Devonian in the North Qilian orogenic belt and Hexi Corridor developed terrestrial molasse of later stage of foreland basin caused by collision between the North China plate and Qaidam microplate. The foreland basin t...Devonian in the North Qilian orogenic belt and Hexi Corridor developed terrestrial molasse of later stage of foreland basin caused by collision between the North China plate and Qaidam microplate. The foreland basin triggered a intense earthquake, and formed seismites and earthquake-related soft-sediment deformation. The soft-sediment deformation structures of Devonian in the eastern North Qilian Mts. consist of seismo-cracks, sandstone dykes, syn-depositional faults, microfoids (micro-corrugated lamination), fluidized veins, load casts, flame structures, pillow structures and brecciation. The seismo-cracks, syn-depositional faults and microfolds are cracks, faults and folds formed directly by oscillation of earthquake. The seismic dykes formed by sediment instilling into seismic cracks. Fluidized veins were made by instilling into the seismo-fissures of the fluidized sands. The load casts, flame structures and pillow structures were formed by sinking and instilling caused from oscillation of earthquake along the face between sandy and muddy beds. The brecciation resulted from the oscillation of earthquake and cracking of sedimentary layers. The seismites and soft-sediment deformations in Devonian triggered the earthquake related to tectonic activities during the orogeny and uplift of North Qilian Mts.展开更多
Air temperature is an important indicator to analyze climate change in mountainous areas.ERA5 reanalysis air temperature data are important products that were widely used to analyze temperature change in mountainous a...Air temperature is an important indicator to analyze climate change in mountainous areas.ERA5 reanalysis air temperature data are important products that were widely used to analyze temperature change in mountainous areas.However,the reliability of ERA5 reanalysis air temperature over the Qilian Mountains(QLM)is unclear.In this study,we evaluated the reliability of ERA5 monthly averaged reanalysis 2 m air temperature data using the observations at 17 meteorological stations in the QLM from 1979 to 2017.The results showed that:ERA5 reanalysis monthly averaged air temperature data have a good applicability in the QLM in general(R2=0.99).ERA5 reanalysis temperature data overestimated the observed temperature in the QLM in general.Root mean square error(RMSE)increases with the increasing of elevation range,showing that the reliability of ERA5 reanalysis temperature data is worse in higher elevation than that in lower altitude.ERA5 reanalysis temperature can capture observational warming rates well.All the smallest warming rates of observational temperature and ERA5 reanalysis temperature are found in winter,with the warming rates of 0.393°C/10a and 0.360°C/10a,respectively.This study will provide a reference for the application of ERA5 reanalysis monthly averaged air temperature data at different elevation ranges in the Qilian Mountains.展开更多
Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pang...Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pangea\|850), evolved through rift basin and became an archipelagic ocean in the Caledonian stage. The Lower Proterozoic strata in Qilian area are mid\|high\|rank metamorphic rocks that constitute the metamorphic basement of the area. The “Huangyuan Movement" (in South Qilian and Central Qilian) and "Alashan Movement" (in North Qilian) in the latest Late Proterozoic formed a regional unconformity. The middle Proterozoic in the area are mudstones and carbonate rocks with stromatolites and ooids. The Qingbaikou System of the upper Proterozoic in the North Qilian and Corridor region is also mudstone and carbonate rock with stromatolites. The Qingbaikou System in Central Qilian is sandstones and mudstones. There are alkaline and tholeiite in the Sinian System in North Qilian and Corridor. The contact between Qingbaikou System and Sinian System is a regional unconformity (Quanji Movement). Qilian ocean began to rift away in Caledonian tectonic stage on the Pre\|Sinian basement.展开更多
Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Q...Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.展开更多
Understanding temperature variability especially elevation dependent warming(EDW)in high-elevation mountain regions is critical for assessing the impacts of climate change on water resources including glacier melt,deg...Understanding temperature variability especially elevation dependent warming(EDW)in high-elevation mountain regions is critical for assessing the impacts of climate change on water resources including glacier melt,degradation of soils,and active layer thickness.EDW means that temperature is warming faster with the increase of altitude.In this study,we used observed temperature data during 1979-2017 from 23 meteorological stations in the Qilian Mountains(QLM)to analyze temperature trend with Mann-Kendall(MK)test and Sen’s slope approach.Results showed that the warming trends for the annual temperature followed the order of T_min>T_mean>T_max and with a shift both occurred in 1997.Spring and summer temperature have a higher increasing trend than that in autumn and winter.T_mean shifts occurred in 1996 for spring and summer,in 1997 for autumn and