The Badain Jaran Desert,located in the Alxa Plateau,Northwest China,features mega-dunes and a unique dune-lake alternation landscape.This paper presented the aeolian sediment structures of three representative dunes i...The Badain Jaran Desert,located in the Alxa Plateau,Northwest China,features mega-dunes and a unique dune-lake alternation landscape.This paper presented the aeolian sediment structures of three representative dunes in the Badain Jaran Desert using ground-penetrating radar (GPR).We processed and analyzed the GPR data and investigated the feasibility of using integrated GPR and sedimentological data to reconstruct dunes structure,sedimentary environment and geomorphological evolution.The results show that the internal structures of star dune and transverse dune represent various stages of mega-dune evolution: the main deposition processes of mega-dune are similar to those of transverse dunes but have a more complicated mechanism of sand transport and deposition because of the superimposition of dunes;the upper section of the mega-dune has a structure similar to that of star dune,with vertical aggradations on top.Diffraction hyperbolae in the GPR profile indicates that the presence of ancient dunes characterized by calcareous cementation layers is involved in the maintenance of mega-dunes,and water levels,shown by continuous,sub-horizontal GPR reflections,are supposed to be closely related to mega-dunes and the interdune lakes.Outcrop of wet sand and horizontal stratifications on the GPR image indicate moisture potentials with different levels inside mega-dunes.The multiplex geomorphology in the Badain Jaran Desert is the result of global climatic undulation,the unique geographical location,the geological structural features,etc.展开更多
Slow,as opposed to catastrophic,landslides are very difficult to recognize their effects and to monitor, which requires,amongst others,the use of accurate topographic information acquired and processed over the years ...Slow,as opposed to catastrophic,landslides are very difficult to recognize their effects and to monitor, which requires,amongst others,the use of accurate topographic information acquired and processed over the years of observation.This paper presents one of such study in which the suitability of an integrated approach of surface information using multi-temporal Digital Elevation Models(DEMs)with subsurface information as revealed by geophysics展开更多
The Dalinor volcanic swarm, located south of Xilinhot, Inner Mongolia of China, was a result of multistage eruptions that occurred since the Neogene period. This swarm is mainly composed of volcanic cones and lava tab...The Dalinor volcanic swarm, located south of Xilinhot, Inner Mongolia of China, was a result of multistage eruptions that occurred since the Neogene period. This swarm is mainly composed of volcanic cones and lava tablelands. The objective of this study is to map the topography and morphology of this volcanic swarm. It is based on a variety of data collected from various sources, such as the digital elevation model （DEM）, Landsat images, and a 1：50,000 topographic map, in addition to various software platforms, including ArcGIS, Envi4.8, Global Mapper, and Google Earth for data processing and interpretation. The results show that the overall topography of the volcanic swarm is a platform with a central swell having great undulation, sizable gradient variations, a rough surface, and small terrain relief. According to the undulating characteristics of the line profile, the volcanic swarm can be divided into four stairs with heights of 1,280 m, 1,360 m, 1,440 m, and 1,500 m. The analysis of the swath profile characterizes the two clusters of volcanoes with different height ranges and evolution. The lava tablelands and volcanic cones are distributed in nearly EW-trending belts, where tableland coverage was delineated with superposed layers of gradients and degrees of relief. According to the morphology, the volcanic cones were classified into four types： conical, composite, dome, and shield. The formation causes and classification basis for each type of volcanic cone were analyzed and their parameters were extracted. The HID ratios of all types of volcanic cones were then statistically determined and projected to create a map of volcanic density distribution. Based on the relationship between distribution and time sequence of the formation of different volcanic cones, itcan be inferred that the volcanic eruptions migrated from the margins to the center of the lava plateau. The central area was formed through superposition of multi-stage eruptive materials. In addition, a large number of early shield volcanoes were distributed on the margins. The morphological analysis of volcanic cones reveals the evolutionary stages of different types of cones. From the interpreted geomorphological indicators of faults, such as surface scarps, the pattern of volcanic cones, and the arrangement of crater major axes, it can be inferred that NE-trending and nearly EW-trending faults are present in this area, which are closely related to the formation and distribution of the volcanoes.展开更多
