Origin of the Newly Discovered Zhunuo Porphyry Cu-Mo-Au Deposit in the Western Part of the Gangdese Porphyry Copper Belt in the Southern Tibetan Plateau,SW China

The newly discovered Zhunuo porphyry Cu-Mo-Au deposit is located in the western part of the Gangdese porphyry copper belt in southern Tibet, SW China. The granitoid plutons in the Zhunuo region are composed of quartz diorite porphyry, diorite porphyry, granodiorite porphyry, biotite monzogranite and quartz porphyry. The quartz diorite porphyry yielded zircon U-Pb ages of 51.9±0.7 Ma（Eocene） using LA-ICP-MS, whereas the diorite porphyry, granodiorite porphyry, biotite monzogranite and quartz porphyry yielded ages ranging from 16.2±0.2 to 14.0±0.2 Ma（Miocene）. CuMo-Au mineralization is mainly hosted in the Miocene granodiorite porphyry. Samples from all granitoid plutons have geochemical compositions consistent with high-K calc-alkaline series magmatism. The samples display highly fractionated light rare-earth element（REE） distributions and heavy REE distributions with weakly negative Eu anomalies on chondrite-normalized REE patterns. The trace element distributions exhibit positive anomalies for large-ion lithophile elements（Rb, K, U, Th and Pb） and negative anomalies for high-field-strength elements（Nb and Ti） relative to primitive mantlenormalized values. The Eocene quartz diorite porphyry yielded εNd（t） values ranging from-3.6 to-5.2,（-（87）Sr/-（86）Sr）i values in the range 0.7046–0.7063 and initial radiogenic Pb isotopic compositions with ranges of 18.599–18.657 -（206）Pb/-（204）Pb, 15.642–15.673 -（207）Pb/-（204）Pb and 38.956–39.199 -（208）Pb/-（204）Pb. In contrast, the Miocene granitoid plutons yielded ε（Nd）（t） values ranging from-6.1 to-7.3 and（87Sr/86Sr）i values in the range 0.7071–0.7078 with similar Pb isotopic compositions to the Eocene quart diorite. The Sr-Nd-Pb isotopic compositions of the rocks are consistent with formation from magma containing a component of remelted ancient crust. Zircon grains from the Eocene quartz diorite have ε（Hf）（t） values ranging from-5.2 to ＋0.9 and two-stage Hf model ages ranging from 1.07 to 1.46 Ga, while zircon grains from the Miocene granitoid plutons have ε（Hf）（t） values from-9.9 to ＋4.2 and two-stage Hf model ages ranging from 1.05–1.73 Ga, indicating that the ancient crustal component likely derives from Paleo- to Mesoproterozoic basement. This source is distinct from that of most porphyry Cu-Mo-Au deposits in the eastern part of the Gangdese porphyry copper belt, which likely originated from juvenile crust. We therefore consider melting of ancient crustal basement to have contributed significantly to the formation Miocene porphyry Cu-Mo-Au deposits in the western part of the Gangdese porphyry copper belt.

Geochronological Constraints on the Haftcheshmeh Porphyry Cu-Mo-Au Ore Deposit, Central Qaradagh Batholith, Arasbaran Metallogenic Belt, Northwest Iran

The Haftcheshmeh porphyry Cu-Mo-Au deposit in the Arasbaran metallogenic belt （AMB） of NW Iran contains more than 185 Mt of ore, with a grade ranging from 0.3% to 0.4%. It is hosted within a porphyritic diorite to granodiorite intruded into an older gabbro - diorite intrusion. 40Ar/39Ar analyses of primary magmatic hornblende from the granodiorite porphyry and gabbro - diorite show plateau ages of 26.41 ± 0.59 Ma, with an inverse isochron age of 25.9 ± 1.0 Ma and a plateau age of 27.47 ± 0.17 Ma, with an inverse isochron age of 27.48 ± 0.35 Ma for these two rock types, respectively. Comparing these new age data with those from the nearby Sungun （20.69 ± 0.35 Ma） and Kighal porphyry deposits defines a northwest-southeast Cu-Mo-Au mineralization zone extending for 20 km over the time span of-27 to 20 Ma. Geochemically, Haftcheshmeh rocks are calc-alkaline with high potassium affinities with tectonic setting in relation to volcanic arc setting. Large ion lithophile elements （LILE） such as Th, U and K show enrichment on a primitive mantle normalized diagram （specially Pb）, and are depleted in high field strength elements （HFSE） such as Ti and Nb, pointing to a mantle magma source contamination with crustal materials by subducted oceanic crust.

