Lop Nur is located at the eastmost end of the Tarim Basin in Xinjiang,Northwestern China.This study reviews the hydrochemical characteristics and evolution of underground brine in Lop Nur,based on analytical data from...Lop Nur is located at the eastmost end of the Tarim Basin in Xinjiang,Northwestern China.This study reviews the hydrochemical characteristics and evolution of underground brine in Lop Nur,based on analytical data from 429 water samples(mainly brine).It is found that in the NE-SW direction,from the periphery to the Luobei sub-depression,while the hydrochemical type varies from the sodium sulfate subtype(S)to the magnesium sulfate subtype(M),the corresponding brine in the phase diagram transfers from the thenardite phase(Then)area,through the bloedite phase(Blo),epsomite phase(Eps),picromerite phase(Picro),finally reaching the sylvite phase(Syl)area.As for the degree of evolution,the sequence is the periphery<Luobei horizontally and the overlying glauberite brine<the underlying clastic brine vertically.It is concluded that the oxygen and hydrogen isotopic compositions of the brine have evidently been affected through the effects of evaporation and altitude,as well as the changes in local water circulation in recent years.Boron and chloride isotopic compositions show that the glauberite brine is formed under more arid conditions than the clastic one.The strontium isotopic composition indicates that the Lop Nur brine primarily originates from surface water;however,deep recharge may also be involved in the evolution of the brine,according to previous noble gas studies.It is confirmed that the brine in Lop Nur has become enriched with potassium prior to halite precipitation over the full course of the salt lake's evolution.Based on chemical compositions of brine from drillhole LDK01 and previous lithological studies,the evolution of the salt lake can be divided into three stages and it is inferred that the brine in Lop Nur may have undergone at least two significant concentration-dilution periods.展开更多
The change in the ecological environment in the arid core area is a critical issue in the context of global warming.To study the paleoclimate evolution,precise identification of minerals deposited in Asia’s arid hint...The change in the ecological environment in the arid core area is a critical issue in the context of global warming.To study the paleoclimate evolution,precise identification of minerals deposited in Asia’s arid hinterland,Lop Nur Salt Lake,NW China was conducted.The hyperspectral data of the salt crust was sampled to identify the species and content of sedimentary minerals,and the multispectral photos were used to reconstruct the salt crust morphology using the unmanned aerial vehicles platform.The SUnSAL(sparse unmixing by variable splitting and augmented Lagrangian)method was employed to inverse the sedimentary mineral components along the shoreline.The heterogeneity of salt and clay minerals in bright and dark ear-shaped strips was evaluated.The paleoclimatic environment associated with salt lake extinction was reconstructed by analyzing paleoclimate records of sediments,spectral reflectance and morphology of the salt crust.Results show that:(1)the variations in the micro-geomorphology of the salt crust are obviously the reason for the formation of bright and dark ear-shaped strips and the differences in the species and relative content of the sedimentary minerals are the microscopic reason.The high ratio of sedimentary salt minerals to clay minerals(RS/C)contributes to the high reflectivity,and the salt crust presents a bright texture.The low RS/C results in the low reflectivity,salt crust presents a dark texture;(2)the bright and dark ear-shaped strips represent warm-arid and cold-humid climates.The shape of the Lop Nur Lake shoreline evolved due to alternating warm-dry and cold-humid paleoclimate changes.展开更多
Lop Nur potash mine greening projects is located in the heart of the Lop Nur, known as the ＂green zone ban＂. The project overcomes the extreme drought, high temperature, gale and dust salt and salt, and many other a...Lop Nur potash mine greening projects is located in the heart of the Lop Nur, known as the ＂green zone ban＂. The project overcomes the extreme drought, high temperature, gale and dust salt and salt, and many other adverse environmen- tal factors. Adopted the suitable salt improvement measures and management tech- nology, the artificial green has emerged in the sea of death. At the same time the greening project improved the office environment of mining area, and shaped ex- treme environment greening projects successful cases.展开更多
