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Showing papers in "Acta Geologica Sinica-english Edition in 2010"


Journal ArticleDOI
TL;DR: In this article, the authors defined the Yanshan movement as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great change that started at ˜165±5 Ma.
Abstract: With acquisition and accumulation of new data of structural geological investigations and high-resolution isotopic dating data, we have greatly improved our understanding of the tectonic events occurring in eastern China during the period from the Late Jurassic to Early Cretaceous and may give a new interpretation of the nature, timing and geodynamic settings of the “Yanshan Movement”. During the Mid-Late Jurassic (165±5 Ma), great readjustment of plate amalgamation kinematics took place in East Asia and the tectonic regime underwent great transformation, thus initiating a new tectonic regime in which the North China Block was the center and different plates converged toward it from the north, east and southwest and forming the “East Asia convergent” tectonic system characterized by intracontinental subduction and orogeny. As a consequence, the crustal lithosphere of the East Asian continent thickened considerably during the Late Jurassic, followed immediately by Early Cretaceous substantial lithospheric thinning and craton destruction featured by drastic lithospheric extension and widespread volcano-magmatic activities, resulting in a major biotic turnover from the Yanliao biota to Jehol Biota. Such a tremendous tectonic event that took place in the continent of China and East Asia is the basic connotation of the “Yanshan Movement”. In the paper, according to the deformation patterns, geodynamic settings and deep processes, the “Yanshan Movement” is redefined as the Late Jurassic East Asian multi-directional plate convergent tectonic regime and its associated extensive intracontinental orogeny and great tectonic change that started at ˜165±5 Ma. The substantial lithospheric attenuation in East China is considered the post-effect of the Yanshanian intracontinental orogeny and deformation.

233 citations


Journal ArticleDOI
TL;DR: By using the SHRIMP U-Pb and single zircon stepwise evaporation methods, the authors have obtained some results for granitoids from eastern Hebei Province as discussed by the authors.
Abstract: By using the SHRIMP U-Pb and single zircon stepwise evaporation methods, the authors have obtained some results for granitoids from eastern Hebei Province. The Yuhuzhai hyperthene tonalitic granite was formed 2550 Ma ago, the Qingyangshu gabbroic gneiss 2536 Ma, the Yinmahe granodioritic gneiss near Lucao, Lulong County, 2533 Ma, the gabbro-dioritic gneiss near Longwan, Qianxi County, 2518-2515 Ma, the Qiuhuayu trondjemitic gneiss at Zunhua 2515 Ma, the Xiaoguanzhuang tonalitic gneiss at Zunhua 2495 Ma, and the Cuizhangzi gneiss in Qianxi County 2492 Ma. These geochronilogical data demonstrate that, though diverse in composition, type and origin, the granitic gneisses in eastern Hebei Province were emplaced and crystallized in a rather short period of magmatic activity. The formation of such a great amount of gneisses in this small time gap suggests that it was a critical crust accretion stage at the end of Neoarchean. The fact that granitoids of various types occurred at the same time implies a large-scale underplating (mantle plume) activity, which was then responsible for the crust accretion.

155 citations


Journal ArticleDOI
TL;DR: The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoics collision events as discussed by the authors. But the authors of this paper focus on the latter and do not address the former.
Abstract: The Tianshan range could have been built by both late Early Paleozoic accretion and Late Paleozoic collision events. The late Early Paleozoic Aqqikkudug-Weiya suture is marked by Ordovician ophiolitic melange and a Silurian flysch sequence, high-pressure metamorphic relics, and mylonitized rocks. The Central Tianshan belt could principally be an Ordovician volcanic arc; whereas the South Tianshan belt, a back-arc basin. Macro- and microstructures, along with unconformities, provide some kinematic and chronological constraints on 2-phase ductile deformation. The earlier ductile deformation occurring at ca. 400 Ma was marked by north-verging ductile shearing, yielding granulite-bearing ophiolitic melange blocks and garnet-pyroxene-facies ductile deformation, and the later deformation, a dextral strike-slip tectonic process, occurred during the Late Carboniferous(Early Permian. Early Carboniferous molasses were deposited unconformably on pre-Carboniferous metamorphic and ductilely sheared rocks, implying the end of the early orogeny. The large-scale ductile strike-slip along the Aqqikkudug-Weiya zone was possibly caused by the second tectonic event, the Hercynian collision between the northern Tarim block and the southern Siberian block. Late Paleozoic granitic magmatism and superimposed structures overprinted this Early Paleozoic deformation belt. Results of geometric and kinematic studies suggest that the primary framework of the Southern-Central Tianshan belt, at least the eastern part of the Tianshan belt, was built by these two phases of accretion events.

