The northeastern Sichuan area in the northern Yangtze margin has unique Ediacaran geological records,especially the Doushantuo Formation(DST),and become a hot research area in recent years.However,the Cryogenian-Ediac...The northeastern Sichuan area in the northern Yangtze margin has unique Ediacaran geological records,especially the Doushantuo Formation(DST),and become a hot research area in recent years.However,the Cryogenian-Ediacaran(C-E)boundary has not been precisely identified,which restricts the in-depth study of geological information during this crucial transitional period and is unfavorable for a systematic and complete understanding of the Yangtze Block and even the global paleogeographic pattern.This study conducted stratigraphy,sedimentology,and chronostratigraphy to establish the stratigraphic framework and sedimentary evolution of the C-E transition strata in northeastern Sichuan.The results showed that the Ediacaran sediments,without the cap dolomite,unconformably overlaid the Cryogenian sediments in the studied area.The Member II of the DST,characterized by 50-160 m of red-green sandstone(approximately equivalent to the original Chengkou“Guanyinya Formation”),directly overlaid the Cryogenian sediments and displayed a 623±2.3 Ma maximum depositional age from the detrital zircon U-Pb dating.Regional stratigraphic correlations indicate that the C-E transition strata in northeastern Sichuan had a consistent lithological association and sedimentary sequence characteristics but differed from the Three Gorges.Typically,the upper Nantuo massive glacial diamictites transition to the icebergs rafted lonestone-bearing mudstones at the top,then change upward to DST barrier coast sandstones.The proposed DST of the northeastern Sichuan Basin was divided into three lithostratigraphic members without the regional Member I cap dolomite:(i)Member II purple-red,gray-green sandstone strata,(ii)MemberⅢblack mudstone strata,and(iii)Member IV P-Mn bearing strata.During the C-E transition,the study area experienced(i)the global deglaciation stage in the terminal Marinoan glaciation and(ii)the filling-leveling up stage with clastic rocks in the early Ediacaran.Overall,the early Ediacaran of northeastern Sichuan succeeded the paleogeographic features of the late Cryogenian.展开更多
Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at ...Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at Gariatong in the Central Lhasa terrane in Tibet.Detailed field studies and logging data revealed that the Rb mineralization mainly occurs in monzogranite and is related to greisenization.LA-ICP-MS U-Pb dating of zircon yielded ages of 19.1±0.2 Ma and 19.0±0.2 Ma for greisenized monzogranite and fresh monzogranite,respectively.The monzogranites are characterized as strongly peraluminous,with high contents of SiO2,Al2O3,K2O and Na2O as well as a high differentiation index.They are enriched in light rare earth and large ion lithophile elements with significant negative Eu anomalies and depleted high fieldstrength elements.Petrological and geochemical features of these ore-related monzogranites suggest that they are highly fractionated S-type granites,derived from remelting of crustal materials in a post-collisional setting.The geochemistry of zircon and apatite points to a low oxygen fugacity of the ore-related monzogranite during the magma’s evolution.The discovery of the Gariatong Rb deposit suggests that the Central Lhasa terrane may be an important region for rare metal mineralization.展开更多
The Shimensi deposit is a recently discovered W-Cu-Mo polymetallic deposit located in the Jiangnan porphyry-skarn W belt in South China.The deposit has a resource of 0.74×10^(6)t of WO_(3)accompanied by 0.4×...The Shimensi deposit is a recently discovered W-Cu-Mo polymetallic deposit located in the Jiangnan porphyry-skarn W belt in South China.The deposit has a resource of 0.74×10^(6)t of WO_(3)accompanied by 0.4×10^(6)t Cu and 28000 t Mo and other useful components like Ga,making it one of the largest W deposits in the world.This paper is aimed to reveal the ore-controlling mechanisms of the Shimensi deposit,involving the role of the ore-related granites,the tectonic background for its formation,and the metallogenesis model.The systematic geological survey suggests multi-types of alteration are developed in the deposit,mainly including greisenization,potassic-alteration,sericitization,chloritization,and silicification.Drilling engineering data and mining works indicate that the Shimensi deposit consists of two main orebodies of I and II.Therein,the W resource has reached a supergiant scale,and the accompanied Cu,Mo,Au,Bi,Ga,and some other useful components are also of economic significance.The main ore-minerals consist of scheelite,wolframite and chalcopyrite.Disseminated mineralization is the dominant type of the W-Cu-Mo polymetallic orebodies,and mainly distributes in the inner and external contact zone that between the Neoproterozoic biotite granodiorite and the Yanshanian granites.The main orebody occurs at the external contact zone,and the pegmatoid crust near the inner contact zone is an important prospecting marker of the W mineralization.Of them,the disseminated W ores within the wall rock of the Neoproterozoic biotite granodiorite is a new mineralization type identified in this paper.Combining previous geochronological and isotopic data,we propose that the mineralization of the Shimensi deposit is closely related to the intruding of the Yanshanian porphyritic biotite granite and granite porphyry.Geochemical data suggest that the biotite granodiorite is rich in Ca and had provided a large amount of Ca for the precipitation of scheelite in this area.Thus,it is a favorable wall rock type for W mineralization.The Shimensi deposit belongs to granitic-type W polymetallic deposit related to post-magmatic hydrothermal,and the ore-forming fluid was initially derived from the Yanshanian magmas.展开更多
The evolution of mountainous topography is the result of the interactions of climate,topography,and erosion.Glaciers are one of the most active erosional forces sculpting mountainous regions.However,our ability to und...The evolution of mountainous topography is the result of the interactions of climate,topography,and erosion.Glaciers are one of the most active erosional forces sculpting mountainous regions.However,our ability to understand this erosional force is limited by the controversy regarding the major factors controlling glacial erosion.We selected the Nianbaoyeze Shan,which is occupied by subcontinental glaciers(likely cold-based or polythermal glaciers)in the northeastern Tibetan Plateau,to study how erosion by alpine glaciers sculpts the landscape.We first applied a power law model(y=axb)fit to the cross-profiles of glacial valleys and analyzed the controlling factor of glacial erosion;we then identified the morphometric characteristics of the cirques to analyze the influencing factors,and investigated the development patterns of glacial valleys and cirques.Finally,we used hypsometry and the slopealtitude curves and reconstructed the palaeo-glacier surfaces and palaeo-Equilibrium Line Altitudes(ELAs)to determine if the glacial buzzsaw effect had impacted this glaciated region with subcontinental glaciers.Our findings show that ice flux is the main factor controlling glacial erosion.In this region,decreasing temperatures promote an increase in glacier mean size(i.e.,ice flux),which enhances the rate of glacial erosion.Cirque morphology is mainly influenced by aspect and the ELA.The development patterns of glacial valleys and cirques were dominated by a widening process.The ELAs of Marine Isotope Stage(MIS)-3 derived from the cirque floor altitudes or the Accumulation Area Ratio(AAR)and Area-Altitude Balance Ratio(AABR)coincide with the hypsometric maximum and the reduction in slopealtitude curves,which indicates that glacial buzzsaw has impacted this region.Furthermore,the glacial buzzsaw effect has profoundly influenced the mountain heights and topographic evolution in this subcontinental glaciated region.展开更多