The Lop Nur Salt Lake, located in the eastern part of the Tarim Basin, Xinjiang, China, has become a playa in the Quaternary. Rhombic in shape, the Lop Nur depression is mainly controlled by the NE-striking and nearly...The Lop Nur Salt Lake, located in the eastern part of the Tarim Basin, Xinjiang, China, has become a playa in the Quaternary. Rhombic in shape, the Lop Nur depression is mainly controlled by the NE-striking and nearly N-S-striking sets of faults. Since 1995, a superlarge brine potash deposit with potash resources of 2.50×10^8s t has been found in the Luobei subbasin in the northeastern part of the Lop Nur. We intensively studied the features and formation mechanism of faults inside the Lop Nur through satellite images, geomorphologic survey and continuous conductivity imaging and found seven subparallel graben faults formed under the action of nearly N 10° E principal compressional stress during deposition of the Lop Nur Salt Lake. These faults are up to 〉60 km long and 1-4 km wide and may extend downward for 1000 m or more. It is just under the action of these tensional faults that potash subbasius formed. The largest subbasin is the Luobei subbasin and the smaller ones are the Luoxi hollow, Erbei hollow and Tienan hollow. Investigation also indicates that the graben faults in the Lop Nur not only control the origin of the potash subbasins, but they themselves are also good brine reservoir structures, in which abundant potash-rich brines are stored. Therefore, The faults had played an important role in the potash formation of the Lop Nur.展开更多
Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seaw...Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seawater or lake water, but rather as a coupling result of particular provenance, tectonics and climate activities. In this paper, we focus on the formative mechanism of the potash deposits of Lop Nur depression in Tarim Basin to interpret the detailed coupling mechanism among provenance, tectonics and climate. In terms of the provenance of Lop Nur Lake, the water of the Tarim River which displays ＂potassium-rich＂ characteristics play an important role. In addition, the Pliocene and Lower-Middle Pleistocene clastic beds surrounding Lop Nur Lake host a certain amount of soluble potassium and thus serves as ＂source beds＂ for potash formation. During the late Pliocene, the Lop Nur region has declined and evolved into a great lake from the previous piedmont and diluvial fan area. Since the mid Pleistocene, the great-united Lop Nur Lake has been separated and has generated a chain system consisting of Taitema Lake, Big Ear Lake and Luobei Lake which has turned into the deepest sag in Lop Nur Lake. Dry climate in Lop Nur region has increased since the Pliocene, and became extreme at the late Pleistocene. The study implies that potash formation in Lop Nur Lake depends on the optimal combination of extreme components of provenance, tectonics and climate during a shorter-term period. The optimal patterns of three factors are generally characterized by the long-term accumulation and preliminary enrichment of potassium, the occurrence of the deepest sub-depression and the appearance of an extremely arid climate in Lop Nur region. These factors have been interacting synergistically since the forming of the saline lake and in the later stages strong ＂vapor extraction＂ caused by extremely arid climate is needed to trigger large scale mineralization of potash deposits.展开更多
Located in the eastern part of the Tarim basin, Xinjiang, the Lop Nur was an ultimate water catchment area of the Tarim basin during the Quaternary. Through nearly ten years of investigation and research, the authors ...Located in the eastern part of the Tarim basin, Xinjiang, the Lop Nur was an ultimate water catchment area of the Tarim basin during the Quaternary. Through nearly ten years of investigation and research, the authors have found a superlarge brine potash deposit in the Luobei subbasin—a secondary basin of the Lop Nur depression. The deposit has been mined now. On that basis, the authors propose new theories on the genesis of the potash rock deposit. In the tectonic and geomorphologic contexts, the Tarim basin lies in a 'high mountain-deep basin' environment. At the beginning of the Quaternary, influenced by the neotectonic movement, the Lop Nur evolved into a 'deep basin' in the Tarim basin. At the end of the middle Pleistocene, neotectonic migration began to take place in the interior of the Lop Nur and a new secondary deep basin—the Luobei subbasin—formed gradually. Despite its small area, it is actually the deepest subbasin in the Lop Nur depression, where brines of the Lop Nur Salt Lake gather and evaporate, thus providing materials for the formation of a superlarge brine potash rock deposit. With respect to the phenomenon of brine concentration and change with deepening of the lake, the authors propose a model of 'high mountain-deep basin' tectonic migration for potash concentration. In the sedimentological context, the honeycomb-shaped voids developed in glauberite rock in the