别代表太平洋古板块、法拉隆板块和科科斯板块向北美板块从俯冲挤压到碰撞后伸展的岩浆成矿环境。     

Timing of formation and geological setting of low-sulphidation epithermal gold deposits in the continental margin of NE China

The margin of NE China, a part of the West Pacific metallogenic belt, contains innumerable low-sulphidation mineral deposits. Gold deposits in this region can be classified into three distinct types based on geology and ore mineral paragenesis: (1) low-sulphidation epithermal silver–gold deposits, (2) low-sulphidation tellurium–gold deposits, and (3) low-sulphidation epithermal tellurium–gold deposits. Ores formed during the late Early Cretaceous and the early Late Cretaceous reflect three distinct metallogenic periods: the Fuxin Stage at 115.98 ± 0.89 Ma, the Quantou Stage at 107.2 ± 0.6 Ma or <103 Ma, and the Qingshankou or Yaojiajie Stage at < 97 Ma and 88.2 ± 1.4 Ma. The Fuxin Stage is dominated by trachyandesitic magmatism, with magmas emplaced at hypabyssal depths. In comparison, the Quantou Stage is characterized by high-K calc-alkaline, calc-alkaline, and sodic andesitic, dacitic, and rhyolitic magmatism of three different suites. The first of these is a high-K calc-alkaline andesitic magmatic suite that was accompanied by the emplacement of a calc-alkaline sodic dacite during the formation of the Ciweigou and Wufeng ore deposits. The second suite is dominated by calc-alkaline sodic rhyolite and high-K calc-alkaline sodic dacite magmatism associated with the formation of the Sipingshan ore deposit. The third suite is typified by high-K calc-alkaline andesitic magmatism associated with the emplacement of calc-alkaline hypabyssal granitoid complexes accompanying the formation of the Dong'an and Tuanjiegou ore deposits. The Qingshankou or Yaojia Stage is characterized by calc-alkaline sodic dacite magmatism associated with the formation of the Wuxing ore deposit. Metallogenesis during the Fuxin Stage characterized by trachytic magmatism is closely related to the formation of a deep-seated fault within a magmatic arc or the back-arc region of an immature continental margin and is associated with the Early Cretaceous subduction of the Pacific plate beneath Eurasia. Ore deposits that formed during the Fuxin Stage were generally related to magmato-hydrothermal fluids associated with mantle-derived magmas. In contrast, metallogenesis during the Quantou and Qingshankou or Yaojiajie stages was closely related to the formation of a mature high-K calc-alkaline magmatic arc within a continental margin setting again associated with the westward subduction of the Pacific plate. This metallogenic event was a product of magmato-hydrothermal systems derived from crust–mantle interaction and mixing of magmas derived from partial melting of different sections of the continental crust.     

Geodynamics of late Mesozoic PGE,Au, and U mineralization in the Aldan shield,North Asian Craton

Late Mesozoic PGE, Au and U mineralization in the Precambrian Aldan Shield constitutes important ore deposits on the southern margin of the Siberian Craton. Here we provide an overview of the salient characteristics of these ore deposits and evaluate their regional geodynamic setting. Geological, geophysical, and geochronological data on the distribution and timing of the ultramafic and alkaline magmatism in the Aldan Shield and the associated Late Jurassic–Early Cretaceous PGE, Au, and U mineralization correlate with the convergence in the Asia-Pacific zone during the Late Mesozoic. The multistage magmatism and ore formation can be traced along the perimeter of the subducted slab now stagnant at the mantle transition zone, the flanks of which coincide with paleo-transform faults. Slab dehydration is considered to have transferred source metals through plume conduits resulting in the formation of productive ore-magmatic systems.     

