Based on the data from the pitting, geoelectrical prospectings, temperature measuring, and the divided layers frost-heaving instruments, this paper, first, discusses the structure features of active layers in this reg...Based on the data from the pitting, geoelectrical prospectings, temperature measuring, and the divided layers frost-heaving instruments, this paper, first, discusses the structure features of active layers in this region, and proves the presence of the bowlshaped frost table in the stone circles area. Second, it analyses the temperature distributive rule in the active layer, meantime, according to the vertical-profile parameters of granularity, clay mineral, salt content and resistivities, it also discusses the different features of permafrost structure and their control actions on the periglacial landform development between high and low places. It suggests that the four-layer structure should exist in the permafrost region (including under-bedrock), that is, active layer, frost sand and gravels layer, frost volcanic rock permeated by sea water, and frost volcanic rock unpermeated by sea water. Finally, the permafrost table and its vertical gradient are deduced.展开更多
In the crystalline rock region of the Huangling anticline center located in the eastern part of the Three Gorges of the Yangtze River, 6 typical geological topographical section lines were selected and their paleotopo...In the crystalline rock region of the Huangling anticline center located in the eastern part of the Three Gorges of the Yangtze River, 6 typical geological topographical section lines were selected and their paleotopographies were reconstructed. Based on the difference between the present topography and the paleotopography, the denudation thicknesses of different topographical positions could be calculated. According to the principle of denudation correlated with deposition, the initial denudation age of the crystalline rock was inferred from the sedimentary strata deposited in the Jianghan basin near the Huangling anticline, including crystalline rock gravel from the Huangling anticline, which was about 56.5 MaBP. The widespread and intensive denudation took place at about 2.4 MaBP. On the basis of the above-mentioned initial denudation age (56.5 MaBP) and the denudation thicknesses, the denudation rates of different topographical summit levels, different topographical terrace levels and various watershed systems were calculated. The greatest denudation rate is 49.56 mm/ka. The average denudation rate is 16.97 mm/ka in the crystalline rock region of the Huangling anticline.展开更多
基金The research is supported by the State Antarctic Committee and the National Natural Science Foundation of China.
文摘Based on the data from the pitting, geoelectrical prospectings, temperature measuring, and the divided layers frost-heaving instruments, this paper, first, discusses the structure features of active layers in this region, and proves the presence of the bowlshaped frost table in the stone circles area. Second, it analyses the temperature distributive rule in the active layer, meantime, according to the vertical-profile parameters of granularity, clay mineral, salt content and resistivities, it also discusses the different features of permafrost structure and their control actions on the periglacial landform development between high and low places. It suggests that the four-layer structure should exist in the permafrost region (including under-bedrock), that is, active layer, frost sand and gravels layer, frost volcanic rock permeated by sea water, and frost volcanic rock unpermeated by sea water. Finally, the permafrost table and its vertical gradient are deduced.
文摘In the crystalline rock region of the Huangling anticline center located in the eastern part of the Three Gorges of the Yangtze River, 6 typical geological topographical section lines were selected and their paleotopographies were reconstructed. Based on the difference between the present topography and the paleotopography, the denudation thicknesses of different topographical positions could be calculated. According to the principle of denudation correlated with deposition, the initial denudation age of the crystalline rock was inferred from the sedimentary strata deposited in the Jianghan basin near the Huangling anticline, including crystalline rock gravel from the Huangling anticline, which was about 56.5 MaBP. The widespread and intensive denudation took place at about 2.4 MaBP. On the basis of the above-mentioned initial denudation age (56.5 MaBP) and the denudation thicknesses, the denudation rates of different topographical summit levels, different topographical terrace levels and various watershed systems were calculated. The greatest denudation rate is 49.56 mm/ka. The average denudation rate is 16.97 mm/ka in the crystalline rock region of the Huangling anticline.
