The Naruo porphyry copper-gold deposit(hereinafter referred to as the Naruo deposit) in Tibet is a potentially ultra-large, typical gold-rich porphyry copper deposit, which was recently discovered in the Bangongco-Nuj...The Naruo porphyry copper-gold deposit(hereinafter referred to as the Naruo deposit) in Tibet is a potentially ultra-large, typical gold-rich porphyry copper deposit, which was recently discovered in the Bangongco-Nujiang metallogenic belt. This study analyzed U-Pb chronology and Hf isotopes of the ore-bearing granodiorite porphyry in the Naruo deposit using the LA-ICPMS dating technique. The results show that the weighted average age is 124.03±0.94Ma(MSWD=1.7, n=20), and 206Pb/238 U isochron age is 126.2±2.7 Ma(MSWD=1.02, n=20), both of which are within the error. The weighted average age represents the crystallization age of the granodiorite porphyry, which indicates that the ore-bearing porphyry in the Naruo deposit area was formed in the Early Cretaceous and further implies that the Neo-tethys Ocean had not been closed before 124 Ma under a typical island-arc subduction environment. The εHf(t) of zircons from the granodiorite porphyry varies from 2.14 to 9.07, with an average of 5.18, and all zircons have εHf(t) values greater than 0; 176Hf/177 Hf ratio is relatively high(0.282725–0.282986). Combined with the zircon age―Hf isotope correlation diagram, the aforementioned data indicate that the source reservoir might be a region that is mixed with depleted mantle and ancient crust, which possibly contains more materials sourced from depleted mantle. Rock-forming ages and ore-forming ages of the Duolong ore concentrate area are 120–124 Ma and 118–119 Ma, respectively, which indicate 124–118 Ma represents the main rockforming and ore-forming stage within the area. The Naruo deposit is located in the north of the Bangongco-Nujiang suture, and it yielded a zircon LA-ICPMS age of 124.03 Ma. This indicates the Bangongco-Nujiang oceanic basin subducted towards the north at about 124 Ma, and the Neo-tethys Ocean had not been closed before the middle Early Cretaceous. It is possible that the crust-mantle mixing formed the series of large and giant porphyry copper-gold deposits in the Bangongco.展开更多
On the basis of the geological and geochemical studies, including chemical analysis of bulk rocks, rare-earth and trace element studies, fluid inclusion, and S and O isotopic analyses, the authors described the geolog...On the basis of the geological and geochemical studies, including chemical analysis of bulk rocks, rare-earth and trace element studies, fluid inclusion, and S and O isotopic analyses, the authors described the geological background of the deposit in detail and presented significant proofs for the conditions of formation of the Shaxi porphyry copper-gold deposit. Compared with other large and supper-large porphyry copper deposits in China and the adjacent Cu-Au mineralized areas, the ore-forming processes and conditions were analyzed; and the possibility of forming large porphyry copper deposits in the Shaxi area was discussed. The present study indicated that the ore-forming fluid and material were mainly of magmatic origin, while meteoric water played a certain role in the ore-forming processes. Interactions between subducting and overriding plates provided a major driving force for the formation of igneous rocks and the deposition of metal elements in East China since Jurassic. Based on the geo- chemical data of the Shaxi intrusive, it is found that the copper (gold) mineralization is closely related to the genesis of adakite-like intrusive in the Shaxi area. This adakite-like intrusive was formed in the subduction environment as a result of the subduction of the West Pacific plate toward the East China continent, where there is a great potentiality to form a large porphyry copper deposit.展开更多
Shaxi porphyry Cu-Au deposit was one of the important discoveries of the exploration in the middle-lower reaches of Yangtze River in China in 1970s. Gold occurrence in the Shaxi porphyry copper-gold deposit (central (...Shaxi porphyry Cu-Au deposit was one of the important discoveries of the exploration in the middle-lower reaches of Yangtze River in China in 1970s. Gold occurrence in the Shaxi porphyry copper-gold deposit (central (Anhui) province, eastern China) was investigated by means of microscope analyses, EPMA and PIXE. Combined with geological and mineralogical methods, the characteristics of occurrence of gold in the large scale sulfide mineralization in this region were fully investigated. The results show that gold distributes in both chalcopyrite and pyrite as submicroscopic inclusions (less than 1 μm) . Au is positively correlated with As, Fe, S, Cu, Zn and Ti. The condition of gold transformation in thermal fluid system controlling deposition of Au in the region is probably the oxidation potential of the red sedimentary rocks of shale and fine grain sandstone which may be crucial as a geochemical barrier to the reducing fluid. This study lays foundation for the further research and exploration of the porphyry copper-gold deposit both theoretically and practically in the lower reaches of Yangtze region.展开更多
The Dexing porphyry deposit is the largest porphyry Cu–Mo–Au deposit in South China.Biotite composition can record the physicochemical conditions and evolution history of magmatic-hydrothermal system.Biotite from th...The Dexing porphyry deposit is the largest porphyry Cu–Mo–Au deposit in South China.Biotite composition can record the physicochemical conditions and evolution history of magmatic-hydrothermal system.Biotite from the Dexing porphyry deposit could be divided to three types:primary magmatic biotite(Bi-M),hydrothermal altered magmatic biotite(Bi-A)and hydrothermal biotite(Bi-H).The temperature of Bi-M and Bi-H range from 719 to 767℃ and 690 to 727℃,respectively.Both magmatic and hydrothermal biotite have high Fe^(3+)/Fe^(2+)ratios(from 0.18 to 0.24)and XMgvalues(from 0.57 to 0.66),indicating a high oxygen fugacity.BiM has F lower than Bi-A and Bi-H(up to 0.26 wt%),but has Cl(Cl=0.18–0.30 wt%)similar to Bi-A and Bi-H(Cl=0.21–0.35 wt%),suggesting that high Cl/F ratios of early hydrothermal fluid may result from the exsolution from high Cl magma.From potassic alteration zone to phyllic and propylitic alteration zones,Cl decreases with increasing Cu,whereas F increases roughly.Therefore,Cl mostly originate from magma,but enrichment of F possibly results from reaction of fluids and Neoproterozoic strata.Negative correlation between Cl and Cu indicates that Cl might act as an important catalyst during Cu mineralization process.Biotite from Dexing has similar halogen compositions to other porphyry Cu-/Mo deposits in the world.Chlorine contents of hydrothermal fluid may be critical for Cu transportation and enrichment,while consumption of Cl would promote Cu deposition.展开更多
The Habo deposit is a typical porphyry Cu-Mo deposit in the Ailaoshan–Red River metallogenic belt.Ore minerals in the Habo deposit typically occur as veins in the monzonite porphyry.Zircon U-Pb dating suggests that t...The Habo deposit is a typical porphyry Cu-Mo deposit in the Ailaoshan–Red River metallogenic belt.Ore minerals in the Habo deposit typically occur as veins in the monzonite porphyry.Zircon U-Pb dating suggests that the monzonite porphyry formed at 35.07±0.38 Ma.The monzonite porphyry is characterized by high SiO_(2),Al_(2)O_(3),K_(2)O and Na_(2)O contents,with A/CNK ratios ranging from 0.97 to 1.02.All samples exhibit fractionated REE patterns,characterized by high(La/Yb)N ratios(9.4–13.6,average of 11.2).They show adakite-like geochemical features,high Sr concentrations(627–751 ppm,average of 700 ppm),low Y concentrations(15.13–16.86 ppm,average of 15.81 ppm)and high Sr/Y values(39.5–47.4,average of 44.3).These samples have high initial^(87)Sr/^(86)Sr ratios(0.7074–0.7076)and negativeεNd(t)values(-5.1 to-3.7),whereas the zirconεHf(t)values range from-2.2 to+0.4,suggesting that the monzonite porphyry was derived from the partial melting of a thickened juvenile lower crust.The oxygen fugacity,calculated on the basis of the chemical composition of the amphiboles,shows?NNO values ranging from+1.65 to+2.16(average of 1.94)and lg(fO_(2))ranging from-12.72 to-11.99(average of-12.25),indicating that the monzonite porphyry has high oxygen fugacity.Zircons have high Ce^(4+)/Ce^(3+)ratios(29.29–164.24,average of 84.92),with high?FMQ values ranging from+0.50 to+1.51(average of 0.87)and high lg(fO_(2))values ranging from-14.72 to-12.85(average of-14.07),which also indicates that the oxygen fugacity of the magma was high.The dissolved water content of the Habo monzonite porphyry is 9.5–11.5 wt%,according to the geochemical characteristics,zircon-saturation thermometry(692–794°C)and the mineral phases(amphibole,no plagioclase)in the deep magma chamber.Combined with previous studies,we propose that the high oxygen fugacity and high water content of magma played key roles in controlling the formation of the Habo and other Cu-Mo-Au deposits in the Ailaoshan–Red River metallogenic belt.展开更多