subbasin are good space for potash-rich brine accumulation. Study indicates that the deposition of glauberite requires recharge of calcium-rich water. In the Tarim area the calcium-rich water might come from deep formation water or oilfield water, and the river water recharging the Lop Nur Salt Lake was rich in sulfate radicals and other components; in addition, the climate in the area was very dry and the brine evaporated steadily, thus resulting in deposition of substantial amount of glauberite, potash accumulation in intercrystal brine and final formation of the potash deposit. Generally, potash formation in a salt lake undergoes a three-stage process of 'carbonates—?sulfates (gypsum and glauberite)—^chlorides (halite etc.)', but in the study area there only occurred a two-stage process of 'carbonates—>sulfates (gypsum and glauberite)'. The authors call this new geological phenomenon the 'two-stage potash formation' model. In conclusion, the superlarge Lop Nur potash deposit is the result of combined 'high mountain-deep basin' tectonism and 'two-stage potash formation'.展开更多
Many yellow silt layers have been identified in the Holocene sediments in the last lake of Lop Nur (playa), Xinjiang, northwestern China. Statistics of drill-hole cores have revealed more than one hundred layers, whic...Many yellow silt layers have been identified in the Holocene sediments in the last lake of Lop Nur (playa), Xinjiang, northwestern China. Statistics of drill-hole cores have revealed more than one hundred layers, which exhibit regularity in time sequence. Study has further verified that these yellow silt layers were deposited through eolian processes. The time-frequency distribution diagram shows an obvious peak occurring at about 8200 a B.P., which is consistent with the dry, windy and cold climate event occurring at 8200 a in other places around the world. Therefore, this event is regarded as a response to the global climate change.展开更多
Since the middle Early Pleistocene (1.20 Ma B.P.), the desert steppe climate and environment have predominated in the Lop Nur area, Xinjiang, characterized by warm humid epochs interrupted by dry cold intervals. The g...Since the middle Early Pleistocene (1.20 Ma B.P.), the desert steppe climate and environment have predominated in the Lop Nur area, Xinjiang, characterized by warm humid epochs interrupted by dry cold intervals. The grain-size and magnetic susceptibility curves record 30 climatic oscillations, each with a ca. 40 ka cycle, in the area since 1.2 Ma B.P., which reflects the controlling effects exerted by the astronomic factor on the environment. The Quaternary sedimentary environment in the Lop Nur gradually changed from a fresh lake through a brackish lake to a saline lake, showing a spiral evolution, and finally it evolved into a playa.展开更多
基金The Major Projects of Xinjiang Uyghur Autonomous Region of China(Grant Nos.2020A03005-2 and 2022A03009-2)from the Chinese governmentthe National Natural Science Foundation of China(Grant No.40830420)provided the funding for this study。
文摘Lop Nur is located at the eastmost end of the Tarim Basin in Xinjiang,Northwestern China.This study reviews the hydrochemical characteristics and evolution of underground brine in Lop Nur,based on analytical data from 429 water samples(mainly brine).It is found that in the NE-SW direction,from the periphery to the Luobei sub-depression,while the hydrochemical type varies from the sodium sulfate subtype(S)to the magnesium sulfate subtype(M),the corresponding brine in the phase diagram transfers from the thenardite phase(Then)area,through the bloedite phase(Blo),epsomite phase(Eps),picromerite phase(Picro),finally reaching the sylvite phase(Syl)area.As for the degree of evolution,the sequence is the periphery<Luobei horizontally and the overlying glauberite brine<the underlying clastic brine vertically.It is concluded that the oxygen and hydrogen isotopic compositions of the brine have evidently been affected through the effects of evaporation and altitude,as well as the changes in local water circulation in recent years.Boron and chloride isotopic compositions show that the glauberite brine is formed under more arid conditions than the clastic one.The strontium isotopic composition indicates that the Lop Nur brine primarily originates from surface water;however,deep recharge may also be involved in the evolution of the brine,according to previous noble gas studies.It is confirmed that the brine in Lop Nur has become enriched with potassium prior to halite precipitation over the full course of the salt lake's evolution.Based on chemical compositions of brine from drillhole LDK01 and previous lithological studies,the evolution of the salt lake can be divided into three stages and it is inferred that the brine in Lop Nur may have undergone at least two significant concentration-dilution periods.