winter.T_max shifts occurred in 1997 for spring and 1996 for summer.T_min shifts occurred in 1997 for spring,summer and winter as well as in 1999 for autumn.Annual mean diurnal temperature range(DTR)shows a significant decreasing trend(-0.18°C/10a)from 1979 to 2017.Summer mean DTR shows a significant decreasing trend(-0.26°C/10a)from 1979 to 2017 with a shift occurred in 2010.After removing longitude and latitude factors,we can learn that the warming enhancement rate of average annual temperature is 0.0673°C/km/10a,indicating that the temperature warming trend is accelerating with the continuous increase of altitude.The increase rate of elevation temperature is 0.0371°C/km/10a in spring,0.0457°C/km/10a in summer,0.0707°C/km/10a in autumn,and 0.0606°C/km/10a in winter,which indicates that there is a clear EDW in the QLM.The main causes of warming in the Qilian Mountains are human activities,cloudiness,ice-snow feedback and El Nino phenomenon.展开更多
The Qilian Orogenic belt is one of the typical orogenic belts globally and a natural laboratory for studying plate tectonics.Many researchers have studied the ophiolite and high pressure and ultra-high pressure metamo...The Qilian Orogenic belt is one of the typical orogenic belts globally and a natural laboratory for studying plate tectonics.Many researchers have studied the ophiolite and high pressure and ultra-high pressure metamorphic rocks in the Qilian orogen and obtained valuable achievements.However,a hot debate exists on the basement property,the distribution of ophiolite,and the boundaries of tectonic units.Large-scale high-precision aeromagnetic surveys have recently been conducted in the Qilian Orogenic belt and adjacent areas.In this study,we are trying to analysis the tectonic framework of the Qilian Orogen using 1:500,000 aeromagnetic data.The results provide geophysical perspectives for studying the structural framework and deformation of this area.According to the aeromagnetic∆T anomaly map,the central and Southern Qilian have the same magnetic anomaly feature that noticeably differs from the North Qilian Orogenic belt and the Qaidam Block.This result indicates that the central and Southern Qilian have a unified magnetic basement and differ from the North Qilian orogenic belt and Qaidam Block.The map shows the distribution of ophiolite in the North Qilian orogenic belt.Linear magnetic anomalies represent the ophiolites because the mafic–ultramafic rocks usually have high magnetic susceptibility.The ophiolite belts are continuously distributed in the western part of North Qilian orogenic belt and have a large scale.However,the scale of the ophiolite belt and the outcropping of mafic–ultramafic rocks reduces when they pass through Qilian County to the east.The results indicate differences in the evolution process between the eastern and western parts of North Qilian,with Qilian County as the transition zone.This study also systematically defines the geophysical boundaries of the Qaidam Block,Qilian Block,North Qilian Orogenic belt,and Alxa block.It is proposed that the sinistral displacement of the Altun Fault is adjusted and absorbed by the series of NE-trending faults in the Qilian orogen and merge into the Longshoushan–Gushi Fault.The extension of the North Qilian Orogenic belt is strengthened by the neotectonics movement along the shearing direction,which separated the North Qilian Orogenic belt into several segments and formed a series of northeast-trending faults.展开更多
Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and sy...Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at423 ± 3 Ma and 432 ± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline series.Both are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.展开更多
Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identifi...Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identified in the North Qilian Orogenic Belt(NQOB).This paper reports an integrated study of petrology,whole-rock geochemistry,Sm-Nd isotope and zircon U-Pb dating,as well as Lu-Hf isotopic data,for two Early Devonian intrusive plutons.The Yongchang and Chijin granites yield zircon U-Pb ages of 394-407 Ma and 414 Ma,respectively.Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium-rich minerals,LREE-enriched patterns with negative Eu anomalies and a negative correlation between P_(2)O_(5) and SiO_(2) contents,consistent with geochemical features of I-type granitoids.Zircons from the studied granites display negative to weak positive ε_(Hf)(t)values(−5.7 to 2.1),which agree well with those of negative ε_(Nd)(t)values(−6.4 to−2.9)for the whole-rock samples,indicating that they were derived from the partial melting of Mesoproterozoic crust.Furthermore,low Sr/Y ratios(1.13-21.28)and high zircon saturation temperatures(745℃ to 839℃,with the majority being>800℃)demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source.Taken together,the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle-derived magmas at high-temperature and low-pressure conditions during postcollisional extensional collapse.The data obtained in this study,when viewed in conjunction with previous studies,provides more information about the tectonic processes that followed the closure of the North Qilian Ocean.The tectonic transition from continental collision to post-collisional delamination could be constrained to~430 Ma,which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon ε_(Hf)(t)values for granitoids.A two-stage tectonic evolution model from continental collision to post-collisional extensional collapse for the NQOB includes(a)continental collision and crustal thickening during ca.455-430 Ma,characterized by granulite-facies metamorphism and widespread low-Mg adakitic magmatism;(b)post-collisional delamination of thickened continental crust and extensional collapse of orogen during ca.430-390 Ma,provided by coeval high-Mg adakitic magmatism,A-type granites and I-type granitoids with low Sr-Y ratios.展开更多