The reserves of the Duobaoshan porphyry Cu-Au-Mo-Ag deposit(also referred to as the Duobaoshan porphyry Cu deposit)ranks first among the copper deposits in China and 33rd among the porphyry copper deposits in the worl...The reserves of the Duobaoshan porphyry Cu-Au-Mo-Ag deposit(also referred to as the Duobaoshan porphyry Cu deposit)ranks first among the copper deposits in China and 33rd among the porphyry copper deposits in the world.It has proven resources of copper(Cu),molybdenum(Mo),gold(Au),and silver(Ag)of 2.28×10^(6)t,80×10^(3)t,73 t,and 1046 t,respectively.The major characteristics of the Duobaoshan porphyry Cu deposit are as follows.It is located in a zone sandwiched by the Siberian,North China,and paleo-Pacific plates in an island arc tectonic setting and was formed by the Paleozoic mineralization and the Mesozoic mineralization induced by superposition and transformation.The metallogenic porphyries are the Middle Hercynian granodiorite porphyries.The alterations of surrounding rocks are distributed in a ring form.With silicified porphyries at the center,the alteration zones of K-feldspar,biotite,sericite,and propylite occur from inside to outside.This deposit is composed of 215 ore bodies(including 14 major ore bodies)in four mineralized zones.Ore body No.X in the No.3 mineralized zone has the largest resource reserves,accounting for more than 78%of the total reserves of the deposit.Major ore components include Cu,Mo,Au,Ag,Se,and Ga,which have an average content of 0.46%,0.015%,0.16 g/t,1.22 g/t,0.0003%,and 0.001%-0.003%,respectively.The ore minerals of this deposit primarily include pyrite,chalcopyrite,bornite,and molybdenite,followed by magnetite,hematite,rutile,gelenite,and sphalerite.The ore-forming fluids of this deposit were magmatic water in the early metallogenic stage and then the mixture of meteoric water and magmatic water at the late metallogenic stage.The ore-forming fluids experienced three stages.The ore-forming fluids of stageⅠhad a hydrochemical type of H_(2)O-CO_(2)-Na Cl,an ore-forming temperature of 375-650℃,and ore-forming pressure of 110-160 MPa.The ore-forming fluids of stageⅡhad a hydrochemical type of H_(2)O-CO_(2)-Na Cl,an ore-forming temperature of 310-350℃,and ore-forming pressure of 58-80 MPa.The ore-forming fluids of stageⅢhad a hydrochemical type of Na Cl-H_(2)O,an ore-forming temperature of 210-290℃,and ore-forming pressure of 5-12 MPa.The CuAu-Mo-Ag mineralization mainly occurred at stagesⅠandⅡ,with the ore-forming materials having a mixed crust-mantle source.The Duobaoshan porphyry Cu deposit was formed in the initial subduction environment of the Paleo-Asian Ocean Plate during the Early Ordovician.Then,due to the closure of the Mongol-Okhotsk Ocean and the subduction and compression of the Paleo-Pacific Ocean,a composite orogenic metallogenic model of the deposit was formed.In other words,it is a porphyry-epithermal copper-gold polymetallic mineralization system of composite orogeny consisting of Paleozoic island arcs and Mesozoic orogeny and extension.展开更多
The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with tot...The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with total molybdenum reserves of 1.65 billion tons,an average molybdenum ore grade of 0.081%,and molybdenum resources of 1.09 million tons.The main ore body is housed in the granodiorite porphyry plutons and their surrounding inequigranular granodiorite plutons,with high-grade ores largely located in the ore-bearing granodiorite porphyries in the middle-upper part of the porphyry plutons.Specifically,it appears as an ore pipe with a large upper part and a small lower part,measuring about 1700 m in length and width,extending for about 500 m vertically,and covering an area of 2.3 km^(2).Mineralogically,the main ore body consists of molybdenite,chalcopyrite,and sphalerite horizontally from its center outward and exhibits molybdenite,azurite,and pyrite vertically from top to bottom.The primary ore minerals include pyrite and molybdenite,and the secondary ore minerals include sphalerite,chalcopyrite,tetrahedrite,and scheelite,with average grades of molybdenum,copper,sulfur,gallium,and rhenium being 0.081%,0.033%,1.67%,0.001%,and 0.0012%,respectively.The ore-forming fluids of the Daheishan deposit originated as the CO_(2)-H_(2)O-NaCl multiphase magmatic fluid system,rich in CO_(2)and bearing minor amounts of CH4,N2,and H2S,and later mixed with meteoric precipitation.In various mineralization stages,the ore-forming fluids had homogenization temperatures of>420℃‒400℃,360℃‒350℃,340℃‒230℃,220℃‒210℃,and 180℃‒160℃and salinities of>41.05%‒9.8%NaCleqv,38.16%‒4.48%NaCleqv,35.78%‒4.49%NaCleqv,7.43%NaCleqv,and 7.8%‒9.5%NaCleqv,respectively.The mineralization of the Daheishan deposit occurred at 186‒167 Ma.The granites closely related to the mineralization include granodiorites(granodiorite porphyries)and monzogranites(monzogranite porphyries),which were mineralized after magmatic evolution(189‒167 Ma).Moreover,these mineralization-related granites exhibit low initial strontium content and high initial neodymium content,indicating that these granites underwent crust-mantle mixing.The Daheishan deposit formed during the Early-Middle Jurassic,during which basaltic magma underplating induced the lower-crust melting,leading to the formation of magma chambers.After the fractional crystallization of magmas,ore-bearing fluids formed.As the temperature and pressure decreased,the ore-bearing fluids boiled drops while ascending,leading to massive unloading of metal elements.Consequently,brecciated and veinlet-disseminated ore bodies formed.展开更多
The Jiama porphyry copper deposit in Tibet is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6) t.Howeve...The Jiama porphyry copper deposit in Tibet is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6) t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.展开更多
Jiama,with more than 11 Mt of copper metal,is the largest porphyry-skarn copper system in the Gangdese metallogenic belt,Tibet,China,creating ideal conditions for deciphering the origin of porphyry ores in a collision...Jiama,with more than 11 Mt of copper metal,is the largest porphyry-skarn copper system in the Gangdese metallogenic belt,Tibet,China,creating ideal conditions for deciphering the origin of porphyry ores in a collision setting.Despite massive studies of the geology,chronology,petrogenesis,and ore-related fluids and their sources in Jiama,there is a lack of systematic summaries and reviews of this system.In contrast to traditional porphyry copper systems in a subduction setting,recent studies and exploration suggest that the Jiama deposit includes porphyry-type Mo-Cu,skarn-type Cu polymetallic,vein-type Au and manto orebodies.This paper reviews the latest studies on the geology,chronology,petrogenesis,fluid inclusions,and isotopic geochemistry(hydrogen,oxygen,sulfur,and lead)of the Jiama deposit.Accordingly,a multi-center complex mineralization model was constructed,indicating that multi-phase intrusions from the same magma reservoir can form multiple hydrothermal centers.These centers are mutually independent and form various orebodies or are superimposed on each other and form thick,high-grade orebodies.Finally,a new comprehensive exploration model was established for the Jiama porphyry copper system.Both models established in this study help to refine the theories on continental-collision metallogeny and porphyry copper systems.展开更多
