Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their for...Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their formation,which cannot occur on Earth due to the high climatic temperature.In this study,we propose an alternative mechanism that attrib-utes the araneiform formation to the erosion of upwelling salt water from the subsurface,relying on the identification of the first terrestrial analog found in a playa of the Qaidam Basin on the northern Tibetan Plateau.Morphological analysis indicates that the structures in the Qaidam Basin have fractal features comparable to araneiforms on Mars.A numerical model is developed to investigate the araneiform formation driven by the water-diffusion mechanism.The simulation res-ults indicate that the water-diffusion process,under varying ground conditions,may be responsible for the diverse aranei-form morphologies observed on both Earth and Mars.Our numerical simulations also demonstrate that the orientations of the saltwater diffusion networks are controlled by pre-existing polygonal cracks,which is consistent with observations of araneiforms on Mars and Earth.Our study thus suggests that a saltwater-related origin of the araneiform is possible and has significant implications for water searches on Mars.展开更多
Surface radioactive survey has been carried with portable gamma ray spectrometer(PGRS) about the 45 km2 around the Srisailam sub basin,the surface radioactive anomalies were found at Chennakesavula gutta in the Srisai...Surface radioactive survey has been carried with portable gamma ray spectrometer(PGRS) about the 45 km2 around the Srisailam sub basin,the surface radioactive anomalies were found at Chennakesavula gutta in the Srisailam sub basin of Cuddapah basin in the age of meso-neo proterozoic,India.The integrated geochemical and radiometric surveys were conducted as part of research work in the Srisailam basin,it has resulted the locating of surface radioactive anomalies near the Chennakesavula gutta.Secondary uranium minerals are observed along with the fracture planes in the Archean basement granite in the proximity of unconformity contact of Srisailam quartzite.The granite underlies the Srisailam formation and forms the source for possible unconformity related uranium mineralisation in the Srisailam sub-basin evidence by the significant radioactive anomalies.The radioactivity recorded by PGRS reflected uraniferous nature of the radioactivity(Average total counts =195 ppm;U = 202 ppm;Th =22ppm;%K = 4.1,n = 15).展开更多
Sedimentary sequences with drastic thickening over short distances have been observed in Qiaojia County,Yunnan Province,Southwest China.These are related to a pull-apart basin controlled by the Xiaojiang strike-slip f...Sedimentary sequences with drastic thickening over short distances have been observed in Qiaojia County,Yunnan Province,Southwest China.These are related to a pull-apart basin controlled by the Xiaojiang strike-slip fault.Our field investigations include determining the surface characteristics of the Qiaojia basin which consists of three terrace sequences and a series of alluvial fans.Several drill holes were used to reveal the internal structure of the basin.The results suggest that the basinal sediments are over 300 m thick.From bottom to top,they can be classified into five different units.We inferred that the units of lacustrine sediments are deposited in a paleolake which was formed by a paleo-landslide.Accelerator mass spectrometry radiocarbon dating(AMS ^(14)C dating) was used to estimate the ages of the terrace and lacustrine sediments.We use the results to infer that the paleo-lake has existed about 15,000 years and that the Qiaojia basin was uplifted at an average rate of 3.3 mm/a.Furthermore,we then model the evolution process of the basin and interpreted 6 phases of development.展开更多
The distribution and verticals variation of geochemical components in the Kasnau-Matasukh lignites of Nagaur Basin, Rajasthan, were investigated using microscopy, proximate and ultimate analyses, Rock-Eval Pyrolysis, ...The distribution and verticals variation of geochemical components in the Kasnau-Matasukh lignites of Nagaur Basin, Rajasthan, were investigated using microscopy, proximate and ultimate analyses, Rock-Eval Pyrolysis, X-ray diffraction and Fourier Transform Infrared analyses, and major/minor/trace element determination. The relationship of elements with ash content and with macerals have also been discussed. These lignites are stratified, black, dominantly composed of huminite group macerals with subordinated amounts of liptinite and inertinite groups. They are classified as type-III kerogen and are mainly gas prone in nature. The concentration （in vol%） of mineral matter is seen to increase towards upper part of seam and so is the concentration （in wt%） of the volatile matter, elemental carbon and sulphur. The common minerals present in these lignitesare mixed clay layer, chlorite, and quartz as identified by X-ray diffraction study. Compared with world average in brown coal, the bulk concentration of Cu is anomalously high in most of the samples while Cd is 2-3 times high and Zn is high in one band. Based on interrelationship, different pyrite forms are noticed to have different preferential enrichment of various elements. The concentration of disseminated pyrite is more than the other pyrite forms and is followed by discrete pyrite grains and massive pyrite.展开更多
There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional c...There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite(SiO_2 ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H_2O contents, positive correlations of La-SiO_2 and Yb-SiO_2, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.展开更多
