Meso-Cenozoic Evolution of the Tanlu Fault and Formation of Sedimentary Basins

Abstract: There are a group of large and medium-scale Meso-Cenozoic petroliferous basins along both sides of the Tanlu fault or within the fault zone, e.g., the Songliao basin, the Bohai Bay basin and the Subei-Yellow Sea basin. As shown by studies of the structural types, sedimentary formations, volcanic activities, tectonic evolution as well as the time-space relationship between the Tanlu fault zone and the basins, the formation and distribution of the basins are controlled by the movement of the Tanlu fault. This paper presents an analysis of the tectono-geometric, kinematic and geodynamic features of the basins on the basis of integrated geological-geophysical data, and an exploration into the internal relations between the fault and the basins as well as the formation mechanism and geodynamic processes of the basins.

Successor Characteristics of the Mesozoic and Cenozoic Songliao Basins

The Songliao basin is a complex successor basin that was initiated in the Mesozoic and experienced multiple periods of reactivation. Based on seismic and drilling data, as well as regional geologic research, we suggest that the Songliao basin contains several different successor basins resting on top of Carboniferous-Permian folded strata forming the basement to the Songliao basin. These basins include the Triassic-Mid Jurassic Paleo-foreland basin, the Late Jurassic-Early Cretaceous downfaulted basin, and an early Cretaceous depressed basin （since the Denglouku Group）. This paper presents a systematic study of the basin-mountain interactions, and reveals that there are different types of prototype basin at different geologic times. These prototype basins sequentially superimposed and formed the large Songliao basin. Discovery of the Triassic-early Middle Jurassic paleo-foreland basin fills a Triassic-early Middle Jurassic gap in the geologic history of the Songliao basin. The paleo- foreland basin, downfaulted basin, and depressed thermal subsidence basin all together represent the whole Mesozoic-Cenozoic geologic history and deformation of the Songliao basin. Discovery of the Triassic-early Middle Jurassic paleo-foreland basin plays an important role both for deep natural gas exploration and the study of basin-mountain coupling in north China and eastern China in general. This example gives dramatic evidence that we should give much more attention to the polyphase tectonic evolution of related basins for the next phase of exploration and study.

Geothermal Regime of Meso-Cenozoic Basins and Their Tectonic Background in East China

? This paper presents a brief analysis of the geothermal fields of Meso-Cenozoic basins and their evolution in East China by means of heat flow, geotemperature gradient, vitrinite reflectence and its gradient in the basins, and reveals a basic framework of the geothermal regime of the basins. The geothermal regime of Meso-Cenozioc basins in East China is mainly dominated by tectonic conditions. The important factor determining the geothermal state of basins is the thickness of lithosphere—burial depth of asthenospheric top, which is related to geodynamic type of basins. Basins in the western zone, represented by Sichuan and Ordos, belong to the flexure basins on the basement of continental block, with thick lithosphere, generally 120-150 km. All basins in this zone fall into middle heat basin type in the light of their lower ancient and present geotemperature gradient. While the middle zone is represented by Songliao and Bohaiwan basins, the continental margin zone is represented by East China Sea shelf basin and northern continental shelf basins of South China Sea. They belong to the extensional basins with thinning lithosphere, the smallest burial depth of paleoasthenospheric top, being 55-60 km. Therefore they should belong to heat basin type. The geothermal state of the basins is correlated positively with extension degree in the majority of basins controlled by dynamic mechanism of extension and transtension.

Stratigraphic Succession,Source-Rock Distribution and Paleoclimatic Zone in Meso-Cenozoic Basins,Eastern China

?The unequal spacetime distribution of the source rocks resulted from the mutual superimposition of the biota evolution, basin type, and paleoclimatic change. The basin type is the most important in controlling the distribution of source rocks. The effect of the paleoclimate on the source rocks varied with different basins. In the rift basin, the source rocks were accumulated in the humid, semihumid and semiarid climates; however, in the flexural basin, only in the humid and semihumid climates. The biota features may control, to a great extent, the distribution pattern and the sourcerock quality. The abundance of the terrestrial flora and lacustrine phytoplankton was essential for the generation of the Meso-Cenozoic source rocks on a large scale.

