Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas, where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton. Apatite fission track dating and therma...Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas, where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton. Apatite fission track dating and thermal history modeling suggest that the northern Tarim experienced multi-stage cooling events which were assumed to be associated with the distant effects of the Cimmerian orogeny and India-Eurasia collision in the past. But the first episode of exhumation in the northern Tarim, occurring in the mid-Permian to Triassic, is here suggested to be induced by docking of the Tarim Craton and final amalgamation of the Central Asian Orogenic Belt. The cooling event at ca. 170 Ma may be triggered by the Qiangtang-Eurasia collision. Widespread Cretaceous exhumation could be linked with docking of the Lhasa terrane in the late Jurassic. Cenozoic reheating and recooling likely occurred because of the northpropagating stress, however, this has not affected the northern Tarim much because the Tarim is characterized by rigid block-like motion.展开更多
Land use change (LUC) in trans-boundary watersheds is of great importance to environmental assessment. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China,but there was little information ...Land use change (LUC) in trans-boundary watersheds is of great importance to environmental assessment. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China,but there was little information on the LUC of the watershed. We quantitatively investigated the processes and trends of its LUC by using analytic models based on the land use data derived from the remote sensing images and topographic maps. The LUC was in the quasi-balanced status with a slight difference between the loss and the gain of the area for most land use types during the period of 1960-1990,whereas transferred to the unbalanced status with significant difference between the loss and gain of the area during the period of 1990-2008. At the same time,land conversion direction changed from two-way transition to one-way transition for the most land use types. The integrated rate of net change of land use during the period of 1990-2008 is 2.1 times of that during the period of 1960-1990. Information on the processes and trends of LUC is valuable for better understanding the environmental changes across the whole trans-boundary watershed,and helpful to decision-making management for Kyrgyzstan and China.展开更多
The relationship between North Atlantic Oscillations (NAO) and Aksu River Runoff (ARR) was investigated by using the wavelet transform (WT), cross wavelet transform (CWT), correlation and linear trend analyses...The relationship between North Atlantic Oscillations (NAO) and Aksu River Runoff (ARR) was investigated by using the wavelet transform (WT), cross wavelet transform (CWT), correlation and linear trend analyses, and abrupt change test. The main results are as follows the interannual/decadal variation and period analyses of ARR and NAO reveal that the both were close correlated each other; the CWT indicates that the correlation was good between ARR and NAO at all periods in the 1990s, because the significant correlation areas mainly concentrated in the 1990s; the variations in the trend strength of ARR and NAO were consistent; the abrupt change of NAO was also temporally consistent with that of ARR, which exerted impact on the Aksu River Basin (ARB) climate and then the ARR through atmospheric circulation variation.展开更多
This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. T...This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. Two hydrological models, the snowmelt-runoff model (SRM) and the Danish NedbФr-AfstrФmnings rainfall-runoff model (NAM), were used to simulate daily discharge processes in the Aksu River Basin. This study used the snow-covered area from MODIS remote sensing data as the SRM input. With the help of ArcGIS software, this study successfully derived the digital drainage network and elevation zones of the basin from digital elevation data. The simulation results showed that the SRM based on MODIS data was more accurate than NAM. This demonstrates that the application of remote sensing data to hydrological snowmelt models is a feasible and effective approach to runoff simulation and prediction in arid unguaged basins where snowmelt is a major runoff factor.展开更多
This study investigates the community-based ecotourism (CBE) model using a sample of the Aksu-Zhabagly nature reserve (NR). The aim is to propose a suitable CBE model for Aksu-Zhabgly nature-based tourism destinations...This study investigates the community-based ecotourism (CBE) model using a sample of the Aksu-Zhabagly nature reserve (NR). The aim is to propose a suitable CBE model for Aksu-Zhabgly nature-based tourism destinations by employing a combination of field observation, examination, evaluation, and SWOT analysis. The study determines the strategic suggestions for CBE model designing by the results of SWOT analysis. It concludes that convenient transportation and superior location, diversified wild animals and plants, rich in ethnocultural resources, traditional and tranquil life in a typical rural setting, hospitality and positive attitude of locals to tourism and great potential of the region for sustainable development of ecotourism are the strengths. At the same time, the far residential location from the provincial cities, low-quality service, outdated facilities and shortage of skilled employees in tourism management are the main weakness. Another group of constraints to tourism development is lack of tourism marketing and promotion agencies, lack of transparency, poor institution arrangement and corruption, and lack of preferential policies for CBE development. Finally, the paper recommends that economic development, environmental protection, culture and heritage, marketing and image, favorable political environment, and local residents’ empowerment are the main essential to effectively implement the sustainable development of CBE in the Aksu-Zhabagly tourist destination.展开更多