富碱斑岩成因与Cu—Mo—Au矿床成矿作用——以金沙江—红河富碱斑岩成矿带为例

富碱斑岩因其产出构造环境独特、岩石类型特殊,并常与铜多金属矿床密切相关,而受到广泛关注。笔者等在回顾相关研究进展的基础上,通过岩石成因和构造环境、岩浆性质和岩浆源区等方面的综合研究,探讨了金沙江—红河富碱斑岩成矿带富碱岩浆成矿作用及成岩成矿机制。系统的矿床地质、年代学、地球化学等研究表明:①金沙江—红河富碱斑岩成矿带内成岩成矿作用集中于43~32 Ma,成矿富碱斑岩系始新世—渐新世I型钾玄质花岗斑岩,是印—亚大陆后碰撞背景下大陆内部大型走滑和伸展等动力过程诱导的岩浆活动产物,金沙江和哀牢山—红河断裂的差异走滑运动可能控制了成矿带差异性成岩成矿事件;②成矿带北段以Cu—Mo为主的成矿富碱斑岩源自新元古代下地壳的部分熔融,且源区有富集地幔和亏损地幔物质的加入,而南段以Cu—Au或Cu(—Mo—Au)为主的成矿富碱斑岩源自具有不同程度富集地幔物质加入的新生下地壳的部分熔融;③带内以Cu为主的斑岩—矽卡岩型矿床中成矿富碱斑岩的氧逸度(ΔFMQ)与矿床规模具有正相关性。除受氧逸度控制外,源区高K2O含量有利于斑岩—矽卡岩型Au矿床的形成。该研究对金沙江—红河富碱斑岩成矿带乃至同类矿床研究和找矿勘查具有理论和实际意义。

Geology,Geochemistry and Zircon U-Pb Geochronology of Porphyries in the Dabate Mo-Cu Deposit,Western Tianshan,China:Petrogenesis and Tectonic Implications

The Dabate Mo-Cu deposit is a medium-sized porphyry-type deposit in the Sailimu Lake region, western Tianshan, China. We present the geology, geochemistry and zircon U-Pb geochronology of granite porphyries from the Dabate district with the intent to constrain their tectonic setting and petrogenesis. Porphyries in the Dabate district include granite porphyry I（gray white color with large phenocrysts）, granite porphyry II（pink color with small phenocrysts） and quartz porphyry. Granite porphyry II is the Cu and Mo ore-bearing granitoid in the Dabate deposit. LA-ICPMS zircon U-Pb analyses indicate that granite porphyry II was emplaced at 284.2±1.8 Ma. Granite porphyry I and II have similar geochemical features and are both highly fractionated granites：（1） They have high SiO2 content（70.93–80.18 wt% and 72.14–72.64 wt%, respectively）, total alkali（7.58–8.95 wt% and 9.35–9.68 wt%, respectively）, mafic index（0.95–0.98 and 0.93–0.94, respectively） and felsic index（0.79–0.94 and 0.89–0.91, respectively）;（2） They are characterized by pronounced negative Eu anomaly, ＂seagullstyle＂ chondrite-normalized REE patterns and ＂tetrad effect＂ of REE;（3） They are rich in Rb, K, Th, Ta, Zr, Hf, Y and REE, but depleted in Sr, P, Ti and Nb. The magma of granite porphyries in Dabate can be interpreted to have been generated by partial melting of the upper crust due to mantle-derived magma underplating in a post-collisional extensional setting.

Geochronology and Geochemistry of Metallogenetic Porphyry Bodies from the Nongping Au-Cu Deposit in the Eastern Yanbian Area, NE China: Implications for Metallogenic Environment

The metallogenetic porphyry bodies in the Nongping Au-Cu deposit, in the eastern Yanbian area, mainly include porphyritic granodiorite and biotite granodiorite porphyry. They are featured with high silicon and enrichment in sodium, and classified into sodic rocks of low-K tholeiitic basalt series. Except slightly low Sr content, the rock basically has the geochemical characteristics of the adakite： relatively high A12O3 content, relatively low MgO content, depletion in Y and Yb; relative enrichment in large ion lithophile elements （LILEs） and light rare-earth elements （LREEs）, relatively low content of high field strength elements （HFSEs）; positive Eu anomaly or weak negative Eu anomaly. In situ zircon dating technology LA-MC-ICP-MS was used to conduct single-grain zircon dating of biotite granodiorite porphyry, and the results show that the age of metallogenetic porphyry body is 100.04±0.88 Ma, indicating that the porphyry bodies were emplaced in the late Cretaceous period. According to the regional tectonic setting and the comparison with the same kind of deposits, we think that the metallogenetic porphyry bodies in the Nongping Au-Cu deposit have a close genetic connection with the subduction of the Pacific plate in the late Yanshanian period. The adakitic magma generated from partial melting of the subducting plate has high formation temperature, high oxygen fugacity, and volatile constituents＇ enrichment, so it is helpful for enrichment of metallogenetic elements and plays an important role in the formation of porphyry Au-Cu deposits in this region.

