Search

Mainland China has the most complex continental tectonics on Earth, making it one of the ideal laboratories for probing the tectonics and evolution of the Earth. However, no consensus has been reached regarding the basement tectonic architectures and evolution of mainland China. This paper focuses on the interpretation of aeromagnetic and seismic refraction data, closely incorporating available surface geological data, borehole data, and seismic data to trace the likely occurrences of oceanic plateau slices in the basement architecture of mainland China. We suggest that the highly positive aeromagnetic anomalies and thick high-velocity lower crustal layer indicate that the Junggar basin is floored by an oceanic plateau. The Tarim basin can be divided into a southeastern oceanic plateau block with strongly positive aeromagnetic anomalies and a northwestern passive continental margin block with weak aeromagnetic anomalies. Both blocks got amalgamated together during the late Paleoproterozoic, and the irregular, promiscuous aeromagnetic anomalies within the northwestern block are spatially consistent with and attributed genetically to the Tarim Large Igneous Province (LIP). The lower crust of the Qaidam basin is characterized by large P-wave velocity, suggesting that the basin is floored by an Early Paleozoic oceanic plateau, and the deep-seated subduction of the oceanic plateau could be responsible for the ultrahigh-pressure (UHP) metamorphism in the northern Qaidam margin during the Early Paleozoic. The western North China craton could be an assembly of multiple oceanic plateau fragments along irregular continental margins during the Paleoproterozoic. An intraplate suture (Miaowan suture) divides the Yangtze craton kernel to the east and the Shennong terrane to the west; both were amalgamated during the Neoproterozoic. The Yangtze craton kernel could be floored by an oceanic plateau basement characterized by large P-wave velocity and strongly positive aeromagnetic anomalies. All these oceanic plateau basements exhibit strong rigidity to resist later tectonic deformation and generally remain intact. • Junggar basin is floored by oceanic plateau of highly positive magnetic anomalies 3 and high velocity • Tarim basin is divided into northeastern oceanic plateau and southwestern passive 5 margin. • Qaidam basin is floored by oceanic plateau, whose subduction resulted in UHPM 7 in N. Qaidam margin • Western North China craton is an assembly of oceanic plateaus during the 9 Paleoproterozoic • Yangtze craton kernel is floored by oceanic plateau and divided by Miaowan suture 11 from Shennong terrane. [ABSTRACT FROM AUTHOR]

The Proterozoic geological records in eastern South China preserve a history linked to the Columbia and Rodinia supercontinent cycles and provide key constraints in understanding the geodynamic evolution of East Asia. However, it is uncertain if SW Hainan, Yangtze and Cathaysia were located in the interior or periphery of the Precambrian supercontinents, how they were connected prior to the formation of a united South China, whether the early Neoproterozoic Proto-Huanan subduction was long- or short-lived, and how and when Yangtze and Cathaysia were assembled along the Jiangnan Orogen. This paper provides an overview of key geological observations for the eastern Yangtze and Cathaysia with respect to Proterozoic tectonics. Our synthesis shows that the SW Hainan in the Mesoproterozoic (ca. 1.45 Ga) developed in a non-orogenic rift setting in the interior of Columbia. SW Hainan, together with SW Yangtze, drifted to the margin of Rodinia by ∼1.05 Ga. Furthermore, SW Hainan might have been part of the Mesoproterozoic Albany Fraser Orogen at ca. 1.30–1.05 Ga. Cathaysia and eastern Yangtze display distinct geological signatures in the early Neoproterozoic and Cathaysia remain separated from Yangtze until at least ca. 1.0 Ga. The ca. 1.0–0.9 Ga felsic igneous rocks in Cathaysia to the east of the Jiangshan-Shaoxing suture zone are mostly characterized by negative ε Hf (t) values, and distinct from those in the coeval Shuangxiwu arc to the west of the Jiangshan-Shaoxing suture zone, which have positive ε Hf (t) values. Igneous rocks dated at ca. 870–830 Ma (mainly ca. 850–830 Ma) are extensive in the Huaiyu and Jiangnan Orogen but poorly developed in Cathaysia. Neoproterozoic sedimentary rocks of Cathaysia contain abundant ca. 980 Ma detrital grains but only minor ca. 860–830 Ma grains. In contrast, in the Jiangnan and Huaiyu, the sedimentary rocks contain a dominant