论新疆东准噶尔陆相火山成矿作用

早石炭世晚期至早二叠世时期，东准噶尔地区陆相火山作用广为发育。近年来的研究证明，这一时期的陆相火山作用形成了两套重要的成矿岩浆建造，即安山－英安质喷溢、喷发岩建造和中性－中酸性潜火山杂岩建造，它们具有同一的成矿专属性，与金、铜、铁成矿密切相关。前者主要形成特征的浅成低温热液陆相火山岩型金矿。后者与金、铜成矿关系极为密切，其突出特征表现为受同－成矿岩浆作用的制约，在不同的外部条件下，形成不同类型的多种矿床，分别构成自成体系的金矿床系列和铜矿床系列，充分揭示了东准噶尔与陆相火山作用有关金、铜成矿的广阔前景和深远意义。     

吉尔吉斯天山晚古生代岩浆活动及相关成矿作用

本文通过对近年来有关吉尔吉斯天山研究进展的梳理,结合在吉尔吉斯斯坦的实地考察,系统论述了吉尔吉斯天山古生代基础地质情况,着重讨论了与岩浆作用相关的成矿过程。吉尔吉斯斯坦境内的天山由"尼古拉耶夫线"和阿特巴什-伊内尔切克断裂划分为北、中、南三部分。两条缝合带限定了早古生代捷尔斯凯伊洋和晚古生代南天山洋的发展和消亡过程。吉尔吉斯天山古生代岩浆作用大致分为两个阶段:早古生代捷尔斯凯伊洋演化过程中,与弧-陆碰撞、弧-弧碰撞相关的岩浆作用和晚古生代与南天山洋闭合相关的岩浆作用。晚古生代存在两个重要的成矿阶段:晚石炭世与南天山洋向北俯冲形成的弧岩浆作用相关的斑岩型、矽卡岩型铜-金矿床;早二叠世与后碰撞花岗岩侵入作用相关,并受剪切带控制的金-多金属矿床。南天山缝合带附近出露的不同岩体在岩石地球化学及矿化特征的差异,反映了位于阿特巴什-伊内尔切克断裂以北的岩浆源区为成矿物质贫瘠的中天山前寒武纪基底,而断裂以南的岩浆作用源区为富集流体及成矿元素的增生杂岩和塔里木被动陆缘沉积物。     

大陆再造与钦杭带北东段多期铜金成矿作用

大陆再造与铜金成矿系统的研究是当前国际矿床学前沿领域。钦杭成矿带是我国21个重点成矿区带之一,也是扬子与华夏地块的拼贴带。近年,对钦杭带北东段一系列铜金矿床的系统研究表明,成矿作用与富铜金大陆地壳形成和随后的多期再造过程密切相关。晚中元古代-早新元古代,在被动大陆边缘的伸展环境,软流圈地幔部分熔融形成铁砂街岩群细碧岩和VMS型铁砂街铜矿。之后新元古代的洋壳俯冲,岛弧环境的俯冲板片部分熔融形成双溪坞岩群岛弧火山岩和VMS型平水矿铜矿体,其成矿流体主要来自于深循环海水,成矿物质主要来自于平水组幔源火山岩。随后发生的扬子与华夏地块的陆陆碰撞造山作用,新元古代双桥山群基底地层发生强烈再造,形成了受韧性剪切带控制的金山造山型金矿,富CO2变质流体的不混溶作用是金富集沉淀的最重要机制。早古生代,华南陆内造山作用导致新元古代双溪坞岩群和陈蔡岩群发生再造,形成了早古生代韧性剪切带及相应的造山型金矿(璜山、平水金矿等),金的富集沉淀与富CO2变质流体的演化密切相关。韧性剪切带及特征的富CO2变质流体,可以作为加里东期造山型金矿的找矿标志。晚中生代,古太平洋板块开始向华南大陆东南缘俯冲,位于华南内陆的德兴地区受到俯冲作用远程效应,导致德兴地区新元古代富铜金新生地壳部分熔融,形成低镁埃达克质岩及与其相关的银山和建德铜金多金属矿床,当部分熔融过程受到岩石圈地幔影响,则形成高镁埃达克质花岗闪长斑岩及超大型德兴斑岩铜矿。因此,钦杭成矿带北东段先后发生晚中元古-新元古代、早古生代和晚中生代多期铜金成矿。新元古代江南造山事件和稍早的板内岩浆作用形成了富铜金的新生地壳,为钦杭带北东段多期铜金成矿作用以及燕山期金属巨量堆积奠定了丰厚的物质基础,是该成矿带产出的关键控制要素。新元古代富铜金大陆再造是大型、超大型铜金矿床形成的一种重要机制。     

