By the measurement of the wind directional indicator of theCretaceous desert in Ordos Basin, the regularity of the paleoprevailing wind directions and pattern of the paleowind belts are revealed. It is considered that...By the measurement of the wind directional indicator of theCretaceous desert in Ordos Basin, the regularity of the paleoprevailing wind directions and pattern of the paleowind belts are revealed. It is considered that the desert was controlled by a planetary wind system. In the early stage, the subtropical high pressure zone drifted south and northwards with short cycles, resulting in the alternation of westerlies and northeast trades; in the late stage, the subtropical high pressure zone drifted southwards with a long cycle, placing the desert under the westerly belt and making the desert completely controlled by the westerly belt. The reconstruction of the paleowind belts has provided the evidence of the general circulation of the atmosphere for the pattern of the circulation before the uplift of the Tibetan Plateau.展开更多
Paleowind activities played a major role in the dry climate predominant in NorthChina during the Permian. However, there is only a little information available dueto the diffculties in exploration. The usual method ba...Paleowind activities played a major role in the dry climate predominant in NorthChina during the Permian. However, there is only a little information available dueto the diffculties in exploration. The usual method based on the original features insediments is significant only in analysing eolian-dune environment, as a majority ofresidues in other eolian environment are hardly preserved in strata because of laterdestruction or disturbance.展开更多
Carbonate eolianites in Houshijing, Putian, Fujian, consist of three sand ridges. The geometry and sedimentary structures of these ridges are described here, and their paleodune types and the paleowind directions are ...Carbonate eolianites in Houshijing, Putian, Fujian, consist of three sand ridges. The geometry and sedimentary structures of these ridges are described here, and their paleodune types and the paleowind directions are reconstructed on the basis of discussion of genesis. The authors consider that they were vegetated longitudinal dunes or sand drifts and wind shadow dunes or sand shadows which were formed by reworking of adjacent beach sand by prevailing northeast monsoon during the latest Middle Holocene. The wind directions in the past and at present do not appear to have obviously changed.展开更多
The anisotropy of magnetic susceptibility (AMS) is a rapid and precise tool for determining paleowind directions. During the past several decades, AMS has been used for determining paleowind directions of Chinese loes...The anisotropy of magnetic susceptibility (AMS) is a rapid and precise tool for determining paleowind directions. During the past several decades, AMS has been used for determining paleowind directions of Chinese loess. The AMS for a loess-paleosol profile in early Quaternary at Longdan in the Linxia Basin, Gansu Province, northeastern fringe of Qinghai-Xizang (Tibetan) Plateau has been obtained. The primary results show that the AMS of the Longdan profile has its typical normal eolian dust deposit. The AMS is mainly controlled by magnetic foliation (F) and the shape parameter of the AMS ellipsoid is oblate. The declination of maximum susceptibility (K1) was used to determine the paleowind direction of that area in early Quaternary and it was found that the paleowind direction is biased towards NW-SE.展开更多