基金Supported by the National Natural Science Foundation of China(Nos.42071313,41571363)the Science and Technology Project for Black Soil Granary(No.XDA28080500)the Scientific Investigation of Natural and Cultural Heritage of Lop Nur Region(No.2014FY210500)。
文摘The change in the ecological environment in the arid core area is a critical issue in the context of global warming.To study the paleoclimate evolution,precise identification of minerals deposited in Asia’s arid hinterland,Lop Nur Salt Lake,NW China was conducted.The hyperspectral data of the salt crust was sampled to identify the species and content of sedimentary minerals,and the multispectral photos were used to reconstruct the salt crust morphology using the unmanned aerial vehicles platform.The SUnSAL(sparse unmixing by variable splitting and augmented Lagrangian)method was employed to inverse the sedimentary mineral components along the shoreline.The heterogeneity of salt and clay minerals in bright and dark ear-shaped strips was evaluated.The paleoclimatic environment associated with salt lake extinction was reconstructed by analyzing paleoclimate records of sediments,spectral reflectance and morphology of the salt crust.Results show that:(1)the variations in the micro-geomorphology of the salt crust are obviously the reason for the formation of bright and dark ear-shaped strips and the differences in the species and relative content of the sedimentary minerals are the microscopic reason.The high ratio of sedimentary salt minerals to clay minerals(RS/C)contributes to the high reflectivity,and the salt crust presents a bright texture.The low RS/C results in the low reflectivity,salt crust presents a dark texture;(2)the bright and dark ear-shaped strips represent warm-arid and cold-humid climates.The shape of the Lop Nur Lake shoreline evolved due to alternating warm-dry and cold-humid paleoclimate changes.
基金Supported by National Natural Science Foundation of China(31300449)Science and Technology Support Program of Xinjiang Uyghur Autonomous Region(201433101)+1 种基金Doctoral Fund in the West of China of the Chinese Academy of Sciences(XBBS201205)Major Science and Technology Program of Xinjiang Uyghur Autonomous Region(201130106-3)
文摘Lop Nur potash mine greening projects is located in the heart of the Lop Nur, known as the ＂green zone ban＂. The project overcomes the extreme drought, high temperature, gale and dust salt and salt, and many other adverse environmen- tal factors. Adopted the suitable salt improvement measures and management tech- nology, the artificial green has emerged in the sea of death. At the same time the greening project improved the office environment of mining area, and shaped ex- treme environment greening projects successful cases.
文摘The Lop Nur Salt Lake, located in the eastern part of the Tarim Basin, Xinjiang, China, has become a playa in the Quaternary. Rhombic in shape, the Lop Nur depression is mainly controlled by the NE-striking and nearly N-S-striking sets of faults. Since 1995, a superlarge brine potash deposit with potash resources of 2.50×10^8s t has been found in the Luobei subbasin in the northeastern part of the Lop Nur. We intensively studied the features and formation mechanism of faults inside the Lop Nur through satellite images, geomorphologic survey and continuous conductivity imaging and found seven subparallel graben faults formed under the action of nearly N 10° E principal compressional stress during deposition of the Lop Nur Salt Lake. These faults are up to 〉60 km long and 1-4 km wide and may extend downward for 1000 m or more. It is just under the action of these tensional faults that potash subbasius formed. The largest subbasin is the Luobei subbasin and the smaller ones are the Luoxi hollow, Erbei hollow and Tienan hollow. Investigation also indicates that the graben faults in the Lop Nur not only control the origin of the potash subbasins, but they themselves are also good brine reservoir structures, in which abundant potash-rich brines are stored. Therefore, The faults had played an important role in the potash formation of the Lop Nur.
基金funded by the National Basic Research Program of China(No.2011CB403007)the State Key Program of National Natural Science of China(No.40830420)
文摘Potash deposits commonly accumulate in highly restricted settings at the final stage of brine evaporation. This does not mean that potash deposits are formed simply as a result of the evaporation concentration of seawater or lake water, but rather as a coupling result of particular provenance, tectonics and climate activities. In this paper, we focus on the formative mechanism of the potash deposits of Lop Nur depression in Tarim Basin to interpret the detailed coupling mechanism among provenance, tectonics and climate. In terms of the provenance of Lop Nur Lake, the water of the Tarim River which displays ＂potassium-rich＂ characteristics play an important role. In addition, the Pliocene and Lower-Middle Pleistocene clastic beds surrounding Lop Nur Lake host a certain amount of soluble potassium and thus serves as ＂source beds＂ for potash formation. During the late Pliocene, the Lop Nur region has declined and evolved into a great lake from the previous piedmont and diluvial fan area. Since the mid Pleistocene, the great-united Lop Nur Lake has been separated and has generated a chain system consisting of Taitema Lake, Big Ear Lake and Luobei Lake which has turned into the deepest sag in Lop Nur Lake. Dry climate in Lop Nur region has increased since the Pliocene, and became extreme at the late Pleistocene. The study implies that potash formation in Lop Nur Lake depends on the optimal combination of extreme components of provenance, tectonics and climate during a shorter-term period. The optimal patterns of three factors are generally characterized by the long-term accumulation and preliminary enrichment of potassium, the occurrence of the deepest sub-depression and the appearance of an extremely arid climate in Lop Nur region. These factors have been interacting synergistically since the forming of the saline lake and in the later stages strong ＂vapor extraction＂ caused by extremely arid climate is needed to trigger large scale mineralization of potash deposits.