Sedimentary Crust and Metallogeny of Granitoid Affinity: Implications from the Geotectonic Histories of the Circum‐Japan Sea Region,Central Andes and Southeastern Australia

Metallogeny of granitoid affinity was reviewed from the aspect of geotectonic history of the continental crust, particularly of the genesis of sedimentary crust involved in magmatism. The redox state of granitoids and related mineralization shows a remarkable contrast between the east and west sides of the Pacific Rim, but if examined closely, the reduced‐type and oxidized‐type granitoid provinces are juxtaposed in three regions: the circum‐Japan Sea region, the central Andes, and the Lachlan Fold Belt in southeastern Australia. Comparative study of these regions revealed that the reduced‐type magmatism associated with Sn mineralization generated in thick sedimentary crust which formed in three geotectonic environments: (i) accretionary terrane along a subduction zone (e.g. Jurassic East Asia), (ii) continental rift (e.g. Early Paleozoic Andes), and (iii) mega‐fan (e.g. Early Paleozoic southeastern Australia). A collisional orogen can provide large amounts of clastic sediment to these environments. The age gap between the magmatism and sedimentation varies depending on the tectonic evolution of individual regions. Thin sedimentary crust may not play an essential role for the reduced‐type magmatism. The oxidized‐type magmatism associated with porphyry Cu and other mineralization generated in the crust which was initially carbon‐free igneous crust or modified from sedimentary crust by magmatism. Subduction‐related basaltic magmas are relatively oxidized, and may enhance fO₂ conditions of granitoid activity. Repeated magmatism in a monotonous convergent margin may be favorable for porphyry Cu mineralization as exemplified in the eastern Pacific Rim.     

环巴尔喀什-西准噶尔成矿省矿床类型、成矿系统和跨境成矿带对接

环巴尔喀什-西准噶尔成矿省地处中亚成矿域核心区,古生代构造和岩浆活动强烈,成矿作用丰富多样,发育许多大型-超大型乃至世界级的金属矿床,包括斑岩型铜矿床、斑岩-石英脉-云英岩型钨钼矿床、矽卡岩型铜(多金属)矿床、火山成因块状硫化物型(VMS)多金属矿床、浅成低温热液型金矿床、石英脉-蚀变岩型中温热液金矿床、与花岗岩有关的Be-U矿床、岩浆熔离型铜镍硫化物矿床和豆荚状铬铁矿等,这些矿床集中分布,形成多处成矿带,包括哈萨克斯坦的扎尔玛-萨吾尔、波谢库尔-成吉斯和北巴尔喀什等成矿带以及新疆西准噶尔的萨吾尔、谢米斯台-沙尔布提和巴尔鲁克-克拉玛依等成矿带。哈萨克斯坦包含大型-超大型和世界级金属矿床的成矿带向东是否延入新疆西准噶尔?能否实现新疆西准噶尔找矿重大突破?都是备受关注的重大地质找矿问题。本文在前人研究并结合作者工作基础上,根据成矿带的成矿构造环境、矿床类型、成矿特点和成矿时代,总结出成矿省至少发育九类成矿系统,即(1)奥陶纪-志留纪岛弧斑岩型Cu-Au成矿系统;(2)奥陶纪岛弧VMS型多金属成矿系统;(3)泥盆纪岛弧岩浆熔离型铜镍硫化物成矿系统;(4)泥盆纪与蛇绿岩有关的豆荚状铬铁矿成矿系统;(5)早石炭世岛弧斑岩-浅成低温热液型Cu-Au成矿系统;(6)石炭纪岛弧斑岩型-矽卡岩型Cu-Mo-Au成矿系统;(7)晚石炭世弧后盆地与花岗岩有关的Be-U成矿系统;(8)早二叠世岛弧或岛弧和陆缘弧过渡弧斑岩-石英脉-云英岩型Mo-W成矿系统;(9)早二叠世岛弧石英脉-蚀变岩型中温热液金成矿系统。对比研究发现境内外相邻成矿带具有相同或相似的成矿系统,二者可以对接,新疆西准噶尔三条成矿带分别是哈萨克斯坦三条成矿带的东延部分,构成了成矿省北部的扎尔玛-萨吾尔Cu-Au成矿带、中部的波谢库尔-成吉斯-谢米斯台Cu-Au-Be-U多金属成矿带和南部的北巴尔喀什-克拉玛依Cu-Mo-W-Au-Cr成矿带。新疆西准噶尔具有形成大型-超大型矿床的成矿系统和成矿条件,有望实现找矿勘探的更大突破。     

