Sanjiang Plain of Heilongjiang Province has become an important commodity grain base in our country after the construction of more than a century. Groundwater is the main water source for industrial and agricultural p...Sanjiang Plain of Heilongjiang Province has become an important commodity grain base in our country after the construction of more than a century. Groundwater is the main water source for industrial and agricultural production and daily life in the area. With the large-scale development and construction in this area, there are a series of ecological and environmental geological problems, such as the reduction of groundwater resources, which seriously restricts the sustainable development of local agriculture and society as well as economy. Based on the characteristics of three-dimensional flowof groundwater in Sanjiang Plain, this paper adopts the simulation software Visual MODFLOW to evaluate groundwater exploitation potential. The results show that overall there is a certain exploitation potential of Sanjiang Plain groundwater but it is unevenly distributed, and overdraft phenomenon exists in seven farms such as Baoquanling and Chuangye. Based on analytic hierarchy process, the evaluation result of eco-geological environment quality in Sanjiang Plain shows that 94.5% of the region features good geological environment quality, medium stability and medium bearing capacity. The study can provide geological evidence for optimal allocation of water resources, land planning and regulation, and the high and stable yield of the commodity grain base in Sanjiang Plain.展开更多
Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenh...Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.展开更多
Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）....Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）. The results indicated that the soil organic carbon （SOC） storage in topsoil （0-0.2 m）, subsoil （0-1 m） and deep soil （0-1.8 m） was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km^2, 12,904.7 t/km^2 and 16,157.5 t/km^2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain （Liaoning）, to the middle （Jilin） and the northern Plain （Heilongjiang） -- particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/kin2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984--1986 （SNSS）, the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt （29.4%）, with an average annual decline of 16.0 Mt （1.73%） over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km^2, 1646.4 t/kin2 and 1300.2 t/km^2, respectively, with an average value of 1389.0 t/km^2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land-use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.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
In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatia...In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.展开更多
Early Ordovician A-type granites in the northeastern(NE) Songnen Block NE China were studied to better understand the geodynamic settings in this region.This research presents new zircon U–Pb ages and wholerock geoch...Early Ordovician A-type granites in the northeastern(NE) Songnen Block NE China were studied to better understand the geodynamic settings in this region.This research presents new zircon U–Pb ages and wholerock geochemical data for the Early Ordovician granites in the NE Songnen Block. Zircon U–Pb dating indicates that the granite in the Cuibei, Hongxing, and Meixi areas in the NE Songnen Block formed in the Early Ordovician with ages of 471–479 Ma. The granites show geochemical characteristics of high SiO2 and K2 O compositions and low FeOT, MgO, CaO, and P2 O5 compositions. They belong to a high K calc-alkaline series and display a weak peraluminous featurPe with A/CNK values of 0.98–1.14. The rocks have aREE composition of 249.98–423.94 ppm,and are enriched in LREE with(La/Yb)Nvalues of2.87–9.87, and display obvious Eu anomalies(d Eu =0.01–0.29). Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm,and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr +Y + Nb+Ce values(324–795 ppm) and Ga/Al ratios consistent with A-type granites. Based on particular geochemical features, such as high Rb/Nb(7.98–24.19) and Y/Nb(1.07–3.43), the studied A-type granites can be further classified as an A2-type subgroup. This research indicates that the Early Ordovician A-type granites were formed by the partial melting of ancient crust in an extensional setting. Lower Sr/Y and(Ho/Yb)Nratios indicate that plagioclase and amphibole are residual in the source, and garnet is absent, implying that the magma was generated at low levels of pressure. By contrast, the contemporaneous granites in the SE Xing'an Block suggest a subduction-related tectonic setting, and its adakitic property indicates a thickened continental crust.We suggest that the Paleo-Asian Ocean plate between the Xing'an and Songnen blocks subducted northward during the Early Ordovician. Meanwhile, the NE Songnen Block was exposed to a passive continental margin tectonic setting.展开更多