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 am...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.展开更多
The Shaki porphyry copper(gold) deposits are a trpical example of porphyry copper deposits associ-ated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9±...The Shaki porphyry copper(gold) deposits are a trpical example of porphyry copper deposits associ-ated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9±1.6Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ionlithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (I<sub>Sr</sub>=0.7058); thus it is the productof differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similarto the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts ofCO<sub>2</sub>, Ca<sup>2+</sup>, Na<sup>+</sup> and Cl<sup>-</sup>. The homogenization temperatures of fluid inclusions for the main mineralization stage rangefrom 280 to 420℃, the δ<sup>18</sup>O values of the ore fluids vary from 3.51 to 5.52‰, the δD values are in the range between-82.4 and -59.8‰, the δ<sup>34</sup>S values of sulphides vary from -0.3 to 2.49‰, and the δ<sup>13</sup>C values of CO<sub>2</sub> in inclusionsrange between -2.66 and -6.53‰. Isotope data indicate that the hydrothermal ore fluids and ore substances of theShaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.展开更多
The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rockseries of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia...The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rockseries of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia pipes. The deposit involves five ore-forming types, Le the porphyry type, crytoexplosivebreccia type. contact-zone veinlet-disseminated type, in-pipe fracture-zone filling-replacement type and out-of-pipetracture-zone filling-replacement type, forming an ore-forming system of 'five ore-forming types within a singlerock body' Fluid inclusion and isotope geochemical studies indicate the following: S, Pb, O and Sr were derivedfrom the lower crust, Nd was derived from the continental crust or depleted mantle and rare earth elements (REE)and trace elements have the crustal source characters; fluids consist dominantly of formation water, metamorphic wa-ter and meteoric water with a part of magmatic mater; heat came from porphyry while the latter originated from par-tial melting caused by shear heating in the lower crust and upper mantle. According to its origin the deposit is classi-fied as the hypabyssal and near-surface, meso-and hypothermal copper deposit ussociated with the late Yanshanianporphyry-cryptoexplosive breccia.展开更多
1 Introduction PCDs are generated in continental arcs in response to plate converging processes(subduction and collision)(Hou et al.,2009;Richards,2013).It is generally accepted that the formation of PCDs is associate...1 Introduction PCDs are generated in continental arcs in response to plate converging processes(subduction and collision)(Hou et al.,2009;Richards,2013).It is generally accepted that the formation of PCDs is associated with igneous activities either originating from lower crust or upper mantle,with contributions of crusts during the evolution of continental lithosphere.展开更多
Kerman area is located in southern parts of central Iranian volcanic belt. The area under study is located in the southern part of this complex copper mineralization in the area, which is mainly porphyry type and is a...Kerman area is located in southern parts of central Iranian volcanic belt. The area under study is located in the southern part of this complex copper mineralization in the area, which is mainly porphyry type and is associated with extensive hydrothermal alteration. This area has a great potential as far as tertiary porphyry copper deposits are concerned. To the exploration of porphyry copper deposits in study area, we have analyzed the lineaments. The lineaments interpreted out from ETM + (band8) data is recognized as another method for locating porphyry type copper mineralization. There is a close correlation between photo lineament factor values and the known copper mineralization in the area. The relationship between 16 porphyry copper deposits with faults and fractures in the area is studied. Photo lineament factor assessments by using satellite photos indicate a strong relationship between a number of lineation intersection in each cell refer to an amount of average lineation in whole map (c/C ratio). In the study area, ratio of c/C even has more relationship refers to PF factor that has previously described in the papers.展开更多
The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zirc...The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.展开更多
Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite-porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc-copper alloy mineral found ...Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite-porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc-copper alloy mineral found for the first time in the porphyry-copper deposit in China. Its intergrown minerals are K-feldspar (mainly perthite), albite-oligoclase, quartz and biotite; and the associated minerals include pyrite and chalcopyrite. It is characterized by a golden reflection colour, being isotropic (isometric), with the grain size ranging from 10 to 50 μm, microhardness VHN10= 190 kg/mm2, and reflectance RVis= 67.97%. Electron microprobe (Model JXA-733) analysis shows Cu = 59.15%-62.55% and Zn= 36.32%-39.85%. The crystallochemical formula is Cu6.27-7.0Zn4.0, simplified as Cu7Zn4.展开更多
The Yulong supper\|large copper deposit is situated within the well\|known S\|N striking Yulong copper\|molybdenum ore belt. The ore\|bearing biotite\|monogranitic porphyry was emplaced within clastic rocks (mainly sh...The Yulong supper\|large copper deposit is situated within the well\|known S\|N striking Yulong copper\|molybdenum ore belt. The ore\|bearing biotite\|monogranitic porphyry was emplaced within clastic rocks (mainly shales and siltstones) of the Jiapila Formation (T 3 j ) and carbonate rocks of the Bolila Formation (T 3 b ) of the Upper Triassic. Five mineralization patterns have been recognized in the deposit, i.e., ①veinlet\|disseminated Cu\|Mo ore in the porphyry; ②skarn\|type Cu ore at the contact zone with carbonates (T 3 b ); ③stratiform\|like oxidized Cu ore between T 3 b carbonate rocks and T 3 j hornstones; ④brecciated Cu ore at the local periphery of porphyry; and ⑤vein Pb\|Zn\|Ag ore in the outer contact zone. They constitute a unique integrated polymetal mineralization series of epigenetic intermediate\|acid magmatic hydrothermal system.Studies have shown that the Yulong deposit was the coupling product of sedimentation, magmatism, and tectonism. The Cu\|bearing sandstones in the Japila Formation have provided partial ore\|bearing materials for the porphyry mineralization during the Himalayan period. The mineralized porphyry mass was passively emplaced and controlled by a nose\|like anticlinal trap opening to the north. The interlayered fractured zone formed during folding between the Jiapila and Bolila Formations acted as favorable host space for stratiform\|like skarn and oxidized ores. A large number of cleavages and fissures developed during folding provided both conduits for the circulation of ore\|forming fluids and host spaces for Pb\|Zn\|Ag ore veins. The veinlet\|disseminated Cu\|Mo ore in the porphyry mass owns the characteristics of typical porphyry copper deposits in the world. The veinlet\|disseminated ore body and the stratiform\|like skarn\|type and/or oxidized ore body, the two main ore bodies in Yulong, are connected with each other and shown as “mushroom\|like" shape, in which the former occurs as “mushroom stem" and the latter as “mushroom cover".展开更多