123 citations


Journal ArticleDOI
TL;DR: Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, Wang et al. as discussed by the authors have drawn the following main conclusions: (1) the high grade basement consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8-1.0 Ga (the Jinningian period); (2) most of the metaargillo-, granitic and granitic rocks have strong negative Eu and Ba anomalies (Eu/E
Abstract: Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilian terrane consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8–1.0 Ga (the Jinningian period); (2) most of the meta-argillo-arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu*= 0.47–0.71 and Ba/Ba*=0.16–0.64), with fDM and ENd (1.0 Ga) ranging from 1.87 to 2.26 Ga and from −8.54 to −4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks are a typical product of continent-continent collision, being probably related to the formation of the supercontinent Rodinia. These studies, combined with the study of high-grade basement rocks near the Qilian terrane, suggest that before the Jinningian period, the Qilian-Qaidam northern-margin terrane and Dunhuang-Alxa terrane were separated from each other, belonging to different plate systems of the North China craton and Yangtze platform respectively. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period.

116 citations


Journal ArticleDOI
TL;DR: In this paper, a synthetic view on the Jurassic tectonics of North China is given, with an attempt to propose a framework for the stepwise tectonic evolution history.
Abstract: This paper gives a synthetic view on the Jurassic tectonics of North China, with an attempt to propose a framework for the stepwise tectonic evolution history. Jurassic sedimentation, deformation and magmatism in North China have been divided into three stages. The earliest Jurassic is marked by a period of magmatism quiescence (in 205–190 Ma) and regional uplift, which are considered to be the continuation of the “Indosinian movement” characterized by continent-continent collision between the North and South China blocks. The Early to Middle Jurassic (in 190–170 Ma) was predominated by weak lithospheric extension expressed by mantle-derived plutonism and volcanism along the Yanshan belt and alongside the Tan-Lu fault zone, normal faulting and graben formation along the Yinshan-Yanshan tectonic belt, depression and resuming of coal-bearing sedimentation in vast regions of the North China block (NCB). The Middle to Late Jurassic stage started at 165±5 Ma and ended up before 136 Ma; it was dominated by intensive intraplate deformation resulting from multi-directional compressions. Two major deformation events have been identified. One is marked by stratigraphic unconformity beneath the thick Upper Jurassic molasic series in the foreland zones of the western Ordos thrust-fold belt and along the Yinshan-Yanshan belt; it was predated 160 Ma. The other one is indicated by stratigraphic unconformity at the base of the Lower Cretaceous and predated 135 Ma. During this last stage, two latitudinal tectonic belts, the Yinshan-Yanshan belt in the north and the Qinling-Dabie belt in the south, and the western margin of the Ordos basin were all activated by thrusting; the NCB itself was deformed by the NE to NNE-trending structural system involving thrusting, associated folding and sinistral strike-slip faulting, which were spatially partitioned. Foliated S-type granitic plutons aged 160–150 Ma were massively emplaced in the Jiao-Liao massif east of the Tan-Lu fault zone and indicate important crustal thickening in this part of the NCB. The Jurassic deformation patterns, different tectonic systems and multi-directional contractions in North China recorded far-field effects of synchronous convergences, toward the East Asian continent, of three different plates, the Siberian plate in the north, the paleo-Pacific oceanic plate in the east and the Lhasa block in the southwest. This Middle to Late Jurassic intraplate orogenesis and pervasive shortening deformation preceded lithospheric attenuation and thinning in East China, which most possibly started by the Early Cretaceous around 135 Ma.