In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of it...In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of its social economy and ecological environment protection. This paper selects the Landsat series remote sensing images of the northern Aksu region in 2013, 2016, and 2019, and uses the tools such as ENVI5.3 and ArcGIS 10.8.1 to process the image data accordingly. The principal component analysis method is used to calculate the Remote Sensing Ecological Index (RSEI) of the northern Aksu region. The data show that: 1) The ecological environment quality index in the northern Aksu region in 2013, 2016, and 2019 was 0.706087, 0.25243 and 0.362991 respectively;2) The areas where the ecological environment quality declined significantly in the northern Aksu region were the human settlements and the Gobi, fan-shaped land and other special terrain areas;3) The humidity index and the heat index are the two factors that have the greatest impact on the ecological environment quality in the northern Aksu area. The data as a whole show that the ecological environment in the northern part of the Aksu region has deteriorated seriously, and the severely deteriorated area is close to the human living area.展开更多
A major proportion of discharge in the Aksu River is contributed from snow-and glacier-melt water.It is therefore essential to understand the cryospheric dynamics in this area for water resource management.The MODIS M...A major proportion of discharge in the Aksu River is contributed from snow-and glacier-melt water.It is therefore essential to understand the cryospheric dynamics in this area for water resource management.The MODIS MOD10A2 remotesensing database from March 2000 to December 2012 was selected to analyze snow cover changes.Snow cover varied significantly on a temporal and spatial scale for the basin.The difference of the maximum and minimum Snow Cover Fraction(SCF)in winter exceeded 70%.On average for annual cycle,the characteristic of SCF is that it reached the highest value of 53.2%in January and lowest value of 14.7%in July and the distributions of SCF along with elevation is an obvious difference between the range of 3,000 m below and 3,000 m above.The fluctuation of annual average snow cover is strong which shows that the spring snow cover was on the trend of increasing because of decreasing temperatures for the period of 2000-2012.However,temperature in April increased significantly which lead to more snowmelt and a decrease of snow cover.Thus,more attention is needed for flooding in this region due to strong melting of snow.展开更多
Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an esse...Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.展开更多
In this study, we analyzed glacier changes in the Aksu River Basin during the period 1975–2016, based on Landsat MSS/TM/ETM+/OLI imagery analysis and the Chinese Glacier Inventory(CGI). The results showed that the to...In this study, we analyzed glacier changes in the Aksu River Basin during the period 1975–2016, based on Landsat MSS/TM/ETM+/OLI imagery analysis and the Chinese Glacier Inventory(CGI). The results showed that the total number, area, and volume of the studied glaciers in the Aksu River Basin decreased by 202(7.65%), 965.7 km^2(25.88%), and 74.85–78.52 km^3(23.72%–24.3%), respectively. The rate of glacier retreat in the basin was slower in the north, northwest and west, but reached the highest in the east(measuring 0.86% yr^(-1)). Furthermore, there were significant regional differences in the distribution and change of glaciers, the Kumalak River Basin had the largest glacier number and area, about 63.15% and 76.47% of the studied basin, and the rate of glacier retreat in the Kumalak River Basin was 0.65% yr^(-1), it was higher than the Toxkan River Basin which reached 0.57% yr^(-1). We found the shrinkage rate of glacier for different periods in the past 41 years, during 1975–1990 the glaciers showed the greatest retreat, while the rate of glacier area retreat slowed down significantly from 1990 to 2000. In recent 16 years since 2000, the rate of glacier retreat in the Toxkan River Basin was higher compared with 1990–2000. The RGI50^(-1)3.04920 glacier of Kumalak River Basin had been in a state of retreat since 1990. Over the past 41 years, the temperature and precipitation in the Aksu River Basin increased obviously, and the warming temperatures were clearly the main reason for glacier retreat in the region, while the increased precipitation in the mountain area may have a direct relation with the retreating rate of glaciers.展开更多
Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on evapotranspiration is helpful in understanding the impact of climate change on hydrological process...Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on evapotranspiration is helpful in understanding the impact of climate change on hydrological processes. In this paper, based on the daily meteorological data from 1960 to 2007 within and around the Aksu River Basin, reference evapotranspiration (RET) was estimated with the FAO Penman-Monteith method. The temporal and spatial variations of RET were analyzed by using ARCGIS and Mann-Kendall method. Multiple Regression Analysis was employed to attribute the effects of the variations of air temperature, solar radiation, relative humidity, vapour pressure and wind speed on RET. The results showed that average annual RET in the eastern plain area of the Aksu River Basin was about 1100 mm, which was nearly twice as much as that in the western mountainous area. The trend of annual RET had significant spatial variability. Annual RET was reduced significantly in the southeastern oasis area and southwestern plain area and increased slightly in the mountain areas. The amplitude of the change of RET reached the highest in summer, contributing most of the annual change of RET. Except in some high elevation areas where relative humidity predominated the change of the RET, the variations of wind velocity predominated the changes of RET almost throughout the basin. Taking Kuqa and Ulugqat stations as an example, the variations of wind velocity accounted for more than 50% of the changes of RET.展开更多
Deerite [Fe 12 2+ Fe 6 3+ Si12O40 (OH)10] was first discovered in the metamorphic magnetite-bearing quartzites which are interlayered with blueschists in Aksu Precambrian blueschist terrane. The deerite-bearing minera...Deerite [Fe 12 2+ Fe 6 3+ Si12O40 (OH)10] was first discovered in the metamorphic magnetite-bearing quartzites which are interlayered with blueschists in Aksu Precambrian blueschist terrane. The deerite-bearing mineral association includes (1) deerite + riebeckite + stilpnomelane + ilvaite + magnetite + quartz and (2) deerite + stilpnomelane + magnetite +quartz based on the investigation under microscope. The study of mineral chemistry shows that the deerites from Aksu Precambrian blueschist are Mn-poor deerite similar to that from Alps. But the deerite from Aksu is the nearest to the end member of deerite. According to the equilibrium P-T region of deerite determined by Lattard and Breton (1994), the deerites in metamorphic magnetite-bearing quartzites from Aksu Precambrian blueschists were formed under the conditions of pressure lower than 1.0 Gpa, temperature ranging from 300 to 400°C and about the l0°C/km geothermal gradient.The deerite in metamorphic magnetite-bearing quartzites from Aksu blueschists is the only one Precambrian deerite reported now. This suggests that the earth began to cool, and the modern cooling subduction regime between plates started at Late Proterozoic. The Late Proterozoic may be the important period during the evolution of the earth.展开更多
This research focused on the Aksu area in the central part of the southern Tianshan. Along the 60 km wide Aksu fold-and-thrust belt, active thrusts reach the surface and offset the youngest sediments. Our research was...This research focused on the Aksu area in the central part of the southern Tianshan. Along the 60 km wide Aksu fold-and-thrust belt, active thrusts reach the surface and offset the youngest sediments. Our research was based on the geomorphologic study that examined the advance and retreat of glaciers cut by thrusts in the Tomur area in the north of Aksu. Our fieldwork revealed that two fault scarps were clearest across three different moraines that represent the maximum of advance of glaciers during three glacial periods along the Tailan River in the Tomur area. The measured heights of the fault scarps that cut the moraines, together with the moraines-inferred age, imply a shortening rate of 1.85 mm/a on the Aksu area since late Pleistocene. This rate, similar to that of the Korla area on its east side and of the Kaping area on its west side, but lower than that of the Kashgar area farther west and of the Manas area in the northern margin of the belt, implies that the distribution of shortening across the Tianshan changed markedly along the mountain.展开更多
基金financially supported by 973 Program(Grant No. 2014CB440801)NSFC(Grant Nos.41230207 and 41302167)+1 种基金China Postdoctoral Council(Grant Nos.20100480452,2012T50135 and International Postdoctoral Exchange Fellowship)State Key Laboratory of Earthquake Dynamics(Grant No.LED2013B03)
文摘Tarim Precambrian bedrocks are well exposed in the Kuluketage and Aksu areas, where twenty four samples were taken to reveal the denudation history of the northern Tarim Craton. Apatite fission track dating and thermal history modeling suggest that the northern Tarim experienced multi-stage cooling events which were assumed to be associated with the distant effects of the Cimmerian orogeny and India-Eurasia collision in the past. But the first episode of exhumation in the northern Tarim, occurring in the mid-Permian to Triassic, is here suggested to be induced by docking of the Tarim Craton and final amalgamation of the Central Asian Orogenic Belt. The cooling event at ca. 170 Ma may be triggered by the Qiangtang-Eurasia collision. Widespread Cretaceous exhumation could be linked with docking of the Lhasa terrane in the late Jurassic. Cenozoic reheating and recooling likely occurred because of the northpropagating stress, however, this has not affected the northern Tarim much because the Tarim is characterized by rigid block-like motion.
