Song Yougui

The Late Cenozoic uplift of the Liupan Shan, China

Based on paleomagnetic measurements and morphostratigraphy of red bed/clay sequences from pediments of the Liupan Shan and the Longdong Basin, the following results are revealed. The red bed/clay sediments became to accumulate at around 8.1 MaBP, which implied that the plantation surface developed since Late Cretaceous was broken by active fault, and its development was terminated. The Liupan Shan began to slightly uplift. The Liupan Shan experienced a small-scale uplift around 5.2 MaBP, inferred from the appearance of fine gravel sediments at that time. Consequently, a pediment was developed. The Liupan Shan accelerated uplift since about 3.8 MaBP at a large scale, which caused the deep incision of the rivers and the termination of fluvial and lacustrine deposition. Meanwhile, typical eolian red clay appeared since then. This uplift process is well correlated and in response to that of the Tibetan Plateau and the mountains around it.Based on paleomagnetic measurements and morphostratigraphy of red bed/clay sequences from pediments of the Liupan Shan and the Longdong Basin, the following results are revealed. The red bed/clay sediments became to accumulate at around 8.1 MaBP, which implied that the plantation surface developed since Late Cretaceous was broken by active fault, and its development was terminated. The Liupan Shan began to slightly uplift. The Liupan Shan experienced a small-scale uplift around 5.2 MaBP, inferred from the appearance of fine gravel sediments at that time. Consequently, a pediment was developed. The Liupan Shan accelerated uplift since about 3.8 MaBP at a large scale, which caused the deep incision of the rivers and the termination of fluvial and lacustrine deposition. Meanwhile, typical eolian red clay appeared since then. This uplift process is well correlated and in response to that of the Tibetan Plateau and the mountains around it.

Red clay sediment in the central Chinese Loess Plateau and its implication for the uplift of the Tibetan Plateau

The widely distributed red clay sediment underlying the Chinese Loess Plateau truly records the Neogene environmental evolution, and its genesis and development are intrinsically related to the uplift processes of the Tibetan Plateau and the evolution of East Asia monsoon system. In this paper, a detailed magnetostratigraphy of a loess-red clay section (107°13′E, 35°02′N) from the central Loess Plateau is reported. The loess-red clay sequence is composed of 175 m Quaternary loess-paleosol sequence and 128 m Neogene red clay sediments. Based on the correlation with the standard geomagnetic polarity time scale, the paleomagnetic results indicate that the age of Chaona red clay sequence extends to 8.1 Ma, which is the older red clay deposition in the central Chinese Loess Plateau. The commencement of red clay at ∼8.1 Ma may imply that the Ordos planation surface was broken by the movement of the Haiyuan-Liupanshan Faults, which was related to the uplift of the Tibetan Plateau induced by the collision of India Plate and Eurasian Plate. And the western part adjacent to the Tibetan Plateau was uplifted to form the embryo of the Liupan Shan (Mts.) and the eastern part was down-faulted to receive red clay deposition. We link this faulting to an initial uplift of the Tibetan Plateau. The undulating nature of the broken Ordos planation surface may explain the chronological differences and depth discrepancies among various cross-sections of red clay.The widely distributed red clay sediment underlying the Chinese Loess Plateau truly records the Neogene environmental evolution, and its genesis and development are intrinsically related to the uplift processes of the Tibetan Plateau and the evolution of East Asia monsoon system. In this paper, a detailed magnetostratigraphy of a loess-red clay section (107°13′E, 35°02′N) from the central Loess Plateau is reported. The loess-red clay sequence is composed of 175 m Quaternary loess-paleosol sequence and 128 m Neogene red clay sediments. Based on the correlation with the standard geomagnetic polarity time scale, the paleomagnetic results indicate that the age of Chaona red clay sequence extends to 8.1 Ma, which is the older red clay deposition in the central Chinese Loess Plateau. The commencement of red clay at ∼8.1 Ma may imply that the Ordos planation surface was broken by the movement of the Haiyuan-Liupanshan Faults, which was related to the uplift of the Tibetan Plateau induced by the collision of India Plate and Eurasian Plate. And the western part adjacent to the Tibetan Plateau was uplifted to form the embryo of the Liupan Shan (Mts.) and the eastern part was down-faulted to receive red clay deposition. We link this faulting to an initial uplift of the Tibetan Plateau. The undulating nature of the broken Ordos planation surface may explain the chronological differences and depth discrepancies among various cross-sections of red clay.