^(40)Ar/^(39)Ar Dating of the Shaxi Porphyry Cu-Au Deposit in the Southern Tan-Lu Fault Zone, Anhui Province

Four samples of plagioclase and biotite from the Shaxi porphyry in the lower part of the Yangtze metallogenic belt were analyzed for age determination with the ^40 Ar/^39Ar method. The results yield reproducible ages of 126 Ma to 135 Ma with a high level of confidence according to the agreement between isochron and plateau ages. The four Ar-Ar ages are relatively consistent within the analytical error. These ages are also consistent with, but more precise than, previous K-Ar and Rb-Sr ages and thus provide better constraints on the time of porphyry formation and associated Cu-Au mineralization along the middle to lower part of the Yangtze metallogenic belt. The ages of 126 to 135 Ma are interpreted to represent the intrusive time of the Shaxi porphyry, so that the Cu-Au mineralization should have occurred later due to the post-magmatic hydrothermal event.

Geochemical Characteristics and Significance of Major Elements, Trace Elements and REE in Mineralized Altered Rocks of Large-Scale Tsagaan Suvarga Cu-Mo Porphyry Deposit in Mongolia

The alteration types of the large-scale Tsagaan Suvarga Cu-Mo porphyry deposit mostly comprise stockwork silicification, argillization, quartz-sericite alteration, K-silicate alteration, and propylitization. The mineralized and altered zones from hydrothermal metallogenic center to the outside successively are Cu-bearing stockwork silicification zone, Cu-beating argillized zone, Cu-Mo-bearing quartz-sericite alteration zone, Cu-Mo-bearing K-silicate alteration zone, and pro- pylitization zone. The K-silicate alteration occurred in the early phase, quartz-sericite alteration in the medium phase, and argillization and carbonatization （calcite） in the later phase. Ore-bearing-altered rocks are significantly controlled by the structure and fissure zones of different scales, and NE- and NW-trending fissure zones could probably be the migration pathways of the porphyry hydrothermal system. Results in this study indicated that the less the concentrations of REE, LREE, and HREE and the more the extensive fractionation between LREE and HREE, the closer it is to the center circulatory hydrothermal ore-forming and the more extensive silicification. The exponential relationship between the fractionation of LREE and HREE and the intensity of silicification and K-silicate alteration was found in the Cu-Mo deposit studied. The negative Eu anomaly, normal Eu, positive Eu anomaly and obviously positive Eu anomaly are coincident with the enhancement of Na2O and K2O concentrations gradually, which indicated that Eu anomaly would be significantly controlled by the alkaline metasomatism of the circulatory hydrothermal ore-forming system. Therefore, such characteristics as the positive Eu anomaly, the obvious fractionation between LREE and HREE and their related special alteration lithofacies are suggested to be metallogenic prognostic and exploration indications for Tsagaan Suvarga-style porphyry Cu-Mo deposits in Mongolia and China.

Geology,Geochemistry,and Genesis of the Tongcun Reduced Porphyry Mo(Cu) Deposit,NW Zhejiang Province,China