Evaluation of the Hydrocarbon Potential in the Meso－Cenozoic Basins of South China

The blocks opening to foreign investors for iointly exploring and developing oil and gas involve Jiangsu.Anhui,Zhejiang.Fujian.Hunan.Jiangxi.Yunnan.Guizhuo.Guangxi.Guangdong and Hainan provinces,where the non-marine sedimentary basins each with an area over 200 km'amount to 167 and the total coverage is more than 400 thousand km*.They were formed respectively in early Indosinian.early Y enshanian,late Ye-.nshanian and Himalayan.

Characteristics and main controlling factors of helium resources in the main petroliferous basins of the North China Craton

At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that's why their methane resource characteristics are essentially the same. The calculated ~4He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ~4He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins;there is almost no contribution of the mantle-derived CH_4, which suggests that the transport and uplift of mantle-derived ~3He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ~3He mixing in the basins. Combined with the results of regional volcanic and geophysical studies,it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ~3He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ~3He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.

Tectonic Setting and Nature of the Provenance of Sedimentary Rocks in Lanping Mesozoic-Cenozoic Basin: Evidence from Geochemistry of Sandstones

The geochemical composition of sandstones in the sedimentary basin is controlled mainly by the tectonic setting of the provenance, and it is therefore possible to reveal the tectonic setting of the provenance and the nature of source rocks in terms of the geochemical composition of sandstones. The major elements, rare\|earth elements and trace elements of the Mesozoic\|Cenozoic sandstones in the Lanping Basin are studied in this paper, revealing that the tectonic settings of the provenance for Mesozoic\|Cenozoic sedimentary rocks in the Lanping Basin belong to a passive continental margin and a continental island arc. Combined with the data on sedimentary facies and palaeogeography, it is referred that the eastern part of the basin is located mainly at the tectonic setting of the passive continental margin before Mesozoic, whereas the western part may be represented by a continental island arc. This is compatible with the regional geology data. The protoliths of sedimentary rocks should be derived from the upper continental crust, and are composed mainly of felsic rocks, mixed with some andesitic rocks and old sediment components. Therefore, the Lanping Mesozoic\|Cenozoic Basin is a typical continental\|type basin. This provides strong geochemical evidence for the evolution of the paleo\|Tethys and the basin\|range transition.

Plate tectonic control on the formation and tectonic migration of Cenozoic basins in northern margin of the South China Sea

The tectonic evolution history of the South China Sea(SCS) is important for understanding the interaction between the Pacific Tectonic Domain and the Tethyan Tectonic Domain,as well as the regional tectonics and geodynamics during the multi-plate convergence in the Cenozoic.Several Cenozoic basins formed in the northern margin of the SCS,which preserve the sedimentary tectonic records of the opening of the SCS.Due to the spatial non-uniformity among different basins,a systematic study on the various basins in the northern margin of the SCS constituting the Northern Cenozoic Basin Group(NCBG) is essential.Here we present results from a detailed evaluation of the spatial-temporal migration of the boundary faults and primary unconformities to unravel the mechanism of formation of the NCBG.The NCBG is composed of the Beibu Gulf Basin(BBGB),Qiongdongnan Basin(QDNB),Pearl River Mouth Basin(PRMB) and Taixinan Basin(TXNB).Based on seismic profiles and gravity-magnetic anomalies,we confirm that the NE-striking onshore boundary faults propagated into the northern margin of the SCS.Combining the fault slip rate,fault combination and a comparison of the unconformities in different basins,we identify NE-striking rift composed of two-stage rifting events in the NCBG:an early-stage rifting(from the Paleocene to the Early Oligocene) and a late-stage rifting(from the Late Eocene to the beginning of the Miocene).Spatially only the late-stage faults occurs in the western part of the NCBG(the BBGB,the QDNB and the western PRMB),but the early-stage rifting is distributed in the whole NCBG.Temporally,the early-stage rifting can be subdivided into three phases which show an eastward migration,resulting in the same trend of the primary unconformities and peak faulting within the NCBG.The late-stage rifting is subdivided into two phases,which took place simultaneously in different basins.The first and second phase of the early-stage rifting is related to back-arc extension of the Pacific subduction retreat system.The third phase of the earlystage rifting resulted from the joint effect of slab-pull force due to southward subduction of the proto-SCS and the back-arc extension of the Pacific subduction retreat system.In addition,the first phase of the late-stage faulting corresponds with the combined effect of the post-collision extension along the Red River Fault and slab-pull force of the proto-SCS subduction.The second phase of the late-stage faulting fits well with the sinistral faulting of the Red River Fault in response to the Indochina Block escape tectonics and the slab-pull force of the proto-SCS.

