Through a comprehensive study of magnetostratigraphy and sedimentology of several basins in the northeastern Tibetan Plateau,we reveal that the study area mainly experienced six tectonic uplift stages at approximately...Through a comprehensive study of magnetostratigraphy and sedimentology of several basins in the northeastern Tibetan Plateau,we reveal that the study area mainly experienced six tectonic uplift stages at approximately 52 Ma,34-30 Ma,24-20 Ma,16-12 Ma,8-6 Ma,and 3.6-2.6 Ma.Comprehensive analyses of pollen assemblages from the Qaidam,Linxia,Xining,and West Jiuquan Basins show that the northeastern Tibetan Plateau has undergone six major changes in vegetation types and climate：50-40 Ma for the warm-humid forest vegetation,40-23 Ma for the warm-arid and temperate-arid forest steppe vegetation,23-18.6 Ma for the warm-humid and temperate-humid forest vegetation,18.6-8.5 Ma for the warm-humid and cool-humid forest steppe vegetation,8.6-5 Ma for the temperate sub-humid savanna steppe vegetation,and 5-1.8 Ma for the cold-arid steppe vegetation.Comprehensive comparisons of tectonic uplift events inferred from sedimentary records,climatic changes inferred from pollen,and global climate changes show that in the northeastern Tibetan Plateau the climate in the Paleogene at low altitude was mainly controlled by the global climate change,while that in the Neogene interval with high altitude landscapes of mountains and basins is more controlled by altitude and morphology.展开更多
A systematic sedimentological and chronological study of typical Paleogene basins in eastcentral Tibet suggests that the depositional characteristics of extensively developed huge-bedded, purplish-red coarse clastic r...A systematic sedimentological and chronological study of typical Paleogene basins in eastcentral Tibet suggests that the depositional characteristics of extensively developed huge-bedded, purplish-red coarse clastic rocks formed in a tectonic setting of regional thrusting and strike-slipping represent a typical dry and hot subaerial alluvial fan environment formed in a proximal and rapidaccumulating sediment body in debris flows and a fan-surface braided river. Combining results from basin-fill sequences, sequences of coarse clastic rocks, fauna and sporo-pollen associations and thermochronological data, it is conduded that the coarse clastic rocks formed in the period of 54.2- 24.1 Ma, nearly coeval with the formation of Paleogene basins in the northern （Nangqen-Yushu thrust belt）, middle （Batang-Lijiang fault belt）, and disintegration of large basins in the southern （LanpingSimao fold belt） segments of Tibet. The widespread massive-bedded coarse clastic rocks, fold thrusting and strike-slip, thrust shortening, and igneous activities in the Paleogene basins of eastcentral Tibet indicate that an early diachronous tectonic uplift might have occurred in the Tibetan Plateau from Middle Eocene to Oligocene, related to the initial stage of collision of the Indian and Asian plates.展开更多
Tectonically active areas,such as forearc regions,commonly show contrasting relief,differential tectonic uplift,variations in erosion rates,in river incision,and in channel gradient produced by ongoing tectonic deform...Tectonically active areas,such as forearc regions,commonly show contrasting relief,differential tectonic uplift,variations in erosion rates,in river incision,and in channel gradient produced by ongoing tectonic deformation.Thus,information on the tectonic activity of a defined area could be derived via landscape analysis.This study uses topography and geomorphic indices to extract signals of ongoing tectonic deformation along the Mexican subduction forearc within the Guerrero sector.For this purpose,we use field data,topographical data,knickpoints,the ratio of volume to area（Rva）.the stream-length gradient index（St）,and the normalized channel steepness index（k_（sn））.The results of the applied landscape analysis reveal considerable variations in relief,topography and geomorphic indices values along the Guerrero sector of the Mexican subduction zone.We argue that the reported differences are indicative of tectonic deformation and of variations in relative tectonic uplift along the studied forearc.A significant drop from central and eastern parts of the study area towards the west in values of R_（VA）（from ~500 to^300）,St（from ~500 to ca.400）,maximum St（from ~1500-2500 to ~ 1000） and k_（sn）（from ~150 to ~100） denotes a decrease in relative tectonic uplift in the same direction.We suggest that applied geomorphic indices values and forearc topography are independent of climate and lithology.Actual mechanisms responsible for the observed variations and inferred changes in relative forearc tectonic uplift call for further studies that explain the physical processes that control the forearc along strike uplift variations and that determine the rates of uplift.The proposed methodology and results obtained through this study could prove useful to scientists who study the geomorphology of forearc regions and active subduction zones.展开更多
The formation of strath and strath terrace is closely related to tectonic uplift in the drainage basin. Based on the investigation of straths at Yandantu and Changcaogou on the eastern segment of the northern margin f...The formation of strath and strath terrace is closely related to tectonic uplift in the drainage basin. Based on the investigation of straths at Yandantu and Changcaogou on the eastern segment of the northern margin fault of Altun, and in combination with the paleoclimatic data, the tectonic uplift since late Epipleistocene as revealed by stream terraces at the two places is discussed. At Yandantu, three levels of stream terraces(T 1, T 2 and T 3)have developed since 16ka BP, where T 1, T 3 and T 2 are fill terraces and the buried major straths are exposed. The ages of three treads are dated to be about 16.1ka BP, 12.8ka BP and 6.2ka BP, respectively. The three terraces reflect three tectonic uplift events, while the ages of the treads represent the occurrence time of these events. The stream is still beveling the bedrock and widening the channel at present, and the modern strath is being generated. The uplift rate is 4.8～4.5mm/a since 16.1 ka BP in this area. From 12.8ka B.P to 6.2ka BP, The uplift rate was 6.4mm/a. The uplift rate is 3.1mm/a since 6.2ka BP. At Changcaogou, four levels of stream terraces(T 1, T 2, T 3 and T 1′)have developed since 7ka BP. All of them are fill terraces. There are buried straths under the deposits. The buried major strath is exposed on T 3 and T 2 and the minor strath on T 1′and T 1. The ages of treads of the three terraces (T 3, T 2 and T 1′) are 7 ka BP, 3 ka BP and 2.5 ka BP, respectively. The four terraces reflect two uplift events induced by tectonic activities. One occurred in about 7 ka BP, and the other in 3ka BP. The uplift rate is 5.9mm/a since 7.0 ka BP at Changcaogou. From 7ka BP to 3ka BP, the uplift rate was 7.0mm/a, and since 3ka BP till now, the uplift rate is 4.7 mm/a.展开更多
High arsenic(As)groundwater is a global problem primarily originating from As-enriched sediments.The provenance(source)and release mechanisms(sinks)of high As sediment have been identified,but the source-sink transfer...High arsenic(As)groundwater is a global problem primarily originating from As-enriched sediments.The provenance(source)and release mechanisms(sinks)of high As sediment have been identified,but the source-sink transfer is poorly understood,especially the influence of geological and surface processes.In this study,we explore the roles of tectonic movement and Yellow River evolution in provenance formation processes and evaluate the combined effects of provenance and sediment age on the As content of aquifer sediments in the northern Hetao Basin of Inner Mongolia.Based on optically stimulated luminescence(OSL)and 14C dating and detrital zircon U-Pb,As content,and lithological analyses of a 400 m core,we reconstructed As changes over the last 160 ka.Our results show clay deposited in a paleo-lake during the Gonghe movement period in the late Pleistocene(∼100 ka B.P.)is enriched in As(31.8μg/g)due to significant provenance contributions of the As-bearing Langshan Group under tectonic uplift and mountain erosion.In contrast,clay deposited in the middle Pleistocene(∼160 ka B.P.)has lower As content(7.3μg/g)due to the Yellow River as the primary provenance.Accordingly,the provenance of basin As forced by tectonic uplift and Yellow River evolution determines the background As of aquifer sediments.After deposition,sediment As content decays over time,with higher decay rates in coarse-grained sands than fine-grained.Overall,both provenance formation and sediment age,representing initial and dynamic states of solid phase As,jointly determine the As content of aquifer sediments.More solid phase As provided by younger sediments from the proximal orogenic provenance and reducing conditions due to frequent river-lake transitions,jointly lead to higher As concentrations in shallow groundwater.The study highlights the potential for using a combined analysis of the tectonic movement-surface processes-environment system to improve understanding of geogenic high As groundwater over global large sedimentary basins in the proximity of young orogenic belts.展开更多
Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-te...Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.展开更多
The western Qinling （秦岭） orogenic belt is one of the outermost ranges in the northeas- tern Tibetan Plateau. Its tectonic uplift history is therefore essential to insight on the evolution history of the plateau. H...The western Qinling （秦岭） orogenic belt is one of the outermost ranges in the northeas- tern Tibetan Plateau. Its tectonic uplift history is therefore essential to insight on the evolution history of the plateau. However, the timing of deformation and uplift history is still poorly known. Fortunately, its Cenozoic orogenic history is recorded in an excellent synorogenic sedimentary sequence exposed in the Tianshui （天水）Ba- sin, the northeastern foot of western Qinling. Ac- cording to sedimentary-tectonic analysis of the Yaodian （尧店） and Lamashan （喇嘛山） sections based on the previous magnetostratigraphy stu- dies, we speculated that two stages （occurred at 9.2-7.4 and -3.6 Ma） of variation in depositional facies were attributed to the uplift and deforma- tion of the western Qinling, and the modern structure geomorphic frame of the northeastern Tibet formed after 2.6 Ma. Furthermore, four stages of active processes along the western Qinling occurred at 49--41, 34-27, 25-19 and -13 Ma, are deciphered from an integrated detrital apatite fission-track data of the Ganquan （甘泉）, Yaodian main sections and seven small ones. The former two are represents the exhumation episodes triggered by tectonism and the others attributed to the volcanic signals.展开更多
The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara d...The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.展开更多
The Xianshuihe-Anninghe fault extends SE–S and constitutes the southeastern margin of the Tibetan Plateau.However,the Dadu River which is associated with the fault does not flow following the path,but makes a 90º...The Xianshuihe-Anninghe fault extends SE–S and constitutes the southeastern margin of the Tibetan Plateau.However,the Dadu River which is associated with the fault does not flow following the path,but makes a 90ºturn within a distance of 1 km at Shimian,heading east,and joins the Yangtze River,finally flowing into the East China Sea.Adjacent to the abrupt turn,a low and wide pass near the Daqiao reservoir at Mianning separates the N–S course of the Dadu River from the headwater of the Anning River which then flows south into the Yunnan Province along the Anninghe fault.Therefore,many previous studies assumed southward flow of the paleo-Dadu River from the Shimian to the Anning River.However,evidences for the capture of the integrated N–S paleo-Dadu-Anning River,its timing,and causes are still insufficient.This study explored the paleo-drainage pattern of the Dadu and Anning Rivers based on bulk mineral and geochemical analyses of the large quantities of fluvial/lacustrine sediments along the trunk of the Dadu and Anning Rivers.Similar with sands in the modern Dadu River,the Xigeda sediments also exhibit a granitoid affinity with the bulk major mineral compositions of quartz(>50%),anorthite(about 10%),orthoclase(about 5%),muscovite(about 5%),and clinochlore(about 4%).Correspondingly,bulk major elements show high SiO_(2),with all samples>60%,and some of them>70%,low TiO_(2)(≤0.75%),P_(2)O_(5)(≤0.55%),FeO*(≤5%),and relatively high CaO(1.02%–8.51%),Na_(2)O(1.60%–2.52%),and K_(2)O(2.17%–2.71%),with a uniform REE patterns.Therefore,synthesizing all these results indicate that these lacustrine sediments have similar material sources,which are mainly derived from its course in the Songpan-Ganzi flysch block,implying that the paleo-Dadu originally flowed southward into the Anning River and provided materials to the Xigeda ancient lake.The rearrangement of the paleo-Dadu River appears to be closely related to the locally focused uplift driven by strong activities of the XianshuiheXiaojiang fault system.展开更多
The Yalong River is an important river that runs across the abruptly changing terrain of the SE Tibetan Plateau. The terraces and Quaternary sediments in its valleys preserve the information of tectonic uplift, climat...The Yalong River is an important river that runs across the abruptly changing terrain of the SE Tibetan Plateau. The terraces and Quaternary sediments in its valleys preserve the information of tectonic uplift, climate changes, and landform evolution since the Middle Pleistocene. Based on geomorphological, sedimentological, and chronological investigations, 6-8 terraces are identified in the lower reaches of Yalong catchment and its tributary--the Anning River. The electron spin resonance （ESR） or optically stimulated luminescence （OSL） data on the alluvial sediments in the upper portion of terraces indicate that they formed in 1.10, 0.90, 0.72, 0.06-0.04, 0.03-0.02, and 0.01 Ma. Tectonic uplift and the climatic cycle controlled the formation of the Yalong River terraces. The former dominated the dissection depths and incision rates, whereas the latter controlled the transformation between accumulation, which developed during the glacial period, and incision, which developed during the glacial-interglacial transition. The Yalong downstream incised rapidly from 1.10 to 0.72 Ma and rapidly from 0.06 Ma until the present; the terraces developed during these two periods. The incision rates in space during the two periods indicate the uplifting extent of the Jinpingshan area, which decreases toward the east and the south. The results reveal two rapidly uplifting stages in the SE Tibetan Plateau, including an accelerated uplifting since 0.06 Ma. Since the Middle Pleistocene, the tectonic uplift of the SE and NE parts of the Tibetan Plateau is synchronous, according to the same development stages of the river terraces of the Yalong downstream and the Yellow River in the Lanzhou area of the NE Tibetan Plateau. The difference in the horizontal displacement between the Xianshuihe Fault and the Anninghe Fault bend resulted in the rapid uplift of the Jinpingshan area. The incision rate for the spatial distribution of the Yalong downstream is the geomorphologicai response of crustal shortening and uplift differences in the SE margin block of the Tibetan Plateau. The southeastward diffusion process of the Tibetan Plateau was recorded.展开更多