The Tongcun Mo（Cu） deposit in Kaihua city of Zhejiang Province,eastern China,occurs in and adjacent to the Songjiazhuang granodiorite porphyry and is a medium-sized and important porphyry type ore deposit.Two irregular Mo（Cu） orebodies consist of various types of hydrothermal veinlets.Intensive hydrothermal alteration contains skarnization,chloritization,carbonatization,silicification and sericitization.Based on mineral assemblages and crosscutting relationships,the oreforming processes are divided into five stages,i.e.,the early stage of garnet ＋ epidote ± chlorite associated with skarnization and K-feldspar ＋ quartz ± molybdenite veins associated with potassicsilicic alteration,the quartz-sulfides stage of quartz ＋ molybdenite ± chalcopyrite ± pyrite veins,the carbonatization stage of calcite veinlets or stockworks,the sericite ＋ chalcopyrite ± pyrite stage,and the late calcite ＋ quartz stage.Only the quartz-bearing samples in the early stage and in the quartzsulfides stage are suitable for fluid inclusions（FIs） study.Four types of FIs were observed,including1） CO2-CH4 single phase FIs,2） CO2-bearing two- or three-phase FIs,3） Aqueous two-phase FIs,and4） Aqueous single phase FIs.FIs of the early stages are predominantly CO2- and CH4-rich FIs of the CO2-CH4-H2O-NaCl system,whereas minerals in the quartz-sulfides stage contain CO2-rich FIs of the CO2-H2O-NaCl system and liquid-rich FIs of the H2O-NaCl system.For the CO2-CH4 single phase FIs of the early mineralization stage,the homogenization temperatures of the CO2 phase range from 15.4 ℃ to 25.3 ℃（to liquid）,and the fluid density varies from 0.7 g/cm^3 to 0.8 g/cm^3;for two- or three-phase FIs of the CO2-CH4-H2O-NaCl system,the homogenization temperatures,salinities and densities range from 312℃ to 412℃,7.7 wt%NaCl eqv.to 10.9 wt%NaCl eqv.,and 0.9 g/cm^3 to 1.0 g/cm^3,respectively.For CO2-H2O-NaCI two- or threephase FIs of the quartz-sulfides stage,the homogenization temperatures and salinities range from255℃ to 418℃,4.8 wt%NaCl eqv.to 12.4 wt%NaCl eqv.,respectively;for H2O-NaCl two-phase FIs,the homogenization temperatures range from 230 ℃ to 368 ℃,salinities from 11.7 wt%NaCl eqv.to16.9 wt%NaCl eqv.,and densities from 0.7 g/cm^3 to 1.0 g/cm^3.Microthermometric measurements and Laser Raman spectroscopy analyses indicate that CO2 and CH4 contents and reducibility（indicated by the presence of CH4） of the fluid inclusions trapped in quartz-sulfides stage minerals are lower than those in the early stage.Twelve molybdenite separates yield a Re-Os isochron age of 163 ± 2.4 Ma,which is consistent with the emplacement age of the Tongcun,Songjiazhuang,Dayutang and Huangbaikeng granodiorite porphyries.The 〈S18OSMow values of fluids calculated from quartz of the quartz-sulfides stage range from 5.6‰ to 8.6‰,and the 〈JDSMOw values of fluid inclusions in quartz of this stage range from-71.8‰ to-88.9‰,indicating a primary magmatic fluid source.〈534SV-cdt values of sulfides range from＋1.6‰ to ＋3.8‰,which indicate that the sulfur in the ores was sourced from magmatic origins.Phase separation is inferred to have occurred from the early stage to the quartz-sulfides stage and resulted in ore mineral precipitation.The characteristics of alteration and mineralization,fluid inclusion,sulfur and hydrogen-oxygen isotope data,and molybdenite Re-Os ages all suggest that the Tongcun Mo（Cu） deposit is likely to be a reduced porphyry Mo（Cu） deposit associated with the granodiorite porphyry in the Tongcun area.

Late Jurassic adakitic ore-bearing granodiorite porphyry intrusions in the Xiaokele porphyry Cu(–Mo)deposit,Northeast China:implications for petrogenesis and tectonic setting

The Xiaokele Cu(–Mo)deposit is a recently discovered porphyry deposit in the northern Great Xing’an Range(GXR)of northeast China.The ore bodies in this deposit are mainly hosted within granodiorite porphyry intrusions.Potassic,phyllic,and propylitic alteration zones develop from center to edge.In this paper,we present zircon LA–ICP–MS U–Pb ages,zircon Hf isotopic compositions,and whole-rock geochemistry of the ore-bearing granodiorite porphyries from the Xiaokele Cu(–Mo)deposit.Zircon U–Pb dating suggests that the Xiaokele granodiorite porphyries were emplaced at 148.8±1.1 Ma(weighted-mean age;n=14).The Xiaokele granodiorite porphyries display high SiO2,Al2O3,Sr,and Sr/Y,low K2O/Na2O,MgO,Yb,and Y,belonging to high-SiO2 adakites produced by partial melting of the subducted oceanic slab.Marine sediments were involved in the magma source of the Xiaokele granodiorite porphyries,as indicated by enriched Sr–Nd isotopic compositions(eNd(-t)=-1.17–-0.27),low positive zircon eHf(t)values(0.4–2.2),and high Th contents(4.06–5.20).The adakitic magma subsequently interacted with the mantle peridotites during ascent through the mantle wedge.The Xiaokele granodiorite porphyries were derived from slab melting during the southward subduction of the Mongol–Okhotsk Ocean.

