The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncert...The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.展开更多
According to the survey data of meteorological disasters in the counties and the ground meteorological observation data of Xing'an League,a disaster risk index assessment model based on Arc GIS 10.3 was establishe...According to the survey data of meteorological disasters in the counties and the ground meteorological observation data of Xing'an League,a disaster risk index assessment model based on Arc GIS 10.3 was established taking hazard factors,hazard inducing environment,hazard-bearing body and disaster prevention and reduction capability into account.According to the degree of influence of each assessment factor,the risk coefficients of three meteorological disasters,drought,sand wind and frost were calculated,and risk zoning was conducted for various meteorological disasters.The results showed that among the major meteorological disasters in Xing'an League,drought had the highest risk degree,followed by frost,and sand wind had the lowest risk degree.In Xing'an League,the areas with high drought risk are mostly located in Aershan City and in the northwest of Horqin Right Wing Front Banner;the high-risk areas of sand wind are located in the north of Jalaid Banner,in the northwest and southeast of Tuquan County,and in the central and southeastern parts of the Horqin Right Wing Middle Banner;and the eastern part of Ulanhot,the southeastern part of Jalaid Banner,the southeastern part of Horqin Right Wing Middle Banner and the central part of Horqin Right Wing Front Banner are highly threatened by frost.The analysis results can provide some reference for disaster prevention and reduction and meteorological decision making in the local areas.展开更多
Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range(SGXR),NE China.Based on previously published geochronology and zircon Hf-isoto...Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range(SGXR),NE China.Based on previously published geochronology and zircon Hf-isotope data,Hf isotope mapping is undertaken to improve our understanding of crustal architecture and its controls on ore deposits.The ore-related Early Cretaceous granitoids were sourced predominantly from juvenile crust,with the involvement of variable proportions of ancient crustal materials.The crustal architecture,as inferred from Hf isotopic contour maps,indicates two distinct Hf isotopic domains in SGXR,including(1)a higher-ε_(Hf)(+7 to+11)juvenile crust containing minor ancient crustal material,and(2)a lower-ε_(Hf)(+2 to+6)juvenile crust containing a greater proportion of ancient crustal materials.The Hf isotopic maps identify links between crustal architecture and regional metallogeny.Copper deposits and other deposits with significant Cu production are restricted mainly to the higher-ε_(Hf)juvenile crustal regions in the northern and eastern SGXR.Deposits dominated by other metals(e.g.,Mo,Sn,W,Pb,Zn,and Ag)occur mainly in the lower-ε_(Hf)juvenile crustal regions in the southern and western SGXR.Interaction between juvenile crust-derived melts and ancient crustal components played an important role on the distribution of various ore metals.展开更多
The accelerated or decelerated freezingethawing processes of the active layer in Xing'an permafrost regions are crucial for the protection of permafrost.To better understand the freezingethawing processes of the a...The accelerated or decelerated freezingethawing processes of the active layer in Xing'an permafrost regions are crucial for the protection of permafrost.To better understand the freezingethawing processes of the active layer and its driving factors,according to the observation from 2017 to 2020 of soil temperature and water content in the active layer of forest and peatland in two representative hemiboreal ecosystems in the Da Xing'anling Mountains,Northeast China,the study explored in detail the effects of climatic conditions and local factors on the hydrothermal and freezingethawing processes of active layer soils.The results showed that during the freezingethawing cycles of 2017-2020,freezing and thawing start times in the peatland and forest ecosystems soils were generally delayed,and it took longer for the active layer soil to completely thaw than to freeze.The annual average soil temperature in the peatland's active layer(5-80 cm)was 0.7-2.0℃ lower than that in the forest,and the annual average soil moisture content on the peatland was 5.5%-26.7%higher than that in the forest.Compared with the forest ecosystem soils,the ground surface freezing time of the peatland was delayed by 3e10 d,and the freezing rate decreased by 1.1-1.5 cm d1,while the beginning time of thawing was advanced by 22-27 d,and the thawing rate decreased by 1.3-1.4 cm d^(-1).In the process of decreasing soil temperature and increasing soil moisture content,the freezing and thawing rate of the active layer would be reduced,decelerating the freezingethawing processes of the active layer in the process of decreasing soil temperature and increasing soil moisture content.The results provide the key original data for studying the formation and evolution of active layer and permafrost in the Xing'an permafrost regions in Northeast China and can be used to validate the prediction of ecosystem succession under the combined influences of climate change and permafrost degradation.展开更多