114 citations


Journal ArticleDOI
TL;DR: Wang et al. as mentioned in this paper used Raman spectrometers to detect gas hydrate in Qilian Mountain permafrost, which was found to have a more complex gas component and coalbed methane origin, suggesting a new type of hydrate.
Abstract: Qilian Mountain permafrost,with an area of about 10×104km2,is located in the north of Qinghai-Tibet plateau. It has of perfect conditions and great prospecting potential for gas hydrate. The Scientific Drilling Project of Gas Hydrate in the Qilian Mountain permafrost,which locates at the Jugenghu Mining Area in the Muli Coalfield,Tianjun County,Qinghai Province,has been implemented by China Geological Survey in 2008~2009. Four scientific drilling wells have been completed with a total footage of 2059.13m. Samples of gas hydrate were collected separately in the holes of DK-1,DK-2 and DK-3. Gas hydrate is hosted under permafrost zone at the 133~396m interval. The samples are white or ivory crystal and easily burning. Distinct low temperature anomaly has been identified by infrared camera. The gas hydrate-bearing cores strongly bubble in water. Gas-bubble and water-drop emit from the samples and then retain characteristic honeycombed structure. The typical spectrum curve of gas hydrate is detected using Raman spectrometry. Furthermore,the logging profile also indicates high electrical resistivity and sonic velocity. Gas hydrate in Qilian Mountain is found within a thinner permafrost zone with a shallower buried depth and characterized by more complex gas component and coalbed methane origin,suggesting a new type of hydrate.

104 citations


Journal ArticleDOI
TL;DR: A new Archaefructus species, A. eoflora sp.
Abstract: Recently, whether Archaefructus has bisexual multi-parted flowers or just inflorescences of unisexual flowers, and whether it is ancestral to all angiosperms or a derived eudicot have been debated. Here, from the same Yixian Formation, NE China, we report a new Archaefructus species, A. eoflora sp. nov., with the generic characteristics of dissected leaves and bisexual reproductive axes. It is entirely preserved with roots, rhizome, shoots and protogynous reproductive organs at different developmental stages. Its lateral and main fertile shoots form a pseudo-indeterminate pattern, while the reproductive branches on the main shoot form a cymose inflorescence. Subtended by 1-2 bract-like leaves, the section of stamen clusters changes into a much shorter section of carpels that have one row of orthotropous ovules. Significantly, one cluster bearing two carpels and one stamen between the two sections demonstrates a true bisexual flower, an important step of the origin of floral bisexuality, and the homology between the stamen and carpel. The complex reproductive axes represent a mix between flowers and inflorescences, and suggest that A. eoflora sp. nov. possesses the potential to evolve into a variety of diverse flower types as found in modern basal and early fossil angiosperms. A comparison with other two species also leads to a revision of the generic diagnosis.

80 citations


Journal ArticleDOI
TL;DR: It was shown and confirmed that most superfamilies appeared in the fossil records before Cucujoidea, and the hypothesis that Cucujiformian beetles are a younger group than other infraordera of Polyphaga was confirmed.
Abstract: The present paper is devoted to an overview on fossil Coleoptera studied from Inner Mongolia, Daohugou (Middle Jurassic, Jiulongshan Formation) and Liaoning (Upper Jurassic-Lower Cretaceous, Yixian Formation) deposited in Chinese collections. As a result, species of the tribe Sperchopsini and Hydrophilini from Hydrophilidae, families and subfamilies Silphidae, Syndesinae from Lucanidae, Pleocomidae, Trogidae, Trogissitidae, Pyrochroidae, Diaperinae from Tenebrionidae, and Cerambycidae were first registered in the Mesozoic and some families were defined as new. It was shown that many superfamilies represented in the Recent Fauna were formed within the Middle Jurassic and Lower Cretaceous. The materials examined confirm the hypothesis that Cucujiformian beetles are a younger group than other infraordera of Polyphaga (Staphyliniformia and Elateriformia) and, therefore, they appeared in the fossil record only in the late Mesozoic. It was shown and confirmed that most superfamilies appeared in the fossil records before Cucujoidea. The synonymy of Notocupes Ponomarenko, 1964; Sinocupes Lin, 1976, syn. nov.; Amblomma Tan, Ren et Liu 2005, syn. nov.; Euryomma Tan, Ren et Shih, 2006, syn. nov., non Stein, 1899 and Ovatocupes Tan et Ren, 2006, syn. nov.; synonymy of Tetraphalerus Waterhouse, 1901 and Odontomma Tan, Ren et Ge 2006, syn. nov.; and synonymy of Priacmopsis Ponomarenko, 1966 and Latocupes Tan et Ren, 2006, syn. nov. are proposed. Sinorhombocoleus papposus Tan et Ren, 2009 is transferred from the family Rhombocoleidae to Schizophoridae. Cervicatinius complanus Tan, Ren et Shih, 2007 and Forticatinius elegans Tan, Ren et Shih, 2007 are transferred from the family Catiniidae (suborder Archostemata) to superfamily Cleroidea (suborder Polyphaga: first among the family Peltidae and second as a closely related group to the latter family). The family Parandrexidae is transferred from the superfamily Cucujoidea to Cleroidea. The ecological circumstances of the past ecosystems and hypotheses of historical development of the order Coleoptera are discussed. The age of faunas examined is considered. The list of the taxa described from Daohugou and Liaoning is compiled.