ca. 860–830 Ma detrital zircon age-peak but ca. 980 Ma grains are scare. Rift-related bi-model igneous rocks, ranging in age from ca. 810 Ma to ca. 750 Ma, represented by the Banxi, Likou and Mamianshan groups and their equivalents, are extensively developed in Cathaysia and Huaiyu, and the Jiangnan Orogen. These rift-related successions are separated from the Cangshuipu and Luojiamen conglomerates across an angular unconformity, which are in turn unconformable on the Lengjiaxi and Xikou groups. It is herein proposed that an early Neoproterozoic (ca. 1.0–0.9 Ga) accretionary orogen developed within the Cathaysia and lay along strike from the synchronous Eastern Ghats Orogen of India. A long-lived Neoproterozoic (ca. 0.97–0.83 Ga) Proto-Huanan arc-trench system resulted in the development of the ca. 0.98–0.88 Ga Shuangxiwu intra-oceanic arc, ca. 0.87–0.83 Huaiyu continental arc and ca. 0.87–0.83 Jiangnan intra-continental back- arc basin in response to the ongoing westward-subduction beneath the eastern Yangtze. At ca. 0.87 Ga, the arc-trench system switched from an intra-oceanic to a continental Andean margin setting. Such a system might be compatible to the NW India South Delhi Orogen at the periphery of Rodinia. Our synthesis shows that the united proto-South China was finally created by the ca. 830–810 Ma assemblage of the Yangtze with Cathaysia along the Jiangnan Orogen and was followed by the post-orogenic rifting due to the breakup of Rodinia. [ABSTRACT FROM AUTHOR]

The Central Asian Orogenic Belt (CAOB) was generated through multiple collisional and accretionary events in the Paleo-Asian Ocean, a major global ocean that existed from the late Neoproterozoic into the late Paleozoic. Nevertheless, the question of when the Paleo-Asian Ocean finally closed has notoriously been enigmatic, especially due to the absence of large-scale investigations. The South Tianshan-Solonker Suture, is the largest and southernmost suture within the CAOB, and records the ultimate collision between the Tarim-North China cratons with the Siberia craton, and is commonly interpreted as marking the eventual closure of the Paleo-Asian Ocean. In this paper, we synthesize and evaluate relevant Chinese papers on the area, which are not readily available to an international audience, and extend this across the full length of the suture zone. Based on this review, we can divide the suture zone into four distinct segments, which are, from west to east: the South Tianshan Belt, the Beishan Belt, the Solonker Belt and the Yanji Belt. This enables us to provide a more systematic understanding of the nature and development of the South Tianshan-Solonker suture. Geochronological data from Paleozoic cover rocks and high-pressure metamorphic rocks show that during the late Carboniferous, the western section of the Paleo-Asian Ocean closed when the Tarim Craton moved northward to collide with the Kazakhstan-Yili Block, thus marking the initial development of the South Tianshan Belt. The Beishan Belt to the east formed when the Dunhuang-Alxa blocks were transported northward to collide with the Tuva-Mongolia Block, with the youngest zircon U Pb data from ophiolites indicating that closure of the local Beishan Ocean was in the early-middle Permian, although its final closure may not have been until the early late Permian along the northern margin of the Alxa Block, thus making it slightly younger than the South Tianshan Belt. Further to the east, the available petrographic, geochronological and paleontological data from the Solonker Belt indicate that this belt was formed in the middle-late Permian, during which time bi-directional subduction occurred and the North China and Siberia cratons were amalgamated during an 'Appalachian-type' orogeny. Furthermore, we observe that a transition in polarity from northward to bi-directional subduction occurred along the boundary between the Beishan and Solonker belts, which may be related to the East Gobi Transform Fault. In contrast, under the influence of the westward subduction of the Paleo-Pacific Ocean, the Jiamusi-Khanka Block moved southwestward along the Yilan-Yitong Fault in the middle-late Triassic (230–220 Ma) to amalgamate with the North China Craton. The formation of the South Tianshan-Solonker Suture can be characterized by four distinct west-to-east accretion/collision events that lasted from the late Carboniferous to the late Permian. The South Tianshan Belt, the Beishan Belt and the Solonker Belt therefore demarcate, respectively, the amalgamation