Formation,tectonic position,and ore genesis of granitoids in the Pautovaya Horst (Northeast Russia)

This paper considers the problems of the existence of unexposed Late Jurassic-Early Cretaceous Priiskatel’skii and Pautovaya granitoid massifs in the core of the Pautovaya Horst and the Late Cretaceous Orotukan-Sulukhachan Massif, which is located at depths of <2 km and projected to the surface as the Verkhnii Orotukan, Sulukhachan, and Solnechnyi granite massifs. The formation of palingenetic-anatectic granitoid magma and its migration to the surface occurred under conditions of general basification of the crust in the Late Mesozoic and led to the formation of the Pautovaya Horst. Granitization of near-surface parts of the crust was accompanied by basification at depths of 8–15 km, where granitoid magma originated in magmatic chambers. The contact-metamorphosed sedimentary cap of the uneroded granitoid core of the Pautovaya Horst is promising for tin-rare metal ore deposits and occurrences and unpromising for gold mineralization.     

U–Pb and Re–Os Geochronology of the Tongcun Molybdenum Deposit and Zhilingtou Gold‐Silver Deposit in Zhejiang Province,Southeast China,and Its Geological Implications

Mesozoic ore deposits in Zhejiang Province, Southeast China, are divided into the northwestern and southeastern Zhejiang metallogenic belts along the Jiangshan–Shaoxing Fault. The metal ore deposits found in these belts are epithermal Au–Ag deposits, hydrothermal‐vein Ag–Pb–Zn deposits, porphyry–skarn Mo (Fe) deposits, and vein‐type Mo deposits. There is a close spatial–temporal relationship between the Mesozoic ore deposits and Mesozoic volcanic–intrusive complexes. Zircon U–Pb dating of the ore‐related intrusive rocks and molybdenite Re–Os dating from two typical deposits (Tongcun Mo deposit and Zhilingtou Au–Ag deposit) in the two metallogenic belts show the early and late Yanshanian ages for mineralization. SIMS U–Pb data of zircons from the Tongcun Mo deposit and Zhilingtou Au–Ag deposit indicate that the host granitoids crystallized at 169.7 ± 9.7 Ma (2σ) and 113.6 ± 1 Ma (2σ), respectively. Re–Os analysis of six molybdenite samples from the Tongcun Mo deposit yields an isochron age of 163.9 ± 1.9 Ma (2σ). Re–Os analyses of five molybdenite samples from the porphyry Mo orebodies of the Zhilingtou Au‐Ag deposit yield an isochron age of 110.1 ± 1.8 Ma (2σ). Our results suggest that the metal mineralization in the Zhejiang Province, southeast China formed during at least two stages, i.e., Middle Jurassic and Early Cretaceous, coeval with the granitic magmatism.     

Ore mineralization related to geological evolution of the Karkonosze–Izera Massif (the Sudetes,Poland) — Towards a model

The Karkonosze–Izera Massif is a large tectonic unit located in the northern periphery of the Bohemian Massif. It includes the Variscan Karkonosze Granite (about 328–304 Ma) surrounded by the following four older units:

• -Izera–Kowary (the Early Paleozoic continental crust of the Saxothuringian Basin),
• -Ještĕd (the Middle Devonian to Lower Viséan sedimentary succession deposited on the NE passive margin of the Saxothuringian Terrane), out of the present study area,
• -Southern Karkonosze (metamorphosed sediments and volcanics filling the Saxothuringian Basin), out of the present study area,
• -Leszczyniec (Early Ordovician, obducted fragment of Saxothuringian Basin sea floor).

The authors present a genetic model of ore mineralization in the Karkonosze–Izera Massif, in which ore deposits and ore minerals occurrences are related to the successive episodes of the geological history of the Karkonosze–Izera Massif:

• -formation of the Saxothuringian Basin and its passive continental margin (about 500–490 Ma)
• -Variscan thermal events:
  • -regional metamorphism (360–340 Ma)
  • -Karkonosze Granite intrusion (328–304 Ma)
• -Late Cretaceous and Neogene-to-Recent hypergenic processes.