77 citations


Journal ArticleDOI
TL;DR: In this article, the authors give a definition of the karst ecosystem and discuss the characteristics of the K-st environment and k-st ecosystem, and the relationship between life and the k -st environment.
Abstract: In this paper the author gives a definition of the karst ecosystem and discusses the characteristics of the karst environment and karst ecosystem and the relationship between life and the karst environment. Finally he clarifies the structure, driving force and functions of the karst system.

74 citations


Journal ArticleDOI
TL;DR: In this paper, an Early Cretaceous amber outcrop, El Soplao, has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far.
Abstract: El Soplao outcrop, an Early Cretaceous amber deposit recently discovered in northern Spain (Cantabria), has been shown to be the largest site of amber with arthropod inclusions that has been found in Spain so far. Relevant data provided herein for biogeochemistry of the amber, palynology, taphonomy and arthropod bioinclusions complement those previously published. This set of data suggests at least two botanical sources for the amber of El Soplao deposit. The nrst (type A amber) strongly supports a source related to Cheirolepidiaceae, and the second (type B amber) shows non-specific conifer biomarkers. Comparison of molecular composition of type A amber with Frenelopsis leaves (Cheirolepidiaceae) strongly suggests a biochemical affinity and a common botanical origin. A preliminary palynologlcal study indicates a regional high taxonomical diversity, mainly of pteridophyte spores and gymnosperm pollen grains. According to the preliminary palynologlcal data, the region was inhabited by conifer forests adapted to a dry season under a subtropical climate. The abundant charcoalified wood associated with the amber in the same beds is evidence of paleofires that most likely promoted both the resin production and an intensive erosion of the litter, and subsequent great accumulation of amber plus plant cuticles. In addition, for the first time in the fossil record, charcoalified plant fibers as bioinclusions in amber are reported. Other relevant taphonomic data are the exceptional presence of serpulids and bryozoans on the surfaces of some amber pieces indicating both a long exposure on marine or brackish-water and a mixed assemblage of amber. Lastly, new findings of insect bioinclusions, some of them uncommon in the fossil record or showing remarkable adaptations, are reported. In conclusion, a documented scenario for the origin of the El Soplao amber outcrop is provided.

67 citations


Journal ArticleDOI
TL;DR: In this article, the authors provided the first highly precise dating of the mineralization and rock-forming in the Donggou Mo deposit, which showed that the Re-Os model ages of the deposit are between 116.5±1.7~115.7
Abstract: Located in the eastern Qinling Molybdenum Belt, the Donggou deposit is a superlarge porphyry Mo deposit discovered in recent years. This study provides the first highly precise dating of the mineralization and rock-forming in the Donggou Mo deposit. The dating of zircon from Donggou aluminous A-type granitic porphyry determined by SHRIMP yields an age of 112±1 Ma. The ~ 187 Re and ~ 187 Os contents of molybdenite from the molybdenum deposit are determined by the Inductively Coupled Plasma Mass Spectrometry (ICP-MS), with analytical errors of Re and Os between 0.2%~0.3% (2σ). The results obtained show that the Re-Os model ages of the deposit are between 116.5±1.7~115.5±1.7 Ma, with average age of 116±1.7 Ma. The SHRIMP zircon U-Pb and molybdenite Re-Os isotopic ages are quite close. The results suggest that the Donggou Mo deposit was formed at least 20 Ma later than the Jinduicheng, Nannihu, Shangfanggou and Leimengou porphyry molybdenum deposits in the same molybdenum belt. On the basis of the accurately confirmed ages of the mineralization and rock-forming, their relationships, the ore-forming mechanism and the geodynamic evolution are further discussed. They formed in different tectonic settings. The Donggou Mo deposit formed during the rapid lithospheric thinning of eastern China at ca. 120 Ma, while the other Mo deposits formed when the tectonic transformation predominated at ca. 140 Ma.