西天山金、铜矿地质特征简述

西天山是我国古生代造山带重要的金、铜矿成矿单元之一,具有Au、Cu地球化学场.各种地球物理场也显示具有良好的金、铜矿成矿地质背景.金、铜矿主要生成于海西期的构造岩浆地质热事件中,形成了浅成低温热液型和韧性剪切带型金矿以及海底火山喷气热水沉积型、矽卡岩型、斑岩型、陆相火山热液充填型铜矿.可划分出赛里木铜金成矿带、吐拉苏也里莫墩金成矿带、察布查尔铜成矿带及胜利达坂金成矿带.主要矿床有阿希金矿、望峰金矿、喇嘛苏铜矿和预须开普台铜矿.     

皖赣沿江地区中生代壳幔相互作用与多成因夕卡岩成矿过程研究综述

在皖赣沿江地区分布着大量中生代侵入岩体及其岩石包体和相关的夕卡岩矿床。本文在综合整理作者研究团队近30年来所获得的区内大部分侵入岩体及其岩石包体和夕卡岩矿床研究资料的基础上,聚焦区域中生代壳幔相互作用与多成因夕卡岩成矿过程分析,为发展壳幔成矿学打下一定基础。基性侵入岩和镁铁质岩石包体的同位素年代学和岩石地球化学资料表明,皖赣沿江地区在中生代发生了碰撞后(145~135 Ma)富铜金和造山后(130~120 Ma)富铁金幔源岩浆底侵作用和相应的壳幔混源岩浆作用。壳幔混源岩浆作用主要包括结晶分异作用、同化混染作用、岩浆混合作用和岩浆熔离作用。夕卡岩矿床地质调研和镜下观察结果显示,两期壳幔混源岩浆侵入晚古生代到早中生代围岩地层后引发了多成因夕卡岩成矿作用,形成了接触交代、层控、岩浆和复合叠加等多成因夕卡岩矿床。接触交代、层控、岩浆和复合叠加夕卡岩矿床分别以热液交代、沉积+热液交代、岩浆结晶+热液交代和沉积+岩浆结晶+热液交代矿物组合和结构构造为特征。在碰撞后酸性-中酸性侵入岩体中产有富Cu和Zn等成矿物质的元古宙变质岩包体,表明碰撞后富铜金的底侵玄武岩浆或其演化岩浆在浅位岩浆房中同化了元古宙变质基底成矿物质(铜锌等)储库导致铜进一步富集,从而形成更富铜的酸性-中酸性岩浆。在碰撞后中基性-基性侵入岩体中产有含大量Cu-Fe硫化物(黄铜矿和磁黄铁矿)和氧化物包裹体的深位和浅位堆积岩,表明碰撞后富铜金的底侵玄武岩浆在深位岩浆房中和其演化岩浆在浅位岩浆房中发生了强烈的结晶分异作用导致铜铁亏损,形成更富金的中基性-基性岩浆。酸性-中酸性侵入岩体中夕卡岩包体和夕卡岩中辉长岩-夕卡岩过渡包体的存在表明,碰撞后富铜金的底侵玄武岩浆在侵位处同化晚古生代含铜铁矿源层的碳酸盐地层导致铜进一步富集,形成更富铜的夕卡岩岩浆。更富铜的酸性-中酸性岩浆、更富金的中基性-基性岩浆和更富铜的夕卡岩岩浆是形成碰撞后时期接触交代和层控夕卡岩铜矿、接触交代夕卡岩金矿和岩浆夕卡岩铜矿的最重要控制因素。在造山后中基性-基性侵入岩体中产有含大量Cu-Fe硫化物(黄铜矿和磁黄铁矿)和氧化物包裹体的堆积岩,表明造山后富铁金的底侵玄武岩浆在深位岩浆房中发生了强烈的结晶分异作用导致铜铁亏损,从而形成更富金的中基性-基性岩浆。造山后富铁金的底侵玄武岩浆在侵位处同化晚古生代含铜铁矿源层的碳酸盐地层、早中生代铁矿源层或者早中生代铁硅矿源层,导致铁、铁和铁硅的进一步富集,分别形成更富铁的夕卡岩岩浆、基性岩浆和中基性岩浆。更富金的中基性-基性岩浆及更富铁的夕卡岩岩浆、基性岩浆和中基性岩浆是形成造山后时期接触交代夕卡岩金矿、岩浆夕卡岩铁矿、矿浆型铁矿和接触交代夕卡岩铁矿的关键控制因素。     