The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition ...The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition from arc to initial collision.Here we present results from zircon U-Pb geochronology,whole-rock geochemistry,and Sr-Nd-Pb isotope geochemistry of the Beidaban granites to provide crucial information for geodynamic evolution of NQOB.Zircon U-Pb dating yields an age of 468±10 Ma for the Beidaban granites and most of the Beidaban samples contain amphibole,are potassium-rich,and have A/CNK values ranging from 0.7 to 0.9,illustrating that the Middle Ordovician Beidaban granites are K-rich,metaluminous,calc-alkaline granitoid.The geochemical characteristics indicate that the Beidaban granites are transitional I/S-type granitoids that formed in an arc setting.The isotopic compositions of initial(87 Sr/86 Sr)i values ranging from 0.70545 to 0.71082(0.70842 on average)andεNd(t)values ranging from−10.9 to−6.7(−8.8 on average)with two-stage Nd model ages(T DM2)of 1.74-2.08 Ga suggest that the Beidaban granites originated from Paleoproterozoic crustal materials.In addition,the initial Pb isotopic compositions(^(206)Pb/^(204)Pb=19.14-20.26;^(207)Pb/^(204)Pb=15.71-15.77;^(208)Pb/^(204)Pb=37.70-38.26)and geochemical features,such as high Th/Ta(17.43-30.12)and Rb/Nb(6.01-15.49)values,suggest that the Beidaban granite magma source involved recycled crustal components with igneous rocks.Based on these results in combination with previously published geochronological and geochemical data from other early Paleozoic igneous rocks,we suggest that the timing of the tectonic transition from arc to the initial collision to the fi nal closure of the North Qilian Ocean can be constrained to the Middle-Late Ordovician(ca.468–450 Ma).展开更多
The mining of limestone mines plays a crucial role in societal and economic advancement.However,mining activities have led to destructive variations in grassland ecology and soil,causing numerous environmental problem...The mining of limestone mines plays a crucial role in societal and economic advancement.However,mining activities have led to destructive variations in grassland ecology and soil,causing numerous environmental problems,and effective artificial restoration measures have been used to restore grasslands in the Shimenhe mining areas to different degrees.In this study,we investigated,examined and analyzed plant community structure and its correlation with soil properties across varying degrees of alpine grassland restoration in Qilian Mountains Shimenhe restoration mines using the sample method,and studied the changes in species diversity using five diversity indexes(Simpson index,Shannon index,Margalef index,Dominance index and Evenness index).This study showed that the plant community characteristics with high recovered degree(HRD)> middle recovered degree(MRD)> low recovered degree(LRD)> very low recovered degree(VLRD),11 plant genera comprising 11 species across 10 families were identified.Dominant families with robust ecological adaptability included Leguminosae,Rosaceae,Gramineae,Asteraceae,and Salicaceae.The highest Simpson,Shannon,Margalef and Evenness index of HRD grassland community species were 0.82,1.96,1.66 and 0.89,respectively.The highest Dominance index of VLRD grassland community species was 0.34,which required several restoration methods such as spraying and mulching.Soil pH and EC tended to decrease with increasing restoration,SOC,SMC,TP,AP,NH4-N,TN,AN and NO3-N tended to increase and the content of soil environmental factors contributed to vegetation growth across various restoration levels the mine grassland.In conclusion,our study indicated that the community structure gradually diversified and soil properties changed positively with the increase of restoration degrees in the Qilian Mountains Shimenhe mine,and the best results of HRD restoration were obtained.This study provides the theoretical basis for the restoration and conservation of grasslands in mining areas by demonstrating examined the correlation between plant characteristics and soil properties in restored grasslands in alpine mining areas.展开更多
