The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past.Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau.The first integrated scienti...The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past.Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau.The first integrated scientific investigation to the desert was carried out during the period of 2004-2006.Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed.The integrated field investigation and studies on sedimentary,chronology and palynology of typical profiles named Suosuo gully,Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP.During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP,the desert largely expanded and formed its modern distribution pattern.The desert was originally developed in the southwest,subsequently,expanded to the north and northeast.The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary.The neotectonic movements played an important role in the formation,development and geomorphology of the desert.On one hand,the movements caused the formation of intermontane fault basin,which was further developed towards the closed drought basin,and caused the formation of natural environment.On the other hand,under the control of surrounding faults,the unique broom-shaped desert landscape was formed,and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45＇-39°55＇N.The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP.The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China,and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.展开更多
The seif dune field over the gravel desert surface in the eastern margin of the Kumtagh Desert is a valuable experimental site for the observation of dune formation and dynamics.We used high-resolution remote sensing ...The seif dune field over the gravel desert surface in the eastern margin of the Kumtagh Desert is a valuable experimental site for the observation of dune formation and dynamics.We used high-resolution remote sensing and station observation approaches,combined with wind and grain size data,to study the characteristics of the aeolian environment and the morphologies of and dynamic changes in seif dunes.We observed the ratio of the resultant drift potential(RDP)to the drift potential(DP),which was 0.37,associated with an obtuse bimodal wind regime.The drift potentials in the west-northwest(WNW)and east-northeast(ENE)directions were dominant,and the angle between the two primary DP directions was 135.00°.The dune orientations ranged from 168.75°-213.75°,which were parallel to the resultant drift direction(186.15°).The dune lengths ranged from 51.68 to 1932.1 m with a mean value of 344.91 m.The spacings of the dunes ranged from 32.34 to 319.77 m with a mean value of 93.39 m.The mean grain size of the sediments became finer,and the sorting became better from upwind tail to downwind tip,which indicated that the sediment of the seif dunes in the study region may be transported from northward to southward.The rate of increase in the length,the mean longitudinal migration rate of the dune tail,and the mean longitudinal extension rate of the dune tip(also called elongation rate)were 4.93,4.63,and 9.55 m/a,respectively.The mean lateral migration vector of the seif dunes was approximately 0.11 m/a towards the west(-0.11 m/a),while the mean amplitude of lateral migration was 0.53 m/a,ignoring the direction of lateral migration.We found that the seif dune field formed first beside seasonal rivers,which can provide sediment,and then expanded downwind.展开更多
Tourism development of aeolian geomorphosites in the Kumtagh Desert is beneficial to both harmonious development of human-nature relationship and the sustainable development of the tourist industry in the Kumtagh Dese...Tourism development of aeolian geomorphosites in the Kumtagh Desert is beneficial to both harmonious development of human-nature relationship and the sustainable development of the tourist industry in the Kumtagh Desert and its sur- rounding area. This paper adopts some research methods including field observation, expert assessment, and systematic investigation to analyze and evaluate the aesthetic value of aeolian geomorphosites in the Kumtagh Desert from three aspects of＂Beauty of Morphology＂, ＂Beauty of Color＂ and ＂Beauty of Forms＂. This research is a creative work in the field of aeolian geomorphosites combining the method of aeolian geomorphology and tourism geography.展开更多