between the Tarim Craton and the Kazakhstan-Yili Block, the Dunhuang-Alxa Block and the Tuva-Mongolia Block, and the North China Craton with the Siberia Craton, representing the final closure of the Paleo-Asian Ocean. During the middle-late Triassic, the Yanji Belt in the far east was influenced by the Paleo-Pacific tectonic domain as a result of amalgamation between the Jiamusi-Khanka Block and the North China Craton. • South Tianshan-Solonker Suture marks the final collision between Tarim-North China and Siberian cratons. • The Suture includes four segments, and closed form Late Carboniferous to Middle Triassic from west to east, respectively. • The Yanji belt was influenced by the Paleo-Pacific tectonic domain during the Middle Triassic. [ABSTRACT FROM AUTHOR]

Despite the enormous potential of continental shale oil resources, only recoverable shale oil is economically valuable. Shale oil development decisions can greatly benefit from an accurate assessment of recoverable shale oil resources. Three crucial factors for evaluating shale oil recoverable resources are shale oil content, movable oil ratio, and recovery factor. However, because of the significant variety of continental shale, it is challenging to define the aforementioned characteristics. The methodologies and technology for determining the shale oil recoverable resource evaluation parameters, particularly the shale oil content, movable oil ratio, and recovery factor, are thoroughly discussed in this paper. Taking the Tertiary Sha-3 continental shale in Dongpu and Nanpu sags in Bohai Bay Basin, eastern China as an example, the shale oil content was obtained by the pyrolysis method with light and heavy hydrocarbon calibration comprehensively considered, and the main controlling factors of shale oil content were explored. Four geological parameters, including the sedimentary facies, pore structure, surrounding rock quality, and burial depth, primarily regulate the variation features of continental shale oil. The formation mechanism and primary governing variables of movable oil were then revealed using a physical simulation experiment. As porosity and permeability rise, clay mineral content falls, oil viscosity falls, and kerogen concentration rises, the movable oil ratio rises as well. Through stepwise linear regression, a quantitative estimation model for movable oil ratio was developed. After that, a literature search was used to determine the average recovery factor for continental shale oil. Finally, using the volume method model and the Monte Carlo methodology, the recoverable shale oil resources in the Gaoliu area of Nanpu Sag were assessed. The retention, movability, and resource potential of continental shale oil are better understood as a result of this study. [ABSTRACT FROM AUTHOR]

Northeast (NE) China is located in the eastern Central Asian Orogenic Belt (CAOB) and evolved from the amalgamation of several microcontinental blocks, which, from west to east, include the Erguna, Xing'an, Songliao, and Jiamusi-Khanka blocks. Since the Paleozoic, NE China has undergone multiple stages of subduction–accretion and tectonic destruction under the tectonic domains of the Paleo-Asian Ocean, Panthalassa, and the Paleo-Pacific Ocean. This complexity has resulted in uncertainty surrounding the amalgamation processes of the various microcontinents. Fortunately, several suture zones in NE China, including the Toudaoqiao–Xinlin Suture, the Hegenshan–Heihe Suture, the Solonker–Xar Moron–Changchun Suture, and the Jilin–Heilongjiang High-pressure Belt contain information that provides key constraints on the tectonic evolution of NE China. This paper reviews the spatial distribution, composition, and formation ages of these suture zones based on published geological records. Our temporal and spatial analyses of these suture zones enable the evolution of NE China to be assigned to those three tectonic domains: (1) In the earliest of these, the Paleo-Asian Ocean tectonic domain (650–250 Ma), the Erguna Block amalgamated with the Xing'an Block along the Toudaoqiao–Xinlin Suture during the Late Cambrian (ca. 500 Ma); the Erguna–Xing'an Block then collided with the Songliao Block along the Hegenshan–Heihe Suture during the Late Carboniferous (ca. 300 Ma), whilst the combined Erguna–Xing'an–Songliao Block amalgamated with the North China Craton along the Solonker–Xar Moron–Changchun Suture at the End-Permian (ca. 250 Ma). (2) in the Panthalassa tectonic domain (315–230 Ma), the subduction of Panthalassa (or locally, the Mongol-Okhotsk