基金the Oriented Foundation Proiect (DKD 95—22) the form er Ministry of Geology and Mineral Resources,State 305 Project(96-915—08—05)+2 种基金 the Ministry of Science Technology and Project 992025 the Ministry of Land and Resources.
文摘Located in the eastern part of the Tarim basin, Xinjiang, the Lop Nur was an ultimate water catchment area of the Tarim basin during the Quaternary. Through nearly ten years of investigation and research, the authors have found a superlarge brine potash deposit in the Luobei subbasin—a secondary basin of the Lop Nur depression. The deposit has been mined now. On that basis, the authors propose new theories on the genesis of the potash rock deposit. In the tectonic and geomorphologic contexts, the Tarim basin lies in a 'high mountain-deep basin' environment. At the beginning of the Quaternary, influenced by the neotectonic movement, the Lop Nur evolved into a 'deep basin' in the Tarim basin. At the end of the middle Pleistocene, neotectonic migration began to take place in the interior of the Lop Nur and a new secondary deep basin—the Luobei subbasin—formed gradually. Despite its small area, it is actually the deepest subbasin in the Lop Nur depression, where brines of the Lop Nur Salt Lake gather and evaporate, thus providing materials for the formation of a superlarge brine potash rock deposit. With respect to the phenomenon of brine concentration and change with deepening of the lake, the authors propose a model of 'high mountain-deep basin' tectonic migration for potash concentration. In the sedimentological context, the honeycomb-shaped voids developed in glauberite rock in the subbasin are good space for potash-rich brine accumulation. Study indicates that the deposition of glauberite requires recharge of calcium-rich water. In the Tarim area the calcium-rich water might come from deep formation water or oilfield water, and the river water recharging the Lop Nur Salt Lake was rich in sulfate radicals and other components; in addition, the climate in the area was very dry and the brine evaporated steadily, thus resulting in deposition of substantial amount of glauberite, potash accumulation in intercrystal brine and final formation of the potash deposit. Generally, potash formation in a salt lake undergoes a three-stage process of 'carbonates—?sulfates (gypsum and glauberite)—^chlorides (halite etc.)', but in the study area there only occurred a two-stage process of 'carbonates—>sulfates (gypsum and glauberite)'. The authors call this new geological phenomenon the 'two-stage potash formation' model. In conclusion, the superlarge Lop Nur potash deposit is the result of combined 'high mountain-deep basin' tectonism and 'two-stage potash formation'.
基金supported by the Orientated Fund Project (DKD95-22)of the former Ministry of Geology and Mineral Resources of Chinathe"305"Project(96-916-08-05)of the Ministry of Science and Technology of China
文摘Many yellow silt layers have been identified in the Holocene sediments in the last lake of Lop Nur (playa), Xinjiang, northwestern China. Statistics of drill-hole cores have revealed more than one hundred layers, which exhibit regularity in time sequence. Study has further verified that these yellow silt layers were deposited through eolian processes. The time-frequency distribution diagram shows an obvious peak occurring at about 8200 a B.P., which is consistent with the dry, windy and cold climate event occurring at 8200 a in other places around the world. Therefore, this event is regarded as a response to the global climate change.
基金This research was supported by Xinjiang Project 305 “Development and Utilization of Potash Resources of the Lop Nur,Xinjiang”(95-915-08-05).
文摘Since the middle Early Pleistocene (1.20 Ma B.P.), the desert steppe climate and environment have predominated in the Lop Nur area, Xinjiang, characterized by warm humid epochs interrupted by dry cold intervals. The grain-size and magnetic susceptibility curves record 30 climatic oscillations, each with a ca. 40 ka cycle, in the area since 1.2 Ma B.P., which reflects the controlling effects exerted by the astronomic factor on the environment. The Quaternary sedimentary environment in the Lop Nur gradually changed from a fresh lake through a brackish lake to a saline lake, showing a spiral evolution, and finally it evolved into a playa.