Recent examination and assessment about the porphyry copper deposits in Gangdise metallogenic belt in southern Tibet have revealed that these porphyry copper deposits are highly prospective. Several methods have been ...Recent examination and assessment about the porphyry copper deposits in Gangdise metallogenic belt in southern Tibet have revealed that these porphyry copper deposits are highly prospective. Several methods have been used for the isotopic dating of the Qulong, Tinggong and Chongjiang porphyry copper deposits, which gives out a petrogenetic age of 17.58±0.74Ma (single-zircon dating of SHRIMP), a metallogenetic age of 15.99±0.32Ma (Re-Os isochron dating) and an alteration age ranging between 12.00Ma and 16.5Ma (K-Ar dating). The metallogenetic age is in general agreement with the alteration age. It can be seen that the petrogenetic and metallogenetic ages for the porphyry copper deposits in Gangdise metallogenic belt are noticeably later than the age for the collisional granitic intrusion in this belt. The authors contend that the porphyry copper deposits in the study area were formed in a post-collisional extensional tectonic setting, and are closely related to the delamination of the mountain roots of the orogenic belts and the uplifting of the Qinghai-Tibet Plateau.展开更多
The porphyry copper belt in the Geza island arc in southwestern China is the only Indosinian porphyry copper metallogenic belt that has been discovered and evaluated so far.The Pulang porphyry copper deposit(also refe...The porphyry copper belt in the Geza island arc in southwestern China is the only Indosinian porphyry copper metallogenic belt that has been discovered and evaluated so far.The Pulang porphyry copper deposit(also referred to as the Pulang deposit)in this area has proven copper reserves of 5.11×106 t.This deposit has been exploited on a large scale using advanced mining methods,exhibiting substantial economic benefit.Based on many research results of previous researchers and the authors’team,this study proposed the following key insights.(1)The Geza island arc was once regarded as an immature island arc with only andesites and quartz diorite porphyrites occurring.This understanding was overturned in this study.Acidic endmember components such as quartz monzonite porphyries and quartz monzonite porphyries have been identified in the Geza island arc,and the mineralization is mainly related to the magmatism of quartz monzonite porphyries.(2)Complete porphyry orebodies and large vein orebodies have developed in the Pulang deposit.Main orebody KT1 occurs in the transition area between the potassium silicate alteration zone of quartz monzonite porphyries and the sericite-quartz alteration zone.Most of them have developed in the potassium silicate alteration zone.The main orebody occurs as large lenses at the top of the hanging wall of rock bodies,with an engineering-controlled length of 1920 m and thickness of 32.5‒630.29 m(average:187.07 m).It has a copper grade of 0.21%-1.56%(average:0.42%)and proven copper resources of 5.11×10^(6) t,which are associated with 113 t of gold,1459 t of silver,and 170×10^(3) t of molybdenum.(3)Many studies on diagenetic and metallogenic chronology,isotopes,and fluid inclusions have been carried out for the Pulang deposit,including K-Ar/Ar-Ar dating of monominerals(e.g.,potassium feldspars,biotites,and amphiboles),zircon U-Pb dating,and molybdenite Re-Os dating.The results show that the porphyries in the Pulang deposit are composite plutons and can be classified into pre-mineralization quartz diorite porphyrites,quartz monzonite porphyries formed during the mineralization,and post-mineralization granite porphyries,which were formed at 223±3.7 Ma,218±4 Ma,and 207±3.9 Ma,respectively.The metallogenic age of the Pulang deposit is 213‒216 Ma.(4)The petrogeochemical characteristics show that the Pulang deposit has the characteristics of volcanic arc granites.The calculation results of trace element contents in zircons show that quartz monzonite porphyries and granite porphyries have higher oxygen fugacity.The isotopic tracing results show that the diagenetic and metallogenic materials were derived from mixed crust-and mantle-derived magmas.展开更多
Compared to other Mo provinces,few studies focused on the South China Mo Province(SCMP),especially for Early Cretaceous Mo mineralization.The Lufeng porphyry Mo deposit in the SCMP is characterized by disseminated and...Compared to other Mo provinces,few studies focused on the South China Mo Province(SCMP),especially for Early Cretaceous Mo mineralization.The Lufeng porphyry Mo deposit in the SCMP is characterized by disseminated and veinlet-type mineralization in granite porphyry,gneiss,and rhyolite.In this study,six molybdenite samples yield a Re–Os isochron age of 108.0±1.8 Ma,which is consistent with the zircon U–Pb age of the granite porphyry(108.4±0.8 Ma).The coincidence of magmatic and hydrothermal activities indicates that Mo mineralization was associated with the intrusion of granite porphyry during the late Early Cretaceous.A compilation of U–Pb and Re–Os chronological data suggests that an extensive and intensive Mo mineralization event occurred in the SCMP during the late Early Cretaceous.The marked difference in molybdenite Re contents between Cu-bearing(85–536 ppm)and Cu-barren(1.3–59 ppm)Mo deposits of the late Early Cretaceous indicates that the ore-forming materials were derived from strong crust–mantle interactions.Together with regional petrological and geochemical data,this study suggests that late Early Cretaceous Mo mineralization in the SCMP occurred in an extensional setting associated with the roll-back of the Paleo-Pacific slab.展开更多
基金financially supported by the Study on mineralization background and conditions of copper-gold in the western part of Bangongco-Nujiang metallogenic belt of Ministry of land and resources of Public industry research and special projects(201011013)Opening Foundation of Key Laboratory of Tectonic Controls on Mineralization and Hydrocarbon Accumulation,Ministry of Land and Resources(gzck2013006)Tectonic metallogeny theory development and practice team fund of Sichuan Province(13TD0008)
文摘The Naruo porphyry copper-gold deposit(hereinafter referred to as the Naruo deposit) in Tibet is a potentially ultra-large, typical gold-rich porphyry copper deposit, which was recently discovered in the Bangongco-Nujiang metallogenic belt. This study analyzed U-Pb chronology and Hf isotopes of the ore-bearing granodiorite porphyry in the Naruo deposit using the LA-ICPMS dating technique. The results show that the weighted average age is 124.03±0.94Ma(MSWD=1.7, n=20), and 206Pb/238 U isochron age is 126.2±2.7 Ma(MSWD=1.02, n=20), both of which are within the error. The weighted average age represents the crystallization age of the granodiorite porphyry, which indicates that the ore-bearing porphyry in the Naruo deposit area was formed in the Early Cretaceous and further implies that the Neo-tethys Ocean had not been closed before 124 Ma under a typical island-arc subduction environment. The εHf(t) of zircons from the granodiorite porphyry varies from 2.14 to 9.07, with an average of 5.18, and all zircons have εHf(t) values greater than 0; 176Hf/177 Hf ratio is relatively high(0.282725–0.282986). Combined with the zircon age―Hf isotope correlation diagram, the aforementioned data indicate that the source reservoir might be a region that is mixed with depleted mantle and ancient crust, which possibly contains more materials sourced from depleted mantle. Rock-forming ages and ore-forming ages of the Duolong ore concentrate area are 120–124 Ma and 118–119 Ma, respectively, which indicate 124–118 Ma represents the main rockforming and ore-forming stage within the area. The Naruo deposit is located in the north of the Bangongco-Nujiang suture, and it yielded a zircon LA-ICPMS age of 124.03 Ma. This indicates the Bangongco-Nujiang oceanic basin subducted towards the north at about 124 Ma, and the Neo-tethys Ocean had not been closed before the middle Early Cretaceous. It is possible that the crust-mantle mixing formed the series of large and giant porphyry copper-gold deposits in the Bangongco.