The Xiejiaba and Fuqiangbei plutons form part of the newly identified Neoproterozoic Niushan complex,which is located in the southern South Qinling belt(SQB).The plutons are compositionally similar,were emplaced at 75...The Xiejiaba and Fuqiangbei plutons form part of the newly identified Neoproterozoic Niushan complex,which is located in the southern South Qinling belt(SQB).The plutons are compositionally similar,were emplaced at 750–711Ma,and provide insights into Neoproterozoic tectonism within the South Qinling belt.The Xiejiaba pluton contains diorite,quartz diorite,granodiorite,and granite phases,all of which are sub-alkaline and have variable major element compositions with negative correlations between SiO_(2)and MgO,TFe_(2)O_(3),Al_(2)O_(3),CaO,TiO_(2)and P_(2)O_(5).These rocks are enriched in light rare earth elements(LREEs)and large ion lithophile elements(LILEs)and have negative Nb,Ta,P and Ti anomalies,all of which are indicative of arc-type magmatism.The Fuqiangbei pluton contains granitoids that are compositionally similar to the rocks in the Xiejiaba pluton.Samples from these plutons have similarε_(Nd)(t)values(1.24–5.99)but very variable(^(87)Sr/^(86)Sr)i values(0.7010–0.7054).Combining these data with the geochemical data for these rocks suggests that the magmas that formed the Niushan complex were derived from the crust–mantle boundary.This,combined with the results of previous research,suggests that the transition from low pressure-low temperature to low pressure-high temperature conditions within a subduction zone caused melting during a period of late subduction and backarc extension.This constrain the timing of subduction within the South Qinling belt and the northern Yangtze Block(YB)to 750–711 Ma,with this Neoproterozoic subduction associated with an ocean to the north overprinting an existing continental rift-type tectonic setting within the northern margin of the Yangtze Block and the South Qinling belt.展开更多
A study of the morphological and microstructural characteristics of helcionelloids from the Nanjiang area(north Sichuan,China)at the northern Yangtze Platform was undertaken,in order to understand their phylogenetic p...A study of the morphological and microstructural characteristics of helcionelloids from the Nanjiang area(north Sichuan,China)at the northern Yangtze Platform was undertaken,in order to understand their phylogenetic position.Helcionelloids fossils from the Kuanchuanpu Formation of the Changtanhe–Maolinzi section include 7 genera and 11 species.There are distinct differences in the degree of shell bending,the apical morphology and apex position,the outline of the aperture and the height of the shell,all of which constitute important identification features.Although helcionelloid apices exhibit varying degrees of rotation towards the aperture,they do not show any signs of evident distortion.A pair of basally-symmetrical muscle scars are discovered on the shells of helcionelloids(such as Bemella simplex),showing a distinct difference when compared with those of the stem-group gastropod(e.g.,Pelagiella).The prismatic shell layer of helcionelloids has been observed,which are common components in Cambrian molluscs,but differ significantly from the dense layer microstructure found in contemporary molluscs.The microstructures,muscle scars and morphological characteristics demonstrate that helcionelloids represent a stem-group of molluscs.展开更多
The Sinongduo mining region includes two types of mineralizations:the epithermal and the carbonate-hosted PbZn-Ag deposits.Despite being studied for many years,the ore formation process and genesis of the carbonate-ho...The Sinongduo mining region includes two types of mineralizations:the epithermal and the carbonate-hosted PbZn-Ag deposits.Despite being studied for many years,the ore formation process and genesis of the carbonate-hosted Pb-Zn-Ag deposits remain poorly understood.The Pb-Zn-Ag ore bodies occur as veins and are hosted by limestone and dolostone of the Permian Xiala Formation.Three sulfide mineralization substages have been identified at the Sinongduo carbonatehosted deposit.Indium coupled with Cu,Co and Sn was incorporated into sphalerite as substitutions:2Zn^(2+)?Cu^(+)+In^(3+),(3n/2+1)Zn^(2+)?Co^(2+)+n In^(3+)or(2n+1)Zn^(2+)?Co^(2+)+n(Cu^(+)+In^(3+))(n>1)and 4Zn^(2+)?Sn2++2In^(3+).Sphalerite and pyrite in the mineralization stage displayδ^(34)S values in a narrow range of+5.7‰to+11.3‰,which are similar to those of Palaeocene igneous rocks,indicative of a magmatic source of sulfur.We present systematic carbon-hydrogen-oxygen isotope results that further support a magmatic source for the ore-forming fluids that were influenced by meteoric water.Furthermore,the Pb isotope compositions of sulfide minerals in the Sinongduo carbonate-hosted deposit overlap with the values of coeval Linzizong volcanic rocks and are similar to those of Indian Ocean sediments,indicating upper crustal sources of metals.We conclude that the Sinongduo carbonate-hosted Pb-Zn-Ag deposit is a medium-to low-temperature magmatic-hydrothermal deposit related to Linzizong magmatism.展开更多
The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite s...The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.展开更多
1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,...1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,while the Honghe Fault represents its southwestern boundary.It is adjacent to the Ailaoshan Fault,and extends to Guangxi and Vietnam to the southeast(Fig.1a;Liu JP et al.,2021).展开更多
Landslide susceptibility assessment is an essential tool for disaster prevention and management. In areas with multiple fault zones, the impact of fault zone on slope stability cannot be disregarded. This study perfor...Landslide susceptibility assessment is an essential tool for disaster prevention and management. In areas with multiple fault zones, the impact of fault zone on slope stability cannot be disregarded. This study performed qualitative analysis of fault zones and proposed a zoning method to assess the landslide susceptibility in Chengkou County, Chongqing Municipality, China. The region within a distance of 1 km from the faults was designated as sub-zone A, while the remaining area was labeled as sub-zone B. To accomplish the assessment, a dataset comprising 388 historical landslides and 388 non-landslide points was used to train the random forest model. 10-fold cross-validation was utilized to select the training and testing datasets for the model. The results of the models were analyzed and discussed, with a focus on model performance and prediction uncertainty. By implementing the proposed division strategy based on fault zone, the accuracy, precision, recall, F-score, and AUC of both two sub-zones surpassed those of the whole region. In comparison to the results obtained for the whole region, sub-zone B exhibited an increase in AUC by 6.15%, while sub-zone A demonstrated a corresponding increase of 1.66%. Moreover, the results of 100 random realizations indicated that the division strategy has little effect on the prediction uncertainty. This study introduces a novel approach to enhance the prediction accuracy of the landslide susceptibility mapping model in areas with multiple fault zones.展开更多
