Loess near Lanzhou in the late Pleistocene is very sensitive to climatic fluctuations. The Beiyuan terrace profile in Linxia City, of which the curve of susceptibility tallies with the trend of isotopic curves of Vost...Loess near Lanzhou in the late Pleistocene is very sensitive to climatic fluctuations. The Beiyuan terrace profile in Linxia City, of which the curve of susceptibility tallies with the trend of isotopic curves of Vostok 2083 m ice core in Antarctica, is 35m thick. There are five layers of paleosols under Malan loess（L<sub>1</sub>）. Upper three layers (S<sub>1-a</sub>,S（1-b）and S<sub>1-c</sub> correspond to three warm stages in last interglaciation, Interstadial of Last Glacial （C stage in Antarctic ice core）was clearly recorded in the Beiyuan profile, in which three layers of paleosols and two of loess were formed. The lowest section of the profile belongs to penultimate glaciation, in which fossils of cold-drought-resistant mammal and mollusc have been discovered.展开更多
Detailed examination of historical data of earthquakes and field investigations of loess landslide caused by the earthquake and tracing of active faults in Lanzhou area indicate that the Yijitanpu town, one of six tow...Detailed examination of historical data of earthquakes and field investigations of loess landslide caused by the earthquake and tracing of active faults in Lanzhou area indicate that the Yijitanpu town, one of six towns of Jincheng city, was devastated by the 1125 Lanzhou earthquake. The citly is now located in the Vinylon Factory south of Hekou (River Mouth) in the Xigu district of Lanzhou city. We delermined that the six old towns mentioned in historical records lie in an area stretching from the south of Xigu district to Hekou in Lanzhou. This is consistent with the distribution of loess landslides caused by the earthquake, the extension of Holocene active faults, and the distribution of traces of the seismic rupture zone. A comprehensive analysis shows that the seismogenic structure for the 1125 Lanzhou M 7.0 earthquake should be the Xianshuigou fault segment at the western termination of the north-border active fault zone of the Maxianshan Mountains which are located in south of Lanzhou city with the distance of only 4 km.展开更多
基金project supported by the National Natural Science Foundation of China.
文摘Loess near Lanzhou in the late Pleistocene is very sensitive to climatic fluctuations. The Beiyuan terrace profile in Linxia City, of which the curve of susceptibility tallies with the trend of isotopic curves of Vostok 2083 m ice core in Antarctica, is 35m thick. There are five layers of paleosols under Malan loess（L<sub>1</sub>）. Upper three layers (S<sub>1-a</sub>,S（1-b）and S<sub>1-c</sub> correspond to three warm stages in last interglaciation, Interstadial of Last Glacial （C stage in Antarctic ice core）was clearly recorded in the Beiyuan profile, in which three layers of paleosols and two of loess were formed. The lowest section of the profile belongs to penultimate glaciation, in which fossils of cold-drought-resistant mammal and mollusc have been discovered.
文摘Detailed examination of historical data of earthquakes and field investigations of loess landslide caused by the earthquake and tracing of active faults in Lanzhou area indicate that the Yijitanpu town, one of six towns of Jincheng city, was devastated by the 1125 Lanzhou earthquake. The citly is now located in the Vinylon Factory south of Hekou (River Mouth) in the Xigu district of Lanzhou city. We delermined that the six old towns mentioned in historical records lie in an area stretching from the south of Xigu district to Hekou in Lanzhou. This is consistent with the distribution of loess landslides caused by the earthquake, the extension of Holocene active faults, and the distribution of traces of the seismic rupture zone. A comprehensive analysis shows that the seismogenic structure for the 1125 Lanzhou M 7.0 earthquake should be the Xianshuigou fault segment at the western termination of the north-border active fault zone of the Maxianshan Mountains which are located in south of Lanzhou city with the distance of only 4 km.