Ocean) was initiated in the eastern Jiamusi-Khanka Block during the Late Carboniferous (ca. 315 Ma), resulting in back-arc extension in the western Jiamusi-Khanka Block, which evolved into the Heilongjiang Ocean separating the Jiamusi-Khanka and Songliao blocks during the Late Permian to Late Triassic (260–230 Ma). (3) in the Paleo-Pacific Ocean tectonic domain (230–130 Ma), the first stage of westward subduction of the Paleo-Pacific oceanic plate occurred during the Late Triassic (ca. 230 Ma), causing the Jiamusi-Khanka Block to amalgamate with the North China Craton during the Late Triassic (ca. 230 Ma) and subsequently with the Songliao Block during the Late Triassic to Early Jurassic (210–180 Ma), forming the Jilin–Heilongjiang High-pressure Belt, whereas the second stage of subduction induced the emplacement of the Nadanhada Terrane during the Early Cretaceous (ca. 130 Ma). This represented the final assembly of NE China in the eastern CAOB. • NE China can be divided into three tectonic domains of the Paleo-Asian Ocean, the Panthalassa, and the Paleo-Pacific Ocean. • The assembly of NE China was accomplished through the generation of five suture zones, which formed from ∼500 Ma to ∼130 Ma. • NE China recorded multiple stages of activity of the Paleo-Asian, Panthalassa (Mongol-Okhotsk), and the Paleo-Pacific oceans. [ABSTRACT FROM AUTHOR]

The early Precambrian tectonic framework and evolution of the North China Craton (NCC) remain diversely contentious. This paper presents an overview mainly of the progresses in metamorphic studies for the NNCC and proposes alternative litho-tectonic division and tectonic scenarios for the Paleoproterozoic NNCC based on the recognized four phases of metamorphism. Five litho-tectonic units can be divided in the NNCC, including the Yinshan Block (YB), Wulashan Reworked Belt (WRB), Jining Mobile Belt (JMB), Huai'an Reworked Belt (HRB) and the Longgang Block (LB). All of them underwent different metamorphic modification during the Orosirian period at 1.98–1.80 Ga. The Orosirian metamorphism in the NNCC includes four phases. The first-phase metamorphism (M-I) occurred at >1.95 Ga, is the medium- P/T type marked by high-pressure (HP) granulites. It shows clockwise P–T paths characterized by the pre- P max (peak pressure) prograde and post- P max decompression, indicating a crustal thickening orogeny. The second-phase metamorphism (M-II) occurred during 1.94–1.90 Ga, is the low- P/T type marked by ultrahigh-temperature (UHT) granulites. It shares clockwise P–T paths characterized by the pre- T max (peak temperature) decompression-heating from HP granulite conditions and post- T max isobaric cooling. This UHT metamorphism may ascribe to conductive and advective heating from mantle upwelling and hyperthermal mafic magma intraplating in a post-orogenic setting with back-arc extension. The third-phase metamorphism (M-III) is the high- P/T type characteristic of eclogites occurred at >1.88 Ga, which, together with ∼1.90 Ga ophiolitic mélanges, suggests oceanic subduction beneath the northern margin of the NCC. The fourth-phase metamorphism (M-IV) is also the medium- P/T type with clockwise P–T paths, occurred during 1.88–1.82 Ga. It is represented by the Barrovian metamorphic zones in the east WRB, staurolite-overprints in the north HRB, metabasic dykes up to HP granulite facies in the north LB, and HP granulites in the south YB, registering another collisional orogeny in the NNCC. Based on these four phases of Orosirian metamorphism, and combined with other geological data in the NNCC, we present an alternative tectonic model which involves the following tectonic scenarios: (i) The Siderian–Rhyacian (2.46–2.00 Ga) extension occurred in back-arc or within-plate settings, resulted in the YB separated from LB, and the Paleoproterozoic volcano-sedimentary sequences, granite intrusions and basic dykes formed in the WRB, JMB, HRB. (ii) The early Orosirian (2.00–1.95 Ga) crust thickening orogeny occurred on account of the collision between the NCC and an unknown continent, as indicated by M-I metamorphism, which gave rise to an orogen trended mainly in north-east between the YB and LB, nominated as the west North China Orogen (WNCO). (iii) The mid-Orosirian (1.95–1.88 Ga) oceanic subduction and back-arc extension occurred as suggested by M-II and M-III metamorphism. And (iv) the late Orosirian (1.88–1.82 Ga) collisional orogeny resulted from a collision between the NCC and the south Siberian Craton, which gave rise to an orogen trended in east–west, named the north North China Orogen (NNCO). [ABSTRACT FROM AUTHOR]

