Chronological Link Between the Abrupt Change of the Loess Grain Size Sequence and the Formation of River Terraces on the Eastern Margin of the Qinghai-Tibetan Plateau Since the Late Early-Pleistocene  

作　　者：LIU Dongyan QIAO Yansong LI Weiran XIE Ruihuang PENG Shasha 

机构地区：[1]College of Marine Geoscience, Ocean University of China, Qingdao 266100, China [2]Key Laboratory of Submarine Science and Prospecting Techniques, Ministry of Education, Qingdao 266100, China [3]Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China [4]College of Physical andEnvironmental Oceanography, Ocean University of China, Qingdao 266100, China [5]Department of Meteorology, University of Hawaii at Manoa, Honolulu 96822, USA

出　　处：《Acta Geologica Sinica(English Edition)》2011年第3期723-732,共10页地质学报（英文版）

基　　金：support was provided by the National Science Foundation of China grant (40472088)

摘　　要：Based on the study of magnetostratigraphy,magnetic susceptibility and grain size of Garze A section on the southeastern margin of the Qinghai-Tibetan Plateau since the late early-Pleistocene,the basal age of Garze loess is located at～1.16 MaBP and a series of abrupt paleoclimatic changes is detected.The times of abrupt changes are of distinct series features,and the interval between each two adjacent abrupt changes is～50 kyr or～100 kyr.The most significant abrupt changes occur at around 1.06,0.85,0.6,0.46,0.39 and 0.14 MaBP.There is a chronological link between the abrupt changes of paleoclimate and the formation of river terraces and it is almost simultaneous with a strengthening trend of neotectonic activities.Therefore,maybe the climatic transition controll the timing of terrace formation,and the tectonic uplift originate potential energy and has a direct effect on channel incision, both the climatic transition and the tectonic uplift are important.Terraces are the products of the interaction of instable climatic variations and tectonic uplift.Like the loess-paleosol sequences,river terrace sequences are also controlled by the climate-tectonic coupling system and are ruled by climate-tectonic gyration with a～100 kyr paracycle,which may be the short eccentricity period of the earth.Based on the study of magnetostratigraphy,magnetic susceptibility and grain size of Garze A section on the southeastern margin of the Qinghai-Tibetan Plateau since the late early-Pleistocene,the basal age of Garze loess is located at～1.16 MaBP and a series of abrupt paleoclimatic changes is detected.The times of abrupt changes are of distinct series features,and the interval between each two adjacent abrupt changes is～50 kyr or～100 kyr.The most significant abrupt changes occur at around 1.06,0.85,0.6,0.46,0.39 and 0.14 MaBP.There is a chronological link between the abrupt changes of paleoclimate and the formation of river terraces and it is almost simultaneous with a strengthening trend of neotectonic activities.Therefore,maybe the climatic transition controll the timing of terrace formation,and the tectonic uplift originate potential energy and has a direct effect on channel incision, both the climatic transition and the tectonic uplift are important.Terraces are the products of the interaction of instable climatic variations and tectonic uplift.Like the loess-paleosol sequences,river terrace sequences are also controlled by the climate-tectonic coupling system and are ruled by climate-tectonic gyration with a～100 kyr paracycle,which may be the short eccentricity period of the earth.

关 键 词：Garze loess grain size TERRACE tectonic uplift the Qinghai-Tibetan Plateau 

分 类 号：P931.1[天文地球—自然地理学] O157.5[理学—数学]