The Outangdi Formation in Jiangshan, Zhejiang, is the mixing deposit of terrigenous clastics and carbonates in Weiningian of the late Carboniferous. The mixing deposits include interbeddings, which constitute a series...The Outangdi Formation in Jiangshan, Zhejiang, is the mixing deposit of terrigenous clastics and carbonates in Weiningian of the late Carboniferous. The mixing deposits include interbeddings, which constitute a series of alternated clastic and carbonate beds and mixing within the same bed which forms ＂hunji rock＂. The Outangdi Formation has the features of intercalated marine and terrestrial deposits with the progradational sequences, which are lower fine and upper coarse sedimentary granularity in the section. Hunji rock is formed in a seashore environment. It is a mixed carbonate sediment found in beaches or tideland facies with quartz sand taken from a bayou or beach by coastwise flow and circumfluence. There are two kinds of hunji sequences： （1） interbeds of sandstone and carbonate rock in seashore environments; and （2） interbeds of clastics in river facies and carbonate rock in ocean facies. It is indicated that mixing depositions belong to ＂facies mixing＂, affected mainly by regional tectonic uplift, rise of the global sea level, and the dynamics of water medium in the basin. Regional sea level periodic changes and progradational sequences probably resulted from the intense uplift of the old land called Cathaysia. The classification and name of mixed sediments are also discussed in the present study. Interbeds and alternated beds of clastic and carbonate beds are named ＂hunji sequence＂, a new genetic term. It is suggested that hunji rock means a special sediment event of mixing terrigenous clastics and carbonates instead of a name of a specific rock.展开更多
[Objective]The aim was to study the influence of Qinghai-Tibet Plateau uplift on regional climate in China.[Method] Trough relevant study of Qinghai-Tibet Plateau and its surrounding movement,the tectonic movement of ...[Objective]The aim was to study the influence of Qinghai-Tibet Plateau uplift on regional climate in China.[Method] Trough relevant study of Qinghai-Tibet Plateau and its surrounding movement,the tectonic movement of the Qinghai-Tibet Plateau and its surrounding areas,especially the case of the impact caused by plateau phased uplift were studied based on paleomagnetic measurements.[Result]The increasing Qinghai-Tibet Plateau led to obvious transition from dry to cold in northwest China and it became dry quickly,which led to loess accumulation,replacement of vegetation types and human activity.Meanwhile,it was dry,and there was certain degree of climate changes in the area.[Conclusion] Qinghai-Tibet Plateau had far-reaching significance on basic climate characteristics in northwest China.展开更多
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 loe...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.展开更多
Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the...Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the development of theories in planetary fluid dynamics and the improvement of computational environment,numerical simulation based on general circulation models(GCMs) has become an increasingly effective tool in investigations of the physical mechanisms and evolutionary processes of paleoclimate associated with the TP uplift.In this paper,we provide a timely review on representative works in the past four decades on the paleoclimatic responses to the plateau uplift.Numerical simulations to study the paleoclimatic effects of the plateau uplift experienced three stages with increasing complexity:1) plateau uplift as a whole in a single episode,as represented by the no-mountain/with-mountain experiments;2) phased uplift in which the uplifting process was divided into multiple stages and within each the plateau rose by a certain proportion of its current height;and3) sub-regional uplift,in which the focus was the effects of the uplift of a certain area within the TP,such as the northern Tibetan Plateau.These studies discovered the cause-effect relations between the plateau uplift and paleoclimate change,especially for the effects on the evolution of Asian monsoon system and aridification of inland Asia.In this review,we also included examples of current on-going studies,such as the relative impacts of the Himalayas vs.those of the TP as the rain barrier and comparative studies on the paleoclimatic effects of the uplifts of the TP and African highland.Toward the end,we identified five areas as the focus of future research regarding the TP uplift:1) the differences in the evolutionary processes of the South Asian and East Asian monsoons in response to the Himalayas-TP uplift at the regional and sub-regional scales;2) climatic feedbacks;3) long-distance effects(teleconnections) of the TP uplift;4) abrupt climatic changes;and 5) comparisons between the results of numerical simulations and geological evidences.展开更多
Landslides are common hazards in orogenic belt areas.However,it is difficult to quantitatively express the driving effects of tectonic uplift and stream erosion on the occurrence of landslides on large spatial scales ...Landslides are common hazards in orogenic belt areas.However,it is difficult to quantitatively express the driving effects of tectonic uplift and stream erosion on the occurrence of landslides on large spatial scales by conducting field investigations.In this study,we analyzed a relatively large region that extends over the Yangbi River basin on the upper Lancang-Mekong in China.A series of quantitative indices,including kernel density of the landslide(KDL),hypsometric integral(HI),steepness index(ksn),stream power(?),and stream power gradient(ω)were used to explore the promoting effects of tectonic uplift and stream action intensity on landslides by mapping geomorphic dynamic parameters combined with actual landslide data.The analysis showed that the HI value in the highest landslide risk area was approximately 0.47,and that the KDL in the region can be expressed as a function of steepness or stream power gradient of the channel network,namely,KDL=0.0127 Ln ksn-0.0167(R2=0.72,P<0.001)and KDL=0.0219 Lnω-0.0558(R2=0.21,P<0.02).Therefore,the lower reach of the Yangbi River basin,with higher steepness and stream power gradient,usually has a high uplifting rate and stream incision that drives landslides and causes the entire river network system to be in a stage of longterm active erosion.Furthermore,the results suggest that sediments were being rapidly discharged from the steep tributary channels to the mainstream.This practical situation highlights that the downstream area of the river basin is a high-risk area for landslide hazards,especially in association with heavy rainfall and earthquakes.展开更多
In terms of tectonic evolution and petroleum geological conditions of the Nepa-Botuoba Sub-basin and its adjacent su4b-basins,the accumulation conditions of the heavy oil were analyzed. The studied area had plenty of ...In terms of tectonic evolution and petroleum geological conditions of the Nepa-Botuoba Sub-basin and its adjacent su4b-basins,the accumulation conditions of the heavy oil were analyzed. The studied area had plenty of oil and gas accumulation,but there were no developed source rocks. It is a typical outside source accumulation,whose origins from thick high-quality source rock deposited in the adjacent sub-basins. The shallow layer has favorable heavy oil reservoir conditions and poor sealing conditions,which benefits the thickening of hydrocarbon. The multi-periods of structural compression not only uplifted the studied area drastically,but also created a series of fault zones and large-scale slope belt. The structural compression also provided channel and sufficient power for migration of hydrocarbon to shallow layers. Based on these conditions,the favorable accumulation zone of heavy oil was predicted,which provided direction for heavy oil exploration in Nepa-Botuoba Subbasin.展开更多