Kumtagh Desert is one of the eight biggest deserts in China, but poorly investigated before our interdisciplinary study because of the difficulty of access. In this paper, 33 representative surface sediment samples we...Kumtagh Desert is one of the eight biggest deserts in China, but poorly investigated before our interdisciplinary study because of the difficulty of access. In this paper, 33 representative surface sediment samples were collected from the Kumtagh Desert and analyzed in the laboratory to obtain heavy mineral components and geochemical element contents. Results show that various kinds of heavy minerals are present in these samples, with high levels of epidote and hornblende. Si and AI take up a large part of chemical composition. Compared with the average composition of geochemical elements of the upper continental crust （UCC）, except Si and Ca, all elements are depleted to a certain degree; Fe, Mg, Ca, P, Ti and Mn have high correlation coefficients in their contents. The mineral and geochemical composition of the Kumtagh Desert sediments have a similarity with that of rocks of Altyn Tagh Mountains, and the surface sediments of the alluvial/diluvial fans around the Altyn Tagh Mountains and that of the Taklamakan Desert, indicating that one major source of the Kumtagh Desert sediments is located in the Altyn Tagh Mountains. Alluvial deposits and lake sediments in Aqik valley and lower reaches of Shule River are prone to be eroded and transported by the strong northeasterly wind into the Kumtagh Desert, forming another source of the desert deposits. An A-CN-K ternary diagram shows that a weak degree chemical weathering by the loss of Na and K occurred in these sediments, whereas A-CNK-FM ternary diagram suggests that Fe and Mg have undergone a significant chemical differentiation. Physical weathering processes cause easy erosion and enrichment in fine particles for mafic minerals, thus coarse desert sand particles can be relatively depleted in Fe and Mg. The mineral and geochemical composition of sediments in arid regions experiencing less chemical weathering are mostly affected by physical weathering.展开更多
Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and alb...Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and albedo between crescent sand ridges and tongue-shaped dunes,and between windward and leeward slopes of tongue-shaped dunes,result in their feathery appearance in aerial and satellite imagery.Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors;i.e.north-northeasterly,easterly and east-northeasterly sectors roughly corresponding to the southeast,northwest and southwest slip faces.Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones.Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types.According to McKee's dune shape classification,the feathered sand ridges are not a deformation dune type but a complex one.According to Wu's dune morphological and genetic classification,they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle,but are complex dune ridges that form under the action of three winds intersecting at an acute angle.展开更多
库姆塔格沙漠腹地广泛出露含古风成砂的第四纪地层剖面。根据含古风成砂地层剖面的野外调查与地层年代的室内分析结果,并与已有的周边区域地质资料对比分析,库姆塔格沙漠形成至少始于早更新世初,到中更新世晚期285.9±42.9 ka BP沙...库姆塔格沙漠腹地广泛出露含古风成砂的第四纪地层剖面。根据含古风成砂地层剖面的野外调查与地层年代的室内分析结果,并与已有的周边区域地质资料对比分析,库姆塔格沙漠形成至少始于早更新世初,到中更新世晚期285.9±42.9 ka BP沙漠已大面积扩展形成,奠定了现代沙漠环境格局。沙漠最初从西南部开始形成,之后向北和东北扩展。依据梭梭沟地层剖面,沙漠在第四纪演化过程中至少经历了19个沙漠正、逆过程旋回,平均周期约为110 ka。新构造运动对沙漠的形成演化和地貌的形成发育具有重要作用,构造了山间断陷盆地并使其逐渐向封闭的干旱盆地演化形成沙漠,受四周断裂控制沙漠整体形态呈"扫帚状"。分布在沙漠北部的独特砾石体地貌形成于晚更新世末(285.9±42.9)ka BP之后。展开更多
基金supported by Natural Science Foundation of Gansu Province (0803RJZH086)National Natural Science Foundation of China (40961013)
文摘The ancient aeolian sand has been regarded as an indicator for the formation and evolution of a desert in the past.Kumtagh Desert is located at the northern fringe of Qinghai-Tibet Plateau.The first integrated scientific investigation to the desert was carried out during the period of 2004-2006.Kumtagh Desert is an ideal natural model for studying the formation and evolution of the desert because the Quaternary strata containing ancient aeolian sands are widely distributed.The integrated field investigation and studies on sedimentary,chronology and palynology of typical profiles named Suosuo gully,Xiaoquan gully and gravel body with ancient aeolian sand layers showed that Kumtagh Desert was probably formed as early as 2,097.7±314.7 ka BP.During the period of 386.9±58.0 ka BP to 285.9±42.9 ka BP,the desert largely expanded and formed its modern distribution pattern.The desert was originally developed in the southwest,subsequently,expanded to the north and northeast.The sedimentary facies of Suosuo gully profile revealed that the desert experienced at least 19 cycles of advance and inverse processes of desertification with an average period of 110 ka in the Quaternary.The neotectonic movements played an important role in the formation,development and geomorphology of the desert.On one hand,the movements caused the formation of intermontane fault basin,which was further developed towards the closed drought basin,and caused the formation of natural environment.On the other hand,under the control of surrounding faults,the unique broom-shaped desert landscape was formed,and the gullies and sand ridges in this region experienced an abrupt directional change from north by west to north by east at the location of 39°45＇-39°55＇N.The unique landscape of gravel body that occurred widely in the northern desert was formed after 285.9±42.9 ka BP.The results in this paper provide the scientific basis for studying the formation age and evolutionary process under the dry climate and environment in the northwestern China,and the uplifting of Qinghai-Tibet Plateau as well as its responses to the global climate changes.