Spatial Relations of Gold-Ore Deposits and Cretaceous Granitoid Magmatism in the Chukotka Peninsula

Analysis of the spatial relations of gold ore occurrences and the enclosing geological environment in the Chukotka Autonomous Okrug (ChAO) has shown that Au–quartz ore occurrences in turbidites are located predominantly in areas of the Early Cretaceous granitoid magmatism with the thick collision-type continental crust. The Cu–Au porphyry deposits are located in areas with complete development of Early Cretaceous magmatism within the outer zone of the Okhotsk–Chukchi volcanoplutonic belt (OChVB). The Au–Ag epithermal deposits are located in the areas of the Late Cretaceous granitoid magmatism within the inner and outer zones of the OChVB. The prospects of island-arc complexes for searching for Kuroku-type Au-bearing ore objects are available.     

西藏冈底斯矿带南缘矽卡岩型铜矿床含矿岩体锆石U-Pb年龄及意义

西藏冈底斯矿带发育大量斑岩铜钼矿床及铜铅锌多金属矿床,形成斑岩铜矿带及多金属矿带。过去的工作表明,冈底斯带南部矿床同位素年龄多小于30Ma,形成于碰撞期后伸展环境。本文测定了冈底斯矿带南缘克鲁-冲木达矽卡岩型铜(金、钼)矿集区桑布加拉矽卡岩型铜(金)矿化岩体锆石LA-ICP-MSU-Pb年龄及锆石Ce4+/Ce3+比值。矿化岩体锆石U-Pb年龄:92.1±0.6Ma,MSWD=1.0,锆石Ce4+/Ce3+比值在90～562之间,平均值为287。锆石Ce4+/Ce3+比值和玉龙矿带含矿岩体锆石的比值基本一致,显示矽卡岩矿化岩体岩浆氧逸度较高。印度板块与欧亚板块碰撞时间在65～45Ma之间,桑布加拉矽卡岩型铜矿化岩体锆石U-Pb年龄表明冈底斯带不但发育碰撞期后大规模成矿作用,也发育与洋壳俯冲构造岩浆事件有关的成矿作用。这为冈底斯矿带洋壳俯冲有关矿床的寻找提供了依据。     

Base and precious metal mineralization in Middle Jurassic rocks of the Lesser Caucasus: A review of geology and metallogeny and new data from the Kapan,Alaverdi and Mehmana districts