基金supported by the Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No. KZCX1-YW-15)the National Natural Science Foundation of China (Grant No. 90814008)parts of experimental work is supported from the Opening Funding of State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences (GPMR0506)
文摘On the basis of the geological and geochemical studies, including chemical analysis of bulk rocks, rare-earth and trace element studies, fluid inclusion, and S and O isotopic analyses, the authors described the geological background of the deposit in detail and presented significant proofs for the conditions of formation of the Shaxi porphyry copper-gold deposit. Compared with other large and supper-large porphyry copper deposits in China and the adjacent Cu-Au mineralized areas, the ore-forming processes and conditions were analyzed; and the possibility of forming large porphyry copper deposits in the Shaxi area was discussed. The present study indicated that the ore-forming fluid and material were mainly of magmatic origin, while meteoric water played a certain role in the ore-forming processes. Interactions between subducting and overriding plates provided a major driving force for the formation of igneous rocks and the deposition of metal elements in East China since Jurassic. Based on the geo- chemical data of the Shaxi intrusive, it is found that the copper (gold) mineralization is closely related to the genesis of adakite-like intrusive in the Shaxi area. This adakite-like intrusive was formed in the subduction environment as a result of the subduction of the West Pacific plate toward the East China continent, where there is a great potentiality to form a large porphyry copper deposit.
文摘Shaxi porphyry Cu-Au deposit was one of the important discoveries of the exploration in the middle-lower reaches of Yangtze River in China in 1970s. Gold occurrence in the Shaxi porphyry copper-gold deposit (central (Anhui) province, eastern China) was investigated by means of microscope analyses, EPMA and PIXE. Combined with geological and mineralogical methods, the characteristics of occurrence of gold in the large scale sulfide mineralization in this region were fully investigated. The results show that gold distributes in both chalcopyrite and pyrite as submicroscopic inclusions (less than 1 μm) . Au is positively correlated with As, Fe, S, Cu, Zn and Ti. The condition of gold transformation in thermal fluid system controlling deposition of Au in the region is probably the oxidation potential of the red sedimentary rocks of shale and fine grain sandstone which may be crucial as a geochemical barrier to the reducing fluid. This study lays foundation for the further research and exploration of the porphyry copper-gold deposit both theoretically and practically in the lower reaches of Yangtze region.
基金supported by the Chinese National Science Fund for Distinguished Young Scholars to Dr.Gao Jian-Feng(42025301).
文摘The Dexing porphyry deposit is the largest porphyry Cu–Mo–Au deposit in South China.Biotite composition can record the physicochemical conditions and evolution history of magmatic-hydrothermal system.Biotite from the Dexing porphyry deposit could be divided to three types:primary magmatic biotite(Bi-M),hydrothermal altered magmatic biotite(Bi-A)and hydrothermal biotite(Bi-H).The temperature of Bi-M and Bi-H range from 719 to 767℃ and 690 to 727℃,respectively.Both magmatic and hydrothermal biotite have high Fe^(3+)/Fe^(2+)ratios(from 0.18 to 0.24)and XMgvalues(from 0.57 to 0.66),indicating a high oxygen fugacity.BiM has F lower than Bi-A and Bi-H(up to 0.26 wt%),but has Cl(Cl=0.18–0.30 wt%)similar to Bi-A and Bi-H(Cl=0.21–0.35 wt%),suggesting that high Cl/F ratios of early hydrothermal fluid may result from the exsolution from high Cl magma.From potassic alteration zone to phyllic and propylitic alteration zones,Cl decreases with increasing Cu,whereas F increases roughly.Therefore,Cl mostly originate from magma,but enrichment of F possibly results from reaction of fluids and Neoproterozoic strata.Negative correlation between Cl and Cu indicates that Cl might act as an important catalyst during Cu mineralization process.Biotite from Dexing has similar halogen compositions to other porphyry Cu-/Mo deposits in the world.Chlorine contents of hydrothermal fluid may be critical for Cu transportation and enrichment,while consumption of Cl would promote Cu deposition.
基金supported by grants from the National Key Research and Development Program of China(Grant Nos.2016YFC0600310 and 2019YFA0708602)the National Natural Science Foundation of China(Grant Nos.41702091,41872083 and 42022014)+2 种基金the Yunnan Applied Basic Research Project(Grant No.202101AT070073)the China Fundamental Research Funds for the Central Universities(Grant No.2652018133)the Scientific Research Fund of the Yunnan Provincial Education Department(Grant No.2022Y016)。
文摘The Habo deposit is a typical porphyry Cu-Mo deposit in the Ailaoshan–Red River metallogenic belt.Ore minerals in the Habo deposit typically occur as veins in the monzonite porphyry.Zircon U-Pb dating suggests that the monzonite porphyry formed at 35.07±0.38 Ma.The monzonite porphyry is characterized by high SiO_(2),Al_(2)O_(3),K_(2)O and Na_(2)O contents,with A/CNK ratios ranging from 0.97 to 1.02.All samples exhibit fractionated REE patterns,characterized by high(La/Yb)N ratios(9.4–13.6,average of 11.2).They show adakite-like geochemical features,high Sr concentrations(627–751 ppm,average of 700 ppm),low Y concentrations(15.13–16.86 ppm,average of 15.81 ppm)and high Sr/Y values(39.5–47.4,average of 44.3).These samples have high initial^(87)Sr/^(86)Sr ratios(0.7074–0.7076)and negativeεNd(t)values(-5.1 to-3.7),whereas the zirconεHf(t)values range from-2.2 to+0.4,suggesting that the monzonite porphyry was derived from the partial melting of a thickened juvenile lower crust.The oxygen fugacity,calculated on the basis of the chemical composition of the amphiboles,shows?NNO values ranging from+1.65 to+2.16(average of 1.94)and lg(fO_(2))ranging from-12.72 to-11.99(average of-12.25),indicating that the monzonite porphyry has high oxygen fugacity.Zircons have high Ce^(4+)/Ce^(3+)ratios(29.29–164.24,average of 84.92),with high?FMQ values ranging from+0.50 to+1.51(average of 0.87)and high lg(fO_(2))values ranging from-14.72 to-12.85(average of-14.07),which also indicates that the oxygen fugacity of the magma was high.The dissolved water content of the Habo monzonite porphyry is 9.5–11.5 wt%,according to the geochemical characteristics,zircon-saturation thermometry(692–794°C)and the mineral phases(amphibole,no plagioclase)in the deep magma chamber.Combined with previous studies,we propose that the high oxygen fugacity and high water content of magma played key roles in controlling the formation of the Habo and other Cu-Mo-Au deposits in the Ailaoshan–Red River metallogenic belt.