Journal ArticleDOI
TL;DR: The classification and phylogeny of the basal Vespina (= Orussoidea + Apocrita) are reconsidered based primarily on rich and well preserved material from the Middle Jurassic of Daohugou in Inner Mongolia, China and six infraorders are proposed for the suborder Vespine with the following taxonomic structure.
Abstract: The classification and phylogeny of the basal Vespina (= Orussoidea + Apocrita) are reconsidered based primarily on rich and well preserved material from the Middle Jurassic of Daohugou in Inner Mongolia, China. Comparatively smooth morphological transitions are traced from a Xiphydriidae-like ancestor toward Orussoidea via the Jurassic family Karatavitidae, and through Karatavitidae and the Jurassic and Early Cretaceous family Ephialtitidae independently to Stephanidae, to Evanioidea, and, via the extinct Jurassic Kuafuidae fam. nov. to the remaining Apocrita. New hypothesis is proposed concerning development of the characteristic wasp-waist of Apocrita, which is supposed to appear independently and in different ways in Evanioidea and in the rest of Apocrita. As a result, six infraorders are proposed for the suborder Vespina with the following taxonomic structure: infraorder Orussomorpha including the only superfamily Orussoidea (Karatavitidae + Paroryssidae + Orussidae), infraorder Stephanomorpha with the only superfamily Stephanoidea (Ephialtitidae + Stephanidae), infraorder Evaniomorpha with the only superfamily Evanioidea of traditional composition, infraorder Ceraphronomorpha with the superfamilies Ceraphronoidea s. str. and monotypical Megalyroidea and Trigonaloidea, and the infraorders Proctotrupomorpha, Ichneumonomorpha, and Vespomorpha of traditional composition. The family Kuafuidae is unplaced to infraorder because it is putatively paraphyletic with respect to Ceraphronomorpha, Proctotrupomorpha, Ichneumonomorpha and Vespomorpha. Described as new are Karatavites junfengi sp. nov., Praeratavites wuhuaensis sp. nov., P. perspicuus sp. nov., Postxiphydria daohugouensis gen. et sp. nov., P. ningchengensis gen. et sp. nov., Postxiphydroides strenuus gen. et sp. nov., Praeratavitoides amabilis gen. et sp. nov., Proapocritus densipediculus sp. nov., P. sculptus sp. nov., P. longantennatus sp. nov., P. formosus sp. nov., P. atropus sp. nov., P. elegans sp. nov., Stephanogaster pristinus sp. nov., Asiephialtites lini sp. nov., Praeproapocritus vulgatus gen. et sp. nov., Sinaulacogastrinus solidus gen. et sp. nov., Sinevania speciosa gen. et sp. nov., Eonevania robusta gen. et sp. nov., Kuafua polyneura gen. et sp. nov. (all from the Middle Jurassic of Daohugou), as well as Kuafuidae fam. nov. including Kuafua gen. nov. as well as Arthrogaster Rasnitsyn, 1975, and Leptogastrella Rasnitsyn, 1975 from the Upper Jurassic of Karatau in Kazakhstan.