Petrochemical Characteristics of the Mesozoic-Cenozoic Volcanic Rock in Huanghua Basin

Based on the data from typical core sampling, combined with K Ar dating, petrochemistry ,trace elemental geochemistry and isotopic compositions of the Mesozoic Cenozoic volcanic rock in the Huanghua basin, Bohai region, the geochemical features of the volcanic rock were studied. The rocks fall into four groups: Cenozoic basalt,Mesozoic late Cretaceous basaltic trachy andesite, Mesozoic late Cretaceous trachy dacite and liparite,and Mesozoic early Triassic dacite. The distribution pattern of the main elemental abundance of late Mesozoic shows a typical bimodal.Chronologically,for the volcanic rock,the amount of SiO 2 decreases gradually,the contents of Fe 2O 3,FeO,CaO,MgO,TiO 2,P 2O 5 and MnO increase little by little.The Cenozoic basalt is derived from the asthenospheric mantle.The late Cretaceous basaltic trachy andesite is derived from the enriched lithospheric mantle.In late Cretaceous and early Palaeogene,the felsic volcanic rock may be derived from fractional melting of the crust.

Mesozoic-Cenozoic Basin Features and Evolution of Southeast China

The Late Triassic to Paleogene （T3-E） basin occupies an area of 143100 km^2, being the sixth area of the whole of SE China; the total area of synchronous granitoid is about 127300 km^2; it provides a key for understanding the tectonic evolution of South China. From a new 1：1500000 geological map of the Mesozoic-Cenozoic basins of SE China, combined with analysis of geometrical and petrological features, some new insights of basin tectonics are obtained. Advances include petrotectonic assemblages, basin classification of geodynamics, geometric features, relations of basin and range. According to basin-forming geodynamical mechanisms, the Mesozoic-Cenozoic basin of SE China can be divided into three types, namely： 1） para-foreland basin formed from Late Triassic to Early Jurassic （T3-J1） under compressional conditions; 2） rift basins formed during the Middle Jurassic （J2） under a strongly extensional setting; and 3） a faulted depression formed during Early Cretaceous to Paleogene （K1-E） under back-arc extension action. From the rock assemblages of the basin, the faulted depression can be subdivided into a volcanic-sedimentary type formed mainly during the Early Cretaceous （K1） and a red -bed type formed from Late Cretaceous to Paleogene （K2-E）. Statistical data suggest that the area of all para-foreland basins （T3-J1） is 15120 km^2, one of rift basins （J2） occupies 4640 km^2, and all faulted depressions equal to 124330 km^2 including the K2-E red-bed basins of 37850 km^2. The Early Mesozoic （T3-J1） basin and granite were mostly co-generated under a post-collision compression background, while the basins from Middle Jurassic to Paleogene （J2-E） were mainly constrained by regional extensional tectonics. Three geological and geographical zones were surveyed, namely： 1） the Wuyishan separating zone of paleogeography and climate from Middle Jurassic to Tertiary; 2） the Middle Jurassic rift zone; and 3） the Ganjiang separating zone of Late Mesozoic volcanism. Three types of basin-granite relationships have been identified, including compressional （a few）, strike-slip （a few）, and extensional （common）. A three-stage geodynamical evolution of the SE-China basin is mooted： an Early Mesozoic basin-granite framework; a transitional Middle Jurassic tectonic regime; intracontinental extension and red-bed faulted depressions since the Late Cretaceous.

A Simulation Study on the Evolution of Groundwater Circulation Systems in Cenozoic Basins of Northern China

Three Cenozoic basins—the Qaidam basin, the Weihe graben-type basin and the North China plain—which are different in climatic conditions, geological settings and run—off types, are selected for the study. Based on an analysis of background information of the transect along the middle-latitude region, studies of groundwater dynamics, geochemistry, simulation of water circulation of the main elements as well as isotopic chronology, the information on global changes is collected, the formation of groundwater circulation systems and their evolution under stacked impacts of natural conditions and human activities are discussed, and a correlation is made between the evolutionary features of the above systems in these basins since 25 ka B.P. All these have laid a good foundation for further generalizing the evolutionary model of land water in northern China.

Logging interpretation method for reservoirs with complex pore structure in Mesozoic-Cenozoic faulted basin around Daqing exploration area

In Mesozoic-Cenozoic faulted basin in the periphery of Daqing exploration area, the clastic reservoirs mainly consist of siltstone and gravel-bearing sandstone. The electrical conductivity of the reservoirs is complicated due to the complex pore structures, which cannot be accurately interpreted with commonly used model. In order to solve the problem, a three-water model has been applied in this study based on in-depth analysis of the conductive mechanism of rocks in the explored area, and favorable application results are achieved.