基金funded by the National Scientific and Technological Basic Resources Investigation Program(2022FY101800)a project of the National Natural Science Foundation of China(42102087)+1 种基金a project of the China Postdoctoral Science Foundation(2022M712966)a major project of the Ministry of Science and Technology of the People’s Republic of China(2021QZKK0304)。
文摘The reserves of the Duobaoshan porphyry Cu-Au-Mo-Ag deposit(also referred to as the Duobaoshan porphyry Cu deposit)ranks first among the copper deposits in China and 33rd among the porphyry copper deposits in the world.It has proven resources of copper(Cu),molybdenum(Mo),gold(Au),and silver(Ag)of 2.28×10^(6)t,80×10^(3)t,73 t,and 1046 t,respectively.The major characteristics of the Duobaoshan porphyry Cu deposit are as follows.It is located in a zone sandwiched by the Siberian,North China,and paleo-Pacific plates in an island arc tectonic setting and was formed by the Paleozoic mineralization and the Mesozoic mineralization induced by superposition and transformation.The metallogenic porphyries are the Middle Hercynian granodiorite porphyries.The alterations of surrounding rocks are distributed in a ring form.With silicified porphyries at the center,the alteration zones of K-feldspar,biotite,sericite,and propylite occur from inside to outside.This deposit is composed of 215 ore bodies(including 14 major ore bodies)in four mineralized zones.Ore body No.X in the No.3 mineralized zone has the largest resource reserves,accounting for more than 78%of the total reserves of the deposit.Major ore components include Cu,Mo,Au,Ag,Se,and Ga,which have an average content of 0.46%,0.015%,0.16 g/t,1.22 g/t,0.0003%,and 0.001%-0.003%,respectively.The ore minerals of this deposit primarily include pyrite,chalcopyrite,bornite,and molybdenite,followed by magnetite,hematite,rutile,gelenite,and sphalerite.The ore-forming fluids of this deposit were magmatic water in the early metallogenic stage and then the mixture of meteoric water and magmatic water at the late metallogenic stage.The ore-forming fluids experienced three stages.The ore-forming fluids of stageⅠhad a hydrochemical type of H_(2)O-CO_(2)-Na Cl,an ore-forming temperature of 375-650℃,and ore-forming pressure of 110-160 MPa.The ore-forming fluids of stageⅡhad a hydrochemical type of H_(2)O-CO_(2)-Na Cl,an ore-forming temperature of 310-350℃,and ore-forming pressure of 58-80 MPa.The ore-forming fluids of stageⅢhad a hydrochemical type of Na Cl-H_(2)O,an ore-forming temperature of 210-290℃,and ore-forming pressure of 5-12 MPa.The CuAu-Mo-Ag mineralization mainly occurred at stagesⅠandⅡ,with the ore-forming materials having a mixed crust-mantle source.The Duobaoshan porphyry Cu deposit was formed in the initial subduction environment of the Paleo-Asian Ocean Plate during the Early Ordovician.Then,due to the closure of the Mongol-Okhotsk Ocean and the subduction and compression of the Paleo-Pacific Ocean,a composite orogenic metallogenic model of the deposit was formed.In other words,it is a porphyry-epithermal copper-gold polymetallic mineralization system of composite orogeny consisting of Paleozoic island arcs and Mesozoic orogeny and extension.
基金This study was jointly funded by a project of the National Natural Science Foundation of China(42102087)a project of the China Postdoctoral Science Foundation(2022M712966)a key special project of the Ministry of Science and Technology of China(2021QZKK0304).
文摘The Daheishan supergiant porphyry molybdenum deposit(also referred to as the Daheishan deposit)is the second largest molybdenum deposit in Asia and ranks fifth among the top seven molybdenum deposits globally with total molybdenum reserves of 1.65 billion tons,an average molybdenum ore grade of 0.081%,and molybdenum resources of 1.09 million tons.The main ore body is housed in the granodiorite porphyry plutons and their surrounding inequigranular granodiorite plutons,with high-grade ores largely located in the ore-bearing granodiorite porphyries in the middle-upper part of the porphyry plutons.Specifically,it appears as an ore pipe with a large upper part and a small lower part,measuring about 1700 m in length and width,extending for about 500 m vertically,and covering an area of 2.3 km^(2).Mineralogically,the main ore body consists of molybdenite,chalcopyrite,and sphalerite horizontally from its center outward and exhibits molybdenite,azurite,and pyrite vertically from top to bottom.The primary ore minerals include pyrite and molybdenite,and the secondary ore minerals include sphalerite,chalcopyrite,tetrahedrite,and scheelite,with average grades of molybdenum,copper,sulfur,gallium,and rhenium being 0.081%,0.033%,1.67%,0.001%,and 0.0012%,respectively.The ore-forming fluids of the Daheishan deposit originated as the CO_(2)-H_(2)O-NaCl multiphase magmatic fluid system,rich in CO_(2)and bearing minor amounts of CH4,N2,and H2S,and later mixed with meteoric precipitation.In various mineralization stages,the ore-forming fluids had homogenization temperatures of>420℃‒400℃,360℃‒350℃,340℃‒230℃,220℃‒210℃,and 180℃‒160℃and salinities of>41.05%‒9.8%NaCleqv,38.16%‒4.48%NaCleqv,35.78%‒4.49%NaCleqv,7.43%NaCleqv,and 7.8%‒9.5%NaCleqv,respectively.The mineralization of the Daheishan deposit occurred at 186‒167 Ma.The granites closely related to the mineralization include granodiorites(granodiorite porphyries)and monzogranites(monzogranite porphyries),which were mineralized after magmatic evolution(189‒167 Ma).Moreover,these mineralization-related granites exhibit low initial strontium content and high initial neodymium content,indicating that these granites underwent crust-mantle mixing.The Daheishan deposit formed during the Early-Middle Jurassic,during which basaltic magma underplating induced the lower-crust melting,leading to the formation of magma chambers.After the fractional crystallization of magmas,ore-bearing fluids formed.As the temperature and pressure decreased,the ore-bearing fluids boiled drops while ascending,leading to massive unloading of metal elements.Consequently,brecciated and veinlet-disseminated ore bodies formed.
基金supported by the National Key Research and Development Program of China(2018YFC0604102)the project of China Geological Survey(DD20190015)。
文摘The Jiama porphyry copper deposit in Tibet is one of the proven supergiant copper deposits in the Qinghai-Tibet Plateau at present,with the reserves of geological resources equivalent to nearly 20×10^(6) t.However,it features wavy and steep terrain,leading to extremely difficult field operation and heavy interference.This study attempts to determine the effects of the tensor controlled-source audiomagnetotellurics(CSAMT)with high-power orthogonal signal sources(also referred to as the high-power tensor CSAMT)when it is applied to the deep geophysical exploration in plateaus with complex terrain and mining areas with strong interference.The test results show that the high current provided by the highpower tensor CSAMT not only greatly improved the signal-to-noise ratio but also guaranteed that effective signals were received in the case of a long transmitter-receiver distance.Meanwhile,the tensor data better described the anisotropy of deep geologic bodies.In addition,the tests also show that when the transmitting current reaches 60 A,it is still guaranteed that strong enough signals can be received in the case of the transmitter-receiver distance of about 25 km,sounding curves show no near field effect,and effective exploration depth can reach 3 km.The 2D inversion results are roughly consistent with drilling results,indicating that the high-power tensor CSAMT can be used to achieve nearly actual characteristics of underground electrical structures.Therefore,this method has great potential for application in deep geophysical exploration in plateaus and mining areas with complex terrain and strong interference,respectively.This study not only serves as important guidance on the prospecting in the Qinghai-Tibet Plateau but also can be used as positive references for deep mineral exploration in other areas.