The Longxi region contains different kinds of Cenozoic sediments, including eolian deposits, reworked loess, fluvial and lacustrine deposits. The provenance evolution of these sediments is of great significance in exp...The Longxi region contains different kinds of Cenozoic sediments, including eolian deposits, reworked loess, fluvial and lacustrine deposits. The provenance evolution of these sediments is of great significance in exploring the uplift, tectonic deformation and associated with geomorphic evolution of the Northeastern Tibetan Plateau. In this paper, we used the single-grain zircon provenance analysis to constrain the provenances for the Paleogene alluvial conglomerates and for the Neogene fluvial-lacustrine sediments, and compared them with results from the loess deposits since the Miocene. The results show that： （1） the Paleogene alluvial conglomerates contain a large number of detrital zircons ranging from 560 to 1100 Ma that were derived from the Yangzi Block. However, the sediments of early Miocene have much fewer zircons of this age span, which are characterized by an abundance of zircon ages in the ranges of 200 360 Ma. This indicates that the Paleogcne alluvial conglomerates mainly come from the middle and/or southern West Qinling, and the early Miocene sediments are primarily from the northern West Qinling; （2） Late Neogene fluvial sediments （11.5 Ma onward） in Tianshui-Qinan region are dominated by zircon ages of 380-450 Ma. This zircon population is similar to that of the exposed intrusive rocks of southern part of the Liupan Mountains, implying that the southern part of Liupan Mountains probably had already uplifted by 11.5 Ma; （3） Late Miocene lacustrine sediments in Tianshui region have a zircon age spectra that is remarkably different from coeval fluvial deposits, but is similar to the zircon age distributions of the Miocene loess in Qinan region, late Miocene-Pliocene Hipparion red clay and Quaternary loess. This indicates that fine particles within these Miocene lacustrine sediments in Tianshui region may be dominated by aeolian materials. This study reveals that provenance changes of Cenozoic sediments in Tianshui-Qinan region and its geomorphic evolution are closely related to the multi-stage uplift of the Northeastern Tibetan Plateau. In particular, the major uplift of the Northem Tibetan Plateau during late Oligocene-early Miocene may have not only provided the source areas and wind dynamic conditions for the deposits of the Miocene loess, but also provided the geomorphic conditions for its accumulation.展开更多
This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS ...This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS analysis of topographic data and geological mapping revealed flanks of raised terraces created on Quaternary marine deposits. Luminescence ages of sediments from the three westernmost marine terraces tend to be consistent OIS-5, OIS-7 and OIS-9, respectively, thus agreeing with the three latest warm stages of the Pleistocene. Moreover, the type and the extent of deformation of the dated marine terraces allowed us to reflect on the neotectonic configuration of western Messenia as well as to conclude that progressive differential uplift over the last 300 ka has induced a dome-like structure to the upper crust of western Messenia.展开更多
Located at the northeastern margin of the Qinghai-Tibet Plateau(QTP) in the Asian interior, the Lake Qinghai is sensitive to environmental change and thus an outstanding site for studying paleoenvironmental changes. T...Located at the northeastern margin of the Qinghai-Tibet Plateau(QTP) in the Asian interior, the Lake Qinghai is sensitive to environmental change and thus an outstanding site for studying paleoenvironmental changes. Thick deposits in the Lake Qinghai provide important geological archives for obtaining high-resolution records of continental environmental history. The longest drilling core obtained from the Lake Qinghai, named Erlangjian(ELJ), reached about 1109 m and was investigated to determine its clay mineral assemblage and grain size distributions. Clay mineralogical proxies, including type, composition, and their ratios, as well as the illite crystallinity(KI) and chemical index(CI), in combination with grain size data, were used for reconstructing the history of paleoenvironmental evolution since the late Miocene in the Lake Qinghai Basin. The clay mineral records indicate that the clay mainly comprise detritus originating from peripheral material and has experienced little or no diagenesis. The proportion of authigenic origin was minor. Illite was the most abundant clay mineral, followed by chlorite, kaolinite, and smectite. Variations of clay mineral indexes reflect the cooling and drying trends in the Lake Qinghai region, and the grain size distribution is coincided with the clay minerals indexes. The paleoclimatic evolution of the Lake Qinghai Basin since the late Miocene can be divided into five intervals. The climate was relatively warm and wet in the early of late Miocene, then long-term trends in climate change character display cooling and drying; later in the late Miocene until early Pliocene the climate was in a short relatively warm and humid period; since then the climate was relatively colder and drier. These results also suggest multiple tectonic uplift events in the northeastern QTP.展开更多
This study focuses on defining rates of fluvial incision for the last 580±5 kyr along valley systems of eight streams that drain the eastern part of the northern Peloponnese. The streams are developed on the upli...This study focuses on defining rates of fluvial incision for the last 580±5 kyr along valley systems of eight streams that drain the eastern part of the northern Peloponnese. The streams are developed on the uplifted block of the offshore-running Xylokastro normal fault, one of the main faults bounding the southern edge of the Gulf of Corinth half-graben, and have incised a set of ten uplifted marine terraces having an amphitheatric shape. These terraces range in age from 60±5 kyr to 580±5 kyr and have been mapped in detail and correlated with late Pleistocene oxygen-isotope stages of high sea-level stands by previous studies. The terraces were used in this paper as reference surfaces in order to define fluvial incision rates at the lower reaches of the studied streams. To evaluate incision rates, thirty-three topographic valley cross-sec- tions were drawn using fieldwork measurements as well as using a highly accurate （2×2 cell size） Digital Elevation Model （DEM） at specific locations where streams cut down the inner edges of the marine terraces. For each cross-section the ratio of valley floor width to valley height （Vf） and long-term mean stream incision rates were estimated for the last 580±5 kyr, while rock uplift rates were estimated for the last 330±5 kyr. The geomorphic evolution of the valleys on the uplifted block of the Xylokastro fault has been mainly driven by the lithology of the bedrock, sea level fluctuations during the late Quaternary, and incision of the channels due to the tectonic uplift. Stream incision rates range from 0.10±0.1 mm/yr for the last 123±7 kyr to 1.14±0.1 mm/yr for the last 310±5 kyr and are gradually greater from east to west depending on the distance from the trace of the fault.Downcutting rates are comparable with the rock uplift rates, which range from 0.4±0.02 mm/yr to 1.49±0.12 mm/yr, over the last 330±5 kyr.展开更多
基金supported by Foundation of Geological Survey of China (no. 1212011121261)the State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences (no. GBL11307)
文摘Through a comprehensive study of magnetostratigraphy and sedimentology of several basins in the northeastern Tibetan Plateau,we reveal that the study area mainly experienced six tectonic uplift stages at approximately 52 Ma,34-30 Ma,24-20 Ma,16-12 Ma,8-6 Ma,and 3.6-2.6 Ma.Comprehensive analyses of pollen assemblages from the Qaidam,Linxia,Xining,and West Jiuquan Basins show that the northeastern Tibetan Plateau has undergone six major changes in vegetation types and climate：50-40 Ma for the warm-humid forest vegetation,40-23 Ma for the warm-arid and temperate-arid forest steppe vegetation,23-18.6 Ma for the warm-humid and temperate-humid forest vegetation,18.6-8.5 Ma for the warm-humid and cool-humid forest steppe vegetation,8.6-5 Ma for the temperate sub-humid savanna steppe vegetation,and 5-1.8 Ma for the cold-arid steppe vegetation.Comprehensive comparisons of tectonic uplift events inferred from sedimentary records,climatic changes inferred from pollen,and global climate changes show that in the northeastern Tibetan Plateau the climate in the Paleogene at low altitude was mainly controlled by the global climate change,while that in the Neogene interval with high altitude landscapes of mountains and basins is more controlled by altitude and morphology.
基金This research was supported by the National Key Project for Basic Research on the Tibetan Plateau （Grant G1998040800-3）；National Natural Science Foundation of China （Grants 49972026 and 39972026）；Chinese Academy of Sciences （CAS） Projects （Grant KZ952-JI408） ； US-NSF project （Grant 980612）.