The Great Xing’an Range(GXAR)is one of the most important metallogenic belts in China.Previous study has shown that porphyry Cu-Mo deposit distributed in the northern Great Xing’an Range formed mainly in two stages:...The Great Xing’an Range(GXAR)is one of the most important metallogenic belts in China.Previous study has shown that porphyry Cu-Mo deposit distributed in the northern Great Xing’an Range formed mainly in two stages:(1)Early Ordovician,such as Duobaoshan and Tongshan deposits(Liu et al.,2017);2)Triassic-Early Jurassic,including Wunugetushan,Taipingchuan and Badaguan deposits(Tang et al.,2016).In recent years,two potential porphyry Cu-Mo deposits,Huoluotai and Xiaokele,were discovered in the Erguna Block,northern GXAR(Figs.1a–b).However,the ore formation ages and regional metallogenic regularity are ambiguous due to the lack of isotopic ages.Two zircon U-Pb ages from the ore-causative granites were reported in this paper,with the aims to constrain the metallogenic ages and provide evidence for study of the regional metallogenic regularity and ore prospect prediction.展开更多
This paper reports new geochronological(U-Pb) and isotope(C,O,and S) data to investigate the timing of mineralization and mode of ore genesis for the recently discovered Changtuxili Mn-Ag-Pb-Zn deposit,located on the ...This paper reports new geochronological(U-Pb) and isotope(C,O,and S) data to investigate the timing of mineralization and mode of ore genesis for the recently discovered Changtuxili Mn-Ag-Pb-Zn deposit,located on the western slopes of the southern Great Hinggan Range in NE China.The mineralization is hosted by intermediate-acidic lavas and pyroclastic rocks of the Baiyingaolao Formation.Three stages of mineralization are identified:quartz-pyrite(Stage I),galena-sphalerite-tetrahedrite-rhodochrosite(Stage II),and quartz-pyrite(Stage Ⅲ).δ13C and δ18O values for carbonate from the ore vary from-8.51‰ to-4.96‰ and 3.97‰ to 15.90‰,respectively,which are indicative of a low-temperature alteration environment.δ34SV-CDT values of sulfides range from-1.77‰ to 4.16‰ and show a trend of equilibrium fractionation(δ34SPy>δ34SSp>δ34SGn).These features indicate that pyrite,sphalerite,and galena precipitated during the period of mineralization.The alteration mineral assemblage and isotope data indicate that the weakly acidic to weakly alkaline ore-forming fluid was derived largely from meteoric water and the ore-forming elements C and S originated from magma.During the mineralization,a geochemical barrier was formed by changes in the pH of the ore-forming fluid,leading to the precipitation of rhodochrosite.On the basis of the mineralization characteristics,new isotope data,and comparison with adjacent deposits,we propose that the Changtuxili Mn-Ag-Pb-Zn deposit is an intermediate-to lowsulfidation epithermal deposit whose formation was controlled by fractures and variability in the pH of the oreforming fluid.The surrounding volcanic rocks yield zircon U-Pb ages of 160-146 Ma(Late Jurassic),indicating that the mineralization is younger than 146 Ma.展开更多
As the largest accretionary orogen, the crustal tectonic framework and evolution of the Central Asian Orogenic Belt(CAOB) have always been one of the hot topics among geologists(Seng?r et al., 1993, 1996;Jahn et al., ...As the largest accretionary orogen, the crustal tectonic framework and evolution of the Central Asian Orogenic Belt(CAOB) have always been one of the hot topics among geologists(Seng?r et al., 1993, 1996;Jahn et al., 2000 a;Badarch et al., 2002;Windley et al., 2007;Li et al., 2009). The formation of the main part of the crust in the CAOB involved continuous lateral accretion of island arcs and accretionary complexes along the margins of the Siberian, Sino-Korean and Tarim paleocontinents and the final collision between these continental margins because of the subduction of the Paleo-Asian Ocean plate since Mesoproterozoic. The ophiolites, which represent the fragments of ancient oceanic lithosphere, are the direct evidence for the study of the evolution of orogenic belts. Based on field geological survey, the mantle peridotite(serpentinite), gabbro, basalt and radiolarian bedded chert, which were deemed as the "ophiolite trinity", were identified as isolated blocks in the matrix of pelitic siltstone and silty mudstone in the Kedanshan, Xingshuwa and Jiujingzi areas along the Xar Monron River in southeast Inner Mongolia of China. Besides, there were plenty of other exotic blocks, such as limestone and sandstone, in the matrix. Both of the matrix and blocks underwent strong foliated deformation. All of these rocks above constitute a tectonic mélange. Zircon U-Pb dating for the gabbro blocks in the Xingshuwa and Jiujingzi ophiolites reveals that they were formed in early Permian(275-280 Ma). The ages of the gabbros, together with the middle