基金Under the auspices of National Natural Science Foundation of China (No.50879033,41001116)Specialized Research Fund for the Doctoral Program of Higher Education (No.20090211110025)Fundamental Research Funds for the Central Universities (No.lzujbky-2010-221)
文摘The Badain Jaran Desert,located in the Alxa Plateau,Northwest China,features mega-dunes and a unique dune-lake alternation landscape.This paper presented the aeolian sediment structures of three representative dunes in the Badain Jaran Desert using ground-penetrating radar (GPR).We processed and analyzed the GPR data and investigated the feasibility of using integrated GPR and sedimentological data to reconstruct dunes structure,sedimentary environment and geomorphological evolution.The results show that the internal structures of star dune and transverse dune represent various stages of mega-dune evolution: the main deposition processes of mega-dune are similar to those of transverse dunes but have a more complicated mechanism of sand transport and deposition because of the superimposition of dunes;the upper section of the mega-dune has a structure similar to that of star dune,with vertical aggradations on top.Diffraction hyperbolae in the GPR profile indicates that the presence of ancient dunes characterized by calcareous cementation layers is involved in the maintenance of mega-dunes,and water levels,shown by continuous,sub-horizontal GPR reflections,are supposed to be closely related to mega-dunes and the interdune lakes.Outcrop of wet sand and horizontal stratifications on the GPR image indicate moisture potentials with different levels inside mega-dunes.The multiplex geomorphology in the Badain Jaran Desert is the result of global climatic undulation,the unique geographical location,the geological structural features,etc.
文摘Slow,as opposed to catastrophic,landslides are very difficult to recognize their effects and to monitor, which requires,amongst others,the use of accurate topographic information acquired and processed over the years of observation.This paper presents one of such study in which the suitability of an integrated approach of surface information using multi-temporal Digital Elevation Models(DEMs)with subsurface information as revealed by geophysics
基金This work was supported by the program ＂Volcanic rock chronology of the Xilinhot volcanic swarm in Inner Mongolia＂ funded by the National Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration （LED2013B05） and the program ＂Genesis and evolution of the Quaternary Dalinor volcanic swarm＂ ffmded by the National Natural Science Foundation of China （Grant No. 41572320）.
文摘The Dalinor volcanic swarm, located south of Xilinhot, Inner Mongolia of China, was a result of multistage eruptions that occurred since the Neogene period. This swarm is mainly composed of volcanic cones and lava tablelands. The objective of this study is to map the topography and morphology of this volcanic swarm. It is based on a variety of data collected from various sources, such as the digital elevation model （DEM）, Landsat images, and a 1：50,000 topographic map, in addition to various software platforms, including ArcGIS, Envi4.8, Global Mapper, and Google Earth for data processing and interpretation. The results show that the overall topography of the volcanic swarm is a platform with a central swell having great undulation, sizable gradient variations, a rough surface, and small terrain relief. According to the undulating characteristics of the line profile, the volcanic swarm can be divided into four stairs with heights of 1,280 m, 1,360 m, 1,440 m, and 1,500 m. The analysis of the swath profile characterizes the two clusters of volcanoes with different height ranges and evolution. The lava tablelands and volcanic cones are distributed in nearly EW-trending belts, where tableland coverage was delineated with superposed layers of gradients and degrees of relief. According to the morphology, the volcanic cones were classified into four types： conical, composite, dome, and shield. The formation causes and classification basis for each type of volcanic cone were analyzed and their parameters were extracted. The HID ratios of all types of volcanic cones were then statistically determined and projected to create a map of volcanic density distribution. Based on the relationship between distribution and time sequence of the formation of different volcanic cones, itcan be inferred that the volcanic eruptions migrated from the margins to the center of the lava plateau. The central area was formed through superposition of multi-stage eruptive materials. In addition, a large number of early shield volcanoes were distributed on the margins. The morphological analysis of volcanic cones reveals the evolutionary stages of different types of cones. From the interpreted geomorphological indicators of faults, such as surface scarps, the pattern of volcanic cones, and the arrangement of crater major axes, it can be inferred that NE-trending and nearly EW-trending faults are present in this area, which are closely related to the formation and distribution of the volcanoes.