Journal ArticleDOI
TL;DR: In this article, high-resolution tomographic images of the belt crossing the Japan Trench-Changbai Mountains-Dong Ujimqin Qi are represented, revealing the shape of a subducted slab in the western Pacific region and characteristics of the lithospheric structures under the Changbai mountains and the Da Hinggan Mountains.
Abstract: High-resolution tomographic images of the belt crossing the Japan Trench-Changbai Mountains-Dong Ujimqin Qi are represented in this paper, revealing the shape of a subducted slab in the western Pacific region and characteristics of the lithospheric structures under the Changbai Mountains and the Da Hinggan Mountains. Studies of the spatial distribution, subduction time and the time-lag between the subduction and magmatism, combined with petrology and isotope geochemistry of the Late Mesozoic volcano-plutonic rocks from the Da Hinggan Mountains-Yanshan Mountains have further proved the independence of magmatic activities from the subduction of the Pacific plate. The Mesozoic tectono-thermal evolutionary history and structural characteristics of the lithosphere in the Da Hinggan Mountains and North China suggest that the formation and evolution of magma have probably a close relationship with the delamination and thinning of the continental lithosphere and the underplating resulting from the consequent upwelling of the asthenosphere. On the other hand, the large-scale strike-slip fault system, resulting from sinistral shearing of the Pacific plate relative to the Asian continent in the Mesozoic, is responsible for the formation and emplacement of magma on the continental margin. It was the intense crust-mantle interaction, together with structural deformation at the shallower levels that led to the large tectono-magmatic belt in the East Asian continental margin.

Journal ArticleDOI
TL;DR: A complete specimen of a symmetrodont mammal with well-preserved hairs and soft tissue from the basal part of the Yixian Formation in the Sihetun area, Beipiao, western Liaoning is described, significant for understanding the morphology, osteology, phylogeny and life habits of Mesozoic symmetRodont mammals.
Abstract: Western Liaoning of northeastern China is world-renowned for the Mesozoic Jehol biota, especially for yielding many feathered dinosaurs, primitive birds, mammals and fossil angiosperm. This paper describes a complete specimen of a symmetrodont mammal with well-preserved hairs and soft tissue from the basal part of the Yixian Formation in the Sihetun area, Beipiao, western Liaoning. It is significant for understanding the morphology, osteology, phylogeny and life habits of Mesozoic symmetrodont mammals.

Journal ArticleDOI
TL;DR: An isochron age of 282±20 (95% conf. limit) for the sulfide ores in the Huangshandong Cu-Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re-Os isotopic measurement.
Abstract: An isochron age of 282±20 (95% conf. limit) Ma of the sulfide ores in the Huangshandong Cu-Ni sulfide deposit, the East Tianshan Mountains has been obtained through Re-Os isotopic measurement. The age implies that the Cu-Ni sulfide deposit and other related deposits in the same area occurred in a Permian extensional environment of post-collision instead of Devonian-Early Carboniferous ophiolite-related oceanic or island arc environments inferred before. It shares the same ages with the orogenic and epithermal gold deposit systems in the same area. An initial 187Os/188Os ratio of 0.25±0.04 (1σ) and a γo8 value of 99 on average display the participation of large quantities of crustal components into the rock-forming and ore-forming system during mineralization and magmatic emplacement.

Journal ArticleDOI
TL;DR: The Baiyun sag is a deep one developed on the slope of the Pearl River Mouth Basin this paper. But it occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift.
Abstract: The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary architecture could be divided into three layers, i.e. the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area, characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upwelling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non-faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.

Journal ArticleDOI
TL;DR: The Ordos basin was developed from mid-late Triassic to early Cretaceous, and then entered into its later reformation period since the Late Cretancy as discussed by the authors, and it's suggested that there were at least four obvious stages of tectonic deformations existing during the basin's evolution.
Abstract: The Ordos basin was developed from Mid-Late Triassic to Early Cretaceous, and then entered into its later reformation period since the Late Cretaceous. Its main body bears the features of an intra-cratonic basin. The basin also belongs to a multi-superposed basin which has overlapped on the large-scale basins of the Early and Late Paleozoic. Currently, Ordos basin has become a residual basin experienced reformation of various styles since the Late Cretaceous. It's suggested that there were at least four obvious stages of tectonic deformations existing during the basin's evolution, dividing the evolution and sedimentation into four stages. The prior two stages were of the most prosperous, during which the lake basin was broad, the deposition range was more than twice larger than the current residual basin, resulting in major oil- and coal-bearing strata. The two stages were separated by regional uplift fluctuations in the area. At the end of the Yan'an Stage, the depositional interruption and erosion were lasting for a short period of time. The third one is the Mid- Jurassic Zhiluo-Anding stage, in which the sedimentation extent was still broad but the lake area was obviously reduced. In the Late Jurassic tectonic deformation was intensive. A thrust-nappe belt was formed on the basin's western margin while conglomerate of different thickness were accumulated within the foredeep of the eastern side. The central and eastern parts of the basin were subject to erosion and reformation. A regional framework with “uplift in the east and depression in the west” took shape in the area west of the Yellow River. In the Early Cretaceous sediments were widely distributed, unconformably overlapping the former western margin thrust belt and the ridges on the northern and southern borders. There are abundant energy resources such as oil, natural gas, coal and uranium deposits formed in Ordos Basin. The main stages of generation, mineralization and positioning of the multiple energy resources have obvious responding connection and close coupling relationships with those of the Mesozoic and Cenozoic evolution and reformation in Ordos Basin.