Permian radiolaria fossils in the chert reported by Wang and Fan(1997), indicate that the oceanic basin was not closed in early-middle Permian. The geochemical compositions of the basaltic blocks distributed in different locations in the Xingshuwa tectonic mélange display different genetic types of normal mid-ocean ridge basalt(N-MORB), enriched mid-ocean ridge basalts(E-MORB), oceanic island basalt(OIB), island arc basalt and continental marginal arc basalt, which indicates what they represented is a complex oceanic basin. Combining with the studies on regional magmatism, strata and structure data, it is suggested that the Xar Moron River Ophiolite belt represented the final suture zone of the Paleo-Asian Ocean in the southeast Inner Mongolia, and the ocean did not close before late Permian.展开更多
文摘Sanjiang Plain of Heilongjiang Province has become an important commodity grain base in our country after the construction of more than a century. Groundwater is the main water source for industrial and agricultural production and daily life in the area. With the large-scale development and construction in this area, there are a series of ecological and environmental geological problems, such as the reduction of groundwater resources, which seriously restricts the sustainable development of local agriculture and society as well as economy. Based on the characteristics of three-dimensional flowof groundwater in Sanjiang Plain, this paper adopts the simulation software Visual MODFLOW to evaluate groundwater exploitation potential. The results show that overall there is a certain exploitation potential of Sanjiang Plain groundwater but it is unevenly distributed, and overdraft phenomenon exists in seven farms such as Baoquanling and Chuangye. Based on analytic hierarchy process, the evaluation result of eco-geological environment quality in Sanjiang Plain shows that 94.5% of the region features good geological environment quality, medium stability and medium bearing capacity. The study can provide geological evidence for optimal allocation of water resources, land planning and regulation, and the high and stable yield of the commodity grain base in Sanjiang Plain.
基金funded by Commonweal Trade Scientific Research from the Ministry of Land and Resources of the People's Republic of China
文摘Against the current background of global climate change, the study of variations in the soil carbon pool and its controlling factors may aid in the evaluation of soil＇s role in the mitigation or enhancement of greenhouse gas. This paper studies spatial and temporal variation in the soil carbon pool and their controlling factors in the southern Song-nen Plain in Heilongjiang Province, using soil data collected over two distinct periods by the Multi-purpose Regional Geochemical Survey in 2005-2007, and another soil survey conducted in 1982-1990. The study area is a carbon source of 1479 t/km2 and in the past 20 years, from the 1980s until 2005, the practical carbon emission from the soil was 0.12 Gt. Temperature, which has been found to be linearly correlated to soil organic carbon, is the domi- nant climatologic factor controlling soil organic carbon contents. Our study shows that in the relevant area and time period the potential loss of soil organic carbon caused by rising temperatures was 0.10 Gt, the potential soil carbon emission resulting from land-use change was 0.09 Gt, and the combined potential loss of soil carbon （0.19 Gt） caused by warming and land-use change is comparable to that of fossil fuel combustion （0.21 Gt）. Due to the time delay in soil carbon pool variation, there is still 0.07 Gt in the potential emission caused by warming and land-use change that will be gradually released in the future.
基金funded by the program"National Soil Current Situation Survey and Pollution Prevention"from the China Ministry of Finance
文摘Employing the Unit Soil Carbon Amount （USCA） approach, soil carbon storage was calcu- lated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004-2006 （MRGS）. The results indicated that the soil organic carbon （SOC） storage in topsoil （0-0.2 m）, subsoil （0-1 m） and deep soil （0-1.8 m） was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km^2, 12,904.7 t/km^2 and 16,157.5 t/km^2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain （Liaoning）, to the middle （Jilin） and the northern Plain （Heilongjiang） -- particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/kin2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984--1986 （SNSS）, the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt （29.4%）, with an average annual decline of 16.0 Mt （1.73%） over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km^2, 1646.4 t/kin2 and 1300.2 t/km^2, respectively, with an average value of 1389.0 t/km^2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land-use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC.
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.
