Calc-sintersdistributed in the middle of lakes and rhizoconcretions scattered at the slopes of sand dunes were observed during three explorations to the Badain Jaran Desert in the past two years. Wet sands were also f...Calc-sintersdistributed in the middle of lakes and rhizoconcretions scattered at the slopes of sand dunes were observed during three explorations to the Badain Jaran Desert in the past two years. Wet sands were also found underneath the dry surface sand layers of about 20-50 cm in thickness. The geochemical parameters were measured on minerals and water samples collected from the Badain Jaran Desert and neighboring areas. The results show that the water system in the desert may be recharged from the groundwater originating from the precipitation of the Qilian Mountains and/or the Tibetan Plateau rather than the local rainfalls.展开更多
Field observations demonstrate that calc-sinters occurred in the lakes of Badain Jaran Desert. 87Sr/86Sr ratios,14C,δ 13C and mineral com-positions of calc-sinters,and 3He/4He,4He/20Ne,δ 18O,δ D,pH and TDS of water...Field observations demonstrate that calc-sinters occurred in the lakes of Badain Jaran Desert. 87Sr/86Sr ratios,14C,δ 13C and mineral com-positions of calc-sinters,and 3He/4He,4He/20Ne,δ 18O,δ D,pH and TDS of water from springs and lakes are analyzed in detail. The results indicate that the lake water is supplied through deep fault zone. The “ker-nel” of stabilized dunes in the Badain Jaran Desert perhaps consists of calc-sinters and calcareous ce-mentation layers. Deep-seated groundwater effuses from this “kernel” and recharges to lakes in desert. Precipitation and snowmelt water from the Qing-hai-Tibet Plateau is fed into the Badain Jaran Desert,Gurinai,Wentougaole and Ejinqi areas through the Xigaze-Langshan Fault zone. The isotopic composi-tions of groundwater in the Alax Plateau are abnor-mal due to the strong evaporation of the Gyaring and Ngoring lake water in the headstream of the Yellow River. Groundwater dissolves dissoluble fractions of rocks during its transportation through the fault zone and flows out of the mouth of spring in the Badan Jaran Desert. The dissoluble fractions are finally de-veloped into calc-sinters and calcareous cementation layers around the spring. Calci-sinters are gradually largened and eventually emerge on the surface of lake water. Eolian sands accumulate on the surfaces of calc-sinters and calcareous cementation layers,and eventually develop into dunes. Invasion of magma causes an increase in the temperature of groundwater within the faults. Groundwater evapora-tion provides water vapor for the formation of humid stabilized dunes during its upwelling. Rhizoconcre-tions found in Yihejigede indicate that the dune was formed and remained immovable 4700 years ago. The height of the megadunes is proportional to thermal quantity carried by the groundwater.展开更多
基金This work is jointly supported by the TC item of LAEA(CPR/8/015)Academician Foundation of Hohai University(2002/05)as.well as the National Natural Science Foundation of China(40442001).
文摘Calc-sintersdistributed in the middle of lakes and rhizoconcretions scattered at the slopes of sand dunes were observed during three explorations to the Badain Jaran Desert in the past two years. Wet sands were also found underneath the dry surface sand layers of about 20-50 cm in thickness. The geochemical parameters were measured on minerals and water samples collected from the Badain Jaran Desert and neighboring areas. The results show that the water system in the desert may be recharged from the groundwater originating from the precipitation of the Qilian Mountains and/or the Tibetan Plateau rather than the local rainfalls.
基金Acknowledgements This work was jointly supported by the Technical Cooperation Programme of International Atomic Energy Agency （Grant No. CPR/8/15）, the National Natural Science Foundation of China （Grant No. 50579017）, Advanced Research Programme of the National Natural Science Foundation of China （Grant No. 40442001） and Jiangsu Foundation for ＂Talents of Six Industries＂.
文摘Field observations demonstrate that calc-sinters occurred in the lakes of Badain Jaran Desert. 87Sr/86Sr ratios,14C,δ 13C and mineral com-positions of calc-sinters,and 3He/4He,4He/20Ne,δ 18O,δ D,pH and TDS of water from springs and lakes are analyzed in detail. The results indicate that the lake water is supplied through deep fault zone. The “ker-nel” of stabilized dunes in the Badain Jaran Desert perhaps consists of calc-sinters and calcareous ce-mentation layers. Deep-seated groundwater effuses from this “kernel” and recharges to lakes in desert. Precipitation and snowmelt water from the Qing-hai-Tibet Plateau is fed into the Badain Jaran Desert,Gurinai,Wentougaole and Ejinqi areas through the Xigaze-Langshan Fault zone. The isotopic composi-tions of groundwater in the Alax Plateau are abnor-mal due to the strong evaporation of the Gyaring and Ngoring lake water in the headstream of the Yellow River. Groundwater dissolves dissoluble fractions of rocks during its transportation through the fault zone and flows out of the mouth of spring in the Badan Jaran Desert. The dissoluble fractions are finally de-veloped into calc-sinters and calcareous cementation layers around the spring. Calci-sinters are gradually largened and eventually emerge on the surface of lake water. Eolian sands accumulate on the surfaces of calc-sinters and calcareous cementation layers,and eventually develop into dunes. Invasion of magma causes an increase in the temperature of groundwater within the faults. Groundwater evapora-tion provides water vapor for the formation of humid stabilized dunes during its upwelling. Rhizoconcre-tions found in Yihejigede indicate that the dune was formed and remained immovable 4700 years ago. The height of the megadunes is proportional to thermal quantity carried by the groundwater.