The global climatic change study is a hot point today.As the pattern of the general circulation of the atmosphere is the key factor for climate,the reconstruction of the pattern of the past general circulation of the ...The global climatic change study is a hot point today.As the pattern of the general circulation of the atmosphere is the key factor for climate,the reconstruction of the pattern of the past general circulation of the atmosphere has become important part of the global climatic change study.The paleowind belts are the comprising part of the past general circulation of the atmosphere and also the records of the circulation,therefore,their reconstruction will be helpful to the reconstruction of the general circulation of the atmosphere.In present years,the pattern of the general circulation of the atmosphere has attracted great concern from scientists.For example,Zhang Linyuan and Liu Dongsheng, based on the existence and inexistence of the Tibetan Plateau and paleogeography,divide the evolution of the general circulation of the atmosphere in eastern asia into two stages:the planetary wind stage before the uplift of the plateau and the monsoon stage after the uplift of the plateau which is subdivided into ancient monsoon and modern monsoon stages.While Dong Guangrong et al., Jiang Xinsheng et al. and Cooke et al, based on the latitudinal distribution of the Cretaceous and Tertiary deserts and the generation of arid climate,suggest that there was a subtropical high pressure zone across the eastern asia and was a planetary wind system,but have not found any direct record of the circulation.It is true that before the Early Tertiary,not only organism, but also inorganism,i.e.,biogeography and lithogeography, show strong zonal distribution.It can only indicate that zonal climate was evident at that time.Of course, as the climate is the result of the influences on the ground by zones of the circulation,it is reasonable to deduce the existence of zonal circulation,i.e. the the existence of the planetary wind system,from the zonal climate.But it would be much better if direct record of planetary wind system were found.Prevailing winds are the main geological agent for a desert which must leave deep stamps on the desert.The stamps on modern desert are reflected by dune migrating directions and on paleodesert by foreset dip directions..It is the most direct geological record for reconstructing paleowind belts and has been extensively used to reconstruct paleowind belts,paleogeography,paleoclimate and even to check the paleolatitude determined by paleomagnetism (for example, Opdyke and Runcorn, 1960; Creer, 1958; Pook, 1962; Bigarella and Salamuni,1961).展开更多
利用遥感图像的风成地貌形态和高分辨率古季风指标,恢复柴达木盆地晚全新世以来的古风况,揭示青藏高原抬升时期东亚季风变迁的历史。结果表明,柴达木盆地晚全新世以来盛行西北风,同时有少量西风和北风,主要由亚洲冬季风控制,夏季风和西...利用遥感图像的风成地貌形态和高分辨率古季风指标,恢复柴达木盆地晚全新世以来的古风况,揭示青藏高原抬升时期东亚季风变迁的历史。结果表明,柴达木盆地晚全新世以来盛行西北风,同时有少量西风和北风,主要由亚洲冬季风控制,夏季风和西风环流的影响甚微。盆地东部沙丘和雅丹地貌记录了末次盛冰期西风环流的风向,中西部地区的风成地貌指示晚全新世以来盆地发育西北向的亚洲冬季风。青藏高原的抬升阻挡西风环流进入柴达木盆地,并加强亚洲冬季风,造成盆地内古风向的改变,大气环流模式的转变发生在4000 a BP左右,此时是柴达木盆地气候从暖湿转向冷干的重要节点。展开更多
基金The field work has been guided by Prof. Qi Hua from Xi'an Institute of Geology and Mineral Resources and the indoor work has been supervised by Academician Liu Baojun and Prof. Pan Guitang, Director of Chengdu Institute of Geology and Mineral Resources.
文摘By the measurement of the wind directional indicator of theCretaceous desert in Ordos Basin, the regularity of the paleoprevailing wind directions and pattern of the paleowind belts are revealed. It is considered that the desert was controlled by a planetary wind system. In the early stage, the subtropical high pressure zone drifted south and northwards with short cycles, resulting in the alternation of westerlies and northeast trades; in the late stage, the subtropical high pressure zone drifted southwards with a long cycle, placing the desert under the westerly belt and making the desert completely controlled by the westerly belt. The reconstruction of the paleowind belts has provided the evidence of the general circulation of the atmosphere for the pattern of the circulation before the uplift of the Tibetan Plateau.
基金Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Academia Sinica.
文摘Paleowind activities played a major role in the dry climate predominant in NorthChina during the Permian. However, there is only a little information available dueto the diffculties in exploration. The usual method based on the original features insediments is significant only in analysing eolian-dune environment, as a majority ofresidues in other eolian environment are hardly preserved in strata because of laterdestruction or disturbance.
基金Project supported by the National Natural Science Foundation of China.