基金supported by the regional geology and mineralization research program of Heilongjiang province (HLJKD201417)
文摘In this paper, we report new whole-rock geochemical and zircon U-Pb data for monzogranites in the NE Xing＇an block. These data constrained the petrogenesis of C type （high Sr/Y） adakitic rocks and showed the spatial extent of the influence of the Mongol-Okhostsk ocean tectonic regime and the collision between the Jiamusi Massif and Songliao Terrane. New zircon laser-ablation inductivity coupled plasma mass spectrometry （LA-ICP-MS） U-Pb data indicated that the monzogranites in the studied area were emplaced in the Early Jurassic （～ 180 Ma）. These rocks were characterized by unusally high SiO2 （≥67.49）, and Sr （461-759 ppm）, but strikingly low Y （4.63-8.06 ppm） and HREE （∑HREE = 3.83-6.49 ppm, Yb = 0.5-0.77 ppm） contents, with therefore high Sr/Y （67.2-119） and （La/Yb）N （29.7-41.5） ratios, showing the geochemical characteristics of C type adakitic granite. The data displayed negligible Eu anomalies （Eu/Eu^＊ =0.77-1.08）, LREE-enriched and pronounced negative Nb and Ta anomalies. The C-type adakites in the studied area were most likely derived from the partial melting of a thickened lower continental curst. The magma source is most likely dominated by amphibolites and garnet amphibolites. In combination with previously-reported data from igneous rocks from the Mesozoic in NE China, we conclude that the Xing＇ an block was influenced by the Mongol-Okhotsk subduction tectonic system, and experiences compressive settings from the amalgamation of the Jiamusi block in the east of the CAOB.
基金supported by the research program of Heilongjiang province (Nos. SDKC2017030 and HDKK201701)
文摘Early Ordovician A-type granites in the northeastern(NE) Songnen Block NE China were studied to better understand the geodynamic settings in this region.This research presents new zircon U–Pb ages and wholerock geochemical data for the Early Ordovician granites in the NE Songnen Block. Zircon U–Pb dating indicates that the granite in the Cuibei, Hongxing, and Meixi areas in the NE Songnen Block formed in the Early Ordovician with ages of 471–479 Ma. The granites show geochemical characteristics of high SiO2 and K2 O compositions and low FeOT, MgO, CaO, and P2 O5 compositions. They belong to a high K calc-alkaline series and display a weak peraluminous featurPe with A/CNK values of 0.98–1.14. The rocks have aREE composition of 249.98–423.94 ppm,and are enriched in LREE with(La/Yb)Nvalues of2.87–9.87, and display obvious Eu anomalies(d Eu =0.01–0.29). Trace elements of the studied granites are characterized by enrichment in Rb, Th, U, Pb, Hf, and Sm,and depletion of Ba, Nb, Ta, and Sr. They display geochemical features of high Zr +Y + Nb+Ce values(324–795 ppm) and Ga/Al ratios consistent with A-type granites. Based on particular geochemical features, such as high Rb/Nb(7.98–24.19) and Y/Nb(1.07–3.43), the studied A-type granites can be further classified as an A2-type subgroup. This research indicates that the Early Ordovician A-type granites were formed by the partial melting of ancient crust in an extensional setting. Lower Sr/Y and(Ho/Yb)Nratios indicate that plagioclase and amphibole are residual in the source, and garnet is absent, implying that the magma was generated at low levels of pressure. By contrast, the contemporaneous granites in the SE Xing'an Block suggest a subduction-related tectonic setting, and its adakitic property indicates a thickened continental crust.We suggest that the Paleo-Asian Ocean plate between the Xing'an and Songnen blocks subducted northward during the Early Ordovician. Meanwhile, the NE Songnen Block was exposed to a passive continental margin tectonic setting.
基金supported by the Land Research Project of Heilongjiang Province(grant No.201701)Innovation Fund of Heilongjiang Institute of Geological Survey(grant No.HDDK201806)
文摘The Great Xing’an Range(GXAR)is one of the most important metallogenic belts in China.Previous study has shown that porphyry Cu-Mo deposit distributed in the northern Great Xing’an Range formed mainly in two stages:(1)Early Ordovician,such as Duobaoshan and Tongshan deposits(Liu et al.,2017);2)Triassic-Early Jurassic,including Wunugetushan,Taipingchuan and Badaguan deposits(Tang et al.,2016).In recent years,two potential porphyry Cu-Mo deposits,Huoluotai and Xiaokele,were discovered in the Erguna Block,northern GXAR(Figs.1a–b).However,the ore formation ages and regional metallogenic regularity are ambiguous due to the lack of isotopic ages.Two zircon U-Pb ages from the ore-causative granites were reported in this paper,with the aims to constrain the metallogenic ages and provide evidence for study of the regional metallogenic regularity and ore prospect prediction.