The polymetallic Cu–Au–Ag–Zn ± Pb, Cu–Au and Cu deposits in the Kapan, Alaverdi and Mehmana mining districts of Armenia and the Nagorno–Karabakh region form part of the Tethyan belt. They are hosted by Middle Jurassic rocks of the Lesser Caucasus paleo-island arc, which can be divided into the Kapan Zone and the Somkheto–Karabakh Island Arc. Mineralization in Middle Jurassic rocks of this paleo-island arc domain formed during the first of three recognized Mesozoic to Cenozoic metallogenic epochs. The Middle Jurassic to Early Cretaceous metallogenic epoch comprises porphyry Cu, skarn and epithermal deposits related to Late Jurassic and Early Cretaceous intrusions. The second and third metallogenic epochs of the Lesser Caucasus are represented by Late Cretaceous volcanogenic massive sulfide (VMS) deposits with transitional features towards epithermal mineralization and by Eocene to Miocene world-class porphyry Mo–Cu and epithermal precious metal deposits, respectively.The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are poorly understood and previous researchers named them as copper–pyrite, Cu–Au or polymetallic deposits. Different genetic origins were proposed for their formation, including VMS and porphyry-related scenarios. The ore deposits in the Kapan, Alaverdi and Mehmana mining districts are characterized by diverse mineralization styles, which include polymetallic veins, massive stratiform replacement ore bodies at lithological contacts, and stockwork style mineralization. Sericitic, argillic and advanced argillic alteration assemblages are widespread in the deposits which have intermediate to high-sulfidation state mineral parageneses that consist of tennantite–tetrahedrite plus chalcopyrite and enargite–luzonite–colusite, respectively. The ore deposits are spatially associated with differentiated calc-alkaline intrusions and pebble dykes are widespread. Published δ³⁴S values for sulfides and sulfates are in agreement with a magmatic source for the bulk sulfur whereas published δ³⁴S values of sulfate minerals partly overlap with the isotopic composition of contemporaneous seawater. Published mineralization ages demonstrate discrete ore forming pulses from Middle Jurassic to the Late Jurassic–Early Cretaceous boundary, indicating time gaps of 5 to 20 m.y. in between the partly subaqueous deposition of the host rocks and the epigenetic mineralization.Most of the described characteristics indicate an intrusion-related origin for the ore deposits in Middle Jurassic rocks of the Lesser Caucasus, whereas a hybrid VMS–epithermal–porphyry scenario might apply for deposits with both VMS- and intrusion-related features.The volcanic Middle Jurassic host rocks for mineralization and Middle to Late Jurassic intrusive rocks from the Somkheto–Karabakh Island Arc and the Kapan Zone show typical subduction-related calc-alkaline signature. They are enriched in LILE such as K, Rb and Ba and show negative anomalies in HFSE such as Nb and Ta. The ubiquitous presence of amphibole in Middle Jurassic volcanic rocks reflects magmas with high water contents. Flat REE patterns ([La/Yb]_N = 0.89–1.23) indicate a depleted mantle source, and concave-upward (listric-shaped) MREE–HREE patterns ([Dy/Yb]_N = 0.75–1.21) suggest melting from a shallow mantle reservoir. Similar trace element patterns of Middle Jurassic rocks from the Somkheto–Karabakh Island Arc and the Kapan Zone indicate that these two tectonic units form part of one discontinuous segmented arc. Similar petrogenetic and ore-forming processes operated along its axis and Middle Jurassic volcanic and volcanosedimentary rocks constitute the preferential host for polymetallic Cu–Au–Ag–Zn ± Pb, Cu–Au and Cu mineralization, both in the Somkheto–Karabakh Island Arc and the Kapan Zone.     

Mineral resources of Southern Africa in time-stratigraphic perspective

The tectono-stratigraphic setting of mineral deposits in southern Africa is reviewed with reference to 5 outline maps portraying stages in the evolution of the subcontinent.The Early and Middle Archaean Eras are characterized by deposits of Cr, Au and Fe; the Late Archaean by Au, U and Ni. In the Early Proterozoic the intrusion of vast mafic complexes supplied Cr, Ni, Pt, Cu and V-Fe ore, while sedimentary basins received Fe, Mn, Cu, Pb and Zn in marginal seas. The Middle Proterozoic was a singularly poor metallogenic Era, producing only pegmatite minerals and a variety of Cu deposits. The Late Proterozoic is typified by widespread occurrence of Cu, Pb, Zn and local U in geosynclinal belts; pegmatite minerals formed on a large scale in rejuvenated basement. Carbon is the most important element of Phanerozoic deposits, accounting for the fossil fuels besides appearing as diamond in kimberlite. It also contributed to the precipitation of sandstone-type U. Post-Gondwana morphology and climate effected further surface concentration and dispersal of minerals.     