The Qilian Mountains, a national key ecological function zone in Western China, play a pivotal role in ecosystem services. However, the distribution of its dominant tree species, Picea crassifolia (Qinghai spruce), ha...The Qilian Mountains, a national key ecological function zone in Western China, play a pivotal role in ecosystem services. However, the distribution of its dominant tree species, Picea crassifolia (Qinghai spruce), has decreased dramatically in the past decades due to climate change and human activity, which may have influenced its ecological functions. To restore its ecological functions, reasonable reforestation is the key measure. Many previous efforts have predicted the potential distribution of Picea crassifolia, which provides guidance on regional reforestation policy. However, all of them were performed at low spatial resolution, thus ignoring the natural characteristics of the patchy distribution of Picea crassifolia. Here, we modeled the distribution of Picea crassifolia with species distribution models at high spatial resolutions. For many models, the area under the receiver operating characteristic curve (AUC) is larger than 0.9, suggesting their excellent precision. The AUC of models at 30 m is higher than that of models at 90 m, and the current potential distribution of Picea crassifolia is more closely aligned with its actual distribution at 30 m, demonstrating that finer data resolution improves model performance. Besides, for models at 90 m resolution, annual precipitation (Bio12) played the paramount influence on the distribution of Picea crassifolia, while the aspect became the most important one at 30 m, indicating the crucial role of finer topographic data in modeling species with patchy distribution. The current distribution of Picea crassifolia was concentrated in the northern and central parts of the study area, and this pattern will be maintained under future scenarios, although some habitat loss in the central parts and gain in the eastern regions is expected owing to increasing temperatures and precipitation. Our findings can guide protective and restoration strategies for the Qilian Mountains, which would benefit regional ecological balance.展开更多
Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and c...Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and channels)of the catchment is assumed.This study focused on sediment connectivity analysis in the SlavíčRiver catchment in the MoravskoslezskéBeskydy Mts in the eastern part of the Czech Republic.The connectivity index and connectivity index target modelling were combined with an analysis of anthropogenic interventions.Additionally,field mapping,grain size of bed sediments and stream power analysis were used to obtain information about connectivity in the catchment.Based on the analysis and obtained results,terrain topography is the current main driving factor affecting the connectivity of sediment movement in the SlavíčRiver catchment.However,the modelling provided valuable information about high sediment connectivity despite different recent land use conditions(highly forested area of the catchment)than those in historical times from the 16th to 19th centuries when the SlavíčRiver catchment was highly deforested and sediment connectivity was probably higher.The analysis of anthropogenic interventions,field mapping,grain size of bed sediments and stream power analysis revealed more deceleration of sediment movement through the catchment,decreased sediment connectivity with bed erosion,and gradual river channel process transformation in some reaches.Field mapping has identified various natural formations and human-induced changes impacting the longitudinal and lateral connectivity in the SlavíčRiver.For instance,embankments along 48%of the river's length,both on the right and left banks,significantly hinder lateral sediment supply to the channel.Stream power index analysis indicates increased energy levels in the flowing water in the river's upper reaches(up to 404.8 W m^(-2)).This high energy is also observed in certain downstream sections(up to 337.6 W m^(-2)),where it is influenced by human activities.These conditions lead to intensified erosion processes,playing a crucial role in sediment connectivity.Similar observations were described in recent studies that pointed out the long-term human interventions on many streams draining European mountains,where a decrease in sediment connectivity in these streams is linked with sediment deficits and the transformation of processes forming channels.展开更多
基金supported by the National Natural Science Foundation of China(NO,40672080,40621002)the Program for Innovative Research Team in University of the Ministry of Education of China(IRT00546)"111 Project"(Grant No.B08030)
文摘Devonian in the North Qilian orogenic belt and Hexi Corridor developed terrestrial molasse of later stage of foreland basin caused by collision between the North China plate and Qaidam microplate. The foreland basin triggered a intense earthquake, and formed seismites and earthquake-related soft-sediment deformation. The soft-sediment deformation structures of Devonian in the eastern North Qilian Mts. consist of seismo-cracks, sandstone dykes, syn-depositional faults, microfoids (micro-corrugated lamination), fluidized veins, load casts, flame structures, pillow structures and brecciation. The seismo-cracks, syn-depositional faults and microfolds are cracks, faults and folds formed directly by oscillation of earthquake. The seismic dykes formed by sediment instilling into seismic cracks. Fluidized veins were made by instilling into the seismo-fissures of the fluidized sands. The load casts, flame structures and pillow structures were formed by sinking and instilling caused from oscillation of earthquake along the face between sandy and muddy beds. The brecciation resulted from the oscillation of earthquake and cracking of sedimentary layers. The seismites and soft-sediment deformations in Devonian triggered the earthquake related to tectonic activities during the orogeny and uplift of North Qilian Mts.
