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Search Results: 1 - 10 of 126797 matches for " Congxian Li "
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Stage characteristics for the development of late Quaternary paleosols in the Yangtze Delta area
Qingqiang Chen,Congxian Li
Chinese Science Bulletin , 1999, DOI: 10.1007/BF02885037
Abstract: The late Quaternary paleosols in the Yangtze Delta area developed in the period of 25 000–12 000 aBP. Phytolith ratios (value A) of contents of fan, square and rectangle types indicating the warm and humid climate to those of bar, hat and point types indicating cold and dry climates decrease upwards overall on profiles of the paleosols, suggesting that the climates turned from warm and humid to cold and dry. So, the paleosols developed mainly during the regression before the last glacial maximum. Changes of value A indicate no trend of warming, suggesting that the transgression was rapid after the last glacial maximum. The development of the paleosols exhibited obvious stages, which were controlled remarkably by transgression and regression: I. Period of alternation of deposition and pedogenesis, which was from the occurrence of regresson before the last glacial maximum to the time when sea levels fell close to the lowest; II. Exposure period with continual pedogenesis, which was terminated when the paleosols were drown in the post-glacial transgression; III. Period of being drown and buried, the paleosols were buried by marine sediments, and reworked by early diagenesis.
Sources of sediments filling the Qiantangjiang estuary incised valley since the Last Glaciation
Guijia Zhang,Congxian Li
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02884142
Abstract: The volumes of each sedimentary facies in the Qiantongjiang estuary area have been calculated based on layer thickness data of about 100 bores. The sediment sources of each facies have been discussed on the basis of the previous work and the above calculations.
Stage characteristics for the development of late Quaternary paleosols in the Yangtze Delta area

Qingqiang Chen,Congxian Li,

科学通报(英文版) , 1999,
Abstract: The late Quaternary paleosols in the Yangtze Delta area developed in the period of 25 000–12 000 aBP. Phytolith ratios (value A) of contents of fan, square and rectangle types indicating the warm and humid climate to those of bar, hat and point types indicating cold and dry climates decrease upwards overall on profiles of the paleosols, suggesting that the climates turned from warm and humid to cold and dry. So, the paleosols developed mainly during the regression before the last glacial maximum. Changes of value A indicate no trend of warming, suggesting that the transgression was rapid after the last glacial maximum. The development of the paleosols exhibited obvious stages, which were controlled remarkably by transgression and regression: I. Period of alternation of deposition and pedogenesis, which was from the occurrence of regresson before the last glacial maximum to the time when sea levels fell close to the lowest; II. Exposure period with continual pedogenesis, which was terminated when the paleosols were drown in the post-glacial transgression; III. Period of being drown and buried, the paleosols were buried by marine sediments, and reworked by early diagenesis.
Paleocurrent of the tidal sand body in Subei coastal plain
Zhang Jiaqiang,Li Congxian,Cong Youzi
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02884646
Abstract: Based on analysis of magnetic febric and magnetic relict, the paleocurrents racorded in drilling cores in Subei coastal plain are bidirectional. NE-SW in the northern core and NW-SE in the southern core. The paleacurrent pattern in the area is similar to that of the tidal current system in the South Yellow Sea. So it is inferred that the convergent-divergent tidal current system existed during stage of sand body formation, and they should be radial in plane.
Relationship between magnetic fabric parameters and dynamic characteristics of deposits in different environments
Qingqiang Chen,Congxian Li,Youzi Cong
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883472
Abstract: Comparison of magnetic fabric parameters of deposits in different modern sedimentary environments indicates that values ofP, F andL of eolian deposits are lower obviously than those of hydrogenic ones respectively. On relationship diagrams of magnetic fabric parameters, data points of eolian samples concentrated in limited area near origin of coordinates indicate that dynamic intensity is lower with less variation; while those of hydrogenic ones depart from origin of coordinates suggest higher intensity of sedimentary dynamics. Analyses of dynamic characteristics of different sedimentary environments indicate that values of magnetic fabric parameters of deposits are determined by dynamic types and characteristics of depositional processes. Magnetic fabric analyses of deposits are effective in determination of sedimentary environments.
Paleovalley in the Yannan-Sancang area of Jiangsu Province and its geological significance
Congxian Li,Minghao Wan,Qingqiang Chen
Chinese Science Bulletin , 1997, DOI: 10.1007/BF02882549
Abstract:
Paleovalley in the Yannan-Sancang area of Jiangsu Province and its geological significance

Li Congxian,Wan Minghao,Chen Qingqiang,

科学通报(英文版) , 1997,
Abstract:
Paleocurrent of the tidal sand body in Subei coastal plain

Zhang Jiaqiang,Li Congxian,Cong Youzi,

科学通报(英文版) , 1998,
Abstract: Based on analysis of magnetic febric and magnetic relict, the paleocurrents racorded in drilling cores in Subei coastal plain are bidirectional. NE-SW in the northern core and NW-SE in the southern core. The paleacurrent pattern in the area is similar to that of the tidal current system in the South Yellow Sea. So it is inferred that the convergent-divergent tidal current system existed during stage of sand body formation, and they should be radial in plane.
Magnetic fabric characteristics of late Quaternary strata in Shanghai area
Daidu Fan,Qingqiang Cheng,Youzi Cong,Congxian Li
Chinese Science Bulletin , 1998, DOI: 10.1007/BF02883453
Abstract: The result of measurements and analyses on magnetic fabrics data for the late Quaternary core at Caoyangxincun in Shanghai shows that abrupt changes of magnetic fabric curves coincide with the boundaries between the marine strata and underlying stiff clay. Littoral, neritic, subtidal and tidal flat facies in the marine strata have distinct magnetic fabric characteristics. The curves of the parameters,K, P, L, q, display clear boundaries between various facies, which could serve as a new method for the stratigraphic subdivision and correlation.
REE geochemistry of suspended sediments from the rivers around the Yellow Sea and provenance indicators
Shouye Yang,Congxian Li,C. B. Lee,T. K. Na
Chinese Science Bulletin , 2003, DOI: 10.1007/BF03185768
Abstract: Rare earth element (REE) compositions of the suspended sediments from the rivers around the Yellow Sea were different in that Korean river sediments (Han, Keum and Yeongsan Rivers) yield stronger fractionations than Chinese river sediments (Changjiang, Huanghe and Yalujiang), shown by obvious enrichments of LREE (light rare earth element) relative to UCC (upper continental crust). Variations of source rock compositions in the drainage basins are responsible for the differences of REE compositions between the river sediments. REE fractionation parameters including (La/Yb)UCC and (Gd/Yb)UCC as well as the ratios of La/Sc and Th/Sc can be treated as proper proxies for identifying the Chinese river sediments from those Korean river matters, and furthermore, for studying the provenances and paleoenvironmental changes of the marginal seas of China.
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