Located in the eastern portion of the Xing'an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high...Located in the eastern portion of the Xing'an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high metamorphic grade. Our filed observation, however, revealed that the complex is composed mainly of metamorphic rocks (Kele complex), tectono-schists (“Xinkailing Group”),and granitoids (Xinkailing granitic complex). Dating on these rocks using advanced SHRIMP zircon U-Pb technique indicates that: (1) Biotite-plagioclase gneiss from the Kele complex has a protolith age of 337±7Ma (2σ) and a metamorphic age of 216±3Ma (2σ); (2) the tectono-schist of the “Xinkailing Group” gave a magmatic age of 292±6Ma (2σ), indicative of felsic volcanic protolith of the schist formed in Late Paleozoic time; and (3) the Menluhedingzi and Lengchuan granites of the Xinkailing granitic complex were emplaced at167±4 (20σ) and 164±4Ma (2σ), respectively. These results suggest that the Xinkailing-Kele complex is not Precambrian metamorphic rocks and the so-called Precambrian “Nenji-ang Block” does essentially not exist. In combination with regional geological data, we propose that the Kele metamorphic complex is likely related to a collisional tectonism that took place in Triassic lime, as indicted by its metamorphic age of 216±3Ma. The Xinkailing granitic complex was emplaced along the collisional zone during Mid-Jurassic time,likely in a post-orogenic or anorogenic setting.展开更多
The formation time of the Fengshuigouhe (风水沟河) Group in the northwestern Lesser Xing'an Range (小兴安岭),NE China,remains controversial owing to the lake of the precise dating data.This article reports zircon ...The formation time of the Fengshuigouhe (风水沟河) Group in the northwestern Lesser Xing'an Range (小兴安岭),NE China,remains controversial owing to the lake of the precise dating data.This article reports zircon U-Pb ages for the leptynite and gneissic granitoids from the Fengshuigouhe Group in the northwestern Lesser Xing'an Range.The aim is to constrain the formation time and provenance of Fengshuigouhe Group.Field observation indicates that the Fengshuigouhe Group consists of a suit of metamorphic rocks (leptynite) and gneissic granitoids intruding the leptynite,and that both of them are cut by late granitic pegmatite.Zircons from two leptynites are euhedral-subhedral in shape and display oscillatory zoning in CL (cathodeluminescence) images.These detrital zircons give weighted mean ages of 255,291,321,361,469,and 520 Ma.The youngest age of them is interpreted to maximum depositional age of the protoliths of these leptynites.Zircons from gneissic granites are euhedral and subhedral in shape and exhibit typical oscillatory zoning in CL images.The dating results indicate that the gneissic granites were formed in the Early Jurassic (185±2 Ma).Zircons from the late granitic pegmatite are subhedral in shape and exhibit two types in CL images:structureless and oscillatory zoning.The former gives a weighted mean age of 143±1 Ma,considered to represent the timing of crystallization of the pegmatite,the latter yield several groups of ages:178,273,319,482,611,and 788 Ma,representing the crystallization age of inherited or captured zircons entrained by the pegmatite.Taken together,we conclude that the Fengshuigouhe Group in the northwestern Lesser Xing'an Range formed between Late Paleozoic (255 Ma) to Early Mesozoic (185 Ma),rather than Neoproterozoic as previously believed,and that the sediments in the Fengshuigouhe Group were sourced directly from geological bodies in the study area and adjacent regions.展开更多
基金financial support from the National Natural Science Foundation of China(Grant Nos.41802222 and 42002102)the China Geological Survey Program(Grant Nos.1212011220453,DD20190570,DD20221692,DD20230053 and DD20230355)+1 种基金the Key R&D and Promotion Projects in Henan Province(Grant No.212102310030)the Open Fund of Hubei Key Laboratory of Resources and Eco-Environment Geology(Grant No.KJ2022-35)。
文摘The southern Great Xing'an Range is the most critical Sn-polymetallic metallogenic belt in northeast China.However,the tectonic setting of the Early Cretaceous magmatic-metallogenic”flare-up“event remains uncertain.This paper presents an integrated study on the occurrence,petrology,zircon U-Pb ages,whole-rock geochemistry,and in situ zircon Hf isotopes for Wenduerchagan granites of Xi Ujimqin Banner,central-eastern Inner Mongolia.These granites consist primarily of granite porphyry(with ages of 137±1 Ma and 138±1 Ma)and(porphyritic)alkali feldspar granite(with an age of 141±2 Ma),corresponding to the early Early Cretaceous.They are A-type granites characterized by high silicon,alkali,and TFeO/MgO contents while being depleted of Ba,Nb,Ta,Sr,P,and Ti.They show right-dipping trend rare-earth element distribution characteristics with negative Eu anomalies(Eu/Eu^(*)=0.01-0.20)and weak heavy rare-earth element fractionation((Gd/Yb)_(N)=0.77-2.30).They demonstrate homogeneous zircon Hf isotopic compositions(positiveε_(Hf)(t)values from+5.3 to+7.1 and young two-stage Hf model ages of 851-742 Ma)and high zircon saturation temperatures(av.810℃).These geochemical characteristics indicate that Wenduerchagan granites originated from the partial melting of juvenile crust under high-temperature and low-pressure conditions.Wenduerchagan granites most likely formed in a post-collisional compression-extension transition regime caused by the closure of the Mongol-Okhotsk Ocean,when combined with regional geology.Such a transition regime can probably be attributed to the upwelling of the asthenospheric mantle caused by the break-off of a subducted Mongol-Okhotsk oceanic slab.Upwelling asthenospheric mantle provided sufficient energy and favorable tectonic conditions for magmatism and mineralization of the Early Cretaceous.