东昆仑造山带东段晚古生代—早中生代构造岩浆演化与成矿作用

东昆仑造山带位于中央造山系西段,在长期的地质演化过程中构造岩浆活动频繁,其中晚古生代—早中生代岩浆活动与成矿关系最为密切。本文系统总结了东昆仑造山带晚古生代—早中生代岩浆岩的分布、演化和成因,对典型矿床的地质特征进行分析,探讨东昆仑东段晚古生代—早中生代构造岩浆演化与成矿作用的联系。东昆仑晚古生代—早中生代构造岩浆演化可分为俯冲阶段(277~240 Ma)、同碰撞阶段(240~230 Ma)和后碰撞阶段(230~200 Ma),壳幔岩浆混合作用贯穿于古特提斯构造演化全过程。镁铁质岩浆岩主体为受俯冲流体交代的地幔部分熔融,花岗质岩浆岩主体为幔源岩浆底侵镁铁质下地壳部分熔融形成。东昆仑造山带东段俯冲阶段壳幔岩浆混合作用不仅带来成矿物质,使部分元素含量增高,还带来热源;经过成矿流体物理化学条件改变,导致大量矿物质沉淀,形成矿床,主要成矿金属组合为Cu、Mo、Au,矿床规模相对较小;同碰撞阶段由于受到挤压应力,岩浆岩出露较少,矿床多沿大型断裂带分布,主要成矿金属组合也以Cu、Mo、Au为主;后碰撞阶段由于岩石圈地幔拆沉,东昆仑整体处于拉张环境,为地幔物质参与成矿和成矿流体运移提供了通道。特别是同碰撞和后碰撞的转换阶段,是东昆仑造山带东段晚古生代—早中生代的主要成矿期,主要成矿金属组合为Cu、Pb、Zn、Fe。     

试论新疆成矿体系与时空演化模式

文章探讨了成矿体系的内涵,在以往研究成果和编制1∶1 500 000中国新疆维吾尔自治区矿床成矿系列图的基础上,根据先时间、后空间、再成因的总体思路,完善了新疆前寒武纪、早古生代、晚古生代、中生代、新生代五个时段成矿体系,初步构建了各时段成矿体系的时空演化模式,总结出5个时段成矿体系的特点是:前寒武纪为基底陆壳的形成与发展各具特色的成矿体系;早古生代板块体制早期发育具中亚成矿域特色的成矿体系;晚古生代板块体制晚期发育具中亚成矿域特色的成矿体系;中生代新疆北部发育板内西域成矿特色的成矿体系和新疆南部发育特提斯成矿域特色的成矿体系;新生代发育板内西域成矿特色的大陆成矿体系。     

东天山成矿带斑岩铜矿和其他类型矿床找矿勘查

东天山地区横跨哈萨克斯坦与塔里木两大板块,是新疆最重要的有色金属、黑色金属和贵金属矿产地之一。经历了前震旦纪基底形成→震旦-泥盆纪古亚洲洋形成、消亡→石炭纪-早二叠世后碰撞造山→晚二叠世至今的陆内造山等阶段。主要成矿期为晚古生代早期(泥盆纪-二叠纪),成矿作用复杂、类型繁多。其中,北部形成岛弧斑岩型和火山岩型铜、钼、金矿,中部形成拉张火山岩型和矽卡岩型金、铜、镍、银矿,中南部形成前寒武纪结晶基底叠加改造的层控-热液型铅、锌、银矿,南部库鲁克塔格和北山地区形成拉张铜、镍、金矿。通过研究认为,东天山地区尤以铜、镍、钼矿产资源潜力很大,优选出28个矿找矿靶区。     

秦岭造山带构造-成矿旋回与演化

构造与成矿活动是否具有旋回性是地质界长期争论的一个命题。本文根据矿床成矿系列理论和方法,论述了秦岭造山带构造-成矿活动,划分出新太古代-古元古代早期、古元古代晚期、中-新元古代、早古生代、晚古生代和中、新生代6个构造-成矿旋回,探讨了每个旋回的矿床成矿系列特征和成矿演化历史。指出该造山带的成矿作用既有长期性和连续性,也有间断性和旋回性;中、新元古代至早古生代和中、新生代两个时期是秦岭造山带中两个主要的成矿高峰期;构造-成矿作用可分为开裂、拼合及相对稳定三个阶段;成矿作用早期以幔源岩浆侵入及海相火山活动为主,晚期以壳幔混源-壳源的陆相中酸性岩浆侵入及火山活动为主;与火成活动及开裂作用有关的成矿活动在南、北两个成矿域之间具有振荡性演化的特征.      