文摘A systematic sedimentological and chronological study of typical Paleogene basins in eastcentral Tibet suggests that the depositional characteristics of extensively developed huge-bedded, purplish-red coarse clastic rocks formed in a tectonic setting of regional thrusting and strike-slipping represent a typical dry and hot subaerial alluvial fan environment formed in a proximal and rapidaccumulating sediment body in debris flows and a fan-surface braided river. Combining results from basin-fill sequences, sequences of coarse clastic rocks, fauna and sporo-pollen associations and thermochronological data, it is conduded that the coarse clastic rocks formed in the period of 54.2- 24.1 Ma, nearly coeval with the formation of Paleogene basins in the northern （Nangqen-Yushu thrust belt）, middle （Batang-Lijiang fault belt）, and disintegration of large basins in the southern （LanpingSimao fold belt） segments of Tibet. The widespread massive-bedded coarse clastic rocks, fold thrusting and strike-slip, thrust shortening, and igneous activities in the Paleogene basins of eastcentral Tibet indicate that an early diachronous tectonic uplift might have occurred in the Tibetan Plateau from Middle Eocene to Oligocene, related to the initial stage of collision of the Indian and Asian plates.
基金funding provided by CONACYT-SEP Ciencia Basica(Grant No.129456):Active Tectonic Deformation along the Pacific Coast of Mexico and by the research grants PAPIIT IN110514 and DGAPA-PASPA 2015-2016a postdoctoral fellowship provided through the DGAPA-UNAM program
文摘Tectonically active areas,such as forearc regions,commonly show contrasting relief,differential tectonic uplift,variations in erosion rates,in river incision,and in channel gradient produced by ongoing tectonic deformation.Thus,information on the tectonic activity of a defined area could be derived via landscape analysis.This study uses topography and geomorphic indices to extract signals of ongoing tectonic deformation along the Mexican subduction forearc within the Guerrero sector.For this purpose,we use field data,topographical data,knickpoints,the ratio of volume to area（Rva）.the stream-length gradient index（St）,and the normalized channel steepness index（k_（sn））.The results of the applied landscape analysis reveal considerable variations in relief,topography and geomorphic indices values along the Guerrero sector of the Mexican subduction zone.We argue that the reported differences are indicative of tectonic deformation and of variations in relative tectonic uplift along the studied forearc.A significant drop from central and eastern parts of the study area towards the west in values of R_（VA）（from ~500 to^300）,St（from ~500 to ca.400）,maximum St（from ~1500-2500 to ~ 1000） and k_（sn）（from ~150 to ~100） denotes a decrease in relative tectonic uplift in the same direction.We suggest that applied geomorphic indices values and forearc topography are independent of climate and lithology.Actual mechanisms responsible for the observed variations and inferred changes in relative forearc tectonic uplift call for further studies that explain the physical processes that control the forearc along strike uplift variations and that determine the rates of uplift.The proposed methodology and results obtained through this study could prove useful to scientists who study the geomorphology of forearc regions and active subduction zones.
文摘The formation of strath and strath terrace is closely related to tectonic uplift in the drainage basin. Based on the investigation of straths at Yandantu and Changcaogou on the eastern segment of the northern margin fault of Altun, and in combination with the paleoclimatic data, the tectonic uplift since late Epipleistocene as revealed by stream terraces at the two places is discussed. At Yandantu, three levels of stream terraces(T 1, T 2 and T 3)have developed since 16ka BP, where T 1, T 3 and T 2 are fill terraces and the buried major straths are exposed. The ages of three treads are dated to be about 16.1ka BP, 12.8ka BP and 6.2ka BP, respectively. The three terraces reflect three tectonic uplift events, while the ages of the treads represent the occurrence time of these events. The stream is still beveling the bedrock and widening the channel at present, and the modern strath is being generated. The uplift rate is 4.8～4.5mm/a since 16.1 ka BP in this area. From 12.8ka B.P to 6.2ka BP, The uplift rate was 6.4mm/a. The uplift rate is 3.1mm/a since 6.2ka BP. At Changcaogou, four levels of stream terraces(T 1, T 2, T 3 and T 1′)have developed since 7ka BP. All of them are fill terraces. There are buried straths under the deposits. The buried major strath is exposed on T 3 and T 2 and the minor strath on T 1′and T 1. The ages of treads of the three terraces (T 3, T 2 and T 1′) are 7 ka BP, 3 ka BP and 2.5 ka BP, respectively. The four terraces reflect two uplift events induced by tectonic activities. One occurred in about 7 ka BP, and the other in 3ka BP. The uplift rate is 5.9mm/a since 7.0 ka BP at Changcaogou. From 7ka BP to 3ka BP, the uplift rate was 7.0mm/a, and since 3ka BP till now, the uplift rate is 4.7 mm/a.
基金supported by the National Natural Science Foundation of China(Grant Nos.42301094,41972192,and 41825017)。
文摘High arsenic(As)groundwater is a global problem primarily originating from As-enriched sediments.The provenance(source)and release mechanisms(sinks)of high As sediment have been identified,but the source-sink transfer is poorly understood,especially the influence of geological and surface processes.In this study,we explore the roles of tectonic movement and Yellow River evolution in provenance formation processes and evaluate the combined effects of provenance and sediment age on the As content of aquifer sediments in the northern Hetao Basin of Inner Mongolia.Based on optically stimulated luminescence(OSL)and 14C dating and detrital zircon U-Pb,As content,and lithological analyses of a 400 m core,we reconstructed As changes over the last 160 ka.Our results show clay deposited in a paleo-lake during the Gonghe movement period in the late Pleistocene(∼100 ka B.P.)is enriched in As(31.8μg/g)due to significant provenance contributions of the As-bearing Langshan Group under tectonic uplift and mountain erosion.In contrast,clay deposited in the middle Pleistocene(∼160 ka B.P.)has lower As content(7.3μg/g)due to the Yellow River as the primary provenance.Accordingly,the provenance of basin As forced by tectonic uplift and Yellow River evolution determines the background As of aquifer sediments.After deposition,sediment As content decays over time,with higher decay rates in coarse-grained sands than fine-grained.Overall,both provenance formation and sediment age,representing initial and dynamic states of solid phase As,jointly determine the As content of aquifer sediments.More solid phase As provided by younger sediments from the proximal orogenic provenance and reducing conditions due to frequent river-lake transitions,jointly lead to higher As concentrations in shallow groundwater.The study highlights the potential for using a combined analysis of the tectonic movement-surface processes-environment system to improve understanding of geogenic high As groundwater over global large sedimentary basins in the proximity of young orogenic belts.