The recently identified Huashan ophiolitic mélange was considered as the eastern part of the Mianlüe suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite...The recently identified Huashan ophiolitic mélange was considered as the eastern part of the Mianlüe suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite and granite intruding basic volcanic rocks indicates crystallization ages of 947±14 Ma and 876±17 Ma respectively. These ages do not support a recently proposed Hercynian Huashan Ocean, but rather favor that a Neoproterozoic suture assemblage (ophiolite) is incorporated into the younger (Phanerozoic) Qinling orogenic belt.展开更多
This paper deals with the metallogenic model of the sandstone type uranium deposit in the northeastern Ordos Basin from aspects of uranium source, migration and deposition. A superposition metallogenic model has been ...This paper deals with the metallogenic model of the sandstone type uranium deposit in the northeastern Ordos Basin from aspects of uranium source, migration and deposition. A superposition metallogenic model has been established due to complex uranium mineralization processes with superposition of oil-gas reduction and thermal reformation.展开更多
The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a ...The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD-1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.展开更多
It is important to determine the properties of the tectonics in Cambrian period for the sake of prospecting deep hydrocarbon in the near future in the southern Ordos Kratogen of North China. Authors chose the marginal...It is important to determine the properties of the tectonics in Cambrian period for the sake of prospecting deep hydrocarbon in the near future in the southern Ordos Kratogen of North China. Authors chose the marginal areas of the southern Ordos basin as the object of research, avoided the effects of both the Qinling Orogenic Belts (QOB) and Weihe River Graben (WRG) whose geological structures are too complicated. By surveying typical Cambrian outcrops and profdes in the basin edges and based on the cores of 57 wells which penetrated the Cambrian in the basin, combined with the seismic profiles, the field gammaray measuement results and the carbon isotope analysis, Authors conclude that the southern margin of the Ordos Kratogen during Cambrian was a passive continental margin which resulted from sea-floor spreading of the Ancient Qinling Ocean. Epicontinental sea carbonate sediments formed in the south Ordos continental margin during Cambrian, and were predominant as tidal flat and o61itic shoal. Both transgression-regression process and the change in palaeostructure have the obvious cyclicity. Using the junction between the late Nangao age of Qiandong epoch and the early Duyun age of Qiandong epoch as a boundary, each had a full transgression cycle at the upper and lower stages. The early cycle is characterized by high energy clastic littoral facies while the late cycle is characterized by carbonate ramp on which clear water and muddy water developed alternately changing to carbonate platform last. During the early stages, An aulacogen was formed in the middle section of the southern margin. The southern Ordos margin was uplifted and denudated by the Huaiyuan Movement which occurred from the late Furongian age to the middle Flolan age and the history of the passive continental margin ended and entering into a new tectonic cycle. The unconformity surface caused by the Huaiyuan Movement, along with its neighborhood areas where dissolved pores and cavities are developed, may be another important district for good hydrocarbon reservoirs (excluding the unconformity surface on the top of the Ordovician in the Ordos basin).展开更多
The Wutai greenstone belt in central North China Craton(NCC) hosts a number of Precambrian gold deposits and ore occurrences. Based on the host rock association, these can be divided into Banded Iron Formation(BIF), m...The Wutai greenstone belt in central North China Craton(NCC) hosts a number of Precambrian gold deposits and ore occurrences. Based on the host rock association, these can be divided into Banded Iron Formation(BIF), meta-volcano-sedimentary and meta-conglomerate types. The two former types formed during ~2.5-2.3 Ga and the third one at ~1.85 Ga. The characteristics of these Precambrian gold deposits are broadly similar with those of the orogenic gold deposits. Based on available geochronological data, here we reconstruct the major tectonic events and their relationship with gold mineralization in the Wutai-Hengshan-Fuping region during Neoarchean to Paleoproterozoic as follows.(1)~2.6-2.5 Ga: widespread intrusion of tonalite-trondhjemite-granodiorite(TTG) magmas in the Hengshan terrane and Fuping continental arc, formation of the Wutai volcanic arc in the southern margin of Hengshan terrane with granitoids emplacement, and the Hengshan-Wutai intra-oceanic arc accretion to the Fuping arc at the end of Neoarchean.(2) ~ 2.5-2.3 Ga: the subduction of Hengshan arc from north leading to persistent magmatism and orogenic gold mineralization.(3)~2.2-2.1 Ga:extension leading to the formation of graben structure in the Wutai and Fuping region, deposition of the Hutuo and Wanzi Group sediments, formation of placer gold through erosion of the orogenic gold deposits.(4)~2.2-2.0 Ga: widespread magmatism in the Wutai-Hengshan-Fuping region.(5)~1.95-1.8 Ga: regional metamorphism associated with collision of the Western and Eastern Blocks of the NCC and associated orogenic gold deposits. The multiple subduction-accretion-collision history and subsequent deep erosion has significantly affected most of the Precambrian gold deposits in the Wutai greenstone belt.展开更多
We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No ind...We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No independent rare earth minerals were detected by scanning electron microscope. Elements detected by the electronic probe for the in situ micro-zone of the sample included: O,Al, Si, Ca, Mg, Fe, Ti, K, Na, S, Cl, C, Cu, Cr, V, and Pt.Rare earth elements were not detected by electron probe.(NH_4)_2 SO_4,(NH_4)Cl, NaCl, and H_2 SO_4 were used as reagents in chemical leaching experiments that easily leached out rare earth elements under the action of 10%reagent, indicating that the rare earth elements in ore are mainly in the ionic state rather than present as rare earth minerals.展开更多
With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi...With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi Zhuang Autonomous Region,with the orebodies directly occurring in diabase or in the contact zone between diabase and strata.The orebodies are strictly controlled by fault structures.The discovery of this type of gold deposits has brought about new prospects for gold ore prospecting in the Yunnan-Guizhou-Guangxi Golden Triangle region.From the preliminary analysis of the geological characteristics of the Qiaoxiang gold deposit in Wangmo County,in combination with the results of research work in the adjacent areas in recent years,this paper roughly described the geological characteristics and metallogenic conditions of this type of gold ore deposits with an attempt to make more and more geologists pay enough attention to this type of gold ore deposits,so as to promote gold ore prospecting in Guizhou Province to develop toward a variety of types of gold deposits in all round way.展开更多