A new scenario for related IOCG and Ni–(Cu) mineralization: the relationship with giant mid-crustal mafic sills, Variscan Iberian Massif

Both magmatic Ni–(Cu) and hydrothermal iron oxide–copper–gold mineralization coexist in ancient belts but their relationship remains poorly known. Geochronology and field geology evidence show that in SW Iberia both styles of mineralization were coeval with widespread metaluminous to peraluminous Variscan magmatism (350–330 Ma). We propose that mineralization was probably related to a hidden large layered mafic–ultramafic layered complex, recently inferred from geophysics, that was emplaced in a mid-crustal decollement zone. Contamination of a primitive mantle-derived magma with continental crust in the layered complex led to fractional crystallization accompanied by high-T–low-P metamorphism and the incorporation of volatiles into the melt. Hot hypersaline CO₂–CH₄-bearing brines were subsequently released and focused along major thrusts and strike-slip faults to produce the IOCG mineralization. Assimilation of continental crust also led to the formation of sulphide magmas that were tectonically injected high into the crust, leading to the formation of pipe-like breccia-hosted Ni–(Cu) ore bodies. All these processes took probably place as a consequence of oblique ridge– and/or continent–continent collision.     

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.     

吉尔吉斯斯坦中天山地质特征及研究进展

文章通过对近年来有关吉尔吉斯中天山研究进展的梳理,结合在吉尔吉斯斯坦的实地考察,系统论述了中天山基础地质情况,并简述与岩浆活动有关的成矿作用。吉尔吉斯斯坦境内的天山由"尼古拉耶夫线"和阿特巴什—伊内尔切克断裂划分为北、中、南3部分。中天山两侧的缝合带限定了早古生代古吉尔吉斯洋和晚古生代南天山洋的发展和消亡过程。组成中天山的不同块体大多具有古元古界的基底,古生代总体处于大陆坡-边缘海沉积环境。晚古生代产出与俯冲相关的岩浆作用和后碰撞岩浆作用,前者与斑岩型铜矿、接触交代型铜-金矿相关,后者与造山型金矿相关。     

祁连山新元古代——早古生代火山作用与铁-铜多金属成矿

祁连山造山带新元古代—早古生代是板块构造演化与成矿的最重要时段,铁、铜多金属矿产资源丰富,成矿作用与新元古代—早古生代火山作用密切相关。根据矿床产出构造位置,将祁连山铁、铜多金属矿床分为4类:大陆裂谷型铁(铜)矿床、岛弧-岛弧裂谷型铜多金属矿床、陆缘裂谷型铜多金属矿床、扩张脊型铜矿床。镜铁山铁(铜)型矿床是新元古代大陆裂谷火山作用过程中热水沉积作用的产物;东沟铜矿为晚寒武世大洋扩张脊火山作用的产物;白银矿田铜多属矿床是奥陶纪与岛弧-岛弧裂谷火山作用的产物;石居里铜矿是晚奥陶纪弧后扩张脊有关火山作用的产物;红沟铜矿则是晚奥陶世陆缘裂谷火山作用的产物。     

秦岭山阳-柞水矿集区150~140Ma斑岩-矽卡岩型CuMoFe(Au)矿床成矿作用研究

秦岭造山带内的山阳-柞水古生代弧前盆地中出露有池沟、小河口、冷水沟、园子街、下官坊及双元沟等CuMo、CuFe(Au)矿床,与这些矿床具有成因联系的岩体为形成于150~140Ma的高钾钙碱性和钾玄岩系列花岗岩,为华北和扬子大陆碰撞后伸展阶段壳、幔混合岩浆的产物。矿化主要发生在岩体与泥盆、石炭纪地层中碳酸盐岩的接触带附近,主要类型为矽卡岩型,少量为斑岩型,部分矿床具有统一的矽卡岩-斑岩型成矿系统,矿化组合主要为CuMo、CuFe(Au)和Cu矿化。外接触带主要发育有矽卡岩和角岩化蚀变,内接触带主要为岩体内部的硅化、钾化、绢云母化、绿泥石化及粘土化,内矽卡岩不发育。矽卡岩矿物主要有石榴石、透辉石、绿帘石、透闪石,阳起石等,其中石榴子石主要为钙铁榴石和钙铝榴石,透辉石是辉石的主体,早期形成的石榴石和透辉石等无水矿物组合常被后期的绿帘石、透闪石和阳起石等含水矿物及石英、方解石等所交代。金属矿物比较简单,最主要的含铜矿物为黄铜矿和斑铜矿,铁矿化主要为磁铁矿和镜铁矿。尽管这些矿床以矽卡岩型矿化为主,但部分矿床中已发现有斑岩型矿化和蚀变特征,这可能暗示了该区可能具有统一的矽卡岩-斑岩型成矿系统,进而表明山阳-柞水矿集区深部具有寻找斑岩型矿床的巨大潜力。