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Terrace dating as an archive of the run-through of the sanmen Gorges

Progress in Natural science:Materials International 2005年第12期15卷 1096-1103页

作者： pan baotian,wang junping,gao hongshan,chen yingying,li jijun and liu xiaofeng key laboratory of western china’s environmental systems,ministry of education,and department of geography,lanzhou university,lanzhou 730000,china key laboratory of western china's environmental systems of ministry of education Department of Geography Lanzhou University Lanzhou 730000 China

Analysis of morphological properties in the sanmen Gorges region of the Yellow River shows that four river terraces have been developed at the entrance to the ***,thick aeolian loess-paleosol sequence was deposited on the terraces,which makes it easy to date the *** dating of paleomagnetic,loess-paleosol sequence matching and thermoluminescence show that terraces T2,T3 and T4 were formed 0.129 Ma,0.625 Ma and 0.865 Ma ago,*** formation of these terraces in this region indicates that the Yellow River has experienced four intensive downcutting events during the last 0.9 *** Yellow River cut through the sanmen Gorges and inpoured into the East china sea no later than 0.865 Ma.

关键词： river terrace paleomagnetic dating Yellow River loess

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Dating and genesis of the upper Weihe River terraces in Longxi basin,china

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Progress in Natural science:Materials International 2007年第11期17卷 1334-1340页

作者： pan baotian, liu xiaofeng, gao hongshan, wang Yong and li jijun(key laboratory of western china’s environmental system, ministry of education, lanzhou university, lanzhou 730000, china) key laboratory of western china's environmental system Lanzhou University Lanzhou 730000 China

seven terraces along the Weihe River in Longxi basin have been investigated. These terraces all consist of archetypal duality in structure, namely the floodplain deposits and the layer of gravels overlaid by varying thickness of the loess. By resorting to various dating approaches such as palaeomagnetic, optically stimulated luminescenece (OsL), 14C and loess-paleosol sequence, we provide preliminary timing of these seven terraces along upper Weihe River. Analysis on sedimentation characteristics and dating of these terraces showed that seven terraces may be jointly generated by tectonic uplifts and climatic changes. Tectonic uplifts may accommodate initial river incision, and climatic change may be responsible for processes of subsequent channel widening and aggradation. Aggradation normally occurs during glacial periods, in contrast to down-cuttings during transitions from glacial to interglacial period. Moreover, on the basis of the timings and heights of these terraces, we infer that the long-term rate of river incision was determined to be 0.2 m/kyr during the last 870 kyr, which differs from other river incision rates. This discrepancy may reflect spatio-temporal differentiation of tectonic activities in the Qinling orogenic belt during the Pleistocene.

关键词： loess stratigraphy river terraces climate change Upper Weihe River

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Fluvial terraces and their implications for Weihe River valley evolution in the sanyangchuan Basin

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science china Earth sciences 2017年第3期60卷 413-427页

作者： gao hongshan li ZongMeng liu xiaofeng pan baotian WU YaJie liu Fenliang key laboratory of western china's environmental system Ministry of EducationCollege of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China lanzhou Institute of seismology China Earthquake AdministrationLanzhou 730000China

Fluvial terraces are important geomorphic markers for modern valley *** coupled with numeric ages,terraces can provide abundant information about tectonic,climatic,paleohydrological and the paleoenvironmental *** the basis of the paleomagnetic,electron spin resonance(EsR) and optically stimulated luminescence(OsL) dating,in addition to an investigation of local loess-paleosol sequences,we confirmed that 13 fluvial terraces were formed,and then preserved,along the course of the Upper Weihe River in the sanyangchuan Basin over the past 1.2 *** of the characteristics and genesis of these terraces indicate that they resulted from the response of this particular river system to climate change over an orbital *** changes can further be placed within the context of local and regional tectonic uplift,and represent an alternation between lateral migration and vertical incision,dependent upon the predominance of climatic and tectonic controls during different *** of the terraces are strikingly similar in that they have several meters of paleosols which have developed directly on top of fluvial deposits located on the terrace treads,suggesting that the abandonment of terraces due to river incision occurred during the transitions from glacial to interglacial *** temporal and spatial differences in the distribution patterns of terraces located on either side of the river valley indicate that a tectonic inversion occurred in sanyangchuan Basin at-0.62 Ma,and that this was characterized by a transition from overall uplift to depression induced by fault *** studies of the Basin's terraces indicate that formation of the modern valley of the Upper Weihe River may have begun in the late Early Pleistocene between1.4-1.2 Ma.

关键词： River terrace Valley evolution Tectonic activity Climate change sanyangchuan Basin

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