The Yellow River is usually assumed to record tectonic activities and climatic changes;however,a systematic study was lack in the sedimentology,stratigraphy,geomorphology and geochronology for the entire Yellow River ...The Yellow River is usually assumed to record tectonic activities and climatic changes;however,a systematic study was lack in the sedimentology,stratigraphy,geomorphology and geochronology for the entire Yellow River though various geologic scholars have conducted numerous works in individual basins.This review focused on well-preserved fluvial terrace sequences that formed along this river on northeastern(NE)Tibetan Plateau and Ordos Block over the past 2.6 Ma.After comparing numerous initial incision ages at different segments along the Yellow River,we found out that the youngest initial incision may occur at ca.150 ka at the Longyang Gorge.The Yellow River may transit from multiple separated endorheic drainages to an entire external drainage after 150 ka,which may cause differentiations in the apparent incision rates before and after 150 ka;thus apparent net incision rates were calculated respectively for the Yellow River before 150 ka and the drainage network post 150 ka.Apparent net incision rates prior to 0.15 Ma were calculated as 0.15,0.29,0.10,0.12 and 0.03 mm/a respectively in Tongde-Xunhua,Lanzhou-Linxia basins,Heishan,Jinshan and Fenwei-Sanmen Gorges in this review,which mainly reflected Kunhuang-Gonghe Tectonic Event,generated by the Indo-Asian collision and diminishing as the NE Tibetan Plateau eastward extruding at ca.1.8-0.15 Ma.Apparent net incision rates post 0.15 Ma were calculated respectively for NE Tibetan Plateau and Ordos Block,considering their different base level.On NE Tibetan Plateau,four fluvial degradational phases were identified between ca.105~70,53~40,25~16 and 12~6 ka associated with terrace levels respectively,at average elevations of 96,40,20 and 10.5 meters above the current river level(m arl)within a range of 5~96 m arl;and four broad periods in the last 150 ka on Ordos Block:possibly marine oxygen isotope stage(MIS)5,ca.118 to 72 ka,most of MIS 3,ca.44~28 ka,transition from LGM to last deglacial ca.20 to 16 ka,and 4~3 ka at average elevations of 67.5,26,19 and 11.5 m arl.These degradational phases post 0.15 Ma were associated with multiple processes including enhanced fluvial discharge with an increase in monsoonal precipitation and/or melt water in deglaciation.展开更多
The geomorphological evolution of the Northeastern Tibetan Plateau （NETP） could provide valuable information for reconstructing the tectonic movements of the region. And the considerable uplift and climatic changes ...The geomorphological evolution of the Northeastern Tibetan Plateau （NETP） could provide valuable information for reconstructing the tectonic movements of the region. And the considerable uplift and climatic changes at here, provide an opportunity for studying the im- pact of tectonic and monsoon climate on fluvial morphological development and sedimentary architecture of fluvial deposits. The development of peneplain-like surface and related land- scape transition from basin filling to incision indicate an intense uplift event with morphologi- cal significance at around 10-17 Ma in the NETP. After that, incision into the peneplain was not continuous but a staircase of terraces, developed as a result of climatic influences. In spite of the generally persisting uplift of the whole region, the neighbouring tectonic blocks had different uplift rates, leading to a complicated fluvial response with accumulation terraces alternating with erosion terraces at a small spatial and temporal scale. The change in fluvial activity as a response to climatic impact is reflected in the general sedimentary sequence on the terraces from high-energy （braided） channel deposits （at full glacial） to lower-energy de- posits of small channels （towards the end of the glacial）, mostly separated by a rather sharp boundary from overlying flood-Ioams （at the glacial-interglacial transition） and overall soil formation （interglacial）. Pronounced incision took place at the subsequent warm-cold transi- tions. In addition, it is hypothesized that in some strongly uplifted blocks energy thresholds could be crossed to allow terrace formation as a response to small climatic fluctuations （10^3-10^4 year timescale）. Although studies of morpho-tectonic and geomorphological evolu- tion of the NETP, improve understanding on the impacts of tectonic motions and monsoonal climate on fluvial processes, a number of aspects, such as the distribution and correlation of peneplain and the related morphological features, the extent and intensity of tectonic move- ments influencing the crossing of climatic thresholds, leading to terrace development, need to be studied further.展开更多