Sequence of the Cenozoic Mammalian Faunas of the Linxia Basin in Gansu, China

In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed. Abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene. The Dzungariotherium fauna comes from the sandstones of the Jiaozigou Formation, including many representative Late Oligocene taxa. The Platybelodon fauna comes from the sandstones of the Dongxiang Formation and the conglomerates of the Laogou Formation, and its fossils are typical Middle Miocene forms, such as Hemicyon, Amphicyon, Platybelodon, Choerolophodon, Anchitherium, and Hispanotherium. The Hipparion fauna comes from the red clay of the Liushu and Hewangjia Formations, and its fossils can be distinctly divided into four levels, including three Late Miocene levels and one Early Pliocene level. In the Linxia Basin, the Hipparion fauna has the richest mammalian fossils. The Equus fauna comes from the Wucheng Loess, and it is slightly older than that of the classical Early Pleistocene Nihewan Fauna. The mammalian faunas from the Linxia Basin provide the reliable evidence to divide the Cenozoic strata of this basin and correlate them with European mammalian sequence.

The Cenozoic activities of Yangjiang-Yitongdong Fault: insights from analysis of the tectonic characteristics and evolution processes in western Zhujiang(Pearl) River Mouth Basin

The Yangjiang-Yitongdong Fault (YJF) is an important NW-trending regional fault, which divides the Zhujiang (Pearl) River Mouth Basin (ZRMB) into western and eastern segments. In Cenozoic, the northern continental margin of the South China Sea (SCS) underwent continental rifting, breakup, seafloor spreading and thermal subsidence processes, and the Cenozoic activities of YJF is one part of this series of complex processes. Two long NW-trending multichannel seismic profiles located on both sides of the YJF extending from the continental shelf to Continent-Ocean Boundary (COB) were used to study the tectonic and sedimentary characteristics of western ZRMB. Using the 2D-Move software and back-stripping method, we constructed the balance cross-section model and calculated the fault activity rate. Through the comprehensive consideration of tectonic position, tectonic evolution history, featured structure, and stress analysis, we deduced the activity history of the YJF in Cenozoic. The results showed that the YJF can be divided into two segments by the central uplift belt. From 65 Ma to 32 Ma, the YJF was in sinistral motion as a whole, inherited the preexisting sinistral motion of Mesozoic YJF, in which, the southern part of YJF was mainly in extension activity, controlling the formation and evolution of Yunkai Low Uplift, coupled with slight sinistral motion. From 32 Ma to 23.8 Ma, the sinistral motion in northern part of YJF continued, while the sinistral motion in southern part began to stop or shifted to a slightly dextral motion. After 23.8 Ma, the dextral motion in southern part of YJF continued, while the sinistral motion in northern part of YJF gradually stopped, or shifted to the slightly dextral motion. The shift of the YJF strike-slip direction may be related to the magmatic underplating in continent-ocean transition, southeastern ZRMB. According to the analysis of tectonic activity intensity and rift sedimentary structure, the activities of YJF in Cenozoic played a regulating role in the rift extension process of ZRMB.

Cenozoic Environmental Changes in the Northern Qaidam Basin Inferred from n-alkane Records

Cenozoic climatic and environmental changes in the arid Asian interior, and their possible relations with global climatic changes and the Tibetan Plateau uplift, have been intensively investigated and debated over past decades. Here we present 40-Myr （million years）-long n-alkane records from a continuous Cenozoic sediment sequence in the Dahonggou Section, Qaidam Basin, northern Tibetan Plateau, to infer environmental changes in the northern basin. A set of n-alkane indexes, including ACL, CPI and Paq, vary substantially and consistently throughout the records, which are interpreted to reflect relative contributions from terrestrial vascular plants vs. aquatic macrophytes, and thus indicate depositional environments. ACL values vary between 21 and 30; CP1 values range from 1.0 to 8.0; and Paq values change from 〈0.1 to 0.8 over the past 40-Myr. We have roughly identified two periods, at 25.8-21.0 Ma （million years ago） and 13.0-17.5 Ma, with higher ACL and CPI and lower Paq values indicating predominant lacustrine environments. Lower ACL and CPI values, together with higher Paq values, occurred at 〉25.8 Ma, 17.5-21.0 Ma, and 〈13.0 Ma, corresponding to alluvial fan/river deltaic deposits and shallow lacustrine settings, consistent with the observed features in sedimentological facies. The inferred Cenozoic environmental changes in the northern Qaidam Basin appear to correspond to global climatic changes.