The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case o...The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.展开更多
The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance...The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance (ESR), optically stimulated luminescence (OSL), thermo-luminescence (TL) and U-series are presented in this paper. The results suggest that there are two planation surfaces, named as the Taihang surface which is a peneplain of Taihang stage formed during Oligocene or Oligocene to early-middle Miocene period, and Tang-hien surface which is a mature wide valley of Tang-hien stage formed during late Miocene-Pliocene or Piiocene-early Pleistocene period and probably ended prior to 2.2-2.6 Ma based on ESR dating. After the Tang-hien stage, the incision and aggradation of the river formed six stream terraces with heights of 3-5 m, 8-12 m, 22-24 m, 28-38 m, 50-62 m and 80-85 m above the river bottom, respectively. The dating results of the alluvium sediments suggest that these terraces were formed during Holocene, 20-23 ka B.P., 110-120 ka B.P., 200-240 ka B.P., 840-1200 ka B.P. or ~450 ka B.P. and 1600-1800 ka B.P. or -1100 ka B.P., respectively. These results indicate that episodic incision of the river, which controls the formation of the scenery in the Yuntaishan World Geopark, was mainly influenced by the periodic dry-wet climate change during late Cenozoic mountain uplift.展开更多
Several stratigraphic breaks and unconformities exist in the Mesoproterozoic successions in the northern margin of the North China Block. Geologic characters and spatial distributions of five of these un- conformities...Several stratigraphic breaks and unconformities exist in the Mesoproterozoic successions in the northern margin of the North China Block. Geologic characters and spatial distributions of five of these un- conformities, which have resulted from different geological processes, have been studied. The uncon- formity beneath the Dahongyu Formation is interpreted as a breakup unconformity, representing the time of transition from continental rift to passive continental margin. The unconformities beneath the Gaoyuzhuang and the Yangzhuang formations are considered to be the consequence of regional eustatic fluctuations, leading to the exposure of highlands in passive margins during low sea-level stands and transgressive deposition on coastal regions during high sea-level stands. The unconformity atop the Tieling Formation might be caused by uplift due to contractional deformation in a back-arc setting, whereas the uplift after the deposition of the Xiamaling Formation might be attributed to a continental collision event. It is assumed that the occurrences of these unconformities in the Mesoproterozoic successions in the northern margin of the North China Block had a close bearing on the assemblage and breakup of the Columbia and Rodinia supercontinents.展开更多
基金supported by the China Geological Survey project(DD20221649)the National Natural Science Foundation of China(Nos.U19B6003,42072135,and 42172119)+1 种基金Chongqing Research Program of Basic Research and Frontier Technology(Grant No.cstc2021jcyj-msxm X0023)Open Fund(DGERA 20211105)of Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources,Chengdu University of Technology。
文摘The northeastern Sichuan area in the northern Yangtze margin has unique Ediacaran geological records,especially the Doushantuo Formation(DST),and become a hot research area in recent years.However,the Cryogenian-Ediacaran(C-E)boundary has not been precisely identified,which restricts the in-depth study of geological information during this crucial transitional period and is unfavorable for a systematic and complete understanding of the Yangtze Block and even the global paleogeographic pattern.This study conducted stratigraphy,sedimentology,and chronostratigraphy to establish the stratigraphic framework and sedimentary evolution of the C-E transition strata in northeastern Sichuan.The results showed that the Ediacaran sediments,without the cap dolomite,unconformably overlaid the Cryogenian sediments in the studied area.The Member II of the DST,characterized by 50-160 m of red-green sandstone(approximately equivalent to the original Chengkou“Guanyinya Formation”),directly overlaid the Cryogenian sediments and displayed a 623±2.3 Ma maximum depositional age from the detrital zircon U-Pb dating.Regional stratigraphic correlations indicate that the C-E transition strata in northeastern Sichuan had a consistent lithological association and sedimentary sequence characteristics but differed from the Three Gorges.Typically,the upper Nantuo massive glacial diamictites transition to the icebergs rafted lonestone-bearing mudstones at the top,then change upward to DST barrier coast sandstones.The proposed DST of the northeastern Sichuan Basin was divided into three lithostratigraphic members without the regional Member I cap dolomite:(i)Member II purple-red,gray-green sandstone strata,(ii)MemberⅢblack mudstone strata,and(iii)Member IV P-Mn bearing strata.During the C-E transition,the study area experienced(i)the global deglaciation stage in the terminal Marinoan glaciation and(ii)the filling-leveling up stage with clastic rocks in the early Ediacaran.Overall,the early Ediacaran of northeastern Sichuan succeeded the paleogeographic features of the late Cryogenian.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFC2905001)the National Natural Science Foundation of China(Grant Nos.42272093,42230813)+1 种基金the Basic Research Fund of the Chinese Academy of Geological Sciences(Grant Nos.JKYZD202316,KK2116)the China Scholarship Council project and the Geological Survey project(Grant No.DD20230054).
文摘Rubidium(Rb)deposits mostly occur in the South China and Central Asia orogenic belts and are often closely associated with highly differentiated granites.This study investigates a newly-discovered giant Rb deposit at Gariatong in the Central Lhasa terrane in Tibet.Detailed field studies and logging data revealed that the Rb mineralization mainly occurs in monzogranite and is related to greisenization.LA-ICP-MS U-Pb dating of zircon yielded ages of 19.1±0.2 Ma and 19.0±0.2 Ma for greisenized monzogranite and fresh monzogranite,respectively.The monzogranites are characterized as strongly peraluminous,with high contents of SiO2,Al2O3,K2O and Na2O as well as a high differentiation index.They are enriched in light rare earth and large ion lithophile elements with significant negative Eu anomalies and depleted high fieldstrength elements.Petrological and geochemical features of these ore-related monzogranites suggest that they are highly fractionated S-type granites,derived from remelting of crustal materials in a post-collisional setting.The geochemistry of zircon and apatite points to a low oxygen fugacity of the ore-related monzogranite during the magma’s evolution.The discovery of the Gariatong Rb deposit suggests that the Central Lhasa terrane may be an important region for rare metal mineralization.
基金supported financially by the National Natural Science Foundation of China(No.41772069)projects of the China Geological Survey(1212011220737,121201004000150015,DD20190570).