The oldest ore deposits and ore minerals occurrences of the Karkonosze–Izera Massif are represented by pyrite and magnetite deposits hosted in the Leszczyniec Unit as well as by magnetite deposit and, presumably, by a small part of tin mineralization hosted in the Izera–Kowary Unit. All these deposits and occurrences were subjected to the pre-Variscan regional metamorphism.Most of the Karkonosze–Izera Massif ore deposits and occurrences are related to the Karkonosze Granite intrusion. This group includes a spatially diversified assemblage of small ore deposits and ore mineral occurrences of: Fe, Cu, Sn, As, U, Co, Au, Ag, Pb, Ni, Bi, Zn, Sb, Se, S, Th, REE, Mo, W and Hg located within the granite and in granite-related pegmatites, in the close contact aureole of the granite and within the metamorphic envelope, at various distances from the granite. Assuming world standards, all these deposits are now uneconomic. Various age determinations indicated that ore formation connected with the Karkonosze Granite might have taken place mostly between about 326 and 270 Ma.The last ore-forming episode in the Karkonosze–Izera Massif is related to hypergenic processes, particularly important in the northern part of the massif, in the Izera–Kowary Unit where some uranium deposits and occurrences resulted from the infiltration of ore solutions that originated from the weathering of pre-existing accumulations of uranium minerals. A separate problem is the presence of oxidation zones of ore deposits and occurrences, both the fossil and the recent.A full list of ore minerals identified in described deposits and occurrences of the Karkonosze–Izera Massif together with relevant, key references is presented in the form of an appendix.     

腾冲棋盘石铅锌多金属矿成矿规律探讨

矿区位于腾冲西北部东河铁、铜、铅锌多金属成矿区,区内早白垩世花岗岩浆活动强烈,矽卡岩型矿床发育,形成众多铁、铜、铅、锌矽卡岩型矿床,是腾冲西北部重要成矿区,棋盘石矽卡岩型铅锌矿即是其中之一。矿床形成与早白垩世中酸性花岗岩关系密切,矿体位于上二叠统碳酸盐岩外接触带矽卡岩中。地层、岩体对矽卡岩及矿体的控制作用明显。     

The gold-silver Okhotsk-Chukotka volcanic belt

The Okhotsk-Chukotka volcanic belt (OChVB) formed over 25 Ma from the middle Albian to the Cenomanian at the boundary of the continental Verkhoyansk-Chukotka and the Koryak-Kamchatka collages of terranes as a special tectonic unit of the Earth℉s crust composed of subaerial volcanic rocks extending for 3000 km. In regard to the oceanic margin, the inner, outer, and flank zones of the OChVB have been recognized. The complex structure of terranes in the basement and the OChVB itself resulted in the formation of diverse epithermal deposits. Porphyry copper-molybdenum deposits are concentrated in the inner zone. The outer zone is characterized by gold-silver ore mineralization and a variety of tin deposits. Silver-base-metal deposits (Dukat, Lunny, Arylakh, etc.) are confined to the rift-related volcanic trough that complicates the OChVB between the Yana-Kolyma and Omolon terranes.     

The New Progress in the Study of Mesozoic Rhyolite-Trachyte Assemblage and Hydrothermal-type Uranium Mineralization in Eastern China

The most intense area of Mesozoic volcanism and main region of hydrothermal-type uranium deposits is located in Eastern China. From the northern to the southern part, it can be divided into seven volcanic belts of Great Xing’an Range, Lesser Xing’an-Zhangguangcai Ranges, Northern Hebei-Western Liaoning, the Lower Yangtze Region, Ganhang areas, Wuyi Mountain areas,the Southeast Coastal areas, five uranium metallogenic belts of Guyuan-Hongshanzi, Qinglong-Xingcheng, Luzong-Qixia, Ganhang, Wuyi Mountain, and Three uranium metallogenic perspective belts of Manzhouli-Erguna, Zhalantun, Yichun. The volcanism of all these volcanic belts can be subdivided into six stages: The Early Jurassic to early Middle Jurassic, late Middle Jurassic to early Late Jurassic, early Early Cretaceous, middle Early Cretaceous, late Early Cretaceous and early Late Cretaceous. High-K calc-alkaline rhyolite-alkali trachyte rock assemblage of the early Early Cretaceous has a close connection with the explored uranium deposits. High-K calc-alkaline rhyolites have high content of uranium, and can provide the epithermal ore forming system with uranium; Alkali trachyte associated with mantle-derived magmatism can provide alkaline ore-forming fluid of rich uranium for deep temperature mineralizing system or act as pioneers of alkaline ore-forming fluid of rich uranium.     