基金supported by the State Key Program of National Natural Science of China(grant no.40739905)Special Projects of Investigation and Evaluation of Countrywide Strategic Petroleum Area Selection(grant no.XQ-2007-07)+1 种基金Science and Technology Project of Sinopec(grant no.GO800-06)the Fund for Basic Scientific Research of the Institute of Geology,Chinese Academy of Geological Sciences(grant no.J0920)
文摘According to the survey data of meteorological disasters in the counties and the ground meteorological observation data of Xing'an League,a disaster risk index assessment model based on Arc GIS 10.3 was established taking hazard factors,hazard inducing environment,hazard-bearing body and disaster prevention and reduction capability into account.According to the degree of influence of each assessment factor,the risk coefficients of three meteorological disasters,drought,sand wind and frost were calculated,and risk zoning was conducted for various meteorological disasters.The results showed that among the major meteorological disasters in Xing'an League,drought had the highest risk degree,followed by frost,and sand wind had the lowest risk degree.In Xing'an League,the areas with high drought risk are mostly located in Aershan City and in the northwest of Horqin Right Wing Front Banner;the high-risk areas of sand wind are located in the north of Jalaid Banner,in the northwest and southeast of Tuquan County,and in the central and southeastern parts of the Horqin Right Wing Middle Banner;and the eastern part of Ulanhot,the southeastern part of Jalaid Banner,the southeastern part of Horqin Right Wing Middle Banner and the central part of Horqin Right Wing Front Banner are highly threatened by frost.The analysis results can provide some reference for disaster prevention and reduction and meteorological decision making in the local areas.
基金funded by the National Natural Science Foundation of China(No.41903043)China Postdoctoral Science Foundation(No.2018M642948)Program of China Geological Survey Bureau:1:50000 Regional Geological Survey of Tubuqin,Bayar Tuhushuo,Hadayingzi,Alahada,and Yidanjialaga in Inner Mongolia(No.DD20160048-15)。
文摘Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range(SGXR),NE China.Based on previously published geochronology and zircon Hf-isotope data,Hf isotope mapping is undertaken to improve our understanding of crustal architecture and its controls on ore deposits.The ore-related Early Cretaceous granitoids were sourced predominantly from juvenile crust,with the involvement of variable proportions of ancient crustal materials.The crustal architecture,as inferred from Hf isotopic contour maps,indicates two distinct Hf isotopic domains in SGXR,including(1)a higher-ε_(Hf)(+7 to+11)juvenile crust containing minor ancient crustal material,and(2)a lower-ε_(Hf)(+2 to+6)juvenile crust containing a greater proportion of ancient crustal materials.The Hf isotopic maps identify links between crustal architecture and regional metallogeny.Copper deposits and other deposits with significant Cu production are restricted mainly to the higher-ε_(Hf)juvenile crustal regions in the northern and eastern SGXR.Deposits dominated by other metals(e.g.,Mo,Sn,W,Pb,Zn,and Ag)occur mainly in the lower-ε_(Hf)juvenile crustal regions in the southern and western SGXR.Interaction between juvenile crust-derived melts and ancient crustal components played an important role on the distribution of various ore metals.