The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Hu...The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping. Three terraces in the Haiyan Basin, four terraces in the Huangyuan Basin, 19 terraces in the Xi＇ning Basin （the four high terraces may belong to another river）, nine terraces in the Ping＇an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized. Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River, which is located at the margin of Tibet, are different from that of the rivers at other regions. The formation process of the terrace is more complicated at the Huang Shui catchment： both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins, indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins. A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper. First, the equilibrium state of the river is broken because of climatic change and/or tectonic movement, and the river incises in all basins in the whole catchment until reaching a new equilibrium state. Then, the downstream basin subsides quickly and the equilibrium state is broken again, and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again. Finally, the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins. The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment. These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin. Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.展开更多
The uplift of the Qilian Shan,which is located at the northeastern margin of the Tibetan Plateau,is a significant event in the plateau's formation.There is an ongoing debate regarding the mechanism of the Qilian S...The uplift of the Qilian Shan,which is located at the northeastern margin of the Tibetan Plateau,is a significant event in the plateau's formation.There is an ongoing debate regarding the mechanism of the Qilian Shan:whether it involves gradual extension or uniform uplift.A key factor in resolving the debate is determining whether the North Qilian Shan fault(NQF),the north boundary thrust fault of the Qilian Shan,accounts for the majority of the crustal shortening across the range.In this study,we focused on the eastern section of the NQF to assess its deformation rate.The Zamu River flows almost perpendicularly through two branch faults of the NQF,and a flight of well-preserved terraces along the river provides an excellent opportunity to constrain a reliable deformation rate.We measured the elevation of these river terraces and dated them by Optically Stimulated Luminescence(OSL)and cosmogenic10Be exposure dating methods.The result shows that each terrace surface is offset at the Kangningqiao fault and is significantly folded in the hanging wall to the Shanggucheng-Shuangta fault.The abandonment ages of the four levels of terraces are determined as~48 ka(T2),~73 ka(T2a),80–85 ka(T3),~122 ka(T4),respectively.Based on the deformation characteristics of the terraces and geometric models of trishear folding and listric faulting,the relationship between these two branch faults and deforming kinematics is established.From this kinematic model,a total slip rate of 1.24±0.12 mm a^(-1)is derived.The rate is consistent with the previously determined rate of 1.3±0.6 mm a^(-1)in the western and central sections of the NQF.The similar shortening rate along the whole NQF indicates that the northern boundary fault accounts for 15%–20%of the total crustal shortening rate across the Qilian Shan.This shortening distribution is not in line with the tectonic wedge model which posits that the boundary fault absorbs the majority of the shortening rate,but rather supports the model of uniform uplift across the Qilian Shan.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.41472155),Grant No.ZR2022QD083,LYHZW202248 and NSFC 417644073Cultivating Young Talents in the Universities of Shandong Province(LUJIAOKEHAN2021-51,granted to L.Yu)。
文摘The Yellow River is usually assumed to record tectonic activities and climatic changes;however,a systematic study was lack in the sedimentology,stratigraphy,geomorphology and geochronology for the entire Yellow River though various geologic scholars have conducted numerous works in individual basins.This review focused on well-preserved fluvial terrace sequences that formed along this river on northeastern(NE)Tibetan Plateau and Ordos Block over the past 2.6 Ma.After comparing numerous initial incision ages at different segments along the Yellow River,we found out that the youngest initial incision may occur at ca.150 ka at the Longyang Gorge.The Yellow River may transit from multiple separated endorheic drainages to an entire external drainage after 150 ka,which may cause differentiations in the apparent incision rates before and after 150 ka;thus apparent net incision rates were calculated respectively for the Yellow River before 150 ka and the drainage network post 150 ka.Apparent net incision rates prior to 0.15 Ma were calculated as 0.15,0.29,0.10,0.12 and 0.03 mm/a respectively in Tongde-Xunhua,Lanzhou-Linxia basins,Heishan,Jinshan and Fenwei-Sanmen Gorges in this review,which mainly reflected Kunhuang-Gonghe Tectonic Event,generated by the Indo-Asian collision and diminishing as the NE Tibetan Plateau eastward extruding at ca.1.8-0.15 Ma.Apparent net incision rates post 0.15 Ma were calculated respectively for NE Tibetan Plateau and Ordos Block,considering their different base level.On NE Tibetan Plateau,four fluvial degradational phases were identified between ca.105~70,53~40,25~16 and 12~6 ka associated with terrace levels respectively,at average elevations of 96,40,20 and 10.5 meters above the current river level(m arl)within a range of 5~96 m arl;and four broad periods in the last 150 ka on Ordos Block:possibly marine oxygen isotope stage(MIS)5,ca.118 to 72 ka,most of MIS 3,ca.44~28 ka,transition from LGM to last deglacial ca.20 to 16 ka,and 4~3 ka at average elevations of 67.5,26,19 and 11.5 m arl.These degradational phases post 0.15 Ma were associated with multiple processes including enhanced fluvial discharge with an increase in monsoonal precipitation and/or melt water in deglaciation.