文摘Carbonate eolianites in Houshijing, Putian, Fujian, consist of three sand ridges. The geometry and sedimentary structures of these ridges are described here, and their paleodune types and the paleowind directions are reconstructed on the basis of discussion of genesis. The authors consider that they were vegetated longitudinal dunes or sand drifts and wind shadow dunes or sand shadows which were formed by reworking of adjacent beach sand by prevailing northeast monsoon during the latest Middle Holocene. The wind directions in the past and at present do not appear to have obviously changed.
基金Supported by 2003 Liu Tungsheng National Top Science and Technology Awards
文摘The anisotropy of magnetic susceptibility (AMS) is a rapid and precise tool for determining paleowind directions. During the past several decades, AMS has been used for determining paleowind directions of Chinese loess. The AMS for a loess-paleosol profile in early Quaternary at Longdan in the Linxia Basin, Gansu Province, northeastern fringe of Qinghai-Xizang (Tibetan) Plateau has been obtained. The primary results show that the AMS of the Longdan profile has its typical normal eolian dust deposit. The AMS is mainly controlled by magnetic foliation (F) and the shape parameter of the AMS ellipsoid is oblate. The declination of maximum susceptibility (K1) was used to determine the paleowind direction of that area in early Quaternary and it was found that the paleowind direction is biased towards NW-SE.
文摘The global climatic change study is a hot point today.As the pattern of the general circulation of the atmosphere is the key factor for climate,the reconstruction of the pattern of the past general circulation of the atmosphere has become important part of the global climatic change study.The paleowind belts are the comprising part of the past general circulation of the atmosphere and also the records of the circulation,therefore,their reconstruction will be helpful to the reconstruction of the general circulation of the atmosphere.In present years,the pattern of the general circulation of the atmosphere has attracted great concern from scientists.For example,Zhang Linyuan and Liu Dongsheng, based on the existence and inexistence of the Tibetan Plateau and paleogeography,divide the evolution of the general circulation of the atmosphere in eastern asia into two stages:the planetary wind stage before the uplift of the plateau and the monsoon stage after the uplift of the plateau which is subdivided into ancient monsoon and modern monsoon stages.While Dong Guangrong et al., Jiang Xinsheng et al. and Cooke et al, based on the latitudinal distribution of the Cretaceous and Tertiary deserts and the generation of arid climate,suggest that there was a subtropical high pressure zone across the eastern asia and was a planetary wind system,but have not found any direct record of the circulation.It is true that before the Early Tertiary,not only organism, but also inorganism,i.e.,biogeography and lithogeography, show strong zonal distribution.It can only indicate that zonal climate was evident at that time.Of course, as the climate is the result of the influences on the ground by zones of the circulation,it is reasonable to deduce the existence of zonal circulation,i.e. the the existence of the planetary wind system,from the zonal climate.But it would be much better if direct record of planetary wind system were found.Prevailing winds are the main geological agent for a desert which must leave deep stamps on the desert.The stamps on modern desert are reflected by dune migrating directions and on paleodesert by foreset dip directions..It is the most direct geological record for reconstructing paleowind belts and has been extensively used to reconstruct paleowind belts,paleogeography,paleoclimate and even to check the paleolatitude determined by paleomagnetism (for example, Opdyke and Runcorn, 1960; Creer, 1958; Pook, 1962; Bigarella and Salamuni,1961).
文摘利用遥感图像的风成地貌形态和高分辨率古季风指标,恢复柴达木盆地晚全新世以来的古风况,揭示青藏高原抬升时期东亚季风变迁的历史。结果表明,柴达木盆地晚全新世以来盛行西北风,同时有少量西风和北风,主要由亚洲冬季风控制,夏季风和西风环流的影响甚微。盆地东部沙丘和雅丹地貌记录了末次盛冰期西风环流的风向,中西部地区的风成地貌指示晚全新世以来盆地发育西北向的亚洲冬季风。青藏高原的抬升阻挡西风环流进入柴达木盆地,并加强亚洲冬季风,造成盆地内古风向的改变,大气环流模式的转变发生在4000 a BP左右,此时是柴达木盆地气候从暖湿转向冷干的重要节点。