Mesozoic molybdenum deposits in the East Xingmeng orogenic belt,northeast China: characteristics and tectonic setting

Numerous molybdenum (Mo) ore deposits have been discovered in the East Xingmeng orogenic belt (East Central Asian orogenic belt), over the past 10 years, and this region is becoming one of the world's most important Mo production areas. It contains 6.18 Mt of proven Mo metal reserves, which accounts for 30% of the total proven Chinese Mo reserves. The ore district includes 37 deposits and 15 occurrences, with three major Mo ore types, that is porphyries, skarns, and hydrothermal veins. The latter can be subdivided into quartz- and volcanic hydrothermal-vein types. With the exception of the Ordovician Duobaoshan porphyry Cu–Mo deposit (477 Ma), all the East Xingmeng Mo deposits formed during the Mesozoic. Re–Os dating of molybdenite has documented three episodes of Mo mineralization: Early Triassic (248–242 Ma), Jurassic (178–146 Ma), and Early Cretaceous (142–131 Ma). Early Triassic Mo deposits are distributed along the northern margin fault of the North China Craton (NCC) and include porphyry and quartz vein types. They are characterized by the association of Mo + Cu. Jurassic Mo deposits are mainly distributed in the eastern area and include porphyry, quartz vein, and skarn types. They are typified by Mo alone and/or the association of Mo, Pb, and Zn. Cretaceous Mo deposits are distributed in all areas and include porphyry and volcanic hydrothermal vein types. Similar to the Jurassic ores, they are simple Mo or Mo + Pb + Zn deposits. Volcanic hydrothermal vein deposits are characterized by an association of molybdenum and uranium. The Triassic Mo deposits formed in a syn-collision setting between the Siberian and North China plates. The Jurassic Mo deposits formed in a compressional setting, which was probably triggered by the westward subduction of the palaeo-Pacific plate. The Early Cretaceous Mo deposits are linked to a tectonic regime of lithosphere thinning, which was caused by delamination of thickened lithosphere. However, the Mo deposits in the Erguna terrane of the northwest Xingmeng orogenic belt may be related to the evolution of the Okhotsk Ocean.     

Phanerozoic magmatic evolution and metallogenesis in the Eastern Jilin and Heilongjiang Provinces,China

ABSTRACT

The eastern Jilin and Heilongjiang provinces in China are located at the junction between the Paleo-Asian Ocean and Circum-Pacific metallogenic domains, and have been affected by the temporal transition between these domains and their superposition, resulting in intensive and complicated mineralization events. This paper provides a progress in exploration for, and geological research into, endogenic metal deposits and related magmatite in the eastern Jilin and Heilongjiang provinces. Four richly mineralized areas are recognized: (1) the Lesser Xing’an–Zhuangguangcai Range metallogenic belt; (2) the Jiamusi–Khanka metallogenic belt; (3) the Yanbian metallogenic belt; and (4) the Wandashan metallogenic belt. Four temporal peaks in magmatism and metallogenesis are identified: (1) Hercynian orogenic Au deposits (260–250 Ma) show a close relationship with magmatism related to a transitional syn- to post-collisional tectonic setting; (2) Indosinian orthomagmatic ore deposits (230–210 Ma) show a close relationship to mafic–ultramafic magmatism in a post-collision extensional setting; (3) porphyry Mo deposits and skarn deposits of the Late Triassic to the Early Jurassic (200–170 Ma) formed in a continental arc setting, triggered by slab subduction; and (4) late Yanshanian large-scale mineralization was caused by tectonic extension at 133–106 Ma. Yanshanian felsic magmatism shows clear metallogenetic specialization; i.e. each rock type hosts a different type of deposit.     