文摘The Shimensi deposit is a recently discovered W-Cu-Mo polymetallic deposit located in the Jiangnan porphyry-skarn W belt in South China.The deposit has a resource of 0.74×10^(6)t of WO_(3)accompanied by 0.4×10^(6)t Cu and 28000 t Mo and other useful components like Ga,making it one of the largest W deposits in the world.This paper is aimed to reveal the ore-controlling mechanisms of the Shimensi deposit,involving the role of the ore-related granites,the tectonic background for its formation,and the metallogenesis model.The systematic geological survey suggests multi-types of alteration are developed in the deposit,mainly including greisenization,potassic-alteration,sericitization,chloritization,and silicification.Drilling engineering data and mining works indicate that the Shimensi deposit consists of two main orebodies of I and II.Therein,the W resource has reached a supergiant scale,and the accompanied Cu,Mo,Au,Bi,Ga,and some other useful components are also of economic significance.The main ore-minerals consist of scheelite,wolframite and chalcopyrite.Disseminated mineralization is the dominant type of the W-Cu-Mo polymetallic orebodies,and mainly distributes in the inner and external contact zone that between the Neoproterozoic biotite granodiorite and the Yanshanian granites.The main orebody occurs at the external contact zone,and the pegmatoid crust near the inner contact zone is an important prospecting marker of the W mineralization.Of them,the disseminated W ores within the wall rock of the Neoproterozoic biotite granodiorite is a new mineralization type identified in this paper.Combining previous geochronological and isotopic data,we propose that the mineralization of the Shimensi deposit is closely related to the intruding of the Yanshanian porphyritic biotite granite and granite porphyry.Geochemical data suggest that the biotite granodiorite is rich in Ca and had provided a large amount of Ca for the precipitation of scheelite in this area.Thus,it is a favorable wall rock type for W mineralization.The Shimensi deposit belongs to granitic-type W polymetallic deposit related to post-magmatic hydrothermal,and the ore-forming fluid was initially derived from the Yanshanian magmas.
基金funded by the National Natural Science Foundation of China(Grant Nos.41971003)the Second Tibetan Plateau Scientific Expedition and Research Program(STEP)(Grant Nos.2019QZKK0205)the Science and technology Project of Tibet Autonomous Region(Grant Nos.XZ202101ZY0001G)。
文摘The evolution of mountainous topography is the result of the interactions of climate,topography,and erosion.Glaciers are one of the most active erosional forces sculpting mountainous regions.However,our ability to understand this erosional force is limited by the controversy regarding the major factors controlling glacial erosion.We selected the Nianbaoyeze Shan,which is occupied by subcontinental glaciers(likely cold-based or polythermal glaciers)in the northeastern Tibetan Plateau,to study how erosion by alpine glaciers sculpts the landscape.We first applied a power law model(y=axb)fit to the cross-profiles of glacial valleys and analyzed the controlling factor of glacial erosion;we then identified the morphometric characteristics of the cirques to analyze the influencing factors,and investigated the development patterns of glacial valleys and cirques.Finally,we used hypsometry and the slopealtitude curves and reconstructed the palaeo-glacier surfaces and palaeo-Equilibrium Line Altitudes(ELAs)to determine if the glacial buzzsaw effect had impacted this glaciated region with subcontinental glaciers.Our findings show that ice flux is the main factor controlling glacial erosion.In this region,decreasing temperatures promote an increase in glacier mean size(i.e.,ice flux),which enhances the rate of glacial erosion.Cirque morphology is mainly influenced by aspect and the ELA.The development patterns of glacial valleys and cirques were dominated by a widening process.The ELAs of Marine Isotope Stage(MIS)-3 derived from the cirque floor altitudes or the Accumulation Area Ratio(AAR)and Area-Altitude Balance Ratio(AABR)coincide with the hypsometric maximum and the reduction in slopealtitude curves,which indicates that glacial buzzsaw has impacted this region.Furthermore,the glacial buzzsaw effect has profoundly influenced the mountain heights and topographic evolution in this subcontinental glaciated region.
基金supported by the National Natural Science Foundation of China(Grant No.41872219)the Key Research and Development Program of Shaanxi(Grant No.2019SF-245)+1 种基金the Natural Science Foundation of Shaanxi Province(Grant No.2023-JC-YB-222)an integrated research project of Integrated Exploration of China Geological Survey(Grant No.WKZB1911BJM300369/002)。
文摘The Xiejiaba and Fuqiangbei plutons form part of the newly identified Neoproterozoic Niushan complex,which is located in the southern South Qinling belt(SQB).The plutons are compositionally similar,were emplaced at 750–711Ma,and provide insights into Neoproterozoic tectonism within the South Qinling belt.The Xiejiaba pluton contains diorite,quartz diorite,granodiorite,and granite phases,all of which are sub-alkaline and have variable major element compositions with negative correlations between SiO_(2)and MgO,TFe_(2)O_(3),Al_(2)O_(3),CaO,TiO_(2)and P_(2)O_(5).These rocks are enriched in light rare earth elements(LREEs)and large ion lithophile elements(LILEs)and have negative Nb,Ta,P and Ti anomalies,all of which are indicative of arc-type magmatism.The Fuqiangbei pluton contains granitoids that are compositionally similar to the rocks in the Xiejiaba pluton.Samples from these plutons have similarε_(Nd)(t)values(1.24–5.99)but very variable(^(87)Sr/^(86)Sr)i values(0.7010–0.7054).Combining these data with the geochemical data for these rocks suggests that the magmas that formed the Niushan complex were derived from the crust–mantle boundary.This,combined with the results of previous research,suggests that the transition from low pressure-low temperature to low pressure-high temperature conditions within a subduction zone caused melting during a period of late subduction and backarc extension.This constrain the timing of subduction within the South Qinling belt and the northern Yangtze Block(YB)to 750–711 Ma,with this Neoproterozoic subduction associated with an ocean to the north overprinting an existing continental rift-type tectonic setting within the northern margin of the Yangtze Block and the South Qinling belt.
基金funded by the National Natural Science Foundation of China(Grant Nos.41872007,41972026)the Sichuan Science and Technology Program(2018JY0491)。
文摘A study of the morphological and microstructural characteristics of helcionelloids from the Nanjiang area(north Sichuan,China)at the northern Yangtze Platform was undertaken,in order to understand their phylogenetic position.Helcionelloids fossils from the Kuanchuanpu Formation of the Changtanhe–Maolinzi section include 7 genera and 11 species.There are distinct differences in the degree of shell bending,the apical morphology and apex position,the outline of the aperture and the height of the shell,all of which constitute important identification features.Although helcionelloid apices exhibit varying degrees of rotation towards the aperture,they do not show any signs of evident distortion.A pair of basally-symmetrical muscle scars are discovered on the shells of helcionelloids(such as Bemella simplex),showing a distinct difference when compared with those of the stem-group gastropod(e.g.,Pelagiella).The prismatic shell layer of helcionelloids has been observed,which are common components in Cambrian molluscs,but differ significantly from the dense layer microstructure found in contemporary molluscs.The microstructures,muscle scars and morphological characteristics demonstrate that helcionelloids represent a stem-group of molluscs.