The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr/Ph ratios (6-11) are very high....The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr/Ph ratios (6-11) are very high. Drimane, cadinanes and homocadinanes exist in high concentration. Anomalously abundant 18α(H)-oleanane and remarkably abundant bicadinanes are present in Yacheng condensates, while 17α(H)-hopanes are in extremely low concentration. Taraxastane and significantly abundant 17α(H)-diahopanes occur in the condensates. In addition, a number of C 29 and C 30 unknown pentacyclic triterpanes were monitored in the condensates, some of which are abundant. The unknown compounds may be terrestrial biomarkers or their occurrence may suggest a sub-oxic (dyacrobic) clay-rich depositional environment. C 29 homologues are relatively predominant in regular and rearranged steranes. The concentration of diasteranes is markedly higher than that of regular steranes. The characteristics of Yacheng condensates are indicative of terrestrial source input. Based on condensate-condensate and condensate-rock correlations, combined with results of studies on sedimentary facies. Yacheng condensates may be sourced from Yacheng and Lingshui Formations in the Qiongdongnan Basin. The maturity of Yacheng condensate is relatively high, at late oil window stage (corresponding to 0.9%-1.3% R 0), based on sterane and terpane maturity parameters.展开更多
[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as ref...[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors： topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity （TS） and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB41000000)the Fundamental Research Funds for the Central Universities(WK2080000144)。
文摘Araneiforms are spider-like ground patterns that are widespread in the southern polar regions of Mars.A gas erosion process driven by the seasonal sublimation of CO_(2) ice was proposed as an explanation for their formation,which cannot occur on Earth due to the high climatic temperature.In this study,we propose an alternative mechanism that attrib-utes the araneiform formation to the erosion of upwelling salt water from the subsurface,relying on the identification of the first terrestrial analog found in a playa of the Qaidam Basin on the northern Tibetan Plateau.Morphological analysis indicates that the structures in the Qaidam Basin have fractal features comparable to araneiforms on Mars.A numerical model is developed to investigate the araneiform formation driven by the water-diffusion mechanism.The simulation res-ults indicate that the water-diffusion process,under varying ground conditions,may be responsible for the diverse aranei-form morphologies observed on both Earth and Mars.Our numerical simulations also demonstrate that the orientations of the saltwater diffusion networks are controlled by pre-existing polygonal cracks,which is consistent with observations of araneiforms on Mars and Earth.Our study thus suggests that a saltwater-related origin of the araneiform is possible and has significant implications for water searches on Mars.
基金BRNS projects coordinator for given opportunity to utilize the data for Ph.D.,and cooperated for publishing of the article
文摘Surface radioactive survey has been carried with portable gamma ray spectrometer(PGRS) about the 45 km2 around the Srisailam sub basin,the surface radioactive anomalies were found at Chennakesavula gutta in the Srisailam sub basin of Cuddapah basin in the age of meso-neo proterozoic,India.The integrated geochemical and radiometric surveys were conducted as part of research work in the Srisailam basin,it has resulted the locating of surface radioactive anomalies near the Chennakesavula gutta.Secondary uranium minerals are observed along with the fracture planes in the Archean basement granite in the proximity of unconformity contact of Srisailam quartzite.The granite underlies the Srisailam formation and forms the source for possible unconformity related uranium mineralisation in the Srisailam sub-basin evidence by the significant radioactive anomalies.The radioactivity recorded by PGRS reflected uraniferous nature of the radioactivity(Average total counts =195 ppm;U = 202 ppm;Th =22ppm;%K = 4.1,n = 15).
基金funded by the Major State Basic Research Development Program of China(2013CB733200)the State Key Program of National Natural Science of China(41572302)
文摘Sedimentary sequences with drastic thickening over short distances have been observed in Qiaojia County,Yunnan Province,Southwest China.These are related to a pull-apart basin controlled by the Xiaojiang strike-slip fault.Our field investigations include determining the surface characteristics of the Qiaojia basin which consists of three terrace sequences and a series of alluvial fans.Several drill holes were used to reveal the internal structure of the basin.The results suggest that the basinal sediments are over 300 m thick.From bottom to top,they can be classified into five different units.We inferred that the units of lacustrine sediments are deposited in a paleolake which was formed by a paleo-landslide.Accelerator mass spectrometry radiocarbon dating(AMS ^(14)C dating) was used to estimate the ages of the terrace and lacustrine sediments.We use the results to infer that the paleo-lake has existed about 15,000 years and that the Qiaojia basin was uplifted at an average rate of 3.3 mm/a.Furthermore,we then model the evolution process of the basin and interpreted 6 phases of development.
文摘The distribution and verticals variation of geochemical components in the Kasnau-Matasukh lignites of Nagaur Basin, Rajasthan, were investigated using microscopy, proximate and ultimate analyses, Rock-Eval Pyrolysis, X-ray diffraction and Fourier Transform Infrared analyses, and major/minor/trace element determination. The relationship of elements with ash content and with macerals have also been discussed. These lignites are stratified, black, dominantly composed of huminite group macerals with subordinated amounts of liptinite and inertinite groups. They are classified as type-III kerogen and are mainly gas prone in nature. The concentration （in vol%） of mineral matter is seen to increase towards upper part of seam and so is the concentration （in wt%） of the volatile matter, elemental carbon and sulphur. The common minerals present in these lignitesare mixed clay layer, chlorite, and quartz as identified by X-ray diffraction study. Compared with world average in brown coal, the bulk concentration of Cu is anomalously high in most of the samples while Cd is 2-3 times high and Zn is high in one band. Based on interrelationship, different pyrite forms are noticed to have different preferential enrichment of various elements. The concentration of disseminated pyrite is more than the other pyrite forms and is followed by discrete pyrite grains and massive pyrite.