基金supported by China Geological Survey (Grant No. 1212010610103)National Natural Science Foundation of China (Grant Nos. 40902060, 40672137)
文摘Four intensive uplift periods, i.e., 60–35, 25–17 and 12–8 Ma (but 18–13 Ma in the Himalayas of the southern Tibet), and since about 5 Ma, can be determined on the Tibetan Plateau by synthetical analysis of low-temperature thermo-chronology data, sedimentary deposit records, and structural deformation records of different areas. The strong tectonic uplift periods in different areas on the Tibetan Plateau are penecontemporaneous, except for the Himalayan area of the southern Tibet, where a rapid uplift and exhumation period, controlled by the activity of the South Tibetan Detachment System faults, occurred during 18–13 Ma. These strong uplift and exhumation periods correspond well to intensive deformation activity periods, suggesting tectonically-controlled uplift and exhumation. The deposit records, such as the distribution of coarse clastic sediments, the distribution of tectonically-controlled basins, stratigraphic discontinuousness or unconformity, and fault-controlled geomorphologic evolution, also match well with the strong uplift and exhumation periods. Expanding processes of the plateau are also discussed.
基金supported by the "Strategic Priority ResearchProgram" of the Chinese Academy of Sciences (No.XDB03020402)the National Basic Research Program (973) of China (No. 2013CB956403)+2 种基金the National Natural Science Foundation of China (Nos. 41201005, 41272128)the Funda-mental Research Funds for the Central Universities (No.lzujbky-2013-122)the NSFC National Innovative ResearchTeam Project (No. 41021091)
文摘The western Qinling （秦岭） orogenic belt is one of the outermost ranges in the northeas- tern Tibetan Plateau. Its tectonic uplift history is therefore essential to insight on the evolution history of the plateau. However, the timing of deformation and uplift history is still poorly known. Fortunately, its Cenozoic orogenic history is recorded in an excellent synorogenic sedimentary sequence exposed in the Tianshui （天水）Ba- sin, the northeastern foot of western Qinling. Ac- cording to sedimentary-tectonic analysis of the Yaodian （尧店） and Lamashan （喇嘛山） sections based on the previous magnetostratigraphy stu- dies, we speculated that two stages （occurred at 9.2-7.4 and -3.6 Ma） of variation in depositional facies were attributed to the uplift and deforma- tion of the western Qinling, and the modern structure geomorphic frame of the northeastern Tibet formed after 2.6 Ma. Furthermore, four stages of active processes along the western Qinling occurred at 49--41, 34-27, 25-19 and -13 Ma, are deciphered from an integrated detrital apatite fission-track data of the Ganquan （甘泉）, Yaodian main sections and seven small ones. The former two are represents the exhumation episodes triggered by tectonism and the others attributed to the volcanic signals.
基金The present study was funded by the Ministry of Earth Sciences(MoES),Government of India in the form of research project(Project 474 No.Mo ES/P.O.(Seismo)/1(170)/2013)MoES/P.O.(Seismo)/1(120)/AFM/2015 to DMM and LSC。
文摘The study deals with stream response to sustained tectonic during the Cenozoic and development of two parallel scarps in the western Kachchh. The study encompasses fluvial networks developed over the Jara and Jumara domes, which are a part of the laterally extensive belt of flexures bounded by the Kachchh Mainland Fault(KMF) to their north and called as Northern Hill Range(NHR). Parameters such as longitudinal profile, Hack profile, stream length gradient index(SL), hypsometric curve, hypsometric integral(HI), valley floor width to height ratio(Vf), elongation ratio(Re) and escarpment sinuosity(ES) were analysed. Hack profiles of the major rivers draining through the area show similar convex up nature suggesting primary influence of the tectonics in controlling and shaping the landscape of the region. Elongation ratio <6 and undergone higher degree of fluvial erosion indicated by the low values of hypsometric integral suggest the tendency of river systems to increase the basin area longitudinally rather than laterally. The study suggests that higher net uplift in the eastern half(Jumara dome) caused the rivers to overcome the structural control and to carve out generally straight north oriented channels. The rivers of western part(Jara dome) show more prominent structural control of cuesta girdles formed in compact lithologies and attributed to the domal structure. The ~10 km long Jaramara scarp believed to the remnant of older KMF scarp, is a product of headward erosion of the fluvial channels through different hard and soft litho-units of the area. The similar orientation of Jaramara scarp and morphology of the Ukra intrusive body suggests that the Ukra intrusive played a significant role in controlling the formation and morphology of the Jaramara scarp.
基金financially supported by the Natural Science Foundation of China(41941016,42072240,41830217)Ministry of Science and Technology of China(2019QZKK0901,2021FY100101)+2 种基金Key Special Project for Introduced Talents Team of the Southern Marine Science and Engineering Guangdong Laboratory(GML2019ZD0201)China Geological Survey(DD20221630)Special Fund of the Institute of Geophysics,China Earthquake Administration(DQJB20B21).
文摘The Xianshuihe-Anninghe fault extends SE–S and constitutes the southeastern margin of the Tibetan Plateau.However,the Dadu River which is associated with the fault does not flow following the path,but makes a 90ºturn within a distance of 1 km at Shimian,heading east,and joins the Yangtze River,finally flowing into the East China Sea.Adjacent to the abrupt turn,a low and wide pass near the Daqiao reservoir at Mianning separates the N–S course of the Dadu River from the headwater of the Anning River which then flows south into the Yunnan Province along the Anninghe fault.Therefore,many previous studies assumed southward flow of the paleo-Dadu River from the Shimian to the Anning River.However,evidences for the capture of the integrated N–S paleo-Dadu-Anning River,its timing,and causes are still insufficient.This study explored the paleo-drainage pattern of the Dadu and Anning Rivers based on bulk mineral and geochemical analyses of the large quantities of fluvial/lacustrine sediments along the trunk of the Dadu and Anning Rivers.Similar with sands in the modern Dadu River,the Xigeda sediments also exhibit a granitoid affinity with the bulk major mineral compositions of quartz(>50%),anorthite(about 10%),orthoclase(about 5%),muscovite(about 5%),and clinochlore(about 4%).Correspondingly,bulk major elements show high SiO_(2),with all samples>60%,and some of them>70%,low TiO_(2)(≤0.75%),P_(2)O_(5)(≤0.55%),FeO*(≤5%),and relatively high CaO(1.02%–8.51%),Na_(2)O(1.60%–2.52%),and K_(2)O(2.17%–2.71%),with a uniform REE patterns.Therefore,synthesizing all these results indicate that these lacustrine sediments have similar material sources,which are mainly derived from its course in the Songpan-Ganzi flysch block,implying that the paleo-Dadu originally flowed southward into the Anning River and provided materials to the Xigeda ancient lake.The rearrangement of the paleo-Dadu River appears to be closely related to the locally focused uplift driven by strong activities of the XianshuiheXiaojiang fault system.