基金funded by the Key Topics in Innovation Engineering of Chinese Academy of Sciences (KZCX2-YW-307-3)the National Basic Research Program of China (2009CB825105)
文摘Land use change (LUC) in trans-boundary watersheds is of great importance to environmental assessment. The Aksu River is the largest trans-boundary river crossing Kyrgyzstan and China,but there was little information on the LUC of the watershed. We quantitatively investigated the processes and trends of its LUC by using analytic models based on the land use data derived from the remote sensing images and topographic maps. The LUC was in the quasi-balanced status with a slight difference between the loss and the gain of the area for most land use types during the period of 1960-1990,whereas transferred to the unbalanced status with significant difference between the loss and gain of the area during the period of 1990-2008. At the same time,land conversion direction changed from two-way transition to one-way transition for the most land use types. The integrated rate of net change of land use during the period of 1990-2008 is 2.1 times of that during the period of 1960-1990. Information on the processes and trends of LUC is valuable for better understanding the environmental changes across the whole trans-boundary watershed,and helpful to decision-making management for Kyrgyzstan and China.
基金Special Fund for Social Public Good Project of the Ministry of Science and Technology,No.2004DIB3J118No.2005DIB6J113+1 种基金GYHY (QX) 2007-6-8Desert Meteorological Fund,No.2007011
文摘The relationship between North Atlantic Oscillations (NAO) and Aksu River Runoff (ARR) was investigated by using the wavelet transform (WT), cross wavelet transform (CWT), correlation and linear trend analyses, and abrupt change test. The main results are as follows the interannual/decadal variation and period analyses of ARR and NAO reveal that the both were close correlated each other; the CWT indicates that the correlation was good between ARR and NAO at all periods in the 1990s, because the significant correlation areas mainly concentrated in the 1990s; the variations in the trend strength of ARR and NAO were consistent; the abrupt change of NAO was also temporally consistent with that of ARR, which exerted impact on the Aksu River Basin (ARB) climate and then the ARR through atmospheric circulation variation.
基金supported by the National Basic Research Program of China(Grant No.2006CB400502)the World Bank Cooperative Project(Grant No.THSD-07)the 111 Program of the Ministry of Education and the State Administration of Foreign Expert Affairs,China(Grant No.B08048)
文摘This study simulated and predicted the runoff of the Aksu River Basin, a typical river basin supplied by snowmelt in an arid mountain region, with a limited data set and few hydrological and meteorological stations. Two hydrological models, the snowmelt-runoff model (SRM) and the Danish NedbФr-AfstrФmnings rainfall-runoff model (NAM), were used to simulate daily discharge processes in the Aksu River Basin. This study used the snow-covered area from MODIS remote sensing data as the SRM input. With the help of ArcGIS software, this study successfully derived the digital drainage network and elevation zones of the basin from digital elevation data. The simulation results showed that the SRM based on MODIS data was more accurate than NAM. This demonstrates that the application of remote sensing data to hydrological snowmelt models is a feasible and effective approach to runoff simulation and prediction in arid unguaged basins where snowmelt is a major runoff factor.
文摘This study investigates the community-based ecotourism (CBE) model using a sample of the Aksu-Zhabagly nature reserve (NR). The aim is to propose a suitable CBE model for Aksu-Zhabgly nature-based tourism destinations by employing a combination of field observation, examination, evaluation, and SWOT analysis. The study determines the strategic suggestions for CBE model designing by the results of SWOT analysis. It concludes that convenient transportation and superior location, diversified wild animals and plants, rich in ethnocultural resources, traditional and tranquil life in a typical rural setting, hospitality and positive attitude of locals to tourism and great potential of the region for sustainable development of ecotourism are the strengths. At the same time, the far residential location from the provincial cities, low-quality service, outdated facilities and shortage of skilled employees in tourism management are the main weakness. Another group of constraints to tourism development is lack of tourism marketing and promotion agencies, lack of transparency, poor institution arrangement and corruption, and lack of preferential policies for CBE development. Finally, the paper recommends that economic development, environmental protection, culture and heritage, marketing and image, favorable political environment, and local residents’ empowerment are the main essential to effectively implement the sustainable development of CBE in the Aksu-Zhabagly tourist destination.