基金supported by the National Key Basic Research Program of China (No. 2013CB429700)the National Natural Science Foundation of China (Nos. 4132 5021, 41306053, 40476044)+8 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (No XDA11030302)the Special Fund for the Taishan Scholar Program of Shandong Province (No. ts201511061)the AoShan Talents Program Supported by Qingdao Nationa Laboratory for Marine Science and Technology (No. 2015 ASTP-0S17)the Innovative Talent Promotion Program (No. 2012RA2191)the Science and Technology Devel opment Program of Shandong Province (No. 2013GRC 31502)the Scientific and Technological Innovation Project Financially Supported by Qingdao National Labora tory for Marine Science and Technology (No. 2015ASKJ 03)the National High Level Talent Special Support Programthe CAS/SAFEA International Partnership Program for Creative Research Teamsthe Qingdao Collaborative Innovation Center of Marine Science and Technology
文摘There has been much recent interest in the origin of intermediate lava and several hypotheses are: 1) direct melting of the mantle under water-saturated conditions, 2) partial melting of altered crust, 3) fractional crystallization of parent magma, and 4) magma mixing of mafic magmas with dacitic/rhyolitic magmas. Volcanic rocks series ranging from basaltic andesite to dacite(SiO_2 ranges from 53.8 to 63.0 wt.%) from the eastern Manus Basin were detected for major and trace element compositions to understand their origin. Low H_2O contents, positive correlations of La-SiO_2 and Yb-SiO_2, oxygen isotope data and the indistinct change of trace element concentrations in oscillatory zoning of plagioclase phenocrysts rule out the models in which silicic lava results from direct melting of hydrous mantle, partial melting of altered oceanic crust or gabbros, and magma mixing, respectively. Besides, the geochemical data of whole rock and melt inclusions indicate that fractional crystallization plays a dominant role in generating the intermediate lava with subduction features.
文摘The condensates from the Yacheng Gas Field, Ying-Qiong Basins, have unusual chemical characteristics, with distribution dominated by terpanes and steranes derived from higher-plants. Pr/Ph ratios (6-11) are very high. Drimane, cadinanes and homocadinanes exist in high concentration. Anomalously abundant 18α(H)-oleanane and remarkably abundant bicadinanes are present in Yacheng condensates, while 17α(H)-hopanes are in extremely low concentration. Taraxastane and significantly abundant 17α(H)-diahopanes occur in the condensates. In addition, a number of C 29 and C 30 unknown pentacyclic triterpanes were monitored in the condensates, some of which are abundant. The unknown compounds may be terrestrial biomarkers or their occurrence may suggest a sub-oxic (dyacrobic) clay-rich depositional environment. C 29 homologues are relatively predominant in regular and rearranged steranes. The concentration of diasteranes is markedly higher than that of regular steranes. The characteristics of Yacheng condensates are indicative of terrestrial source input. Based on condensate-condensate and condensate-rock correlations, combined with results of studies on sedimentary facies. Yacheng condensates may be sourced from Yacheng and Lingshui Formations in the Qiongdongnan Basin. The maturity of Yacheng condensate is relatively high, at late oil window stage (corresponding to 0.9%-1.3% R 0), based on sterane and terpane maturity parameters.
文摘[Objective] Saline-alkali wasteland is a kind of land use type that formed by soil salinization and secondary salinization. To study the causes of spatial distri- bution of saline-alkali wasteland could be used as reference for the amelioration and is significant for developing the reserved land with great potential. [Method] The re- search set a total of 1 729 sampling points in the study area of 34 433 hm2. Spa- tial analyses were used to find out the causes of saline-alkali wasteland in Datong basin from four factors： topography, geology, hydrology and soil. DEM and land use data were used to calculate distribution index of topography, and distribution of the total salinity （TS） and pH was analyzed by means of IDW interpolation. [Result] The results showed that saline-alkali wasteland was distributed on flat and low-lying ter- rains with poor drainage, which led to salt accumulation. 87% of saline-alkali wasteland was distributed on Quaternary Holocene alluvium whose performance of soil hydraulic conductivity was poor. TS value distribution was that in midstream re- gion was the highest, less in upstream region and the least in downstream region along the rivers, and TS value decreased when distance between saline-alkali wasteland and rivers increased. The major soil types in Datong basin were fluvo- aquic soil and saline soil. Both of the two soil types were of high TS value and pH value, and heavily salinized and strongly alkalized. [Conclusion] High groundwater table and the existence of two salt accumulation centers are the two causes of saline-alkali wasteland in Datong basin. The key to ameliorate saline-alkali waste- land is to descend the groundwater table and lessen salt accumulation.