Temporal Periods and Duration of Formation of Cu-Mo Porphyry Deposits(Siberia and Mongolia)

Copper-molybdenum porphyry deposits of Russia (Sib eria) and Mongolia were formed within the interaction zone of the Siberian conti nent with Paleo-As ian (Pt 2-Pz 2), Paleo-Tethys (Pz 3) and Mongolo-Okhotsk (Pz 2-Mz) ocean s. Ore-beari ng magmatic (porphyry) complexes, which are closely associated in time and space with Cu-Mo mineralization, are represented by small stocks (up to 1 km 2) and numerous dikes of basic to acid composition. Rb-Sr and 40 Ar/ 39 Ar dating fix three temporal periods of activity o f ore-form ing process within Siberia and Mongolia which resulted in a wide appearance of C u-Mo porphyry mineralization. A series of large-scale deposits was formed at t ha t time: 1) Early Devonian (Mo-porphyry Sora deposit, Kuznetsk-Alatau; Cu-Mo- porp hyry Aksug deposit, Tuva), 2) Triassic (Cu-Mo-porphyry Erdenetuin-Obo, Northe rn Mongolia), 3) Late Jurassic (Cu-Mo-porphyry Zhireken and Shakhtama deposits, Eastern Transbaikalia). The deposits of small size were formed between these periods (Cu-Mo-porphyry Tsagan-Suburga, Cu-porphyry Kharmagtai deposits in Southern Mongolia, etc.). C u- Mo-porphyry deposits within Siberia and Mongolia as a whole were formed with a regular periodicity at 20～30 Ma intervals. Large copper-molybdenum porphyry deposits are characterized by the manifestat ion of multiple ore-forming processes which are related to separate pulses of o r e-bearing magmatism. Three pulses of ore-bearing magmatism are established at th e large scale Erdenetuin-Obo deposit: I-250～240 Ma, II-225～220 Ma, III-225 ～195 M a. Every magmatic pulse is accompanied by ore mineralization. The Erdenet ore di strict includes three deposits of different sizes. Large-scale deposits are in principle multi-stage formations. They are charac terized by the repeated manifestation of ore-bearing magmatism and the ore-for mi ng processes during the long period of geological time within a relatively limit ed space.

Geological, Alteration and Mineralization Characteristics of Ali Javad Porphyry Cu-Au Deposit, Arasbaran Zone, NW Iran

Ali Javad porphyry Cu-Au deposit is located 20 Km north of Ahar city in Arasbaran metallogenic zone which is considered as a part of Alp-Himalayan mineralization belt. Magmatism in this area began in Late Cretaceous, followed by extensive magmatism in Cenozoic and Quaternary periods. Porphyry type mineralization developed in Ali Javad quartz monzonitic porphyry stock and Eocene pyroclastic and volcanic country rocks. Ali Javad porphyry intrusion has shoshonitic nature and shows characteristics of volcanic arc granitoids that it is have been emplaced in a post-collision tectonic setting. Alteration zones at the deposit demonstrated zoning which is comparable with Lowel-Guilbert model proposed for quartz-monzonite type porphyry copper deposits. Phyllic, argillic, silicic and propylitic alteration zones were observed at the surface while potassic alteration zone could be observed at depth in drill core samples. Mineralization was recognized both as supergene and hypogene, the latter was as veins, veinlets and disseminations. Dominant hypogene minerals were chalcopyrite, bornite, molybdenite, pyrite and magnetite while chalcocite, covellite and limonite were dominant supergene minerals. Four mineralization zones were observed in the deposit as leached, transitional, supergene and hypogene zones. Average grades were 0.75% for copper and 1.86 ppm for gold with 81.5 Mt proved reserve for copper and 37.8 Mt for gold.

云南金平铜厂斑岩Cu(Mo-Au)矿床含矿石英正长斑岩地球化学特征及成因机制探讨

铜厂斑岩型Cu(Mo-Au)矿床位于金沙江-红河富碱侵入岩带的南段,其含矿的石英正长斑岩侵入体属金沙江-红河富碱侵入岩带的重要组成部分。对铜厂石英正长斑岩开展详细的地球化学研究结果表明,其具有高碱、富钾及准铝质-弱过铝质等特征,属钾玄岩系列岩石;微量和稀土元素分析表明,铜厂石英正长斑岩明显富集Rb、Ba、Th、U、K、La和Sr等大离子亲石元素,相对亏损Nb、Ta和Ti等高场强元素,具有明显的"TNT"负异常,稀土总量高,明显富集轻稀土而亏损重稀土,轻重稀土分馏显著;(87Sr/86Sr)i为0.707097～0.707138,εNd(t)为-7.1～-6.8,在Sr-Nd同位素相关图上,与EMII来源岩石相似。对比金沙江-红河富碱侵入岩带北段的玉龙含矿的二长花岗斑岩和中段的马厂箐含矿的花岗斑岩的地球化学特征,铜厂含矿斑岩具有高的全碱、微量元素和稀土元素含量、高的(87Sr/86Sr)i值和低的εNd(t)值、不具埃达克质岩属性等特征。综合研究表明,铜厂含矿的石英正长斑岩在成因类型上属于A型花岗岩类,形成于～35Ma的晚碰撞走滑环境且直接起源于EMII地幔的部分熔融。铜厂与玉龙及马厂箐斑岩型Cu(Mo-Au)矿床含矿斑岩地球化学特征和成矿规模存在差异,与源区物质的部分熔融程度和地壳物质的混染程度密切相关。