基金the Fundamental Research Funds for the Central Non-profit Research Institution of Chinese Academy of Forestry(CAFYBB2019MA009,CAFYBB2017ZE005)the New Project of Surplus Project Fund for Institute of Desertification Studies,Chinese Academy of Forestry(IDS2019JY-4)+1 种基金the National Natural Science Foundation of China(41471151,41701010,41877530)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2018459).
文摘The seif dune field over the gravel desert surface in the eastern margin of the Kumtagh Desert is a valuable experimental site for the observation of dune formation and dynamics.We used high-resolution remote sensing and station observation approaches,combined with wind and grain size data,to study the characteristics of the aeolian environment and the morphologies of and dynamic changes in seif dunes.We observed the ratio of the resultant drift potential(RDP)to the drift potential(DP),which was 0.37,associated with an obtuse bimodal wind regime.The drift potentials in the west-northwest(WNW)and east-northeast(ENE)directions were dominant,and the angle between the two primary DP directions was 135.00°.The dune orientations ranged from 168.75°-213.75°,which were parallel to the resultant drift direction(186.15°).The dune lengths ranged from 51.68 to 1932.1 m with a mean value of 344.91 m.The spacings of the dunes ranged from 32.34 to 319.77 m with a mean value of 93.39 m.The mean grain size of the sediments became finer,and the sorting became better from upwind tail to downwind tip,which indicated that the sediment of the seif dunes in the study region may be transported from northward to southward.The rate of increase in the length,the mean longitudinal migration rate of the dune tail,and the mean longitudinal extension rate of the dune tip(also called elongation rate)were 4.93,4.63,and 9.55 m/a,respectively.The mean lateral migration vector of the seif dunes was approximately 0.11 m/a towards the west(-0.11 m/a),while the mean amplitude of lateral migration was 0.53 m/a,ignoring the direction of lateral migration.We found that the seif dune field formed first beside seasonal rivers,which can provide sediment,and then expanded downwind.
基金supported by the National Natural Science Foundation of China(No.41071090)
文摘Tourism development of aeolian geomorphosites in the Kumtagh Desert is beneficial to both harmonious development of human-nature relationship and the sustainable development of the tourist industry in the Kumtagh Desert and its sur- rounding area. This paper adopts some research methods including field observation, expert assessment, and systematic investigation to analyze and evaluate the aesthetic value of aeolian geomorphosites in the Kumtagh Desert from three aspects of＂Beauty of Morphology＂, ＂Beauty of Color＂ and ＂Beauty of Forms＂. This research is a creative work in the field of aeolian geomorphosites combining the method of aeolian geomorphology and tourism geography.