基金financially supported by the National Natural Science Foundation of China(No.41621001)。
文摘Air temperature is an important indicator to analyze climate change in mountainous areas.ERA5 reanalysis air temperature data are important products that were widely used to analyze temperature change in mountainous areas.However,the reliability of ERA5 reanalysis air temperature over the Qilian Mountains(QLM)is unclear.In this study,we evaluated the reliability of ERA5 monthly averaged reanalysis 2 m air temperature data using the observations at 17 meteorological stations in the QLM from 1979 to 2017.The results showed that:ERA5 reanalysis monthly averaged air temperature data have a good applicability in the QLM in general(R2=0.99).ERA5 reanalysis temperature data overestimated the observed temperature in the QLM in general.Root mean square error(RMSE)increases with the increasing of elevation range,showing that the reliability of ERA5 reanalysis temperature data is worse in higher elevation than that in lower altitude.ERA5 reanalysis temperature can capture observational warming rates well.All the smallest warming rates of observational temperature and ERA5 reanalysis temperature are found in winter,with the warming rates of 0.393°C/10a and 0.360°C/10a,respectively.This study will provide a reference for the application of ERA5 reanalysis monthly averaged air temperature data at different elevation ranges in the Qilian Mountains.
文摘Qilian orogenic belt is a typical orogenic belt formed by polycyclic collisions between the North China plate and Qaidam microplate. Qilian ocean originated from the rift of the late Proterozoic Rodinia continent(Pangea\|850), evolved through rift basin and became an archipelagic ocean in the Caledonian stage. The Lower Proterozoic strata in Qilian area are mid\|high\|rank metamorphic rocks that constitute the metamorphic basement of the area. The “Huangyuan Movement" (in South Qilian and Central Qilian) and "Alashan Movement" (in North Qilian) in the latest Late Proterozoic formed a regional unconformity. The middle Proterozoic in the area are mudstones and carbonate rocks with stromatolites and ooids. The Qingbaikou System of the upper Proterozoic in the North Qilian and Corridor region is also mudstone and carbonate rock with stromatolites. The Qingbaikou System in Central Qilian is sandstones and mudstones. There are alkaline and tholeiite in the Sinian System in North Qilian and Corridor. The contact between Qingbaikou System and Sinian System is a regional unconformity (Quanji Movement). Qilian ocean began to rift away in Caledonian tectonic stage on the Pre\|Sinian basement.
基金supported by Basic Research Operating Expenses of the Central level Non-profit Research Institutes (IDM2022003)National Natural Science Foundation of China (42375054)+2 种基金Regional collaborative innovation project of Xinjiang (2021E01022,2022E01045)Young Meteorological Talent Program of China Meteorological Administration,Tianshan Talent Program of Xinjiang (2022TSYCCX0003)Youth Innovation Team of China Meteorological Administration (CMA2023QN08).
文摘Tree radial growth can have significantly differ-ent responses to climate change depending on the environ-ment.To elucidate the effects of climate on radial growth and stable carbon isotope(δ^(13)C)fractionation of Qing-hai spruce(Picea crassifolia),a widely distributed native conifer in northwestern China in different environments,we developed chronologies for tree-ring widths and δ^(13)C in trees on the southern and northern slopes of the Qilian Mountains,and analysed the relationship between these tree-ring variables and major climatic factors.Tree-ring widths were strongly influenced by climatic factors early in the growing season,and the radial growth in trees on the northern slopes was more sensitive to climate than in trees on the southern.Tree-ring δ^(13)C was more sensitive to climate than radial growth.δ^(13)C fractionation was mainly influenced by summer temperature and precipitation early in the growing season.Stomatal conductance more strongly limited stable carbon isotope fractionation in tree rings than photosynthetic rate did.The response between tree rings and climate in mountains gradually weakened as climate warmed.Changes in radial growth and stable carbon isotope fractionation of P.crassifolia in response to climate in the Qilian Mountains may be further complicated by continued climate change.
基金financially supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA23060301)the National Natural Science Foundation of China(No.41621001).
文摘Understanding temperature variability especially elevation dependent warming(EDW)in high-elevation mountain regions is critical for assessing the impacts of climate change on water resources including glacier melt,degradation of soils,and active layer thickness.EDW means that temperature is warming faster with the increase of altitude.In this study,we used observed temperature data during 1979-2017 from 23 meteorological stations in the Qilian Mountains(QLM)to analyze temperature trend with Mann-Kendall(MK)test and Sen’s slope approach.Results showed that the warming trends for the annual temperature followed the order of T_min>T_mean>T_max and with a shift both occurred in 1997.Spring and summer temperature have a higher increasing trend than that in autumn and winter.T_mean shifts occurred in 1996 for spring and summer,in 1997 for autumn and winter.T_max shifts occurred in 1997 for spring and 1996 for summer.T_min shifts occurred in 1997 for spring,summer and winter as well as in 1999 for autumn.Annual mean diurnal temperature range(DTR)shows a significant decreasing trend(-0.18°C/10a)from 1979 to 2017.Summer mean DTR shows a significant decreasing trend(-0.26°C/10a)from 1979 to 2017 with a shift occurred in 2010.After removing longitude and latitude factors,we can learn that the warming enhancement rate of average annual temperature is 0.0673°C/km/10a,indicating that the temperature warming trend is accelerating with the continuous increase of altitude.The increase rate of elevation temperature is 0.0371°C/km/10a in spring,0.0457°C/km/10a in summer,0.0707°C/km/10a in autumn,and 0.0606°C/km/10a in winter,which indicates that there is a clear EDW in the QLM.The main causes of warming in the Qilian Mountains are human activities,cloudiness,ice-snow feedback and El Nino phenomenon.