基金Foundation： National Natural Science Foundation of China, No.41522101 National Key Research and Development Program, No.2016YFA0600500 Dutch-Chinese Exchange Program
文摘The geomorphological evolution of the Northeastern Tibetan Plateau （NETP） could provide valuable information for reconstructing the tectonic movements of the region. And the considerable uplift and climatic changes at here, provide an opportunity for studying the im- pact of tectonic and monsoon climate on fluvial morphological development and sedimentary architecture of fluvial deposits. The development of peneplain-like surface and related land- scape transition from basin filling to incision indicate an intense uplift event with morphologi- cal significance at around 10-17 Ma in the NETP. After that, incision into the peneplain was not continuous but a staircase of terraces, developed as a result of climatic influences. In spite of the generally persisting uplift of the whole region, the neighbouring tectonic blocks had different uplift rates, leading to a complicated fluvial response with accumulation terraces alternating with erosion terraces at a small spatial and temporal scale. The change in fluvial activity as a response to climatic impact is reflected in the general sedimentary sequence on the terraces from high-energy （braided） channel deposits （at full glacial） to lower-energy de- posits of small channels （towards the end of the glacial）, mostly separated by a rather sharp boundary from overlying flood-Ioams （at the glacial-interglacial transition） and overall soil formation （interglacial）. Pronounced incision took place at the subsequent warm-cold transi- tions. In addition, it is hypothesized that in some strongly uplifted blocks energy thresholds could be crossed to allow terrace formation as a response to small climatic fluctuations （10^3-10^4 year timescale）. Although studies of morpho-tectonic and geomorphological evolu- tion of the NETP, improve understanding on the impacts of tectonic motions and monsoonal climate on fluvial processes, a number of aspects, such as the distribution and correlation of peneplain and the related morphological features, the extent and intensity of tectonic move- ments influencing the crossing of climatic thresholds, leading to terrace development, need to be studied further.
基金supported by the National Natural Science Foundation of China(Grant no.40901002 and 40325007)the 985 project to Nanjing University and the CAS-KNAW PhD project(05-PhD-10)
文摘The Huang Shui River, a main tributary of the Yellow River, crosses a series of tectonically subsided and uplifted areas that show different patterns of terrace formation. The distribution of fluvial terrace of the Huang Shui River is studied through topographic and sedimentologic terrace mapping. Three terraces in the Haiyan Basin, four terraces in the Huangyuan Basin, 19 terraces in the Xi＇ning Basin （the four high terraces may belong to another river）, nine terraces in the Ping＇an Basin, five terraces in the Ledu Basin and 12 terraces in the Minhe Basin are recognized. Sedimentology research shows that the geomorphologic and sedimentological pattern of the Huang Shui River, which is located at the margin of Tibet, are different from that of the rivers at other regions. The formation process of the terrace is more complicated at the Huang Shui catchment： both accumulation terrace and erosion terrace were formed in each basin and accumulation terraces were developed in some basins when erosion terraces were formed in other basins, indicating fluvial aggradation may occur in some basins simultaneously with river incision in other basins. A conceptual model of the formation process of these two kinds of fluvial terraces at Huang Shui catchment is brought forward in this paper. First, the equilibrium state of the river is broken because of climatic change and/or tectonic movement, and the river incises in all basins in the whole catchment until reaching a new equilibrium state. Then, the downstream basin subsides quickly and the equilibrium state is broken again, and the river incises at upstream basins while the river accumulates at the subsidence basin quickly until approaching a new equilibrium state again. Finally, the river incises in the whole catchment because of climatic change and/or tectonic movement and the accumulation terrace is formed at the subsidence basin while the erosion terrace is formed at other basins. The existence of the accumulation terrace implied the tectonic subsidence in the sub-basins in Huang Shui catchment. These tectonic subsidence movements gradually developed from the downstream Minhe Basin to the upstream Huangyuan Basin. Dating the terrace sequence has potential to uncover the relationship between the subsidence in the catchment and the regional tectonic at the northeastern Tibetan Plateau.
基金supported by the National Natural Science Foundation of China(Grant No.42071001)the Second Tibetan Plateau Scientific Expedition(Grant No.2019QZKK0704)。
文摘The uplift of the Qilian Shan,which is located at the northeastern margin of the Tibetan Plateau,is a significant event in the plateau's formation.There is an ongoing debate regarding the mechanism of the Qilian Shan:whether it involves gradual extension or uniform uplift.A key factor in resolving the debate is determining whether the North Qilian Shan fault(NQF),the north boundary thrust fault of the Qilian Shan,accounts for the majority of the crustal shortening across the range.In this study,we focused on the eastern section of the NQF to assess its deformation rate.The Zamu River flows almost perpendicularly through two branch faults of the NQF,and a flight of well-preserved terraces along the river provides an excellent opportunity to constrain a reliable deformation rate.We measured the elevation of these river terraces and dated them by Optically Stimulated Luminescence(OSL)and cosmogenic10Be exposure dating methods.The result shows that each terrace surface is offset at the Kangningqiao fault and is significantly folded in the hanging wall to the Shanggucheng-Shuangta fault.The abandonment ages of the four levels of terraces are determined as~48 ka(T2),~73 ka(T2a),80–85 ka(T3),~122 ka(T4),respectively.Based on the deformation characteristics of the terraces and geometric models of trishear folding and listric faulting,the relationship between these two branch faults and deforming kinematics is established.From this kinematic model,a total slip rate of 1.24±0.12 mm a^(-1)is derived.The rate is consistent with the previously determined rate of 1.3±0.6 mm a^(-1)in the western and central sections of the NQF.The similar shortening rate along the whole NQF indicates that the northern boundary fault accounts for 15%–20%of the total crustal shortening rate across the Qilian Shan.This shortening distribution is not in line with the tectonic wedge model which posits that the boundary fault absorbs the majority of the shortening rate,but rather supports the model of uniform uplift across the Qilian Shan.