青海东昆仑托克妥Cu-Au(Mo)矿床含矿斑岩成因:锆石U-Pb年代学和地球化学约束

东昆仑造山带是我国斑岩型矿床的重要成矿区之一。对东昆仑托克妥Cu-Au（Mo）矿床含矿斑岩利用原位LA-ICP-MS锆石U-Pb测年和地球化学分析方法,探讨该地区岩体成因以及岩浆作用与成矿作用的深部约束机制。东昆仑托克妥Cu-Au（Mo）矿床含矿二长花岗斑岩年龄为（232.49±0.93）Ma,花岗闪长斑岩年龄为（232.6±1.2）Ma,处于东昆仑碰撞造山阶段。含矿斑岩为二长花岗斑岩和花岗闪长斑岩,具有富硅（w（SiO2）=63.11%~71.78%）、高钾（w（K2O）=2.62%~3.61%）、高镁（w（MgO）=0.52%~1.89%）、低钛（w（TiO2）=0.26%~0.53%）和偏铝质（A/CNK=1.05~1.10）的特征,富集大离子亲石元素Rb、Ba、K和Pb等,亏损高场强元素Nb、Ta、Ti和P,属于高钾钙碱性系列的I型花岗岩。研究认为,托克妥Cu-Au（Mo）矿床形成于大陆动力体制下的伸展背景,与阿尼玛卿洋壳岩石圈北向俯冲碰撞有关的俯冲板片断离有关。

鄂东南地区Cu-Au-Mo-(W)矿床的成矿时代及其成矿地球动力学背景探讨:辉钼矿Re-Os同位素年龄

鄂东南地区Cu-Au-Mo-(W)矿床是长江中下游地区金属成矿带的重要组成部分。本文利用Re-Os同位素定年方法对该地区5个典型矿床(丰山洞铜钼金银多金属矿床、阮家湾钨铜钼矿床、千家湾铜金矿床、铜绿山铜铁金钼多金属矿床和铜山口铜钼矿床)进行了成矿时代的研究,获得其辉钼矿Re-Os同位素年龄分别为(144.0±2.1)Ma、(143.6±1.7)Ma、(137.7±1.7)Ma、(137.8±1.7)^(138.1±1.8)Ma和(143.5±1.7)^(142.3±1.8)Ma,代表各矿床的成矿时代。研究结果表明,鄂东南矿集区内的Cu-Au-Mo-(W)矿床与铜陵、安庆、九瑞矿集区内的矿床几乎是同时形成的,成矿时代可能主要集中于(140±5)Ma,相当于晚侏罗世-早白垩世。在综合已有的岩石学、地球化学和地球物理学资料的基础上,笔者认为,这一成矿事件的深部动力学过程可能是处于中国东部南北向印支期构造域向北东向古太平洋构造域大转折的背景下,与软流圈上涌和玄武质岩浆底侵而导致壳幔同熔有关。

