In the Southeast Margin of the Tibetan Plateau, low-velocity sedimentary layers that would significantly affect the accuracy of the H-κ stacking of receiver functions are widely distributed.In this study, we use tele...In the Southeast Margin of the Tibetan Plateau, low-velocity sedimentary layers that would significantly affect the accuracy of the H-κ stacking of receiver functions are widely distributed.In this study, we use teleseismic waveform data of 475 events from 97 temporary broadband seismometers deployed by ChinArray Phase I to obtain crustal thicknesses and Poisson's ratios within the Chuxiong-Simao Basin and adjacent area, employing an improved method in which the receiver functions are processed through a resonance-removal filter, and the H-κ stacking is time-corrected.Results show that the crustal thickness ranges from 30 to 55 km in the study area, reaching its thickest value in the northwest and thinning toward southwest, southeast and northeast.The apparent variation of crustal thickness around the Red River Fault supports the view of southeastern escape of the Tibetan Plateau.Relatively thin crustal thickness in the zone between Chuxiong City and the Red River Fault indicates possible uplift of mantle in this area.The positive correlation between crustal thickness and Poisson's ratio is likely to be related to lower crust thickening.Comparison of results obtained from different methods shows that the improved method used in our study can effectively remove the reverberation effect of sedimentary layers.展开更多
There are many active faults in the southeast margin of Tibetan Plateau,where three large active faults zones,the Longmenshan,Xianshuihe and Anninghe,merge to form a"Y"shape.Strong crustal deformation and a ...There are many active faults in the southeast margin of Tibetan Plateau,where three large active faults zones,the Longmenshan,Xianshuihe and Anninghe,merge to form a"Y"shape.Strong crustal deformation and a complicated fault distribution accompany strong earthquake activity in this zone.In this paper,we investigate a multi-scale gravity anomaly in the southeastern margin of the Tibetan Plateau using the wavelet transform;we find that the pattern of the gravity field is closely related to the fault system in the study area.Analyzing the characteristics of this Bouguer gravity anomaly at different orders indicates that the eastern Himalayan syntaxis has produced a strong eastward push during its northward movement,resulting in a shortening of the crust from west to east and a rapid uplift of the Tibetan Plateau.The Songpan–Garzêand Sichuan–Yunnan blocks have been forced to slip and extrude southward and eastward laterally.The distributions of seven large earthquakes from 1970 to 2018 reflects the relationship between large earthquakes and characteristics of the gravity anomaly.Comparing the tectonic backgrounds of several earthquakes reveals that the large earthquakes occur usually in the high gravity anomaly gradient zone,which corresponds in general to the boundary zones of the blocks.We infer that large earthquakes occur primarily in high Bouguer gravity anomaly zones in the upper crust,while low Bouguer gravity anomalies encompass the lower crust and the uppermost mantle.展开更多
Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study sh...Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study shows a similar variation pattern of fixed-site river water δ 18O with that of the precipitation δ 18O in southeast Tibet. δ 18O in regional rivers in southeast Tibet demonstrates a gradual depletion with increasing altitude, though the rates vary seasonally. The most depleted river 18O occurs during the monsoon period, with the lowest δ 18O/altitude lapse rate. The river 18O during the westerly period is also depleted, together with low δ 18O/altitude lapse rate. The pre-monsoon rivers witness the most enriched 18O with least significant correlation coefficient with the linear regression, whilst the postmonsoon rivers witness the largest δ 18O/altitude lapse rate. Different coherence of seasonal δ 18O variation with the altitude effect is attributed to different moisture supplies. Though sampling numbers vary with seasons, the δ 18O-H linear correlation coefficients all reach the 0.05 confidence level, thus witnessing the variation features of δ 18O in seasonal river water due to the influence of atmospheric general circulation and land surface processes revealed from the altitudinal lapse rates.展开更多
Little is known about recent variation of temperate glaciers on the Tibetan Plateau,although they are of particular theoretical and practical interests in terms of climate change and water supply.The study of glacier ...Little is known about recent variation of temperate glaciers on the Tibetan Plateau,although they are of particular theoretical and practical interests in terms of climate change and water supply.The study of glacier mass balance and terminus variation for six temperate glaciers in the Parlung Zangbo River basin,southeast Tibetan Plateau,shows the facts of the overall negative mass balance and the continued terminus retreat from 2005/2006 to 2007/2008.The mass balances of smaller glaciers were more negative compared to larger glaciers.Referring the trend of glacier mass balance in the Hengduan Mountains,the Himalayas and glacier shrinkage in southeast Tibetan Plateau,the mass loss and recession of temperate glacier in this region are expected if the current climate condition continues.展开更多
基金supported by the National Natural Science Foundation of China (Project 41730212)the Basic Research Project of the Institute of Earthquake Forecasting, China Earthquake Administration (2017IES0102)
文摘In the Southeast Margin of the Tibetan Plateau, low-velocity sedimentary layers that would significantly affect the accuracy of the H-κ stacking of receiver functions are widely distributed.In this study, we use teleseismic waveform data of 475 events from 97 temporary broadband seismometers deployed by ChinArray Phase I to obtain crustal thicknesses and Poisson's ratios within the Chuxiong-Simao Basin and adjacent area, employing an improved method in which the receiver functions are processed through a resonance-removal filter, and the H-κ stacking is time-corrected.Results show that the crustal thickness ranges from 30 to 55 km in the study area, reaching its thickest value in the northwest and thinning toward southwest, southeast and northeast.The apparent variation of crustal thickness around the Red River Fault supports the view of southeastern escape of the Tibetan Plateau.Relatively thin crustal thickness in the zone between Chuxiong City and the Red River Fault indicates possible uplift of mantle in this area.The positive correlation between crustal thickness and Poisson's ratio is likely to be related to lower crust thickening.Comparison of results obtained from different methods shows that the improved method used in our study can effectively remove the reverberation effect of sedimentary layers.