基金supported by the Project of China Geological Survey (grant nos.1212011120071,201211077-3 and 1212011120182)
文摘The Yalong River is an important river that runs across the abruptly changing terrain of the SE Tibetan Plateau. The terraces and Quaternary sediments in its valleys preserve the information of tectonic uplift, climate changes, and landform evolution since the Middle Pleistocene. Based on geomorphological, sedimentological, and chronological investigations, 6-8 terraces are identified in the lower reaches of Yalong catchment and its tributary--the Anning River. The electron spin resonance （ESR） or optically stimulated luminescence （OSL） data on the alluvial sediments in the upper portion of terraces indicate that they formed in 1.10, 0.90, 0.72, 0.06-0.04, 0.03-0.02, and 0.01 Ma. Tectonic uplift and the climatic cycle controlled the formation of the Yalong River terraces. The former dominated the dissection depths and incision rates, whereas the latter controlled the transformation between accumulation, which developed during the glacial period, and incision, which developed during the glacial-interglacial transition. The Yalong downstream incised rapidly from 1.10 to 0.72 Ma and rapidly from 0.06 Ma until the present; the terraces developed during these two periods. The incision rates in space during the two periods indicate the uplifting extent of the Jinpingshan area, which decreases toward the east and the south. The results reveal two rapidly uplifting stages in the SE Tibetan Plateau, including an accelerated uplifting since 0.06 Ma. Since the Middle Pleistocene, the tectonic uplift of the SE and NE parts of the Tibetan Plateau is synchronous, according to the same development stages of the river terraces of the Yalong downstream and the Yellow River in the Lanzhou area of the NE Tibetan Plateau. The difference in the horizontal displacement between the Xianshuihe Fault and the Anninghe Fault bend resulted in the rapid uplift of the Jinpingshan area. The incision rate for the spatial distribution of the Yalong downstream is the geomorphologicai response of crustal shortening and uplift differences in the SE margin block of the Tibetan Plateau. The southeastward diffusion process of the Tibetan Plateau was recorded.
基金supported by the State Key Laboratory Foundation Project(No.GPMR0508) from the State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences
文摘The Outangdi Formation in Jiangshan, Zhejiang, is the mixing deposit of terrigenous clastics and carbonates in Weiningian of the late Carboniferous. The mixing deposits include interbeddings, which constitute a series of alternated clastic and carbonate beds and mixing within the same bed which forms ＂hunji rock＂. The Outangdi Formation has the features of intercalated marine and terrestrial deposits with the progradational sequences, which are lower fine and upper coarse sedimentary granularity in the section. Hunji rock is formed in a seashore environment. It is a mixed carbonate sediment found in beaches or tideland facies with quartz sand taken from a bayou or beach by coastwise flow and circumfluence. There are two kinds of hunji sequences： （1） interbeds of sandstone and carbonate rock in seashore environments; and （2） interbeds of clastics in river facies and carbonate rock in ocean facies. It is indicated that mixing depositions belong to ＂facies mixing＂, affected mainly by regional tectonic uplift, rise of the global sea level, and the dynamics of water medium in the basin. Regional sea level periodic changes and progradational sequences probably resulted from the intense uplift of the old land called Cathaysia. The classification and name of mixed sediments are also discussed in the present study. Interbeds and alternated beds of clastic and carbonate beds are named ＂hunji sequence＂, a new genetic term. It is suggested that hunji rock means a special sediment event of mixing terrigenous clastics and carbonates instead of a name of a specific rock.
文摘[Objective]The aim was to study the influence of Qinghai-Tibet Plateau uplift on regional climate in China.[Method] Trough relevant study of Qinghai-Tibet Plateau and its surrounding movement,the tectonic movement of the Qinghai-Tibet Plateau and its surrounding areas,especially the case of the impact caused by plateau phased uplift were studied based on paleomagnetic measurements.[Result]The increasing Qinghai-Tibet Plateau led to obvious transition from dry to cold in northwest China and it became dry quickly,which led to loess accumulation,replacement of vegetation types and human activity.Meanwhile,it was dry,and there was certain degree of climate changes in the area.[Conclusion] Qinghai-Tibet Plateau had far-reaching significance on basic climate characteristics in northwest China.
基金support was provided by the National Science Foundation of China grant (40472088)
文摘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.
基金National Natural Science Foundation of China(Grant Nos.40825008,41075067,40921120406)the National Basic Research Program of China(Grant No.2010CB833406)
文摘Tectonic uplift of the Tibetan Plateau(TP) is a major event in the recent geological history of the earth,which produced far-reaching impacts on the Asian and global climates and environments.Since the 1970 s,with the development of theories in planetary fluid dynamics and the improvement of computational environment,numerical simulation based on general circulation models(GCMs) has become an increasingly effective tool in investigations of the physical mechanisms and evolutionary processes of paleoclimate associated with the TP uplift.In this paper,we provide a timely review on representative works in the past four decades on the paleoclimatic responses to the plateau uplift.Numerical simulations to study the paleoclimatic effects of the plateau uplift experienced three stages with increasing complexity:1) plateau uplift as a whole in a single episode,as represented by the no-mountain/with-mountain experiments;2) phased uplift in which the uplifting process was divided into multiple stages and within each the plateau rose by a certain proportion of its current height;and3) sub-regional uplift,in which the focus was the effects of the uplift of a certain area within the TP,such as the northern Tibetan Plateau.These studies discovered the cause-effect relations between the plateau uplift and paleoclimate change,especially for the effects on the evolution of Asian monsoon system and aridification of inland Asia.In this review,we also included examples of current on-going studies,such as the relative impacts of the Himalayas vs.those of the TP as the rain barrier and comparative studies on the paleoclimatic effects of the uplifts of the TP and African highland.Toward the end,we identified five areas as the focus of future research regarding the TP uplift:1) the differences in the evolutionary processes of the South Asian and East Asian monsoons in response to the Himalayas-TP uplift at the regional and sub-regional scales;2) climatic feedbacks;3) long-distance effects(teleconnections) of the TP uplift;4) abrupt climatic changes;and 5) comparisons between the results of numerical simulations and geological evidences.
基金financially supported by the National Key Research and Development Program of China(2018YFC1505002)National Natural Science Foundation of China(41672359,42107218,41807299)+2 种基金China Three Gorges Corporation(YMJ(XLD)(19)110)China Geology Survey Project(DD20190717)Natural Science Foundation of Hebei Province(D2019205090)。
文摘Landslides are common hazards in orogenic belt areas.However,it is difficult to quantitatively express the driving effects of tectonic uplift and stream erosion on the occurrence of landslides on large spatial scales by conducting field investigations.In this study,we analyzed a relatively large region that extends over the Yangbi River basin on the upper Lancang-Mekong in China.A series of quantitative indices,including kernel density of the landslide(KDL),hypsometric integral(HI),steepness index(ksn),stream power(?),and stream power gradient(ω)were used to explore the promoting effects of tectonic uplift and stream action intensity on landslides by mapping geomorphic dynamic parameters combined with actual landslide data.The analysis showed that the HI value in the highest landslide risk area was approximately 0.47,and that the KDL in the region can be expressed as a function of steepness or stream power gradient of the channel network,namely,KDL=0.0127 Ln ksn-0.0167(R2=0.72,P<0.001)and KDL=0.0219 Lnω-0.0558(R2=0.21,P<0.02).Therefore,the lower reach of the Yangbi River basin,with higher steepness and stream power gradient,usually has a high uplifting rate and stream incision that drives landslides and causes the entire river network system to be in a stage of longterm active erosion.Furthermore,the results suggest that sediments were being rapidly discharged from the steep tributary channels to the mainstream.This practical situation highlights that the downstream area of the river basin is a high-risk area for landslide hazards,especially in association with heavy rainfall and earthquakes.