基金supported by the Key Joint Program of the National Natural Science Foundation of China(NSFC)and Heilongjiang Province for Regional Development(U20A2082)the National Natural Science Foundation of China(NSFC)(41971151,41901072 and 42271135)the Natural Science Foundation of Heilongjiang Province of China(TD2019D002)。
文摘The accelerated or decelerated freezingethawing processes of the active layer in Xing'an permafrost regions are crucial for the protection of permafrost.To better understand the freezingethawing processes of the active layer and its driving factors,according to the observation from 2017 to 2020 of soil temperature and water content in the active layer of forest and peatland in two representative hemiboreal ecosystems in the Da Xing'anling Mountains,Northeast China,the study explored in detail the effects of climatic conditions and local factors on the hydrothermal and freezingethawing processes of active layer soils.The results showed that during the freezingethawing cycles of 2017-2020,freezing and thawing start times in the peatland and forest ecosystems soils were generally delayed,and it took longer for the active layer soil to completely thaw than to freeze.The annual average soil temperature in the peatland's active layer(5-80 cm)was 0.7-2.0℃ lower than that in the forest,and the annual average soil moisture content on the peatland was 5.5%-26.7%higher than that in the forest.Compared with the forest ecosystem soils,the ground surface freezing time of the peatland was delayed by 3e10 d,and the freezing rate decreased by 1.1-1.5 cm d1,while the beginning time of thawing was advanced by 22-27 d,and the thawing rate decreased by 1.3-1.4 cm d^(-1).In the process of decreasing soil temperature and increasing soil moisture content,the freezing and thawing rate of the active layer would be reduced,decelerating the freezingethawing processes of the active layer in the process of decreasing soil temperature and increasing soil moisture content.The results provide the key original data for studying the formation and evolution of active layer and permafrost in the Xing'an permafrost regions in Northeast China and can be used to validate the prediction of ecosystem succession under the combined influences of climate change and permafrost degradation.
文摘Located in the eastern portion of the Xing'an-Mongolian Orogenic Belt (XMOB), the Xinkailing-Kele complex has previously been considered to be Precambrian metamorphic rocks, mainly according to its relatively high metamorphic grade. Our filed observation, however, revealed that the complex is composed mainly of metamorphic rocks (Kele complex), tectono-schists (“Xinkailing Group”),and granitoids (Xinkailing granitic complex). Dating on these rocks using advanced SHRIMP zircon U-Pb technique indicates that: (1) Biotite-plagioclase gneiss from the Kele complex has a protolith age of 337±7Ma (2σ) and a metamorphic age of 216±3Ma (2σ); (2) the tectono-schist of the “Xinkailing Group” gave a magmatic age of 292±6Ma (2σ), indicative of felsic volcanic protolith of the schist formed in Late Paleozoic time; and (3) the Menluhedingzi and Lengchuan granites of the Xinkailing granitic complex were emplaced at167±4 (20σ) and 164±4Ma (2σ), respectively. These results suggest that the Xinkailing-Kele complex is not Precambrian metamorphic rocks and the so-called Precambrian “Nenji-ang Block” does essentially not exist. In combination with regional geological data, we propose that the Kele metamorphic complex is likely related to a collisional tectonism that took place in Triassic lime, as indicted by its metamorphic age of 216±3Ma. The Xinkailing granitic complex was emplaced along the collisional zone during Mid-Jurassic time,likely in a post-orogenic or anorogenic setting.
基金supported by the National Natural Science Foundation of China(No.41072038)China Geological Survey(No.1212010070301)the Opening Foundation of the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan
文摘The formation time of the Fengshuigouhe (风水沟河) Group in the northwestern Lesser Xing'an Range (小兴安岭),NE China,remains controversial owing to the lake of the precise dating data.This article reports zircon U-Pb ages for the leptynite and gneissic granitoids from the Fengshuigouhe Group in the northwestern Lesser Xing'an Range.The aim is to constrain the formation time and provenance of Fengshuigouhe Group.Field observation indicates that the Fengshuigouhe Group consists of a suit of metamorphic rocks (leptynite) and gneissic granitoids intruding the leptynite,and that both of them are cut by late granitic pegmatite.Zircons from two leptynites are euhedral-subhedral in shape and display oscillatory zoning in CL (cathodeluminescence) images.These detrital zircons give weighted mean ages of 255,291,321,361,469,and 520 Ma.The youngest age of them is interpreted to maximum depositional age of the protoliths of these leptynites.Zircons from gneissic granites are euhedral and subhedral in shape and exhibit typical oscillatory zoning in CL images.The dating results indicate that the gneissic granites were formed in the Early Jurassic (185±2 Ma).Zircons from the late granitic pegmatite are subhedral in shape and exhibit two types in CL images:structureless and oscillatory zoning.The former gives a weighted mean age of 143±1 Ma,considered to represent the timing of crystallization of the pegmatite,the latter yield several groups of ages:178,273,319,482,611,and 788 Ma,representing the crystallization age of inherited or captured zircons entrained by the pegmatite.Taken together,we conclude that the Fengshuigouhe Group in the northwestern Lesser Xing'an Range formed between Late Paleozoic (255 Ma) to Early Mesozoic (185 Ma),rather than Neoproterozoic as previously believed,and that the sediments in the Fengshuigouhe Group were sourced directly from geological bodies in the study area and adjacent regions.