冈底斯东段南部第三纪夕卡岩型Cu-Au±Mo矿床地质特征、矿物组合及其深部找矿意义

在冈底斯Cu—Au成矿带东南部的山南地区分布有克鲁、劣布、冲木达和陈坝等中到大型Cu—Au±Mo矿床。与含铜夕卡岩有关的侵入岩形成于20～30Ma之间，为高钾钙碱性中酸性浅成岩，形成于印-亚大陆碰撞晚期构造背景。矿化赋存于岩体外接触带下白垩统比马组的碳酸盐岩和其他钙质岩石内。主要矿化类型为夕卡岩型、热液脉型和斑岩型，构成完整的斑岩-夕卡岩、热液脉状铜-金（钼）多金属成矿体系，矿化组合主要为Cu—Mo、Cu—Au和Cu。外接触带的蚀变以夕卡岩化、角岩化为主，而内接触带上主要为岩体的绢云母化、硅化、绿泥石化等，内夕卡岩不发育。夕卡岩化可分为早期夕卡岩和晚期含水硅酸盐阶段。早期夕卡岩主要为钙铁、钙铝石榴石夕卡岩，含少量透辉石、磁铁矿等，晚期的含水硅酸盐阶段主要是绿泥石-绿帘石、方解石、石英交代石榴石夕卡岩，并伴随含铜硫化物的沉淀，为本区夕卡岩型铜矿形成的主要阶段。含铜硫化物以富含斑铜矿为特征，Au、Ag主要赋存于斑铜矿、硫铋铜矿及黄铜矿等矿物中。山南地区的夕卡岩型铜-金矿床均为浅部夕卡岩，在某些夕卡岩型铜金矿床中显示了斑岩型矿化的存在，可能暗示该区的夕卡岩型矿化与北带相似，具有统一的斑岩型-夕卡岩型成矿系统。因此本区具有在深部寻找斑岩型金矿的可能性，而且找矿潜力较大。

云南省马厂箐Cu-Mo-Au矿床花岗斑岩成矿地质证据

马厂箐铜钼(金)矿床是金沙江-哀牢山构造带内与喜马拉雅期富碱侵入岩有关的典型的斑岩型矿床之一,其铜钼(金)矿(化)体在空间上与花岗斑岩紧密相伴,且主要位于花岗斑岩脉(体)的上、下盘。花岗斑岩内发育有具斑岩型矿化特征的细网脉状、浸染状矿化,其上盘的(似)斑状花岗岩和下盘的向阳组围岩内均发育有脉状、细脉状矿化,且总体表现出向接触带附近花岗斑岩倾斜的特点。(似)斑状花岗岩中的矿化脉体北倾,围岩地层中的矿化脉体南倾。花岗斑岩脉(体)上、下盘的矿化脉体表现出越靠近接触带(花岗斑岩脉体)蚀变矿化越强、矿化体的规模越大、出现的频率越高,而远离接触带(花岗斑岩脉体)则蚀变矿化越弱、矿化体的规模越小、出现的频率越低。铜钼(金)的成矿时代与花岗斑岩的成岩时代较为一致,其同位素年龄集中在34～36Ma。花岗斑岩含有源于富集地幔的镁铁质暗色微粒包体,并发育浸染状的黄铁矿化、磁铁矿化。暗色微粒包体及其寄主岩(花岗斑岩)具有同源性,且与壳-幔岩混合作用及成分分异有关,具有提供成矿物质、成矿流体的基础。因此,该区的铜钼(金)成矿与花岗斑岩有关。

冈底斯东段山南地区第三纪矽卡岩-斑岩Cu-Mo-W(Au)多金属矿床勘查模型及深部找矿意义

冈底斯东段南缘的山南地区分布有努日、明则、克鲁、冲木达和陈坝等中到大型Cu-Mo-W(±Au)矿床,与含矿矽卡岩有关的侵入岩形成于20～30Ma之间,为高钾钙碱性中酸性岩,形成于碰撞晚期构造背景。矿化赋存于下白垩统比马组的碳酸盐岩和其它钙质岩石与岩体的外接触带内及斑岩体内,主要矿化类型为矽卡岩型、斑岩型和热液脉型,构成完整的斑岩-矽卡岩、脉状铜-钼-钨±金多金属成矿体系,矿化组合主要为Cu-W-Mo、Mo、Cu-Au和Cu矿化。外接触带的蚀变以矽卡岩化、角岩化为主,而内接触带上主要为岩体的绢云母化、硅化、绿泥石化等,内矽卡岩不发育。山南地区的矽卡岩型铜-钼-钨(金)矿床均赋存于浅部矽卡岩中,在明则矿区矽卡岩型矿化之下发现了斑岩型钼矿化的存在,暗示该区的矽卡岩型矿化可能与冈底斯中带相似,具有统一的斑岩型-矽卡岩型成矿系统,由此建立了该地区的成矿模式,指出了找矿方向。