This paper summarizes available lithostratigraphic, tectonothermal, geochronological and geophysical data to investigate the formation and evolution of the Yinshan Block, the tectonic nature of the Ordos Block, and the subduction to collision history of the Khondalite Belt, and establishes Paleoproterozoic accretion and assembly of the Western Block of the North China Craton. New critical evidence indicates that a magmatic arc developed in the Ordos Block caused by the initiation of northward slab subduction beneath the southern margin of the Ordos Block during 2.3–2.0 Ga, which contributed to the opening of the back-arc basin between the Ordos and Yinshan blocks. And then, the north margin of the Ordos Block was then transformed into a passive-type continental margin and collided with the Yinshan Block along the Khondalite Belt to form the Western Block after final closure of the back-arc basin during 1.97–1.91 Ga. Seismic data across the Western Block including a 300-km-long south-north-trending receiver function profile and a common conversion point stacking image in depth domain obviously show its crustal structure, in which the relics of two subduction slabs were preserved beneath the Ordos Block and the Khondalite Belt, respectively. Therefore, we propose a new tectonic model to help to better constrain Paleoproterozoic accretion and assembly of the Western Block in North China. [ABSTRACT FROM AUTHOR]

Subduction and closure of the Proto-Tethys and Palaeo-Tethys oceans were important events in the assembly of Eurasia, and created the Central China Orogenic Belt (CCOB). This paper presents a new tectonic model for the CCOB in which we propose that elongate Precambrian basement blocks within the CCOB were originally part of a single ribbon continent, here named K-Qubed after the K unlun- Q aidam- Q ilian- Q inling regions. K-Qubed separated from the South China Block in the Neoproterozoic. Dextral-oblique subduction of the Proto-Tethys Ocean took place southwards (present co-ordinates) under K-Qubed in latest Precambrian - Cambrian times (ca. 550–500 Ma). Subduction-accretion complexes were generated alongside the basement, while arc magmatism overprinted both basement and accretionary crust. Initial collision of the northern side of the ribbon continent and the North China and Tarim blocks occurred at ca. 500 Ma. High-pressure and ultrahigh-pressure metamorphism resulted by ca. 490 Ma, in the North Qilian, South Altun/North Qaidam and North Qinling regions. Collision triggered a flip in subduction polarity, and caused a subduction-accretion complex and magmatic arc to build out southwards from K-Qubed, as Palaeo-Tethys was consumed northwards in the Ordovician. Magmatic timings were similar between different tectonic units; twin peaks in magmatism at ca. 500–490 Ma and ca. 440–430 Ma occurred in several terranes. Oblique subduction caused strain partitioning, in turn causing slivering and across-strike repetition of basement and accretionary crust. Tectonic units in the Qilian Shan and Kunlun can be partly correlated with equivalents in the Qinling Orogen. We suggest a match between the North Qilian Orogenic Belt and the Erlangping Unit, between the Central Qilian Block and the North Qinling Belt, between the South Qilian Accretionary Belt and the Shangdan Suture Zone. Basement terranes of the Qaidam region and the East Kunlun Orogen have no obvious lateral equivalents in the Qinling, and are truncated at the eastern margins by the West Qinling Belt. There are similar ages for peak metamorphism at ca. 440–420 Ma in an eclogite belt in the North Qaidam Ultra High-pressure Metamorphic Belt (NQUB) and eclogite localities in the East Kunlun Orogen. We interpret this metamorphism to be result of slab break-off beneath the K-Qubed continent, with metamorphic rocks repeated across-strike by dextral shear. The component of Precambrian crust in the Kunlun diminishes westwards into the West Kunlun, where Early Palaeozoic accretion of crust was more continuous. A magmatic gap throughout the CCOB between ca. 370 and ca. 290 Ma was possibly related to extremely oblique and/or slow plate convergence, or represents a time through which subduction stopped. Renewed northwards subduction of the Palaeo-Tethyan Ocean took place under the south side of the Kunlun and Qinling in the Permian, completed by Triassic collisions of the Qiangtang and South China blocks with the southern side of the CCOB. This model for the CCOB is an alternative to collisional and accretionary end members for orogeny, whereby oblique subduction and collision of a ribbon continent produces interleaving of basement and more juvenile terranes. Closure of Proto-Tethys did not involve multiple, separate and synchronous subduction zones, or repetition of a subduction zone by oroclinal bending, as previously proposed. [ABSTRACT FROM AUTHOR]