Late Cenozoic Stratigraphy and Paleomagnetic Chronology of the Zanda Basin,Tibet, and Records of the Uplift of the Qinghai-Tibet Plateau

The characteristics of Late Cenozoic tectonic uplift of the southern margin of the Qinghai- Tibet Plateau may be inferred from fluvio-lacustrine strata in the Zanda basin, Ngari, Tibet. Magnetostratigraphic study shows that the very thick fluvio-lacustrine strata in the basin are 5.89- 0.78 Ma old and that their deposition persisted for 5.11 Ma, i.e. starting at the end of the Miocene and ending at the end of the early Pleistocene, with the Quaternary glacial stage starting in the area no later than 1.58 Ma. Analysis of the sedimentary environment indicates that the Zanda basin on the southern Qinghai-Tibet Plateau began uplift at -5.89 Ma, later than the northern Qinghai-Tibet Plateau. Presence of gravel beds in the Guge and Qangze Formations reflects that strong uplift took place at -5.15 and -2.71 Ma, with the uplift peaking at -2.71 Ma.

Fossil Equidae in the Linxia Basin with Biostratigraphic and Paleozoogeographic Significance

The Linxia Basin is characterized by an abundance of Cenozoic sediments,that contain exceptionally rich fossil resources.Equids are abundant in the Linxia Basin,the fossil record of equids in this region including 16 species that represent 10 genera.In comparison to other classic late Cenozoic areas in China,the Linxia Basin stands out,because the fauna and chronological data accompanying Linxia equids render them remarkably useful for biostratigraphy.The anchitheriines in the region,such as Anchitherium and Sinohippus,represent early equids that appeared in the late stages of the middle and late Miocene,respectively.Among the equines,most species of Chinese hipparions have been identified in the Linxia Basin and some species of the genera Hipparion and Hippotherium have FAD records for China.Furthermore,Equus eisenmannae is one of the earliest known species of Equus in the Old World and is well-represented at the Longdan locality.Some species with precise geohistorical distributions can serve as standards for high-resolution chronological units within this framework.Located at the eastern margin of the Tibetan Plateau and subject to considerable uplift,the Linxia Basin has served as a biogeographic transition area for equids throughout the late Cenozoic.

MASS ACCUMULATION IN THE CENOZOIC HOH XIL BASIN,NORTHERN TIBET

Sedimentary basins are where the products or erosion of the related reliefs accumulate.The sedimentary records preserved in the basins offer the possibility of quantifying the paleotopography z(x,y,t) at each point( x,y )of a given region at any time t in the past by using methods of mass balanced reconstruction(Hay et al.,1989,Métivier and Gaudemer,1997),The importance of paleotopography is on that atmospheric circulation models and the ocean circulation models which depend on them require knowledge of the topography of the land as an important input boundary condition which strongly affects the model output(Barron and Washington,1984,Ruddiman et al.,1997).Thus,a first step towards establishing paleoelevations is to reconstitute the history of sedimentary basins in terms of mass accumulation(Hay et al.,1989).This work reconstructs the space\|time depositional history and estimates the mass stored in the Hoh Xil basin,northern Tibet.The Hoh Xil basin,with an area of 101000km\+2 and an average elevation of over 5000m,is the largest Cenozoic sedimentary basin in the hinterland of the Tibetan plateau.From the Early Eocene to the Early Miocene,a sediment pile of approximately 5 4km thick of fluvial mudstone,sandstone,and conglomerate and 0 3km thick of limestone was formed in the basin (Liu and Wang,2000;Liu et al.,2000).the mass estimate is derived from 21 measured field cross\|sections,with total thickness of 13479 3m.The results show that the Hoh Xil basin has undergone 7 stages of evolution from the Early Eocene to the Early Oligocene,with a period of no sedimentation during the Late Oligocene.The Fenghuoshan Group was formed from the first four stages as 56 0～52 0,52 0～46 7,46 7～39 7,and 39 7～33 2Ma ago,with the depocenter moving eastward and northward.The Yaxicuo Group was formed from the two next stages as 33 2～32 2 and 33 2～30 2Ma ago.The Wudaoliang Group spread the entire basin during the last stage of ca.23 0～16 0Ma ago,with its depocenter in the northern part.The strata of the Fenghuoshan and Yaxicuo Groups have undergone strong deformation mainly during 30 0 to ca.23 0Ma,whereas only minor tilting has occurred in the Wudaoliang Group later.The space\|time evolution indicates that the Hoh Xil basin could be formed by the collision between Indi and Asia during the Early Eocene,and that its filling processes were controlled by early uplift and crustal shortening of the Tibetan plateau.The sedimentation budget is estimated as 297 15×10 12 t for the Cenozoic sediments deposited in the Hoh Xil basin.The accumulation rate curve shows that the value rises suddenly to around 800t/(m\+2 Ma -1 )during 32 2～30 0Ma ago from around 400t/(m\+2·Ma -1 )during 56～32 2Ma ago.The sudden increase of accumulation rate could be produced by early uplift of the Tibetan plateau.