云南省马厂箐Cu-Mo-Au多金属矿集区成矿系统

马厂箐地区是滇西成矿带内一个典型的与喜马拉雅期富碱侵入岩有关的斑岩型铜-钼-金多金属矿集区,发育有斑岩型钼铜、接触交代型铜钼(金)和热液脉型金银铅锌等多种类型矿化。其矿化和蚀变类型及成矿元素组合,在空间上具有明显的以岩体为中心的分带性;岩浆活动与铜钼金成矿作用具有同时性。这3种矿化类型的形成受控于马厂箐斑岩岩浆系统,该岩浆系统提供了成矿的物质、流体和动力。文章在分析成矿证据的基础上,通过对成矿系统结构的剖析,认为正是马厂箐岩体所提供的热动力条件促使从岩浆体中分异出来的成矿流体由岩体向外运移,随着岩体内构造裂隙、接触带构造以及围岩中破碎带等成矿物理化学条件的改变,在不同的边界条件下发生了不同性质的成矿作用,形成了不同的蚀变和矿化类型及成矿元素组合,总体显示出,随着热液成矿作用的进行,矿化由斑岩体向接触带和围岩推进,成矿由高温向低温的演化趋势。马厂箐铜-钼-金多金属矿集区成矿系统的建立,将对滇西成矿带内其他矿集区的成矿理论研究和找矿勘查实践具有借鉴和指导意义。

岛弧-陆缘弧环境斑岩Cu±Mo±Au矿床勘查：地质标志应用

斑岩Cu±Mo±Au矿床(以下简称斑岩铜矿)因其巨大的经济价值而倍受勘查界重视。文章基于国内外,尤其是国外斑岩型铜-金(多金属)矿床最新勘查和研究进展,系统总结了岛弧-陆缘弧环境斑岩铜矿勘查地质标志及其找矿应用实践,包括:①大地构造环境分析,宏观上确定斑岩铜矿勘查选区。弧环境斑岩铜矿勘查应重点部署在与大洋俯冲有关的岛弧、陆缘弧等增生造山火山岩浆弧环境;②区域及矿田构造解析,不断缩小找矿靶区。与弧/造山带形成演化应力有关的超壳深大断裂系统控制矿带空间展布,断裂、褶皱、火山(地层)以及岩浆侵入等矿田构造体系控制矿床(体)分布;③岩石化学成分、矿物组成以及岩石结构等含矿斑岩体特征及成矿专属性判断,确定斑岩铜矿找矿目标体;④蚀变分带对成矿斑岩体和富矿区(矿体)指向。从深部到浅部、从核心到外围,钙碱性斑岩铜矿蚀变类型分别为钠-钙(硅酸盐)化、钾(硅酸盐)化、青磐岩化(细化为高温阳起石内带、中温绿帘石中带和低温绿泥石外带)、绢英岩化和泥化;碱性斑岩铜矿蚀变组合为钙-钾化、钾化、内青磐岩化带(阳起石-赤铁矿-绿帘石带)、外青磐岩化带(钠长石-阳起石带)和远青磐岩化带(绿泥石带);⑤岩帽特征对深部斑岩体和潜在富矿中心指向。钙碱性斑岩铜矿形成的岩帽由多孔状(晶洞发育)的硅质核,外侧高级泥化带(石英-明矾石带)和泥化带(高岭石±迪开石带)组成;碱性斑岩铜矿形成以钠长石化为核心、外围(上部)为钠长石-绢云母带的碱性岩帽;⑥脉体和角砾岩(筒)时空分布及其对勘查靶区(位)指向。A、B、D型脉以及C、M型脉等脉体类型、密度以及石英中残余硫化物详细填图是矿区勘查靶区定位和矿石品位预测有效指标之一;3大类、7种主要类型角砾岩在斑岩铜矿中时、空间分布可作为找矿评价的参考标志;⑦矿化元素、金属矿物和矿化类型分带及其找矿相互指示。从矿化中心到外围(浅部),出现[Mo-Cu→Cu-Mo(Au)→Cu-S(Au)]→[Pb-Zn(Au)]→Au-Ag(Mn)→Au(As,Sb)的元素分带,斑铜矿→黄铜矿→黄铁矿硫化物晕分带;斑岩型、矽卡岩型、次浅成环境脉型、高硫型和中硫型浅成低温热液型等矿化类型在斑岩铜矿成矿系统中分布具有显著的规律性,是勘查评价最重要的地质标志;⑧矿体剥蚀与保存,是评价矿田(体)找矿潜力重要因素。

鸡笼山Cu-Au-Mo多金属矿已采中段漏采矿体勘探思路探讨

鸡笼山Cu-Au-Mo多金属矿床是鄂东南矿集区丰山矿田中一个典型的夕卡岩型、斑岩型铜金钼多金属矿,矿体主要赋存于燕山期中酸性侵入岩与大冶组碳酸盐岩建造的接触带及附近,受地层、构造、岩浆岩的联合控制。文章讨论了矿山已采中段中构造错失矿体、边部矿体及盲矿体等漏采矿体的勘探思路、方法及实践,运用成矿规律分析-坑道地质调查-采样分析-重点靶区圈定-坑内钻探验证的工作程序得以实施。