In their thoughtful paper entitled "An equable subtropical climate throughout China in the Miocene based on palaeofloral evidence", Qing Wang, Yan Li, David K. Ferguson, Wen-Bo Mo, and Nan Yang (2021) imply that China exhibited negligible latitudinal mean annual precipitation (MAP) gradients and lacked arid regions during the Miocene. They also speculate that there was no abrupt change in elevation of the Tibetan Plateau, nor that the plateau attained its present altitude or orography during that period. These conclusions were derived mainly by using a co-existence approach (CA) and 'incomplete data'. Here, we use CA with training data and also integrate a coexistence likelihood estimation, a pollen-MAP boundary, a desert-MAP boundary, and other newly published MAP data to show that Northwest China consistently exhibited drier conditions than South China and East China during the entire Miocene, with our new values being 300–500 mm lower than those of Wang et al. (2021). This implies that there were large spatial gradients of MAP in China during the Miocene, which may be directly linked with the growth of the Tibetan Plateau, the global cooling, as well as other factors. We recommend the comprehensive consideration of multiple methods and proxies for reconstructing past climate conditions as opposed to a single proxy. [ABSTRACT FROM AUTHOR]

In comparison with the amount of study undertaken on the end-Permian mass extinction, the preceding Guadalupian mass extinction has received little investigation, even though it marks a significant biotic turnover associated with global environmental changes. During the earlier event, reef carbonate production shut down and was replaced by siliceous, mud-rich deposits (SRDs) in South China. However, changes in carbonate platform productivity during this epoch remain to be clarified. This paper presents sedimentological and conodont biostratigraphic investigations on the Guadalupian SRDs developed on the Yangtze Carbonate Platform (YCP) in central Guizhou. The findings are viewed in the context of Guadalupian sequence correlation of South China successions, which shows that the integrity of the YCP failed to match the platform tectonic evolution. The platform evolution saw the onset of major intra-platform depressions and the gradual onlap by SRDs along the platform margin. Stratigraphic correlation reveals that the platform experienced three phases of onlap by SRDs during the early Roadian, the late Wordian and the late Capitanian upwards. Platform carbonates re-expanded their extent following the first two phases, but not during the final phase. An evolutionary model is proposed for the Guadalupian carbonate platform, which follows the contemporaneous eustatic sea-level fluctuations. The partial drowning observed within the platform interior and increasing retreat along the platform margin could suggest an insufficient carbonate sediment supply shedding from the platform top during the Guadalupian. The variation in carbonate productivity raises our attention to the change in shallow-water carbonate factories, which is closely related to the fortunes of carbonate-secreting biota and environmental factors impacting the carbonate platform producers during the Guadalupian. [ABSTRACT FROM AUTHOR]

Sedimentary basins in China are globally special for retaining large volumes of carbon dioxide. To date, over 40 CO 2 gas fields (>60 vol% CO 2) and many more CO 2 -rich hydrocarbon fields (15–60 vol% CO 2) have been discovered across China. Valuable knowledge of CO 2 migration, accumulation, and long-term sequestration processes in sedimentary basins can be acquired by analysing various CO 2 fields in China. This paper reviews three key aspects of CO 2 reservoirs in Chinese sedimentary basins: (1) CO 2 origin, (2) factors controlling the distribution of CO 2 gas, and (3) the long-term effect of CO 2 emplacement on reservoir rocks. Both the eastern and western parts of China have several giant sedimentary basins. CO 2 -rich gases are predominantly discovered in eastern China among rift basins, with sandstone, carbonate, and volcanic rocks being the principal