基金supported by the National Natural Science Foundation of China(Project 41730212)the Basic Research Project of the Institute of Earthquake Forecasting,China Earthquake Adm inistration(Grant No.2017IES0102)
文摘There are many active faults in the southeast margin of Tibetan Plateau,where three large active faults zones,the Longmenshan,Xianshuihe and Anninghe,merge to form a"Y"shape.Strong crustal deformation and a complicated fault distribution accompany strong earthquake activity in this zone.In this paper,we investigate a multi-scale gravity anomaly in the southeastern margin of the Tibetan Plateau using the wavelet transform;we find that the pattern of the gravity field is closely related to the fault system in the study area.Analyzing the characteristics of this Bouguer gravity anomaly at different orders indicates that the eastern Himalayan syntaxis has produced a strong eastward push during its northward movement,resulting in a shortening of the crust from west to east and a rapid uplift of the Tibetan Plateau.The Songpan–Garzêand Sichuan–Yunnan blocks have been forced to slip and extrude southward and eastward laterally.The distributions of seven large earthquakes from 1970 to 2018 reflects the relationship between large earthquakes and characteristics of the gravity anomaly.Comparing the tectonic backgrounds of several earthquakes reveals that the large earthquakes occur usually in the high gravity anomaly gradient zone,which corresponds in general to the boundary zones of the blocks.We infer that large earthquakes occur primarily in high Bouguer gravity anomaly zones in the upper crust,while low Bouguer gravity anomalies encompass the lower crust and the uppermost mantle.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40571039, 40701037 and 40830638) and group program of Chinese Academy of Sciences
文摘Seasonal δ 18O variation in water on the southeast Tibetan Plateau has been studied, showing the consistent variation pattern of δ 18O with altitude indicative of relevant atmospheric circulation processes. Study shows a similar variation pattern of fixed-site river water δ 18O with that of the precipitation δ 18O in southeast Tibet. δ 18O in regional rivers in southeast Tibet demonstrates a gradual depletion with increasing altitude, though the rates vary seasonally. The most depleted river 18O occurs during the monsoon period, with the lowest δ 18O/altitude lapse rate. The river 18O during the westerly period is also depleted, together with low δ 18O/altitude lapse rate. The pre-monsoon rivers witness the most enriched 18O with least significant correlation coefficient with the linear regression, whilst the postmonsoon rivers witness the largest δ 18O/altitude lapse rate. Different coherence of seasonal δ 18O variation with the altitude effect is attributed to different moisture supplies. Though sampling numbers vary with seasons, the δ 18O-H linear correlation coefficients all reach the 0.05 confidence level, thus witnessing the variation features of δ 18O in seasonal river water due to the influence of atmospheric general circulation and land surface processes revealed from the altitudinal lapse rates.
基金supported by the National Basic Research Program of China (2005CB422004)the National Natural Science Foundation of China (40810019001 and 40901047)+1 种基金BRAHMATW INN(FP6-036952)the Program of Tibet Science and Technology Agency
文摘Little is known about recent variation of temperate glaciers on the Tibetan Plateau,although they are of particular theoretical and practical interests in terms of climate change and water supply.The study of glacier mass balance and terminus variation for six temperate glaciers in the Parlung Zangbo River basin,southeast Tibetan Plateau,shows the facts of the overall negative mass balance and the continued terminus retreat from 2005/2006 to 2007/2008.The mass balances of smaller glaciers were more negative compared to larger glaciers.Referring the trend of glacier mass balance in the Hengduan Mountains,the Himalayas and glacier shrinkage in southeast Tibetan Plateau,the mass loss and recession of temperate glacier in this region are expected if the current climate condition continues.
