We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, a...We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration.展开更多
Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of...Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.展开更多
Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change （LUCC） in Ningwu County, located in the eastern Loe...Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change （LUCC） in Ningwu County, located in the eastern Loess Plateau of China, from 1990 to 2010. We found that grassland, woodland, and farmland were the main land use types in the study area, and the area of each type changed slightly from 1990 to 2010, whereas the area of water, construction land, and unused land increased greatly. For the whole area, the net change and total change were insignificant due to weak human activity intensity in most of the study area, and the LUCC was dominated by quasi-balanced two-way transitions from 1990 to 2010. The insignificant overall amount of LUCC appears to have resulted from offsetting of rapid increases in population, economic growth, and the im- plementation of a program to return farmland to woodland and grassland in 2000. This program converted more farmland into woodland and grassland from 2000 to 2010 than from 1990 to 2000, but reclamation of woodland and grassland for use as farmland continued from 2000 to 2010, and is a cause for concern to the local government.展开更多
Conversion of cropland to forestry and grassland is an important method to reduce soil erosion and improve the biophysical environment in the Loess Plateau. The feasibility, methods, and environmental effects of cropl...Conversion of cropland to forestry and grassland is an important method to reduce soil erosion and improve the biophysical environment in the Loess Plateau. The feasibility, methods, and environmental effects of cropland conversion were studied based on 11 typical watersheds of national experimental bases instead of different geographic areas of the Loess Plateau. Between 1986 and 2000, cropland, sloping cropland and non-agricultural land decreased by 8%, 92.5% and 8% respectively, while forestry increased by 15.7%. The land use change not only decreased annual soil erosion by 74%, but also increased vegetation coverage by 100% and improved the soil condition and biodiversity. This can be achieved by building basic farmland, increasing capital and scientific input, and planting trees and grasses according to the natural biophysical restrictions.展开更多
As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed...As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.展开更多
In order to reveal the characteristics of land use change in the south loess plateau,this paper tentatively divided Loess Plateau into North and South under the support of GIS,and then introduced land use spatial temp...In order to reveal the characteristics of land use change in the south loess plateau,this paper tentatively divided Loess Plateau into North and South under the support of GIS,and then introduced land use spatial temporal dynamic model,analyzed land use dynamic change in provincial scale. The results showed: during the 25 years,construction land area increased from 3 555. 99 km2 to 4 794. 28 km2,unused land decreased by 0. 02 percentage points,forest land area increased from 51 011. 31 km2 to 51 066. 79 km2,waters increased of 0. 01 percentage points,farmland area decreased to 98 561. 57 km2 from 100 004. 79 km2,grassland area increased by 0.08 percentage points. Land use change important values in province scale on each were not identical,showed obvious regional differences.展开更多
基金granted by the China's National Mineral Resources Investigation Program (Grant No.1212011220598) the Inner Mongolia Mineral Survey Fund(Grant No.KD-05-09)
文摘We report the finding of the Wolitu Pb-Zn deposit in Inner Mongolia, China, through a series of geochemical surveys. The Wolitu area, located in the loess-cover area in the Hure Banner, Tongliao City,Inner Mongolia, and neighboring the Horqin Sandy Land to the north, had no previous history of Pb-Zn mining or record of Pb-Zn mineralization. Our study identified a large Pb-Zn anomaly with potential zones of mineralization by stream sediment survey. Random rock sampling reveals limonitization at sporadic outcrops in the gullies. The high concentrations of Pb in the residual debris provided guidelines to fix the position for exploratory trench. Oxidized concealed orebodies were identified by trenching.Blind orebodies in veins hosted within the structural zone between slates and marbles of the upper Carboniferous Shizuizi Formation and the Permian granite were discovered by drilling. It is computed that the ore reserve may reach up to 540,000 tones with Pb grade of 1.27% and Zn of 1.9%. This case study is an excellent example for identifying potential polymetallic deposits in loess covered terrains using geochemical exploration.
基金supported by the National Key Research and Development Program of China (2016YFC0402404, 2016YFC0402407)the National Natural Science Foundation of China (L1624052, 41330858, 41471226, and 51509203)the Dr.Innovation Fund of Xi’an University of Technology (310-252071505)
文摘Aeolian-fluvial interplay erosion regions are subject to intense soil erosion and are of particular concern in loess areas of northwestern China. Understanding the composition, distribution, and transport processes of eroded sediments in these regions is of considerable scientific significance for controlling soil erosion. In this study, based on laboratory rainfall simulation experiments, we analyzed rainfall-induced erosion processes on sand-covered loess slopes （SS） with different sand cover patterns （including length and thickness） and uncovered loess slopes （LS） to investigate the influences of sand cover on erosion processes of loess slopes in case regions of aeolian-fluvial erosion. The grain-size curves of eroded sediments were fitted using the Weibull function. Compositions of eroded sediments under different sand cover patterns and rainfall intensities were analyzed to explore sediment transport modes of SS. The influences of sand cover amount and pattern on erosion processes of loess slopes were also discussed. The results show that sand cover on loess slopes influences the proportion of loess erosion and that the compositions of eroded sediments vary between SS and LS. Sand cover on loess slopes transforms silt erosion into sand erosion by reducing splash erosion and changing the rainfall-induced erosion processes. The percentage of eroded sand from SS in the early stage of runoff and sediment generation is always higher than that in the late stage. Sand cover on loess slopes aggravates loess erosion, not only by adding sand as additional eroded sediments but also by increasing the amount of eroded loess, compared with the loess slopes without sand cover. The influence of sand cover pattern on runoff yield and the amount of eroded sediments is larger than that of sand cover amount. Furthermore, given the same sand cover pattern, a thicker sand cover could increase sand erosion while a thinner sand cover could aggravate loess erosion. This difference explains the existence of intense erosion on slopes that are thinly covered with sand in regions where aeolian erosion and fluvial erosion interact.