基金supported by the National Natural Science Foundation of China grant(U2244220)China Geological Survey Project grant(DD20190551,DD20230351)。
文摘The Qilian Orogenic belt is one of the typical orogenic belts globally and a natural laboratory for studying plate tectonics.Many researchers have studied the ophiolite and high pressure and ultra-high pressure metamorphic rocks in the Qilian orogen and obtained valuable achievements.However,a hot debate exists on the basement property,the distribution of ophiolite,and the boundaries of tectonic units.Large-scale high-precision aeromagnetic surveys have recently been conducted in the Qilian Orogenic belt and adjacent areas.In this study,we are trying to analysis the tectonic framework of the Qilian Orogen using 1:500,000 aeromagnetic data.The results provide geophysical perspectives for studying the structural framework and deformation of this area.According to the aeromagnetic∆T anomaly map,the central and Southern Qilian have the same magnetic anomaly feature that noticeably differs from the North Qilian Orogenic belt and the Qaidam Block.This result indicates that the central and Southern Qilian have a unified magnetic basement and differ from the North Qilian orogenic belt and Qaidam Block.The map shows the distribution of ophiolite in the North Qilian orogenic belt.Linear magnetic anomalies represent the ophiolites because the mafic–ultramafic rocks usually have high magnetic susceptibility.The ophiolite belts are continuously distributed in the western part of North Qilian orogenic belt and have a large scale.However,the scale of the ophiolite belt and the outcropping of mafic–ultramafic rocks reduces when they pass through Qilian County to the east.The results indicate differences in the evolution process between the eastern and western parts of North Qilian,with Qilian County as the transition zone.This study also systematically defines the geophysical boundaries of the Qaidam Block,Qilian Block,North Qilian Orogenic belt,and Alxa block.It is proposed that the sinistral displacement of the Altun Fault is adjusted and absorbed by the series of NE-trending faults in the Qilian orogen and merge into the Longshoushan–Gushi Fault.The extension of the North Qilian Orogenic belt is strengthened by the neotectonics movement along the shearing direction,which separated the North Qilian Orogenic belt into several segments and formed a series of northeast-trending faults.
基金funded by Gansu Provincial Natural Science Foundation (Grant Numbers 21JR7RA503 and22JR5RA819)the Fundamental Research Funds for the Central Universities (Grant lzujbky-2021-ct07)+1 种基金the Key Talent Project of Gansu Province (2022-Yangzhenxi)the National Second Expedition to the Tibetan Plateau (2019QZKK0704)。
文摘Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at423 ± 3 Ma and 432 ± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline series.Both are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.
基金supported by the Natural Science Foundation of Shandong Province(Grant No.ZR2022QD055)the Taishan Scholars(Grant No.tstp 20231214)the National Natural Science Foundation of China(Grant No.42372247).
文摘Post-collisional magmatism contains important clues for understanding the reworking and growth of continental crust,as well as lithospheric delamination and orogenic collapse.Early Devonian magmatism has been identified in the North Qilian Orogenic Belt(NQOB).This paper reports an integrated study of petrology,whole-rock geochemistry,Sm-Nd isotope and zircon U-Pb dating,as well as Lu-Hf isotopic data,for two Early Devonian intrusive plutons.The Yongchang and Chijin granites yield zircon U-Pb ages of 394-407 Ma and 414 Ma,respectively.Both of them are characterized by weakly peraluminous to metaluminous without typical aluminium-rich minerals,LREE-enriched patterns with negative Eu anomalies and a negative correlation between P_(2)O_(5) and SiO_(2) contents,consistent with geochemical features of I-type granitoids.Zircons from the studied granites display negative to weak positive ε_(Hf)(t)values(−5.7 to 2.1),which agree well with those of negative ε_(Nd)(t)values(−6.4 to−2.9)for the whole-rock samples,indicating that they were derived from the partial melting of Mesoproterozoic crust.Furthermore,low Sr/Y ratios(1.13-21.28)and high zircon saturation temperatures(745℃ to 839℃,with the majority being>800℃)demonstrated a relatively shallow depth level below the garnet stability field and an additional heat source.Taken together,the Early Devonian granitic magmatism could have been produced by the partial melting of ancient crustal materials heated by mantle-derived magmas at high-temperature and low-pressure conditions during postcollisional extensional collapse.The data obtained in this study,when viewed in conjunction with previous studies,provides more information about the tectonic processes that followed the closure of the North Qilian Ocean.The tectonic transition from continental collision to post-collisional delamination could be constrained to~430 Ma,which is provided by the sudden decrease of Sr/Y and La/Yb ratios and an increase in zircon ε_(Hf)(t)values for granitoids.A two-stage tectonic evolution model from continental collision to post-collisional extensional collapse for the NQOB includes(a)continental collision and crustal thickening during ca.455-430 Ma,characterized by granulite-facies metamorphism and widespread low-Mg adakitic magmatism;(b)post-collisional delamination of thickened continental crust and extensional collapse of orogen during ca.430-390 Ma,provided by coeval high-Mg adakitic magmatism,A-type granites and I-type granitoids with low Sr-Y ratios.