基金supported by the National Key Research and Development Program of China (2022YFC2905001)the National Natural Science Foundation of China (42272093,42230813)+1 种基金China Scholarship Council projectthe Geological Survey project (DD20230054)
文摘Jiama,with more than 11 Mt of copper metal,is the largest porphyry-skarn copper system in the Gangdese metallogenic belt,Tibet,China,creating ideal conditions for deciphering the origin of porphyry ores in a collision setting.Despite massive studies of the geology,chronology,petrogenesis,and ore-related fluids and their sources in Jiama,there is a lack of systematic summaries and reviews of this system.In contrast to traditional porphyry copper systems in a subduction setting,recent studies and exploration suggest that the Jiama deposit includes porphyry-type Mo-Cu,skarn-type Cu polymetallic,vein-type Au and manto orebodies.This paper reviews the latest studies on the geology,chronology,petrogenesis,fluid inclusions,and isotopic geochemistry(hydrogen,oxygen,sulfur,and lead)of the Jiama deposit.Accordingly,a multi-center complex mineralization model was constructed,indicating that multi-phase intrusions from the same magma reservoir can form multiple hydrothermal centers.These centers are mutually independent and form various orebodies or are superimposed on each other and form thick,high-grade orebodies.Finally,a new comprehensive exploration model was established for the Jiama porphyry copper system.Both models established in this study help to refine the theories on continental-collision metallogeny and porphyry copper systems.
文摘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.
文摘The Shaki porphyry copper(gold) deposits are a trpical example of porphyry copper deposits associ-ated with diorite in eastern China. Quartz diorite, which hosts the deposits, has a Rb-Sr isochron age of 127.9±1.6Ma. Geochemically, the rock is rich in alkalis (especially sodium), light rare earth elements (LREE) and large-ionlithophile elements (LILE), and has a relatively low initial strontium isotopic ratio (I<sub>Sr</sub>=0.7058); thus it is the productof differentiation of crust-mantle mixing source magma. The model of alteration and mineralization zoning is similarto the Hollister (1974) diorite model. The ore fluids have a relatively high salinity and contain significant amounts ofCO<sub>2</sub>, Ca<sup>2+</sup>, Na<sup>+</sup> and Cl<sup>-</sup>. The homogenization temperatures of fluid inclusions for the main mineralization stage rangefrom 280 to 420℃, the δ<sup>18</sup>O values of the ore fluids vary from 3.51 to 5.52‰, the δD values are in the range between-82.4 and -59.8‰, the δ<sup>34</sup>S values of sulphides vary from -0.3 to 2.49‰, and the δ<sup>13</sup>C values of CO<sub>2</sub> in inclusionsrange between -2.66 and -6.53‰. Isotope data indicate that the hydrothermal ore fluids and ore substances of theShaxi porphyry copper (gold) deposits were mainly derived from magmatic systems.
文摘The Hongshan porphyry-cryptoexplosive breccia type copper deposit occurs in a metamorphic rockseries of the Mesoproterozoic Zhongcun Group. Orebodies are distributed inside and outside porphyry-cryptoexplosive breccia pipes. The deposit involves five ore-forming types, Le the porphyry type, crytoexplosivebreccia type. contact-zone veinlet-disseminated type, in-pipe fracture-zone filling-replacement type and out-of-pipetracture-zone filling-replacement type, forming an ore-forming system of 'five ore-forming types within a singlerock body' Fluid inclusion and isotope geochemical studies indicate the following: S, Pb, O and Sr were derivedfrom the lower crust, Nd was derived from the continental crust or depleted mantle and rare earth elements (REE)and trace elements have the crustal source characters; fluids consist dominantly of formation water, metamorphic wa-ter and meteoric water with a part of magmatic mater; heat came from porphyry while the latter originated from par-tial melting caused by shear heating in the lower crust and upper mantle. According to its origin the deposit is classi-fied as the hypabyssal and near-surface, meso-and hypothermal copper deposit ussociated with the late Yanshanianporphyry-cryptoexplosive breccia.
基金supported by the National Key R&D Program of China(Grant No.2016YFC0600501)the National Natural Science Foundation of China(NSFC)(Grant No.41430320).
文摘1 Introduction PCDs are generated in continental arcs in response to plate converging processes(subduction and collision)(Hou et al.,2009;Richards,2013).It is generally accepted that the formation of PCDs is associated with igneous activities either originating from lower crust or upper mantle,with contributions of crusts during the evolution of continental lithosphere.
文摘Kerman area is located in southern parts of central Iranian volcanic belt. The area under study is located in the southern part of this complex copper mineralization in the area, which is mainly porphyry type and is associated with extensive hydrothermal alteration. This area has a great potential as far as tertiary porphyry copper deposits are concerned. To the exploration of porphyry copper deposits in study area, we have analyzed the lineaments. The lineaments interpreted out from ETM + (band8) data is recognized as another method for locating porphyry type copper mineralization. There is a close correlation between photo lineament factor values and the known copper mineralization in the area. The relationship between 16 porphyry copper deposits with faults and fractures in the area is studied. Photo lineament factor assessments by using satellite photos indicate a strong relationship between a number of lineation intersection in each cell refer to an amount of average lineation in whole map (c/C ratio). In the study area, ratio of c/C even has more relationship refers to PF factor that has previously described in the papers.
基金funded by the projects of China Geological Survey (Grant Nos. DD20160123 (DD-16-049, D1522), 12120114020901, 1212011220928 and 1212011121075)
文摘The Chalukou porphyry Mo deposit, located in the Great Hinggan Range, is the largest Mo deposit in northeast China, although the age and genesis of the associated magmatic intrusions remain debated.Here we report zircon U-Pb ages and trace elements, whole rock geochemistry and Sre Nd isotope data with a view to understand the relationship between the magmatism and molybdenum mineralization.Zircon U-Pb analysis yield an age of 475 Ma for rhyolite in the older strata, 168 Ma for the premineralization monzogranite, and 154 Ma for the syn-mineralization granite porphyry. The granite porphyry and quartz porphyry are considered as the ore-forming intrusions. These rocks are peraluminous, alkali-calcic, and belong to high-K to shoshonitic series with a strong depletion of Eu. They also display characteristics of I-type granites. The rocks exhibit wide variations of(87 Sr/86 Sr)iin the range of 0.705426 -0.707363, and ε_(Nd)(t) of -3.7 to 0.93. Zircon REE distribution patterns show characteristics between crust and the mantle, implying magma genesis through crust-mantle interaction. The Fe_2O_3/FeO values(average 1) for the whole rock and EuN/Eu*Nvalues(average 0.45), Ce^(4+)/Ce^(3+) values(average 301)for zircon grains from the granite porphyry are higher than those from other lithologies. These features suggest that the ore-forming intrusions(syn-mineralization porphyry) had higher oxygen fugacity conditions than those of the pre-mineralization and post-mineralization rocks. The Chalukou Mo deposit formed in relation to the southward subduction of the Mongol-Okhotsk Ocean. Our study suggests that the subduction-related setting, crust-mantle interaction, and the large-scale magmatic intrusion were favorable factors to generate the super-large Mo deposits in this area.
文摘Zinccopperite (tentatively named) is a rare native alloy mineral discovered in quartz monzonite-porphyry in the Xifanping area, Yanyuan County, Sichuan Province. It is a new variety of zinc-copper alloy mineral found for the first time in the porphyry-copper deposit in China. Its intergrown minerals are K-feldspar (mainly perthite), albite-oligoclase, quartz and biotite; and the associated minerals include pyrite and chalcopyrite. It is characterized by a golden reflection colour, being isotropic (isometric), with the grain size ranging from 10 to 50 μm, microhardness VHN10= 190 kg/mm2, and reflectance RVis= 67.97%. Electron microprobe (Model JXA-733) analysis shows Cu = 59.15%-62.55% and Zn= 36.32%-39.85%. The crystallochemical formula is Cu6.27-7.0Zn4.0, simplified as Cu7Zn4.