Meso-Cenozoic Evolution of Earth Surface System under the East Asian Tectonic Superconvergence

The East Asian geological setting has a long duration related to the superconvergence of the Paleo-Asian, Tethyan and Paleo-Pacific tectonic domains. The Triassic Indosinian Movement contributed to an unified passive continental margin in East Asia. The later ophiolites and I-type granites associated with subduction of the Paleo-Pacific Plate in the Late Triassic, suggest a transition from passive to active continental margins. With the presence of the ongoing westward migration of the Paleo-Pacific Subduction Zone, the sinistral transpressional stress field could play an important role in the intraplate deformation in East Asia during the Late Triassic to Middle Jurassic, being characterized by the transition from the E-W-trending structural system controlled by the Tethys and Paleo-Asian oceans to the NE-trending structural system caused by the Paleo-Pacific Ocean subduction. The continuously westward migration of the subduction zones resulted in the transpressional stress field in East Asia marked by the emergence of the Eastern North China Plateau and the formation of the Andean-type active continental margin from late Late Jurassic to Early Cretaceous （160-135 Ma）, accompanied by the development of a small amount of adakites. In the Late Cretaceous （135-90 Ma）, due to the eastward retreat of the Paleo-Pacific Subduction Zone, the regional stress field was replaced from sinistral transpression to transtension. Since a large amount of late-stage adakites and metamorphic core complexes developed, the Andean-type active continental margin was destroyed and the Eastern North China Plateau started to collapse. In the Late Cretaceous, the extension in East Asia gradually decreased the eastward retreat of the Paleo-Pacific subduction zones. Futhermore, a significant topographic inversion had taken place during the Cenozoic that resulted from a rapid uplift of the Tibet Plateau resulting from the India-Eurasian collision and the formation of the Bohai Bay Basin and other basins in the East Asian continental margin. The inversion caused a remarkable eastward migration of deformation, basin formation and magmatism. Meanwhile, the basins that mainly developed in the Paleogene resulted in a three-step topography which typically appears to drop eastward in altitude. In the Neogene, the basins underwent a rapid subsidence in some depressions after basin-controlled faulting, as well as the intracontinental extensional events in East Asia, and are likely to be a contribution to the uplift of the Tibetan Plateau.

LATE CENOZOIC TECTONICS ALONG THE NORTHWESTERN MARGIN OF THE TARIM BASIN: INTERACTIONS BETWEEN THE TARIM BASIN AND THE SOUTHERN TIAN SHAN, WEST CHINA

The Late Cenozoic fold\|and\|thrust zone along the northwestern margin of the Tarim Basin and the adjacent Tian Shan of Central Asia is an actively deforming part of the India\|Asia collision system. This deformation zone has two remarkable oppositely vergence arcuate fold\|and\|thrust systems (Kepingtage and Kashi\|Atushi fold\|and\|thrust belts) reaching from east of Keping to west of Kashi. This shape is manifested by structure, topography and seismicity. From north to south, this deformation zone is characterized by four main kinematic elements: (1) a hanging\|wall block (Maidan fault and Tuotegongbaizi\|Muziduke thrust system) that represents the Cenozoic reactivation of a late Paleozoic thrust system; (2) an imbricated thrust stack (Kepingtage\|Tashipeshake thrust system) where slices of Tarim platform sediments are thrust south toward the basin; (3) the Kashi\|Atushi fold\|and\|thrust system where thrusting and folding verge toward the Tian Shan; (4) a foot\|wall block (Tarim craton) that dips gently northwest below the sediment\|filled southern Tian Shan basin and generally has little internal deformation.