基金This study was fi nancially supported by the Youth Science and Technology Talent Recruitment Project of Gansu Province(2022-19)Technological Innovation Project of Gansu Provincial Department of Natural Resources(2022-3,2022-4,2022-28)+2 种基金National Natural Science Foundation of China(Nos.42073059 and 42303034)Outstanding Youth Fund of Anhui Provincial Department of Education(No.2022AH020084)Doctoral Startup Foundation of Suzhou University(2021BSK038)。
文摘The tectonic evolution and crustal accretion process of the North Qilian Orogenic Belt(NQOB)are still under debate because of a lack of integrated constraints,especially the identifi cation of the tectonic transition from arc to initial collision.Here we present results from zircon U-Pb geochronology,whole-rock geochemistry,and Sr-Nd-Pb isotope geochemistry of the Beidaban granites to provide crucial information for geodynamic evolution of NQOB.Zircon U-Pb dating yields an age of 468±10 Ma for the Beidaban granites and most of the Beidaban samples contain amphibole,are potassium-rich,and have A/CNK values ranging from 0.7 to 0.9,illustrating that the Middle Ordovician Beidaban granites are K-rich,metaluminous,calc-alkaline granitoid.The geochemical characteristics indicate that the Beidaban granites are transitional I/S-type granitoids that formed in an arc setting.The isotopic compositions of initial(87 Sr/86 Sr)i values ranging from 0.70545 to 0.71082(0.70842 on average)andεNd(t)values ranging from−10.9 to−6.7(−8.8 on average)with two-stage Nd model ages(T DM2)of 1.74-2.08 Ga suggest that the Beidaban granites originated from Paleoproterozoic crustal materials.In addition,the initial Pb isotopic compositions(^(206)Pb/^(204)Pb=19.14-20.26;^(207)Pb/^(204)Pb=15.71-15.77;^(208)Pb/^(204)Pb=37.70-38.26)and geochemical features,such as high Th/Ta(17.43-30.12)and Rb/Nb(6.01-15.49)values,suggest that the Beidaban granite magma source involved recycled crustal components with igneous rocks.Based on these results in combination with previously published geochronological and geochemical data from other early Paleozoic igneous rocks,we suggest that the timing of the tectonic transition from arc to the initial collision to the fi nal closure of the North Qilian Ocean can be constrained to the Middle-Late Ordovician(ca.468–450 Ma).
基金supported by the National Key R&D Program of China (Nos. 2022YFF1303301, 2022YFF1302603)the National Natural Science Foundation of China (Nos. 52179026, 42001035, 42101115)+5 种基金the Science and Technology Program of Gansu Province (Nos. 22JR5RA072, 22JR5RA068)the Postdoctoral Funding Program of Gansu Province (No. E339880139)the Natural Science Foundation of Gansu Province (No. E331040901)the Science and Technology Fund of Gansu Province (No. 23JRRA640)the Consulting and Research Project of the Gansu Research Institute of Chinese Engineering Science and Technology Development Strategy (No. GS2022ZDI03)the Open Fund of Technology Innovation Center for Mine Geological Environment Restoration in the Alpine and Arid Regions (No. HHGCKK2204)
文摘The mining of limestone mines plays a crucial role in societal and economic advancement.However,mining activities have led to destructive variations in grassland ecology and soil,causing numerous environmental problems,and effective artificial restoration measures have been used to restore grasslands in the Shimenhe mining areas to different degrees.In this study,we investigated,examined and analyzed plant community structure and its correlation with soil properties across varying degrees of alpine grassland restoration in Qilian Mountains Shimenhe restoration mines using the sample method,and studied the changes in species diversity using five diversity indexes(Simpson index,Shannon index,Margalef index,Dominance index and Evenness index).This study showed that the plant community characteristics with high recovered degree(HRD)> middle recovered degree(MRD)> low recovered degree(LRD)> very low recovered degree(VLRD),11 plant genera comprising 11 species across 10 families were identified.Dominant families with robust ecological adaptability included Leguminosae,Rosaceae,Gramineae,Asteraceae,and Salicaceae.The highest Simpson,Shannon,Margalef and Evenness index of HRD grassland community species were 0.82,1.96,1.66 and 0.89,respectively.The highest Dominance index of VLRD grassland community species was 0.34,which required several restoration methods such as spraying and mulching.Soil pH and EC tended to decrease with increasing restoration,SOC,SMC,TP,AP,NH4-N,TN,AN and NO3-N tended to increase and the content of soil environmental factors contributed to vegetation growth across various restoration levels the mine grassland.In conclusion,our study indicated that the community structure gradually diversified and soil properties changed positively with the increase of restoration degrees in the Qilian Mountains Shimenhe mine,and the best results of HRD restoration were obtained.This study provides the theoretical basis for the restoration and conservation of grasslands in mining areas by demonstrating examined the correlation between plant characteristics and soil properties in restored grasslands in alpine mining areas.