文摘The Yulong supper\|large copper deposit is situated within the well\|known S\|N striking Yulong copper\|molybdenum ore belt. The ore\|bearing biotite\|monogranitic porphyry was emplaced within clastic rocks (mainly shales and siltstones) of the Jiapila Formation (T 3 j ) and carbonate rocks of the Bolila Formation (T 3 b ) of the Upper Triassic. Five mineralization patterns have been recognized in the deposit, i.e., ①veinlet\|disseminated Cu\|Mo ore in the porphyry; ②skarn\|type Cu ore at the contact zone with carbonates (T 3 b ); ③stratiform\|like oxidized Cu ore between T 3 b carbonate rocks and T 3 j hornstones; ④brecciated Cu ore at the local periphery of porphyry; and ⑤vein Pb\|Zn\|Ag ore in the outer contact zone. They constitute a unique integrated polymetal mineralization series of epigenetic intermediate\|acid magmatic hydrothermal system.Studies have shown that the Yulong deposit was the coupling product of sedimentation, magmatism, and tectonism. The Cu\|bearing sandstones in the Japila Formation have provided partial ore\|bearing materials for the porphyry mineralization during the Himalayan period. The mineralized porphyry mass was passively emplaced and controlled by a nose\|like anticlinal trap opening to the north. The interlayered fractured zone formed during folding between the Jiapila and Bolila Formations acted as favorable host space for stratiform\|like skarn and oxidized ores. A large number of cleavages and fissures developed during folding provided both conduits for the circulation of ore\|forming fluids and host spaces for Pb\|Zn\|Ag ore veins. The veinlet\|disseminated Cu\|Mo ore in the porphyry mass owns the characteristics of typical porphyry copper deposits in the world. The veinlet\|disseminated ore body and the stratiform\|like skarn\|type and/or oxidized ore body, the two main ore bodies in Yulong, are connected with each other and shown as “mushroom\|like" shape, in which the former occurs as “mushroom stem" and the latter as “mushroom cover".
基金jointly supported by China National Natural Science Foundation(Grant No.40272047)China National Key Basic Development Program(Grant No.(2002CB412609)large-scale Geological Survey Program of China Geological Survey(Project No.1212010330101).
文摘Recent examination and assessment about the porphyry copper deposits in Gangdise metallogenic belt in southern Tibet have revealed that these porphyry copper deposits are highly prospective. Several methods have been used for the isotopic dating of the Qulong, Tinggong and Chongjiang porphyry copper deposits, which gives out a petrogenetic age of 17.58±0.74Ma (single-zircon dating of SHRIMP), a metallogenetic age of 15.99±0.32Ma (Re-Os isochron dating) and an alteration age ranging between 12.00Ma and 16.5Ma (K-Ar dating). The metallogenetic age is in general agreement with the alteration age. It can be seen that the petrogenetic and metallogenetic ages for the porphyry copper deposits in Gangdise metallogenic belt are noticeably later than the age for the collisional granitic intrusion in this belt. The authors contend that the porphyry copper deposits in the study area were formed in a post-collisional extensional tectonic setting, and are closely related to the delamination of the mountain roots of the orogenic belts and the uplifting of the Qinghai-Tibet Plateau.
基金jointly funded by the national key research and development program project“Strategic Mineral Information and Metallogenic Regularity of the Tethyan Metallogenic Domain”(2021YFC2901803)a project of the National Natural Science Foundation of China entitled“Geological Structure Mapping and Regional Comparative Study of the Tethyan Tectonic Domain”(92055314),International Geoscience Programme(IGCP-741)a project initiated by the China Geological Survey(DD20221910).
文摘The porphyry copper belt in the Geza island arc in southwestern China is the only Indosinian porphyry copper metallogenic belt that has been discovered and evaluated so far.The Pulang porphyry copper deposit(also referred to as the Pulang deposit)in this area has proven copper reserves of 5.11×106 t.This deposit has been exploited on a large scale using advanced mining methods,exhibiting substantial economic benefit.Based on many research results of previous researchers and the authors’team,this study proposed the following key insights.(1)The Geza island arc was once regarded as an immature island arc with only andesites and quartz diorite porphyrites occurring.This understanding was overturned in this study.Acidic endmember components such as quartz monzonite porphyries and quartz monzonite porphyries have been identified in the Geza island arc,and the mineralization is mainly related to the magmatism of quartz monzonite porphyries.(2)Complete porphyry orebodies and large vein orebodies have developed in the Pulang deposit.Main orebody KT1 occurs in the transition area between the potassium silicate alteration zone of quartz monzonite porphyries and the sericite-quartz alteration zone.Most of them have developed in the potassium silicate alteration zone.The main orebody occurs as large lenses at the top of the hanging wall of rock bodies,with an engineering-controlled length of 1920 m and thickness of 32.5‒630.29 m(average:187.07 m).It has a copper grade of 0.21%-1.56%(average:0.42%)and proven copper resources of 5.11×10^(6) t,which are associated with 113 t of gold,1459 t of silver,and 170×10^(3) t of molybdenum.(3)Many studies on diagenetic and metallogenic chronology,isotopes,and fluid inclusions have been carried out for the Pulang deposit,including K-Ar/Ar-Ar dating of monominerals(e.g.,potassium feldspars,biotites,and amphiboles),zircon U-Pb dating,and molybdenite Re-Os dating.The results show that the porphyries in the Pulang deposit are composite plutons and can be classified into pre-mineralization quartz diorite porphyrites,quartz monzonite porphyries formed during the mineralization,and post-mineralization granite porphyries,which were formed at 223±3.7 Ma,218±4 Ma,and 207±3.9 Ma,respectively.The metallogenic age of the Pulang deposit is 213‒216 Ma.(4)The petrogeochemical characteristics show that the Pulang deposit has the characteristics of volcanic arc granites.The calculation results of trace element contents in zircons show that quartz monzonite porphyries and granite porphyries have higher oxygen fugacity.The isotopic tracing results show that the diagenetic and metallogenic materials were derived from mixed crust-and mantle-derived magmas.
基金the Postdoctoral Science Foundation of China (No. 2018M630203)National Natural Science Foundation of China (Grant No. 41502090)
文摘Compared to other Mo provinces,few studies focused on the South China Mo Province(SCMP),especially for Early Cretaceous Mo mineralization.The Lufeng porphyry Mo deposit in the SCMP is characterized by disseminated and veinlet-type mineralization in granite porphyry,gneiss,and rhyolite.In this study,six molybdenite samples yield a Re–Os isochron age of 108.0±1.8 Ma,which is consistent with the zircon U–Pb age of the granite porphyry(108.4±0.8 Ma).The coincidence of magmatic and hydrothermal activities indicates that Mo mineralization was associated with the intrusion of granite porphyry during the late Early Cretaceous.A compilation of U–Pb and Re–Os chronological data suggests that an extensive and intensive Mo mineralization event occurred in the SCMP during the late Early Cretaceous.The marked difference in molybdenite Re contents between Cu-bearing(85–536 ppm)and Cu-barren(1.3–59 ppm)Mo deposits of the late Early Cretaceous indicates that the ore-forming materials were derived from strong crust–mantle interactions.Together with regional petrological and geochemical data,this study suggests that late Early Cretaceous Mo mineralization in the SCMP occurred in an extensional setting associated with the roll-back of the Paleo-Pacific slab.