文摘In order to understand the development status of ecological environment quality in the Aksu region of China, to effectively adjust the ecological environment quality, so as to promote the sustainable development of its social economy and ecological environment protection. This paper selects the Landsat series remote sensing images of the northern Aksu region in 2013, 2016, and 2019, and uses the tools such as ENVI5.3 and ArcGIS 10.8.1 to process the image data accordingly. The principal component analysis method is used to calculate the Remote Sensing Ecological Index (RSEI) of the northern Aksu region. The data show that: 1) The ecological environment quality index in the northern Aksu region in 2013, 2016, and 2019 was 0.706087, 0.25243 and 0.362991 respectively;2) The areas where the ecological environment quality declined significantly in the northern Aksu region were the human settlements and the Gobi, fan-shaped land and other special terrain areas;3) The humidity index and the heat index are the two factors that have the greatest impact on the ecological environment quality in the northern Aksu area. The data as a whole show that the ecological environment in the northern part of the Aksu region has deteriorated seriously, and the severely deteriorated area is close to the human living area.
基金supported by the National Natural Science Foundation(Grant Nos.41301067,41671057,41671075)
文摘A major proportion of discharge in the Aksu River is contributed from snow-and glacier-melt water.It is therefore essential to understand the cryospheric dynamics in this area for water resource management.The MODIS MOD10A2 remotesensing database from March 2000 to December 2012 was selected to analyze snow cover changes.Snow cover varied significantly on a temporal and spatial scale for the basin.The difference of the maximum and minimum Snow Cover Fraction(SCF)in winter exceeded 70%.On average for annual cycle,the characteristic of SCF is that it reached the highest value of 53.2%in January and lowest value of 14.7%in July and the distributions of SCF along with elevation is an obvious difference between the range of 3,000 m below and 3,000 m above.The fluctuation of annual average snow cover is strong which shows that the spring snow cover was on the trend of increasing because of decreasing temperatures for the period of 2000-2012.However,temperature in April increased significantly which lead to more snowmelt and a decrease of snow cover.Thus,more attention is needed for flooding in this region due to strong melting of snow.
基金National Natural Science Foundation of China,No.42071076,No.41501085Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions,No.PAPD-20181105Jiangsu Normal University Support Fund for Doctoral Teachers Research,No.17XLR002。
文摘Against the backdrop of global warming,the dynamics of glaciers and their water resources have significant implications for hydrological processes in the arid regions of Northwest China.The Aksu River,which is an essential inland river enriched by substantial meltwater contributions,plays a pivotal role in the economic,ecological,and social development of the region.Based on 231 water samples collected during the period of intense glacial ablation in 2023,this study conducted a comprehensive analysis of the hydrochemical and stable isotopic characteristics of the Little Kurgan glacial basin in the Aksu River source region.A Piper diagram classified the hydrochemical type of the river water as Calcium-Bicarbonate.Analysis based on a Gibbs diagram indicated that rock weathering is the predominant factor affecting the hydrochemical properties within the studied basin.Through application of principal component analysis and end-member mixing analysis,it was determined that the glacier meltwater contribution to runoff was 67%,61%,and 55%in July,August,and September,respectively.The findings of this study reveal that glacier meltwater is the principal component of the river water,and highlight the critical impact of alterations in glacier ablation on the hydrological cycle within the Aksu River source region,which is vitally important for sustainable water resource management.