基金supported by the National Natural Science Foundation of China(No.42071057).
文摘The Qilian Mountains, a national key ecological function zone in Western China, play a pivotal role in ecosystem services. However, the distribution of its dominant tree species, Picea crassifolia (Qinghai spruce), has decreased dramatically in the past decades due to climate change and human activity, which may have influenced its ecological functions. To restore its ecological functions, reasonable reforestation is the key measure. Many previous efforts have predicted the potential distribution of Picea crassifolia, which provides guidance on regional reforestation policy. However, all of them were performed at low spatial resolution, thus ignoring the natural characteristics of the patchy distribution of Picea crassifolia. Here, we modeled the distribution of Picea crassifolia with species distribution models at high spatial resolutions. For many models, the area under the receiver operating characteristic curve (AUC) is larger than 0.9, suggesting their excellent precision. The AUC of models at 30 m is higher than that of models at 90 m, and the current potential distribution of Picea crassifolia is more closely aligned with its actual distribution at 30 m, demonstrating that finer data resolution improves model performance. Besides, for models at 90 m resolution, annual precipitation (Bio12) played the paramount influence on the distribution of Picea crassifolia, while the aspect became the most important one at 30 m, indicating the crucial role of finer topographic data in modeling species with patchy distribution. The current distribution of Picea crassifolia was concentrated in the northern and central parts of the study area, and this pattern will be maintained under future scenarios, although some habitat loss in the central parts and gain in the eastern regions is expected owing to increasing temperatures and precipitation. Our findings can guide protective and restoration strategies for the Qilian Mountains, which would benefit regional ecological balance.
基金supported by an internal grant of the University of Ostrava[SGS10/PřF/2021-Specificity of fluvial landscape in the context of historical and future changes].
文摘Mountain streams act as conveyors of sediments within the river continuum,where the physical transport of sediments between river reaches through the catchment or between individual parts(e.g.,between hillslopes and channels)of the catchment is assumed.This study focused on sediment connectivity analysis in the SlavíčRiver catchment in the MoravskoslezskéBeskydy Mts in the eastern part of the Czech Republic.The connectivity index and connectivity index target modelling were combined with an analysis of anthropogenic interventions.Additionally,field mapping,grain size of bed sediments and stream power analysis were used to obtain information about connectivity in the catchment.Based on the analysis and obtained results,terrain topography is the current main driving factor affecting the connectivity of sediment movement in the SlavíčRiver catchment.However,the modelling provided valuable information about high sediment connectivity despite different recent land use conditions(highly forested area of the catchment)than those in historical times from the 16th to 19th centuries when the SlavíčRiver catchment was highly deforested and sediment connectivity was probably higher.The analysis of anthropogenic interventions,field mapping,grain size of bed sediments and stream power analysis revealed more deceleration of sediment movement through the catchment,decreased sediment connectivity with bed erosion,and gradual river channel process transformation in some reaches.Field mapping has identified various natural formations and human-induced changes impacting the longitudinal and lateral connectivity in the SlavíčRiver.For instance,embankments along 48%of the river's length,both on the right and left banks,significantly hinder lateral sediment supply to the channel.Stream power index analysis indicates increased energy levels in the flowing water in the river's upper reaches(up to 404.8 W m^(-2)).This high energy is also observed in certain downstream sections(up to 337.6 W m^(-2)),where it is influenced by human activities.These conditions lead to intensified erosion processes,playing a crucial role in sediment connectivity.Similar observations were described in recent studies that pointed out the long-term human interventions on many streams draining European mountains,where a decrease in sediment connectivity in these streams is linked with sediment deficits and the transformation of processes forming channels.