Journal ArticleDOI
TL;DR: In this paper, sensitive high resolution ion micro-probe U-Pb zircon ages for the Huoqiu Group and granitoids of the Early Precambrian basement were reported.
Abstract: This paper reports sensitive high resolution ion micro-probe U-Pb zircon ages for the “Huoqiu Group” and granitoids of the Early Precambrian basement in the Huoqiu area, southeastern margin of the North China Craton. The “Huoqiu Group” is similar in rock association and metamorphism to the khondalite series, apart from it containing considerable amounts of banded iron formation. All detrital zircons from the “Huoqiu Group” meta-sedimentary rocks are 3.0 Ga and 2.75 Ga, without any 2.5 Ga and younger ones, as is commonly found in Paleoproterozoic khondalite series in other areas of the North China Craton. In the Huoqiu area, 2.75 Ga and 2.56 Ga granitoids have also been identified. This basement assemblage underwent strong metamorphism during the late Paleoproterozoic (∼ 1.84 Ga) tectonothermal event that is widely developed in the North China Craton. Thus the formation time of the “Huoqiu Group” can be constrained between 2.75 and 1.84 Ga in terms of detrital and metamorphic zircon ages. It is considered, combined with regional data, that there may be a Paleoproterozoic collision orogen extending in a NWW–SEE direction to the southern margin of the North China Craton.

Journal ArticleDOI
TL;DR: The new taxon possesses a large postorbital with a long tapering jugal process indicating that some enantiornithines may have had a fully diapsid skull, as in Confuciusornis, and likely represents a previously unknown trophic specialization within Enantiornithes.
Abstract: We report on a new species of enantiornithine bird from the Lower Cretaceous Qiaotou Formation of northern Hebei, China. The new taxon, Shenqiornis mengi gen. et sp. nov., possesses several enantiornithine synapomorphies but is unique from other known species. The specimen has a well-preserved skull that reveals new information about enantiornithine cranial morphology. The new taxon possesses a large postorbital with a long tapering jugal process indicating that some enantiornithines may have had a fully diapsid skull, as in Confuciusornis. The tooth morphology of the specimen is unique and likely represents a previously unknown trophic specialization within Enantiornithes.

Journal ArticleDOI
TL;DR: In this article, first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt.
Abstract: An earthquake of Ms 8 struck Wenchuan County, western Sichuan, China, on May 12th, 2008 and resulted in long surface ruptures (>300 km). The first-hand observations about the surface ruptures produced by the earthquake in the worst-hit areas of Yingxiu, Beichuan and Qingchuan, ascertained that the causative structure of the earthquake was in the central fault zones of the Longmenshan tectonic belt. Average co-seismic vertical displacements along the individual fault of the Yingxiu-Beichuan rupture zone reach 2.5-4 m and the cumulative vertical displacements across the central and frontal Longmenshan fault belt is about 5–6 m. The surface rupture strength was reduced from north of Beichuan to Qingchuan County and shows 2–3 m dextral strike-slip component. The Wenchuan thrust-faulting earthquake is a manifestation of eastward growth of the Tibetan Plateau under the action of continuous convergence of the Indian and Eurasian continents.