西准噶尔萨吾尔地区主要矿床类型及成矿规律

本文基于萨吾尔地区目前发育的主要矿床(点)吐尔库班套铜镍矿点、阔尔真阔腊金铜矿床、布尔克斯岱金矿床、罕哲尕能铜矿床、塔斯特金矿床、黑山头金矿点、那林卡拉铜钼矿点等的研究,分析了区域矿化类型及成矿规律。认为萨吾尔地区矿床成因类型可分为三类,岩浆Cu-Ni硫化物矿床、斑岩型-浅成低温热液型Au-Cu-Mo矿床、与中酸性侵入岩有关的构造蚀变岩型Au矿床。矿化以Au、Cu矿化为主,Cu-Ni、Mo矿化次之。成矿时代分布在中泥盆世、早石炭世、晚石炭世,集中于早石炭世(354~336Ma)。空间上,岩浆Cu-Ni硫化物矿床分布于萨吾尔北部科克森套地区,斑岩型-浅成低温热液型Au-Cu-Mo矿床、与中酸性侵入岩有关的构造蚀变岩型Au矿床主要分布于萨吾尔山南部。成矿构造背景分别对应于区域中泥盆世岛弧环境、早石炭世岛弧环境、晚石炭世碰撞造山后环境。区域成矿规律显示了进一步的找矿潜力:萨吾尔北部科克森套地区发育的镁铁-超镁铁岩体的岩浆Cu-Ni硫化物矿床的找矿潜力;阔尔真阔腊-布尔克斯岱地区斑岩型-浅成低温热液型金铜矿床的找矿潜力;区域晚石炭世-早二叠世斑岩型Cu-Mo矿床的找矿潜力;萨吾尔断裂及其次级断裂控制范围内的Au-Cu找矿潜力。     

Multiple Mesozoic mineralization events in South China—an introduction to the thematic issue

Mesozoic mineral deposits in South China include world-class deposits of W, Sn and Sb and those that provide the major sources of Ta, Cu, Hg, As, Tl, Pb, Zn, Au and Ag for the entire country. These deposits can be classified into polymetallic hydrothermal systems closely related to felsic intrusive rocks (Sn–W –Mo granites, Cu porphyries, polymetallic and Fe skarns, and polymetallic vein deposits) and low-temperature hydrothermal systems with no direct connection to igneous activities (MVT deposits, epithermal Au and Sb deposits). Recent studies have shown that they formed in the Triassic (Indosinian), Jurassic–Cretaceous (Early Yanshanian), and Cretaceous (Late Yanshanian) stages. Indosinian deposits include major MVT (Pb–Zn–Ag) deposits and granite-related W–Sn deposits. Early Yanshanian deposits are low-temperature Sb–Au and high-temperature W–Sn and Cu porphyry types. Many Late Yanshanian deposits are low-temperature Au–As–Sb–Hg and U deposits, and also include high-temperature W–Sn polymetallic deposits. The formation of these deposits is linked with a specific tectonothermal evolution and igneous activities. This special issue brings together some of the latest information in eight papers that deal with the origins and tectonic environments of mineral deposits formed in these stages. We anticipate that this issue will stimulate more interests in these ore deposits in South China.     

吉林晚三叠世-早白垩世花岗岩类型与盆地演化的关系及其成矿专属性

依据区域地质构造演化、岩石组合及同位素测年资料, 将吉林省晚三叠世-早白垩世花岗岩划分为裂解型、走滑型和会聚型3类成因构造类型。其中, 裂解型岩套与铜镍、磷、钒钛磁铁矿相关; 走滑型岩套与贵金属、多金属矿相关; 会聚型陆内板片(A型) 俯冲亚型花岗岩套与斑岩型钼矿、金矿及铜矿等相关。早侏罗世岩浆作用形成的矿床以钼矿为主, 晚侏罗世-早白垩世转向金、铜、铅锌矿为优势。成因构造类型岩浆岩套呈节律式地更新递进, 反映出太平洋板块与东北亚滨太平洋大陆边缘互动的复杂性, 及岩浆演化活动的规律和动态过程。     

Geology,geochronology and geochemistry of large Duobaoshan Cu-Mo-Au orefield in NE China: Magma genesis and regional tectonic implications

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.     

辽东五龙金矿周缘早白垩世花岗岩体侵位深度及其地质意义

早白垩世岩浆活动对辽东半岛五龙地区金矿形成可能具有明显的制约作用,并可能为含金流体提供了热源及动力.五龙金矿南、北早白垩世三股流岩体和五龙背岩体角闪石-斜长石温压计计算结果表明,这2个岩体角闪石结晶温度为640.8～757.4℃,对应岩浆的侵位深度为5.9～9.7 km.角闪石TiO2-Al2O3图解表明,三股流和五龙...     