The Causes of Fluvial Terraces Inland and Its Implication

Terraces in tectonically active mountains and uplands record both tectonic uplift and climatic changes. The author discusses the methods of how to distinguish the role of both tectonic and climatic factors. Fluvial system in inland is a process of reaction between aggradation and incision controlled by tectonic movement or climate changes. Through studying the cause of formation of terrace, point out that climate-controlled terrace mainly deposits in the glacial period, and incises during glacial-interglacial transition. Incision of tectonic-controlled terrace takes place in active phase. At the same time, the palaeo- channel begins abandoning. People can determinate the cause of terraces through geology features analysis and contrast them with others that were put forward before. Every one of climate- caused terraces reveals that there is/are one/several glacial to interglacial cycle(s), the gravel interbedded with slope deposition, the declining terraces bottom; while every one of tectonic-caused terraces implies that there is a tectonic event during its formation. Some terraces result from both tectonic movements and climate changes.

Magnetostratigraphy study on the Miocene sediments of Suerkal Basin, Altyn Tagh and its significance

The Altyn Tagh fault is the northernmost controlling boundary of the Tibetan Plateau, which plays an important role in growth of the Tibetan Plateau. We carried out integrated research on Cenozoic stratigraphic sections in the intermontane basin of the Alty Tagh. Existing biostratigraphic data, and magnetostratigraphic analysis were used to establish chronostratigraphy, whereas composition of sandstone and coarse clastic sedimentary rocks was used to determine the unlift history of the source region. Much of the detrital grains in our measured sections can be correlated with uplifted of the surrounding mountains, implying a temporal link between sedimentation and deformation. The results of our studies, together with existing uplift period of the Kunlun Mountains, suggest that uplifting events started about 18Ma in northern Tibet. KeywordsThe Altyn Tagh fault; Magnetostratigraphy; Suerkal Basin; Lithology; stratigraphy

The evolution of river topography of Northern Tibet since 8Ma B P

River sediments derived from mountains are sensitive to record the information of uplift and erosion of mountains. Fluvial and alluvial sediments, which mainly consist of sand and gravel, of 21 sites from 14 inland rivers in the north side of Qilianshan Mts. were sampled. The volume of sediments sampled is 1 m. The result indicates that the variations of grain-sizes are closely related to the altitude difference between the highest peak of mountains in drainage basins and the sampling sites,and this relationship can be modeled based on the statistical analysis. This model is then used to the Laojunmiao Section which is located at the north of Tibetan Plateau to reconstruct the ancient topography of the Shiyouhe Drainage Basin since 8Ma. The reconstruction curve suggests that topography of Shiyouhe drainage uplifted fluctuantly since 8Ma B.P. and abruptly uplifted at the ages of 6.36Ma B.P. and 2.70Ma B.P.. There are three evident stages during the evolution of topographic difference. Mean topographic difference is about 500 m during 8-6.2Ma B.P., about 1,500 m during 6.2-2.7Ma B.P., more than 2,000 m during 2.7Ma B.P. to present days. The result basically agrees well with the claiming that northern Tibet uplift by phases since 8Ma B.P., after that come through an evident uplift at the age about 6Ma B.P., and accelerate to uplift since 3.66Ma B.P..