基金supported by the Open Fund Project of the Key Laboratory of Desert and Desertification, Chinese Academy of Sciences (No. KLDD-2014-001)the Important Specialized Science and Technology Item of Shanxi Province, China (No. 20121101011)the Natural Science Foundation of China (Nos. 41271513, 41271030)
文摘Using Landsat remote sensing images, we analyzed changes in each land use type and transitions among different land use types during land use and land cover change （LUCC） in Ningwu County, located in the eastern Loess Plateau of China, from 1990 to 2010. We found that grassland, woodland, and farmland were the main land use types in the study area, and the area of each type changed slightly from 1990 to 2010, whereas the area of water, construction land, and unused land increased greatly. For the whole area, the net change and total change were insignificant due to weak human activity intensity in most of the study area, and the LUCC was dominated by quasi-balanced two-way transitions from 1990 to 2010. The insignificant overall amount of LUCC appears to have resulted from offsetting of rapid increases in population, economic growth, and the im- plementation of a program to return farmland to woodland and grassland in 2000. This program converted more farmland into woodland and grassland from 2000 to 2010 than from 1990 to 2000, but reclamation of woodland and grassland for use as farmland continued from 2000 to 2010, and is a cause for concern to the local government.
基金Knowledge Innovation ProjectofCAS,No.KZCX3-SW -421NationalKey Task Research ofthe Ninth Five-YearPlan, No.96-004-05+1 种基金 Knowledge Innovation Project of CAS, No.KZCX1-06 Special Research Foundation ofISW C,CAS,No.ISW C-SP-C128
文摘Conversion of cropland to forestry and grassland is an important method to reduce soil erosion and improve the biophysical environment in the Loess Plateau. The feasibility, methods, and environmental effects of cropland conversion were studied based on 11 typical watersheds of national experimental bases instead of different geographic areas of the Loess Plateau. Between 1986 and 2000, cropland, sloping cropland and non-agricultural land decreased by 8%, 92.5% and 8% respectively, while forestry increased by 15.7%. The land use change not only decreased annual soil erosion by 74%, but also increased vegetation coverage by 100% and improved the soil condition and biodiversity. This can be achieved by building basic farmland, increasing capital and scientific input, and planting trees and grasses according to the natural biophysical restrictions.
基金supported by the National Basic Research Program of China (2007CB407207)National Natural Science Foundation of China (30800888)
文摘As more and more farmland is converted to forestry, the need for effective decision support regarding the use of land in the fragile ecological environment of the Loess Plateau hilly-gully area. The Luoyugou watershed was chosen as the study area to calculate the single dynamic degree, integrated dynamic degree, and change indexes of land use, as well as the land-use type transition matrix. This was done by interpreting the TM and SPOT images of the Luoyugou watershed in 1986, 1995, and2004 and making statistical analysis. The results of ou statistical analysis show that the conversion of slope farm land to terrace and forest land plays a dominant role in land-use changes in the Luoyugou watershed from 1986 to2004. The land-use changes are mainly driven by popula tion growth, socio-economic development, consume spending, and investment in forest ecology.
基金Supported by National Natural Science Foundation of China(41271159)Research Training Fund of Xi'an University of Technology(201103)+1 种基金Doctor Startup Fund of Xi'an University of Technology(2011QDJ036)National College Students' Innovation and Entrepreneurship Training Program(201210704006)
文摘In order to reveal the characteristics of land use change in the south loess plateau,this paper tentatively divided Loess Plateau into North and South under the support of GIS,and then introduced land use spatial temporal dynamic model,analyzed land use dynamic change in provincial scale. The results showed: during the 25 years,construction land area increased from 3 555. 99 km2 to 4 794. 28 km2,unused land decreased by 0. 02 percentage points,forest land area increased from 51 011. 31 km2 to 51 066. 79 km2,waters increased of 0. 01 percentage points,farmland area decreased to 98 561. 57 km2 from 100 004. 79 km2,grassland area increased by 0.08 percentage points. Land use change important values in province scale on each were not identical,showed obvious regional differences.