基金This study was funded in part by the China Geological Survey(Grant Nos.DD20190075 and DD20160041).
文摘This paper reports new geochronological(U-Pb) and isotope(C,O,and S) data to investigate the timing of mineralization and mode of ore genesis for the recently discovered Changtuxili Mn-Ag-Pb-Zn deposit,located on the western slopes of the southern Great Hinggan Range in NE China.The mineralization is hosted by intermediate-acidic lavas and pyroclastic rocks of the Baiyingaolao Formation.Three stages of mineralization are identified:quartz-pyrite(Stage I),galena-sphalerite-tetrahedrite-rhodochrosite(Stage II),and quartz-pyrite(Stage Ⅲ).δ13C and δ18O values for carbonate from the ore vary from-8.51‰ to-4.96‰ and 3.97‰ to 15.90‰,respectively,which are indicative of a low-temperature alteration environment.δ34SV-CDT values of sulfides range from-1.77‰ to 4.16‰ and show a trend of equilibrium fractionation(δ34SPy>δ34SSp>δ34SGn).These features indicate that pyrite,sphalerite,and galena precipitated during the period of mineralization.The alteration mineral assemblage and isotope data indicate that the weakly acidic to weakly alkaline ore-forming fluid was derived largely from meteoric water and the ore-forming elements C and S originated from magma.During the mineralization,a geochemical barrier was formed by changes in the pH of the ore-forming fluid,leading to the precipitation of rhodochrosite.On the basis of the mineralization characteristics,new isotope data,and comparison with adjacent deposits,we propose that the Changtuxili Mn-Ag-Pb-Zn deposit is an intermediate-to lowsulfidation epithermal deposit whose formation was controlled by fractures and variability in the pH of the oreforming fluid.The surrounding volcanic rocks yield zircon U-Pb ages of 160-146 Ma(Late Jurassic),indicating that the mineralization is younger than 146 Ma.
基金granted by the National Key Research and Development Program of China from the Ministry of Science and Technology of China(No.2017YFC0601301)the National Natural Science Foundation of China(No.41472055)the China Geological Survey(Nos.DD20160201-01,DD20190004)
文摘As the largest accretionary orogen, the crustal tectonic framework and evolution of the Central Asian Orogenic Belt(CAOB) have always been one of the hot topics among geologists(Seng?r et al., 1993, 1996;Jahn et al., 2000 a;Badarch et al., 2002;Windley et al., 2007;Li et al., 2009). The formation of the main part of the crust in the CAOB involved continuous lateral accretion of island arcs and accretionary complexes along the margins of the Siberian, Sino-Korean and Tarim paleocontinents and the final collision between these continental margins because of the subduction of the Paleo-Asian Ocean plate since Mesoproterozoic. The ophiolites, which represent the fragments of ancient oceanic lithosphere, are the direct evidence for the study of the evolution of orogenic belts. Based on field geological survey, the mantle peridotite(serpentinite), gabbro, basalt and radiolarian bedded chert, which were deemed as the "ophiolite trinity", were identified as isolated blocks in the matrix of pelitic siltstone and silty mudstone in the Kedanshan, Xingshuwa and Jiujingzi areas along the Xar Monron River in southeast Inner Mongolia of China. Besides, there were plenty of other exotic blocks, such as limestone and sandstone, in the matrix. Both of the matrix and blocks underwent strong foliated deformation. All of these rocks above constitute a tectonic mélange. Zircon U-Pb dating for the gabbro blocks in the Xingshuwa and Jiujingzi ophiolites reveals that they were formed in early Permian(275-280 Ma). The ages of the gabbros, together with the middle Permian radiolaria fossils in the chert reported by Wang and Fan(1997), indicate that the oceanic basin was not closed in early-middle Permian. The geochemical compositions of the basaltic blocks distributed in different locations in the Xingshuwa tectonic mélange display different genetic types of normal mid-ocean ridge basalt(N-MORB), enriched mid-ocean ridge basalts(E-MORB), oceanic island basalt(OIB), island arc basalt and continental marginal arc basalt, which indicates what they represented is a complex oceanic basin. Combining with the studies on regional magmatism, strata and structure data, it is suggested that the Xar Moron River Ophiolite belt represented the final suture zone of the Paleo-Asian Ocean in the southeast Inner Mongolia, and the ocean did not close before late Permian.