reservoirs. Analyses of carbon and helium isotopes suggest that the high abundance of CO 2 in eastern China is primarily of mantle origin, with subordinate crustal CO 2. Igneous intrusives and faults control the migration and accumulation of CO 2 -rich gases within the basins. The offshore Yinggehai Basin, however, is an exception in eastern China, where the majority of CO 2 appears to be of crustal origin, resulting from thermolysis of carbonate minerals. For this type of CO 2 , mud diapirs in the deep basin, which serve as upward passages for geothermal fluids, control the distribution of CO 2 -rich gases. In comparison, sedimentary basins in western China generally contain minor amounts of CO 2 (< 5 vol%) in the produced gases. The low-concentration CO 2 is mostly of crustal origin, from the decomposition of organic matter and carbonate minerals or, in a few places, from the thermochemical sulphate reduction process. Pore fluids in CO 2 reservoirs of China are characterised by high salinity, owing to elevated concentrations of Na+ and HCO- 3 induced by CO 2 emplacement. Pervasive dissolutions of feldspars are widely observed in sandstone and volcanic reservoirs in China, and dawsonite is the most common authigenic mineral. Dawsonite growth did not cause significant variations in the reservoir porosity in most cases. Mantle-derived CO 2 has been suggested to promote kerogen maturation and oil migration in sedimentary basins, thereby helping to form some oilfields in China. [ABSTRACT FROM AUTHOR]

East Asia is exceptionally rich in diverse geological phenomena related to processes of major global significance in Earth history. Its tectonic evolution is closely related to the subduction of the Izanagi and Pacific plates and the India-Eurasia collision. Thus, this domain presents a vast natural laboratory within which some of the most topical and fundamental problems in Pacific-Asian Tectonics can be addressed. Recent breakthroughs in understanding the tectonic evolution of East Asia have been achieved, involving intraplate deformation, plate fragmentation, plate boundary processes, orogenic collapse, and craton destruction. These advances have been achieved via multidisciplinary work including structural geology, basin research, land and marine geophysics, thermochronology, numerical modeling, geochemistry and classical field geology. In the current context of research in East Asia the time is ripe for a thematic volume of review papers. This special issue is focused on the theme "Pacific-Asian Tectonics". It describes interdisciplinary methods adopted to study Meso-Cenozoic basin-forming mechanisms and evolutionary processes, unravels the timing and characteristics of major intraplate deformation, depicts the spatial-temporal distribution of Meso-Cenozoic igneous rocks, discusses the deep lithospheric structures overlying the subducting oceanic plates, and probes the natures and fates of subduction or collision processes. [ABSTRACT FROM AUTHOR]

Thermal regime and thermal history are of significant important in basin dynamics and hydrocarbon generation of source rocks. The sedimentary basins in three typical cratons of China, North China Craton (NCC), Yangtze Craton (YC) and Tarim Craton (TC), underwent completely different tectonic background and dynamic mechanism, which resulted in the differentials of their thermal regimes. In this paper, the thermal regimes of the Bohai Bay Basin in the eastern NCC, Tarim Basin in TC, and Sichuan basin in the Upper YC were studied. There has some lower thermal background in the area of western China than eastern side of the NCC. The mean heat flow value of Tarim basin is 42.5 mW/m2, 53.8 mW/m2 in the Sichuan basin and 66.7 mW/m2 in the eastern NCC. And the temperature at 10000 m ultra-depth in the Tarim Basin also shows lower values than that of Sichuan and Bohai Bay basins. The thermal history, modeled from thermal indicators of vitrinite reflectance (R o), equivalent vitrinite reflectance data (R equ), fission track and (U Th)/He data of apatite and zircon, evolved differently because of the different tectonic history in these basins. The Tarim basin underwent a cooling history with the heat flow of 55–65 mW/m2 in the Cambrian decreasing to the present-day of 40–50 mW/m2. The Meso-Cenozoic thermal history of the Bohai Bay basin experienced four evolutionary stages with two heat flow peaks in the late Early Cretaceous and in the Middle to Late Paleogene, which correspond to the destruction peaks of the eastern NCC and had heat flow values