Platinum Mineralization in Multimetal Gold–Polymetallic,Au–Bi,Cu–Mo Porphyry,Cu–Ni,Titanomagnetite, and Copper–Sulfide Ore Deposits and Occurrences of the Upper Amur Region (Far East,Russia)

New data on platinum mineralization in ores, metasomatic rocks, concentrates, and tailings and wastes of some gold–polymetallic, Au–Bi, Cu–Mo porphyry, Cu–Ni, and titanomagnetite ore deposits and occurrences of the Upper Amur Region are presented. The contents of platinoids, Au and Ag in multimetal ores of gold-polymetallic, Au–Bi, Cu–Mo porphyry, Cu–Ni, and titanomagnetite ore deposits and ore occurrences are given. In addition, recommendations on the necessity of continuing scientific studies, revision, and resampling works in the search for platinoids in other complex ores of deposits and occurrences of the Upper Amur Region are given.     

Source and possible tectonic driver for Jurassic–Cretaceous gold deposits in the West Qinling Orogen,China

The West Qinling Orogen (WQO) in Central China Orogenic Belt contains numerous metasedimentary rock-hosted gold deposits (>2000 t Au), which mainly formed during two pulses: one previously recognized in the Late Triassic to Early Jurassic (T3–J1) and one only recently identified in the Late Jurassic to Early Cretaceous (J3–K1). Few studies have focused on the origin and geotectonic setting of the J3–K1 gold deposits.Textural relationships, LA-ICP-MS trace element and sulfur isotope compositions of pyrites in hydrothermally altered T3 dykes within the J3–K1 Daqiao deposit were used to constrain relative timing relationships between mineralization and pyrite growth in the dykes, and to characterize the source of ore fluid. These results are integrated with an overview of the regional geodynamic setting, to advance understanding of the tectonic driver for J3–K1 hydrothermal gold systems. Pyrite in breccia- and dyke-hosted gold ores at Daqiao have similar chemical and isotopic compositions and are considered to be representative of J3–K1 gold deposits in WQO. Co/Ni and sulfur isotope ratios suggest that ore fluids were derived from underlying Paleozoic Ni- and Se-rich carbonaceous sedimentary rocks. The geochemical data do not support the involvement of magmatic fluids. However, in the EQO (East Qinling Orogen), J3–K1 deposits are genetically related to magmatism. Gold mineralization in WQO is contemporaneous with magmatic deposits in the EQO and both are mainly controlled by NE- and EW-trending structures produced by changes in plate motion of the Paleo-Pacific plate as it was subducted beneath the Eurasian continent. We therefore infer that the J3–K1 structural regime facilitated the ascent of magma in the EQO and metamorphic fluids in the WQO with consequent differences in the character of contemporaneous ore deposits. If this is correct, then the far-field effects of subduction along the eastern margin of NE Asia extended 1000's of km into the continental interior.     

Geodynamic setting of gold deposits in Eastern and Central Trans-Baikal (Chita Region, Russia)

It is proposed that there are three types of gold deposits in Eastern and Central Transbaikalia (Trans-Baikal province), namely: (i) high-sulphide intrusion-related deposits with some signs of porphyry deposits, (ii) low-sulphide intrusion-related deposits, and (iii) low-sulphide epithermal Au–Ag deposits. Most of the gold deposits belong to the first two types, and their ages are Middle–Late Jurassic. Deposits of the third type are not numerous, and their age is Early Cretaceous.The majority of the gold mineralization is spatially related to the two branches of the Mongolia–Okhotsk suture, along which Siberia collided, at the Early/Middle Jurassic boundary, with the Mongolia–North China continent and the Onon island-arc terrane located between the two continents. Collision-related thrusting, folding and magmatism lasted until the latest Jurassic, when they gave way to post-collisional rifting that continued until the end of Early Cretaceous.According to their age, relation to magmatism and tectonic framework, the intrusion-related deposits (high- and low-sulphide) were formed in a regional collisional setting. Extensional environments at that time existed only in local areas in the roofs of great magmatic chambers. Low-sulphide epithermal deposits were formed during Early Cretaceous post-collisional rifting.