基金jointly supported by the National Key Research and Development Program of China(2022YFC2905001)the National Natural Science Foundation(42230813)。
文摘The Sinongduo mining region includes two types of mineralizations:the epithermal and the carbonate-hosted PbZn-Ag deposits.Despite being studied for many years,the ore formation process and genesis of the carbonate-hosted Pb-Zn-Ag deposits remain poorly understood.The Pb-Zn-Ag ore bodies occur as veins and are hosted by limestone and dolostone of the Permian Xiala Formation.Three sulfide mineralization substages have been identified at the Sinongduo carbonatehosted deposit.Indium coupled with Cu,Co and Sn was incorporated into sphalerite as substitutions:2Zn^(2+)?Cu^(+)+In^(3+),(3n/2+1)Zn^(2+)?Co^(2+)+n In^(3+)or(2n+1)Zn^(2+)?Co^(2+)+n(Cu^(+)+In^(3+))(n>1)and 4Zn^(2+)?Sn2++2In^(3+).Sphalerite and pyrite in the mineralization stage displayδ^(34)S values in a narrow range of+5.7‰to+11.3‰,which are similar to those of Palaeocene igneous rocks,indicative of a magmatic source of sulfur.We present systematic carbon-hydrogen-oxygen isotope results that further support a magmatic source for the ore-forming fluids that were influenced by meteoric water.Furthermore,the Pb isotope compositions of sulfide minerals in the Sinongduo carbonate-hosted deposit overlap with the values of coeval Linzizong volcanic rocks and are similar to those of Indian Ocean sediments,indicating upper crustal sources of metals.We conclude that the Sinongduo carbonate-hosted Pb-Zn-Ag deposit is a medium-to low-temperature magmatic-hydrothermal deposit related to Linzizong magmatism.
基金supported by the National Natural Science Foundation of China(Grant Nos.42162012,42072094)the Key Laboratory of Sanjiang Metallogeny and Resource Exploration and Utilization,Ministry of Natural Resources(Project No.ZRZYBSJSYS2022001).
文摘The Dahongshan Group,situated at the southwestern margin of the Yangtze Block,represents a geological unit characterized by relatively high-grade metamorphism in the region.This paper investigates the garnet-biotite schist from the Laochanghe Formation of the Dahongshan Group,employing an integrated approach that includes petrological analysis,phase equilibrium modeling,and zircon U-Pb dating.The schist is mainly composed of garnet,biotite,plagioclase,quartz,rutile,and ilmenite.Phase equilibrium modeling revealed the peak metamorphic conditions of 8-9 kbar and 635-675°C.By further integrating the prograde metamorphic profile of garnet and geothermobarometric results,a clockwise P-T metamorphic evolution path is constructed,which includes an increase in temperature and pressure during the prograde stage.LA-ICP-MS zircon U-Pb dating and zircon Ti thermometry constrains the post-peak metamorphic age of 831.2±7.2 Ma.Integrated with previously reported results,it is revealed that the southwestern margin of the Yangtze Block experienced a large-scale regional metamorphism during the Neoproterozoic(890-750 Ma),which is related to the collisional orogenic process.This may be associated with the late-stage assembly of the Rodinia supercontinent or with local compression and subduction processes during the breakup of the Rodinia supercontinent.
基金supported by Yunnan Major Scientific and Technological Projects(202202AG050006)National Natural Science Foundation of China(42362010)Bozhushan Late Yanshanian magmatic metallogenic system and metallogenic regularity project(202202AG05006-2)。
文摘1.Objective The Gejiu-Bozhushan-Laojunshan tin-tungsten polymetallic metallogenic belt is located in southeastern Yunnan.It is bounded by the Mile-Shizong Fault and the Yangzi Plate to the north and west,respectively,while the Honghe Fault represents its southwestern boundary.It is adjacent to the Ailaoshan Fault,and extends to Guangxi and Vietnam to the southeast(Fig.1a;Liu JP et al.,2021).
基金Postdoctoral Research Foundation of China (2021M700608)Natural Science Foundation Project of Chongqing, Chongqing Science and Technology Commission (cstc2021jcyj-bsh0047)+1 种基金Scientific Project Supported by the Bureau of Planning and Natural Resources, Chongqing (2301DH09002)Sichuan Transportation Science and Technology Project (2018ZL-01)。
文摘Landslide susceptibility assessment is an essential tool for disaster prevention and management. In areas with multiple fault zones, the impact of fault zone on slope stability cannot be disregarded. This study performed qualitative analysis of fault zones and proposed a zoning method to assess the landslide susceptibility in Chengkou County, Chongqing Municipality, China. The region within a distance of 1 km from the faults was designated as sub-zone A, while the remaining area was labeled as sub-zone B. To accomplish the assessment, a dataset comprising 388 historical landslides and 388 non-landslide points was used to train the random forest model. 10-fold cross-validation was utilized to select the training and testing datasets for the model. The results of the models were analyzed and discussed, with a focus on model performance and prediction uncertainty. By implementing the proposed division strategy based on fault zone, the accuracy, precision, recall, F-score, and AUC of both two sub-zones surpassed those of the whole region. In comparison to the results obtained for the whole region, sub-zone B exhibited an increase in AUC by 6.15%, while sub-zone A demonstrated a corresponding increase of 1.66%. Moreover, the results of 100 random realizations indicated that the division strategy has little effect on the prediction uncertainty. This study introduces a novel approach to enhance the prediction accuracy of the landslide susceptibility mapping model in areas with multiple fault zones.
基金the National Natural Science Foundation of China (Grant No. 40234045, 40473030).
文摘The recently identified Huashan ophiolitic mélange was considered as the eastern part of the Mianlüe suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite and granite intruding basic volcanic rocks indicates crystallization ages of 947±14 Ma and 876±17 Ma respectively. These ages do not support a recently proposed Hercynian Huashan Ocean, but rather favor that a Neoproterozoic suture assemblage (ophiolite) is incorporated into the younger (Phanerozoic) Qinling orogenic belt.
文摘This paper deals with the metallogenic model of the sandstone type uranium deposit in the northeastern Ordos Basin from aspects of uranium source, migration and deposition. A superposition metallogenic model has been established due to complex uranium mineralization processes with superposition of oil-gas reduction and thermal reformation.