基金The Global Change Program of China, No.2010CB950203 China National S＆T Basic Work Program, No.2006FY110800 Natural Science Foundation of China, No.40930103, 41021002
文摘Kumtagh Desert is one of the eight biggest deserts in China, but poorly investigated before our interdisciplinary study because of the difficulty of access. In this paper, 33 representative surface sediment samples were collected from the Kumtagh Desert and analyzed in the laboratory to obtain heavy mineral components and geochemical element contents. Results show that various kinds of heavy minerals are present in these samples, with high levels of epidote and hornblende. Si and AI take up a large part of chemical composition. Compared with the average composition of geochemical elements of the upper continental crust （UCC）, except Si and Ca, all elements are depleted to a certain degree; Fe, Mg, Ca, P, Ti and Mn have high correlation coefficients in their contents. The mineral and geochemical composition of the Kumtagh Desert sediments have a similarity with that of rocks of Altyn Tagh Mountains, and the surface sediments of the alluvial/diluvial fans around the Altyn Tagh Mountains and that of the Taklamakan Desert, indicating that one major source of the Kumtagh Desert sediments is located in the Altyn Tagh Mountains. Alluvial deposits and lake sediments in Aqik valley and lower reaches of Shule River are prone to be eroded and transported by the strong northeasterly wind into the Kumtagh Desert, forming another source of the desert deposits. An A-CN-K ternary diagram shows that a weak degree chemical weathering by the loss of Na and K occurred in these sediments, whereas A-CNK-FM ternary diagram suggests that Fe and Mg have undergone a significant chemical differentiation. Physical weathering processes cause easy erosion and enrichment in fine particles for mafic minerals, thus coarse desert sand particles can be relatively depleted in Fe and Mg. The mineral and geochemical composition of sediments in arid regions experiencing less chemical weathering are mostly affected by physical weathering.
基金supported by the National Basic Research Development of China(Grant No.2007CB407203)the National Scientific&Technical Basic Work Program(Grant No.2006FY110800)+1 种基金the National Natural Science Foundation of China(Grant No.49971013)the Gansu Provincial Natural Science Foundation(Grant No.0710RJZH084)
文摘Feathered sand ridges in the northeastern Kumtagh Desert in China cover an area of 4016 km 2 and consist of crescent sand ridges and interridge tongue-shaped dunes.Differences in grain size,mineral composition and albedo between crescent sand ridges and tongue-shaped dunes,and between windward and leeward slopes of tongue-shaped dunes,result in their feathery appearance in aerial and satellite imagery.Measurements of the sand drift potential in the region show that the sand-moving wind for feathered sand ridges can be divided into three sectors;i.e.north-northeasterly,easterly and east-northeasterly sectors roughly corresponding to the southeast,northwest and southwest slip faces.Our findings suggests that the crescent sand ridges resulting from the connection of barchan dunes along the prevailing wind direction are longitudinal dune ridges rather than transverse ones.Tongue-shaped dunes and quasi-dune shapes have obvious distinctions and are new transverse dune types.According to McKee's dune shape classification,the feathered sand ridges are not a deformation dune type but a complex one.According to Wu's dune morphological and genetic classification,they are not dune ridges or compound dune ridges that form under the action of unidirectional winds or two winds intersecting at an acute angle,but are complex dune ridges that form under the action of three winds intersecting at an acute angle.
文摘库姆塔格沙漠腹地广泛出露含古风成砂的第四纪地层剖面。根据含古风成砂地层剖面的野外调查与地层年代的室内分析结果,并与已有的周边区域地质资料对比分析,库姆塔格沙漠形成至少始于早更新世初,到中更新世晚期285.9±42.9 ka BP沙漠已大面积扩展形成,奠定了现代沙漠环境格局。沙漠最初从西南部开始形成,之后向北和东北扩展。依据梭梭沟地层剖面,沙漠在第四纪演化过程中至少经历了19个沙漠正、逆过程旋回,平均周期约为110 ka。新构造运动对沙漠的形成演化和地貌的形成发育具有重要作用,构造了山间断陷盆地并使其逐渐向封闭的干旱盆地演化形成沙漠,受四周断裂控制沙漠整体形态呈"扫帚状"。分布在沙漠北部的独特砾石体地貌形成于晚更新世末(285.9±42.9)ka BP之后。