基金National Natural Science Foundation of China,No.41630859,No.41471030
文摘In this study, we analyzed glacier changes in the Aksu River Basin during the period 1975–2016, based on Landsat MSS/TM/ETM+/OLI imagery analysis and the Chinese Glacier Inventory(CGI). The results showed that the total number, area, and volume of the studied glaciers in the Aksu River Basin decreased by 202(7.65%), 965.7 km^2(25.88%), and 74.85–78.52 km^3(23.72%–24.3%), respectively. The rate of glacier retreat in the basin was slower in the north, northwest and west, but reached the highest in the east(measuring 0.86% yr^(-1)). Furthermore, there were significant regional differences in the distribution and change of glaciers, the Kumalak River Basin had the largest glacier number and area, about 63.15% and 76.47% of the studied basin, and the rate of glacier retreat in the Kumalak River Basin was 0.65% yr^(-1), it was higher than the Toxkan River Basin which reached 0.57% yr^(-1). We found the shrinkage rate of glacier for different periods in the past 41 years, during 1975–1990 the glaciers showed the greatest retreat, while the rate of glacier area retreat slowed down significantly from 1990 to 2000. In recent 16 years since 2000, the rate of glacier retreat in the Toxkan River Basin was higher compared with 1990–2000. The RGI50^(-1)3.04920 glacier of Kumalak River Basin had been in a state of retreat since 1990. Over the past 41 years, the temperature and precipitation in the Aksu River Basin increased obviously, and the warming temperatures were clearly the main reason for glacier retreat in the region, while the increased precipitation in the mountain area may have a direct relation with the retreating rate of glaciers.
基金National Key Basic Research Development Program of China No.2009CB421307 No.2010CB428404 National Natural Science Foundation of China No.41071024
文摘Evapotranspiration is one of the key components of hydrological processes. Assessing the impact of climate factors on evapotranspiration is helpful in understanding the impact of climate change on hydrological processes. In this paper, based on the daily meteorological data from 1960 to 2007 within and around the Aksu River Basin, reference evapotranspiration (RET) was estimated with the FAO Penman-Monteith method. The temporal and spatial variations of RET were analyzed by using ARCGIS and Mann-Kendall method. Multiple Regression Analysis was employed to attribute the effects of the variations of air temperature, solar radiation, relative humidity, vapour pressure and wind speed on RET. The results showed that average annual RET in the eastern plain area of the Aksu River Basin was about 1100 mm, which was nearly twice as much as that in the western mountainous area. The trend of annual RET had significant spatial variability. Annual RET was reduced significantly in the southeastern oasis area and southwestern plain area and increased slightly in the mountain areas. The amplitude of the change of RET reached the highest in summer, contributing most of the annual change of RET. Except in some high elevation areas where relative humidity predominated the change of the RET, the variations of wind velocity predominated the changes of RET almost throughout the basin. Taking Kuqa and Ulugqat stations as an example, the variations of wind velocity accounted for more than 50% of the changes of RET.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 49572157 and 49772103).
文摘Deerite [Fe 12 2+ Fe 6 3+ Si12O40 (OH)10] was first discovered in the metamorphic magnetite-bearing quartzites which are interlayered with blueschists in Aksu Precambrian blueschist terrane. The deerite-bearing mineral association includes (1) deerite + riebeckite + stilpnomelane + ilvaite + magnetite + quartz and (2) deerite + stilpnomelane + magnetite +quartz based on the investigation under microscope. The study of mineral chemistry shows that the deerites from Aksu Precambrian blueschist are Mn-poor deerite similar to that from Alps. But the deerite from Aksu is the nearest to the end member of deerite. According to the equilibrium P-T region of deerite determined by Lattard and Breton (1994), the deerites in metamorphic magnetite-bearing quartzites from Aksu Precambrian blueschists were formed under the conditions of pressure lower than 1.0 Gpa, temperature ranging from 300 to 400°C and about the l0°C/km geothermal gradient.The deerite in metamorphic magnetite-bearing quartzites from Aksu blueschists is the only one Precambrian deerite reported now. This suggests that the earth began to cool, and the modern cooling subduction regime between plates started at Late Proterozoic. The Late Proterozoic may be the important period during the evolution of the earth.
基金The research was supported in part by the National Natural Science Foundation of China (Grant No.79972077).
文摘This research focused on the Aksu area in the central part of the southern Tianshan. Along the 60 km wide Aksu fold-and-thrust belt, active thrusts reach the surface and offset the youngest sediments. Our research was based on the geomorphologic study that examined the advance and retreat of glaciers cut by thrusts in the Tomur area in the north of Aksu. Our fieldwork revealed that two fault scarps were clearest across three different moraines that represent the maximum of advance of glaciers during three glacial periods along the Tailan River in the Tomur area. The measured heights of the fault scarps that cut the moraines, together with the moraines-inferred age, imply a shortening rate of 1.85 mm/a on the Aksu area since late Pleistocene. This rate, similar to that of the Korla area on its east side and of the Kaping area on its west side, but lower than that of the Kashgar area farther west and of the Manas area in the northern margin of the belt, implies that the distribution of shortening across the Tianshan changed markedly along the mountain.