基金supported jointly by grants No K1 022K0901 from the Scientific Research Fund of the China Central Non-Commercial Institutegrant No 40772063 from the National Natural Science Foundation of Chinathe Programme of Excellent Young Scientists of the Ministry of Land and Resources and Geological Survey Program Grant 1212010561603-2 from the China Geological Survey
文摘The Huangsha-Tieshanlong quartz-vein tungsten polymetallic ore deposit, located in the northern Pangushan-Tieshanlong tungsten ore field in eastern Ganxian-Yudu prospecting areas of the Yushan metallogenic belt, is a well-known tungsten deposit in southern Jiangxi province, China. SHRIMP-determined dating of zircons from the Tieshanlong granite yields ages of 168.1±2.1 Ma (n=11, MSWD-1.3). Rhenium and osmium isotopic dating of molybdenite from the Huangsha quartz-vein tungsten deposit determined by ICP-MS yields a weighted average ages of 153-3 Ma and model ages of 150.22.1 Ma - 155.4-2.3 Ma. The age of the Huangsha tungsten deposit is 10 to 15 Ma later than the Tieshanlong granite, which shows that there might have been another early Late Jurassic magmatic activity between 150 and 160 Ma, a process which is closely related with tungsten mineralization in this area. The Tieshanlong granite, the Hnangsha tungsten deposit and the Pangushan-Tieshanlong ore field were all formed around 150-170 Ma, belonging to products of a Mesozoic second large-scale mineralization. According to the collected molybdenite Re-Os dating results in southern Jiangxi province, the timescale of the associated molybdenum mineralization is 2-6 Ma in the tungsten deposit and the timescale of independent molybdenum mineralization is 1-4 Ma, implying the complexity of tungsten mineralization. Times of molybdenum mineralization are mainly concentrated in the Yanshanian, which includes three stages of 133-135 Ma, 150-162 Ma, and 166-170 Ma, respectively. The 150-162 Ma-stage is in accordance with ages of large-scale WoSn mineralization, which is mainly molybdenum mineralization characterized by associated molybdenum mineralization with development of an even greater-intensity independent molybdenum mineralization. Independent molybdenum mineralization occurred before and after large-scale W-Sn mineralization, which indicates that favorable prospecting period for molybdenum may be in Cretaceous and early late Jurassic.
基金supported by a grant from the special research project-Key Technologies of Exploration and Development in Marine Carbonatite for Major Oil-Gas Fields in China (Code: 2008E-0700)sponsored by the State funding and PetroChina
文摘It is important to determine the properties of the tectonics in Cambrian period for the sake of prospecting deep hydrocarbon in the near future in the southern Ordos Kratogen of North China. Authors chose the marginal areas of the southern Ordos basin as the object of research, avoided the effects of both the Qinling Orogenic Belts (QOB) and Weihe River Graben (WRG) whose geological structures are too complicated. By surveying typical Cambrian outcrops and profdes in the basin edges and based on the cores of 57 wells which penetrated the Cambrian in the basin, combined with the seismic profiles, the field gammaray measuement results and the carbon isotope analysis, Authors conclude that the southern margin of the Ordos Kratogen during Cambrian was a passive continental margin which resulted from sea-floor spreading of the Ancient Qinling Ocean. Epicontinental sea carbonate sediments formed in the south Ordos continental margin during Cambrian, and were predominant as tidal flat and o61itic shoal. Both transgression-regression process and the change in palaeostructure have the obvious cyclicity. Using the junction between the late Nangao age of Qiandong epoch and the early Duyun age of Qiandong epoch as a boundary, each had a full transgression cycle at the upper and lower stages. The early cycle is characterized by high energy clastic littoral facies while the late cycle is characterized by carbonate ramp on which clear water and muddy water developed alternately changing to carbonate platform last. During the early stages, An aulacogen was formed in the middle section of the southern margin. The southern Ordos margin was uplifted and denudated by the Huaiyuan Movement which occurred from the late Furongian age to the middle Flolan age and the history of the passive continental margin ended and entering into a new tectonic cycle. The unconformity surface caused by the Huaiyuan Movement, along with its neighborhood areas where dissolved pores and cavities are developed, may be another important district for good hydrocarbon reservoirs (excluding the unconformity surface on the top of the Ordovician in the Ordos basin).
基金supported by the Ministry of Science and Technology of China for the National Key Research and Development Program(Grand No.2016YFC0600106)the National Natural Science Foundation of China(Grand Nos.41602028 and 90914002)contributed to the 1000 Talent Award to M.Santosh from the Chinese Government
文摘The Wutai greenstone belt in central North China Craton(NCC) hosts a number of Precambrian gold deposits and ore occurrences. Based on the host rock association, these can be divided into Banded Iron Formation(BIF), meta-volcano-sedimentary and meta-conglomerate types. The two former types formed during ~2.5-2.3 Ga and the third one at ~1.85 Ga. The characteristics of these Precambrian gold deposits are broadly similar with those of the orogenic gold deposits. Based on available geochronological data, here we reconstruct the major tectonic events and their relationship with gold mineralization in the Wutai-Hengshan-Fuping region during Neoarchean to Paleoproterozoic as follows.(1)~2.6-2.5 Ga: widespread intrusion of tonalite-trondhjemite-granodiorite(TTG) magmas in the Hengshan terrane and Fuping continental arc, formation of the Wutai volcanic arc in the southern margin of Hengshan terrane with granitoids emplacement, and the Hengshan-Wutai intra-oceanic arc accretion to the Fuping arc at the end of Neoarchean.(2) ~ 2.5-2.3 Ga: the subduction of Hengshan arc from north leading to persistent magmatism and orogenic gold mineralization.(3)~2.2-2.1 Ga:extension leading to the formation of graben structure in the Wutai and Fuping region, deposition of the Hutuo and Wanzi Group sediments, formation of placer gold through erosion of the orogenic gold deposits.(4)~2.2-2.0 Ga: widespread magmatism in the Wutai-Hengshan-Fuping region.(5)~1.95-1.8 Ga: regional metamorphism associated with collision of the Western and Eastern Blocks of the NCC and associated orogenic gold deposits. The multiple subduction-accretion-collision history and subsequent deep erosion has significantly affected most of the Precambrian gold deposits in the Wutai greenstone belt.