基金National Science and Technology Major Project(2011ZX05028-002)The Science and Technology Major Project of PetroChina Company Limited(2012E-0501)
文摘In terms of tectonic evolution and petroleum geological conditions of the Nepa-Botuoba Sub-basin and its adjacent su4b-basins,the accumulation conditions of the heavy oil were analyzed. The studied area had plenty of oil and gas accumulation,but there were no developed source rocks. It is a typical outside source accumulation,whose origins from thick high-quality source rock deposited in the adjacent sub-basins. The shallow layer has favorable heavy oil reservoir conditions and poor sealing conditions,which benefits the thickening of hydrocarbon. The multi-periods of structural compression not only uplifted the studied area drastically,but also created a series of fault zones and large-scale slope belt. The structural compression also provided channel and sufficient power for migration of hydrocarbon to shallow layers. Based on these conditions,the favorable accumulation zone of heavy oil was predicted,which provided direction for heavy oil exploration in Nepa-Botuoba Subbasin.
基金supported by National Natural Science Foundation of China(Grant Nos. 41572339,41002051 & 41322013)Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)(Grant No. CUG160217)
文摘The Longxi region contains different kinds of Cenozoic sediments, including eolian deposits, reworked loess, fluvial and lacustrine deposits. The provenance evolution of these sediments is of great significance in exploring the uplift, tectonic deformation and associated with geomorphic evolution of the Northeastern Tibetan Plateau. In this paper, we used the single-grain zircon provenance analysis to constrain the provenances for the Paleogene alluvial conglomerates and for the Neogene fluvial-lacustrine sediments, and compared them with results from the loess deposits since the Miocene. The results show that： （1） the Paleogene alluvial conglomerates contain a large number of detrital zircons ranging from 560 to 1100 Ma that were derived from the Yangzi Block. However, the sediments of early Miocene have much fewer zircons of this age span, which are characterized by an abundance of zircon ages in the ranges of 200 360 Ma. This indicates that the Paleogcne alluvial conglomerates mainly come from the middle and/or southern West Qinling, and the early Miocene sediments are primarily from the northern West Qinling; （2） Late Neogene fluvial sediments （11.5 Ma onward） in Tianshui-Qinan region are dominated by zircon ages of 380-450 Ma. This zircon population is similar to that of the exposed intrusive rocks of southern part of the Liupan Mountains, implying that the southern part of Liupan Mountains probably had already uplifted by 11.5 Ma; （3） Late Miocene lacustrine sediments in Tianshui region have a zircon age spectra that is remarkably different from coeval fluvial deposits, but is similar to the zircon age distributions of the Miocene loess in Qinan region, late Miocene-Pliocene Hipparion red clay and Quaternary loess. This indicates that fine particles within these Miocene lacustrine sediments in Tianshui region may be dominated by aeolian materials. This study reveals that provenance changes of Cenozoic sediments in Tianshui-Qinan region and its geomorphic evolution are closely related to the multi-stage uplift of the Northeastern Tibetan Plateau. In particular, the major uplift of the Northem Tibetan Plateau during late Oligocene-early Miocene may have not only provided the source areas and wind dynamic conditions for the deposits of the Miocene loess, but also provided the geomorphic conditions for its accumulation.
基金supported by the State Scholarships Foundation of Greece(No.1500521537.008.040)
文摘This project studies marine terraces in western Messenia, southwestern Peloponnese, Greece, to propose a model of neotectonic configuration and paleogeographic evolution of western Messenia during the Quaternary. GIS analysis of topographic data and geological mapping revealed flanks of raised terraces created on Quaternary marine deposits. Luminescence ages of sediments from the three westernmost marine terraces tend to be consistent OIS-5, OIS-7 and OIS-9, respectively, thus agreeing with the three latest warm stages of the Pleistocene. Moreover, the type and the extent of deformation of the dated marine terraces allowed us to reflect on the neotectonic configuration of western Messenia as well as to conclude that progressive differential uplift over the last 300 ka has induced a dome-like structure to the upper crust of western Messenia.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40972230, 41290250)Institute of Earth Environment, Chinese Academy of Sciences (Grant No. ZZBS1301)the National Basic Research Program of China (Grant No. 2010CB833406)
文摘Located at the northeastern margin of the Qinghai-Tibet Plateau(QTP) in the Asian interior, the Lake Qinghai is sensitive to environmental change and thus an outstanding site for studying paleoenvironmental changes. Thick deposits in the Lake Qinghai provide important geological archives for obtaining high-resolution records of continental environmental history. The longest drilling core obtained from the Lake Qinghai, named Erlangjian(ELJ), reached about 1109 m and was investigated to determine its clay mineral assemblage and grain size distributions. Clay mineralogical proxies, including type, composition, and their ratios, as well as the illite crystallinity(KI) and chemical index(CI), in combination with grain size data, were used for reconstructing the history of paleoenvironmental evolution since the late Miocene in the Lake Qinghai Basin. The clay mineral records indicate that the clay mainly comprise detritus originating from peripheral material and has experienced little or no diagenesis. The proportion of authigenic origin was minor. Illite was the most abundant clay mineral, followed by chlorite, kaolinite, and smectite. Variations of clay mineral indexes reflect the cooling and drying trends in the Lake Qinghai region, and the grain size distribution is coincided with the clay minerals indexes. The paleoclimatic evolution of the Lake Qinghai Basin since the late Miocene can be divided into five intervals. The climate was relatively warm and wet in the early of late Miocene, then long-term trends in climate change character display cooling and drying; later in the late Miocene until early Pliocene the climate was in a short relatively warm and humid period; since then the climate was relatively colder and drier. These results also suggest multiple tectonic uplift events in the northeastern QTP.
文摘This study focuses on defining rates of fluvial incision for the last 580±5 kyr along valley systems of eight streams that drain the eastern part of the northern Peloponnese. The streams are developed on the uplifted block of the offshore-running Xylokastro normal fault, one of the main faults bounding the southern edge of the Gulf of Corinth half-graben, and have incised a set of ten uplifted marine terraces having an amphitheatric shape. These terraces range in age from 60±5 kyr to 580±5 kyr and have been mapped in detail and correlated with late Pleistocene oxygen-isotope stages of high sea-level stands by previous studies. The terraces were used in this paper as reference surfaces in order to define fluvial incision rates at the lower reaches of the studied streams. To evaluate incision rates, thirty-three topographic valley cross-sec- tions were drawn using fieldwork measurements as well as using a highly accurate （2×2 cell size） Digital Elevation Model （DEM） at specific locations where streams cut down the inner edges of the marine terraces. For each cross-section the ratio of valley floor width to valley height （Vf） and long-term mean stream incision rates were estimated for the last 580±5 kyr, while rock uplift rates were estimated for the last 330±5 kyr. The geomorphic evolution of the valleys on the uplifted block of the Xylokastro fault has been mainly driven by the lithology of the bedrock, sea level fluctuations during the late Quaternary, and incision of the channels due to the tectonic uplift. Stream incision rates range from 0.10±0.1 mm/yr for the last 123±7 kyr to 1.14±0.1 mm/yr for the last 310±5 kyr and are gradually greater from east to west depending on the distance from the trace of the fault.Downcutting rates are comparable with the rock uplift rates, which range from 0.4±0.02 mm/yr to 1.49±0.12 mm/yr, over the last 330±5 kyr.