of 82–86 mW/m2 and 81–88 mW/m2, respectively. The Sichuan basin was stable with heat flow value of less than 65 mW/m2 from the Late Sinian to Late Paleozoic, and the heat flow increased rapidly to the peak value (75–100 mW/m2) at the end of Early Permian by thermal effect of the Emeishan mantle plume. From Mesozoic to present, the heat flow decreased to the present value (60–70 mW/m2). In addition, the comparation of thermal characteristics of typical cratons around the world, including heat flow, thermal history, lithospheric thermal structure and thermal lithospheric thickness, also have been caried out. The differential thermal histories of Tarim and Sichuan basins resulted in the different thermal evolution of Cambrian source rocks. This study may provide some new geothermal evidence for hydrocarbon generation and phase distribution of oil and gas in the deep and/or ultra-deep basin. Thermal regime and thermal history of typical sedimentary basins in three typical cratons of China underwent completely different evolution. The Tarim basin underwent a cooling history, the Bohai Bay basin experienced four evolutionary stages with two heat flow peaks, and the Sichuan basin was stable with heat flow but to a peak at the end of Early Permian. Nansheng Qiu, Chang Jian, Zhu Chuanqing, Liu Wen, Zuo Yinhui, Xu Wei, Li Dan. [Display omitted] • Three typical cratons of China show great differences in heat flow and deep-temperature. • Three typical cratons of China show great differences in lithospheric thickness from 76–170 km. • Thermal histories of Bohai Bay, Sichuan and Tarim basins are summarized. • Thermal regime between stable and destabilized cratons are compared. • Three thermal evolution patterns of source rocks are obtained. [ABSTRACT FROM AUTHOR]

The development of evaporite–carbonate assemblages is a common sedimentary process in restricted and evaporitic marine environments. These assemblages provide important reservoir spaces for oil and gas. To establish a systematic understanding of, and scientific basis for, oil and gas exploration, this paper reviews the major genetic environments of evaporite–carbonate assemblages and associated hydrocarbon reservoirs. Based on the review, carbonate reservoir-forming marine evaporite sequence worldwide can be categorized into four major settings: marginal-marine sabkhas, marginal-marine evaporative lagoons, coastal salinas and regional evaporite basins. In addition, a new type of reservoir that developed in the Ordos Basin of China during the Ordovician greenhouse is proposed based on a synthesis of new and existing chemical and physical data. This new model is identified in the supra-salt reservoir in the fifth Member of the Middle Ordovician Majiagou Formation in the Ordos Basin and is termed an "epeiric basin-scale moldic reservoirs". In this newly identified type of dolomite reservoir, irregular–circular moldic pores and vugs that are uniformly distributed in micritic dolomite matrix formed high-quality reservoir spaces, examples of which are rare worldwide to date. The primary evaporitic mineral in these molds is disseminated halite crystal, which formed in a restricted and evaporitic epeiric-basin environment. The selective dissolution of disseminated halite crystals and enlargement of its surrounding rocks in the upper part of the sedimentary cycle by meteoric water during late highstand system tract formed the unique distribution of halite-moldic pores and vugs. Within the evaporitic epeiric basin, high-frequency sea-level fluctuation and syngenetic exposure are also likely to have occurred, conditions that have been neglected in the classic models. Coupling of the extremely high atmospheric CO 2 content, low-amplitude location and high-frequency sea-level fluctuations during the Middle Ordovician greenhouse, together with the flat and broad restricted evaporative environment, controlled the formation of this rare end-member sedimentary assemblage and associated reservoirs. The reservoirs were developed within the sedimentary framework of the North China Platform, which was characterized by a general depression surrounded by three uplifted areas during the Middle Ordovician Majiagou period. The model characterized by epeiric basin-scale disseminated evaporites allowed the formation of reservoirs with high exploration potential. Exploration of this type of reservoir requires that attention is paid to hydrocarbon sweet spots generated by later diagenesis and to heterogeneous hydrocarbon accumulation. [ABSTRACT FROM AUTHOR]