Two quantitative methods of studying Orogenic belt uplift and denudation through basin-range sedimentary coupling

Intensive uplifting of mountains has great impact on the changes of climate and environment, the uplift and denudation process of orogenic belts have been a major problem in geosciences studies. The sediment basin adjacent to mountains had truthfully recorded plentiful information about the uplift and denudation process of orogenic belts. Therefore, the history of uplift and denudation process of orogenic belts could be reconstructed by using basin-range sedimentary coupling theory. In this context, two quantitative methods were introduced to reconstruct the uplift and denudation process of orogenic belts. The uplift and denudation process of orogenic belts has been a major problem in geosciences studies. Uplift of Orogenic belt is not only the exterior presentation of locomotion from interior lithosphere of the earth, but also one of the important driving forces for great changes of geographic and ecological environment. The tremendous geomorphic diversity and ecological environmental effect caused by uplift of Orogenic belt have been widely concerned. The Late Cenozoic intensive uplift of Qinghai-Tibet Plateau has greatly influenced the physiographic pattern, atmospheric circulation and anthropic living environment (1-4). Here, many methods, such as paleomorphology, paleontology, palaeoclimate, thermochronology and cosmogenic radionuclide, have played an important role and obtained many great achievements (5-10). These methods generally study the uplift process of orogenic belts directly bymountains and orogenic belts themselves or deduce the uplift rate and range of mountains indirectly by paleontology and palaeoclimatic controlled eolian loess-paleosol sequences. During the last twenty years, Scholars both home and abroad have carried out plentiful investigations on the uplift of the Tibetan Plateau (11-12). Based on the high-resolution geomagnetic polarity time scale, many paleoclimatic proxies, such as the spatio-temporal variation of grain size, mineral components and sedimentary rate, obtained from the detrital sediment sequences in basins. All these proxies were used to reconstruct the uplift process, and affirmably indicated the regional structure, especially the orogenic belt uplift and its influence on the environmental evolution. These achievements produced a marked effect on sedimentary basin-orogenic belt systems researches, and promoted the research of uplift of mountains. However, the quantification researches of uplift rate, range and dimensions of orogenic belt should go further. In the studies, we have noticed that the study of thermal history on basement rock or sediment stratum in the

Determination and implications of the rock physical parameter in the Maergaichaka fault, Tibet, China, using remote sensing data

Synthetic aperture radar interferometry was used to study the Maergaichaka fault where Manyi earthquake occured on Nov. 8, 1997 in Tibet, China. With a more appropriate base line, we present the coseismic interferometric fringe. With the prior knowledge of strike-slip movements, the decomposition of the displacement vector in the direction of the fault strike indicates that the horizontal displacement amount to 5.03 meters near the epicenter of the Manyi earthquake, which is more consistent with the field observation (4.5 meters) than the previous work (Peltzer et al., 1999; Shan Xinjian et al., 2002). We also modeled the rock physical parameter using Okada elastic model of half space, which was characterized by a high Poisson ratio. The high Poisson ratio of the upper crust indicate the structural back grounding that it is more possible that the interior crustal shortening play an more important role in the development of Tibet plateau than the doubling the continental crust by replacement of the Tibetan upper mantle by underthrust of Indian continental crustSynthetic aperture radar interferometry was used to study the Maergaichaka fault where Manyi earthquake occured on Nov. 8, 1997 in Tibet, China. With a more appropriate base line, we present the coseismic interferometric fringe. With the prior knowledge of strike-slip movements, the decomposition of the displacement vector in the direction of the fault strike indicates that the horizontal displacement amount to 5.03 meters near the epicenter of the Manyi earthquake, which is more consistent with the field observation (4.5 meters) than the previous work (Peltzer et al., 1999; Shan Xinjian et al., 2002). We also modeled the rock physical parameter using Okada elastic model of half space, which was characterized by a high Poisson ratio. The high Poisson ratio of the upper crust indicate the structural back grounding that it is more possible that the interior crustal shortening play an more important role in the development of Tibet plateau than the doubling the continental crust by replacement of the Tibetan upper mantle by underthrust of Indian continental crust