基金funded by the Guizhou Geological exploration fund (No. [2015]21)the Guizhou Geological mineral science cooperation fund (Nos. [2015]5, [2016]5, [2017]1092)
文摘We studied the states of rare earth elements in ore of the Xianglushan rare earth deposit. Rare earth ore samples were tested and examined by scanning electron microscope, electron probe, and chemical leaching. No independent rare earth minerals were detected by scanning electron microscope. Elements detected by the electronic probe for the in situ micro-zone of the sample included: O,Al, Si, Ca, Mg, Fe, Ti, K, Na, S, Cl, C, Cu, Cr, V, and Pt.Rare earth elements were not detected by electron probe.(NH_4)_2 SO_4,(NH_4)Cl, NaCl, and H_2 SO_4 were used as reagents in chemical leaching experiments that easily leached out rare earth elements under the action of 10%reagent, indicating that the rare earth elements in ore are mainly in the ionic state rather than present as rare earth minerals.
文摘With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi Zhuang Autonomous Region,with the orebodies directly occurring in diabase or in the contact zone between diabase and strata.The orebodies are strictly controlled by fault structures.The discovery of this type of gold deposits has brought about new prospects for gold ore prospecting in the Yunnan-Guizhou-Guangxi Golden Triangle region.From the preliminary analysis of the geological characteristics of the Qiaoxiang gold deposit in Wangmo County,in combination with the results of research work in the adjacent areas in recent years,this paper roughly described the geological characteristics and metallogenic conditions of this type of gold ore deposits with an attempt to make more and more geologists pay enough attention to this type of gold ore deposits,so as to promote gold ore prospecting in Guizhou Province to develop toward a variety of types of gold deposits in all round way.
基金financially supported by the NSFC-Shandong Joint Fund Program entitled“Control Mechanisms of Faults on Deep Gold Deposits in Jiaodong Peninsula”(Grant No.U2006201)Science and Technology Project of Shandong Bureau of Geology and Mineral Exploration and Development entitled“Fault system and its relationship with gold mineralization,northwestern Jiaodong Peninsula”(Grant No.KY202208)Open Fund of Big Data Application and Development Engineering Laboratory for Deep Gold Exploration in Shandong Province entitled“Ore-forming fluid and ore-forming material source of Jiudian gold deposit,Jiaodong”(Grant No.SDK202211).
文摘The Dayin’gezhuang gold deposit is located in the central part of the Zhaoping Fault metallogenic belt in the Jiaodong gold province-the world’s third-largest gold metallogenic area.It is a typical successful case of prospecting at a depth of 500-2000 m in recent years,with cumulative proven gold resources exceeding 180 t.The main orebodies(No.1 and No.2 orebody)generally have a pitch direction of NNE and a plunge direction of NEE.As the ore-controlling fault,the Zhaoping Fault is a shovel-shaped stepped fault,with its dip angle presenting stepped high-to-low transitions at the elevation of -2000-0 m.The gold mineralization enrichment area is mainly distributed in the step parts where the fault plane changes from steeply to gently,forming a stepped metallogenic pattern from shallow to deep.It can be concluded from previous studies that the gold mineralization of the Dayin’gezhuang gold deposit occurred at about 120 Ma.The ore-forming fluids were H_(2)O-CO_(2)-NaCl-type hydrothermal solutions with a medium-low temperature and medium-low salinity.The H-O isotopic characteristics indicate that the fluids in the early ore-forming stage were possibly magmatic water or mantle water and that meteoric water gradually entered the ore-forming fluids in the late ore-forming stage.The S and Pb isotopes indicate that the ore-forming materials mainly originate from the lower crust and contain a small quantity of mantle-derived components.The comprehensive analysis shows that the Dayin’gezhuang gold deposit was formed by thermal uplifting-extensional tectonism.The strong crust-mantle interactions,large-scale magmatism,and the material exchange arising from the transformation from adakitic granites to arc granites and from the ancient lower crust to the juvenile lower crust during the Early Cretaceous provided abundant fluids and material sources for mineralization.Moreover,the detachment faults formed by the rapid magmatic uplift and the extensional tectonism created favorable temperature and pressure conditions and space for fluid accumulation and gold precipitation and mineralization.
基金the work of "Study of the geo-scientific settings of geo-tourist landscapes in Yuntaishan World Geopark",and supported by the Department of International Cooperation of Ministry of Science and Technology of China. (Grant No. 2006DFA21320)the Science Foundation of institute of geomechanics, CAGS (Grant No. DZLXJK200706) the National Natural Science Foundation of China (Grant No. 40501006)
文摘The late Cenozoic geomorphic features and geochronologic data of the Zhingfang River catchment in the Yuntaishan World Geopark are studied. Several quarternary geochronologic methods, including electron spin resonance (ESR), optically stimulated luminescence (OSL), thermo-luminescence (TL) and U-series are presented in this paper. The results suggest that there are two planation surfaces, named as the Taihang surface which is a peneplain of Taihang stage formed during Oligocene or Oligocene to early-middle Miocene period, and Tang-hien surface which is a mature wide valley of Tang-hien stage formed during late Miocene-Pliocene or Piiocene-early Pleistocene period and probably ended prior to 2.2-2.6 Ma based on ESR dating. After the Tang-hien stage, the incision and aggradation of the river formed six stream terraces with heights of 3-5 m, 8-12 m, 22-24 m, 28-38 m, 50-62 m and 80-85 m above the river bottom, respectively. The dating results of the alluvium sediments suggest that these terraces were formed during Holocene, 20-23 ka B.P., 110-120 ka B.P., 200-240 ka B.P., 840-1200 ka B.P. or ~450 ka B.P. and 1600-1800 ka B.P. or -1100 ka B.P., respectively. These results indicate that episodic incision of the river, which controls the formation of the scenery in the Yuntaishan World Geopark, was mainly influenced by the periodic dry-wet climate change during late Cenozoic mountain uplift.
文摘Several stratigraphic breaks and unconformities exist in the Mesoproterozoic successions in the northern margin of the North China Block. Geologic characters and spatial distributions of five of these un- conformities, which have resulted from different geological processes, have been studied. The uncon- formity beneath the Dahongyu Formation is interpreted as a breakup unconformity, representing the time of transition from continental rift to passive continental margin. The unconformities beneath the Gaoyuzhuang and the Yangzhuang formations are considered to be the consequence of regional eustatic fluctuations, leading to the exposure of highlands in passive margins during low sea-level stands and transgressive deposition on coastal regions during high sea-level stands. The unconformity atop the Tieling Formation might be caused by uplift due to contractional deformation in a back-arc setting, whereas the uplift after the deposition of the Xiamaling Formation might be attributed to a continental collision event. It is assumed that the occurrences of these unconformities in the Mesoproterozoic successions in the northern margin of the North China Block had a close bearing on the assemblage and breakup of the Columbia and Rodinia supercontinents.