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TL;DR: In this paper, trace elements and isotopic geochemistry suggest that the ore-forming materials of gold deposits in the Jiaodong granite-greenstone belt have multiple sources, especially the mantle source.
Abstract: An analysis of trace elements and isotopic geochemistry suggest that the ore-forming materials of gold deposits in the Jiaodong granite-greenstone belt have multiple sources, especially the mantle source. Seismic wave, magnetic and gravity fields show that the crust-mantle structure and its coupling mechanism are the fundamental dynamic causes for the exchange and accumulation of materials and energy in the metallogenic system. Considering the evolution history of the structural setting, the tectono-metallogenic dynamics model of the area can be summarized as follows: (1) occurrence of the greenstone belt during the Archean-Proterozoic-the embryonic form of Au-source system; (2) stable tectonic setting in the Paleozoic-an intermittence in gold mineralization; (3) intensive activation and reformation of the greenstone belt in the Mesozoic-tectono-mineralization and tectono-diagensis; (4) posthumous structural activity in the Cenozoic-destruction of orebodies in the later stage. In the middle and late Indosinian, the Tancheng-Lujiang fault zone cut deeply into the upper mantle so that the ore-bearing fluids migrated to higher layers through the crust-mantle interaction, resulting in alteration and mineralization.

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TL;DR: The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China.
Abstract: The Shangzhuang altered-rock type gold ore deposit is located in the middle segment of and controlled by the Wang'ershan fault zone in the northwestern part of the Jiaodong gold province, China. The deformation evolution, the structure of strain and stress fields and its ore-controlling effect in the Shangzhuang deposit are discussed in this paper, It is revealed that the deformation evolution has mainly undergone four phases: the early ductile deformation, the second NE-striking horizontal simple shear, the third NE-striking compression-shear and the final NW-striking compression. The mineralization happened during the third stage in which the maximum principal stress gradually transited from NE to NW. The 3-D numerical simulations of the stress field show that, on the condition that the maximum principal stress is NE-striking, the fracture development in the fault zone is favored, while when the maximum principal stress is NW-striking, the fault zone is relatively extensional and it is suitable for the influx and emplacement of ore-forming fluids. The compression-shear strain field during the mineralization is characterized by the Ltype structure, the positive flower structure, etc. Orebodies are mostly equidistantly located in the dilatational spaces, which are distributed in the integral compressional circumstances. And the dilatational spaces are developed where the fault attitude changes or shear joint systems develop. In the overall compression-shear stress field, the strain field bears self-similarity at multiple scales, including the orebody, ore deposit and orefield. The self- similarity of the structure comprises the subequidistant distribution of fractures at the same scale and the similar shape of the fractures at various scales. Yet, due to the special geological structure, the orebodies are mostly located in the hanging wall in the Shangzhuang deposit, which is different from most deposits in the Jiaodong gold province. Analyses of the ore-controlling stress and strain fields in the deposit provide an important basis for deposit seeking.

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TL;DR: The Ordos Basin is a large-scale sedimentary basin in northwestern China as discussed by the authors, and three groundwater systems are present in the Ordos basin, based on the geological settings, i.e., the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system.
Abstract: The Ordos Basin is a large-scale sedimentary basin in northwestern China. The hydrostratigraphic units from bottom to top are pre-Cambrian metamorphic rocks, Lower Paleozoic carbonate rocks, Upper Paleozoic to Mesozoic clastic rocks and Cenozoic deposits. The total thickness is up to 6000 m. Three groundwater systems are present in the Ordos Basin, based on the geological settings, i.e. the karst groundwater system, the Cretaceous clastic groundwater system and the Quaternary groundwater system. This paper describes systematically the groundwater flow patterns of each system and overall assessment of groundwater resources.

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TL;DR: Based on the geological surveys, laboratory measurements and field works, a four-level analytic hierarchy process (AHP) model for coalbed methane reservoir (CBMR) evaluation is proposed in this paper.
Abstract: Coalbed methane reservoir (CBMR) evaluation is important for choosing the prospective target area for coalbed methane exploration and production. This study aims at identifying the characteristic parameters and methods to evaluate CBMR. Based on the geological surveys, laboratory measurements and field works, a four-level analytic hierarchy process (AHP) model for CBMR evaluation is proposed. In this model, different weights are prioritized and assigned on the basis of three main criteria (including reservoir physical property, storage capacity and geological characteristics), 15 sub-criteria, and 18 technical alternatives; the later of which are discussed in detail. The model was applied to evaluate the CBMR of the Permo-Carboniferous coals in the Qinshui Basin, North China. This GIS-based fuzzy AHP comprehensive model can be used for the evaluation of CBMR of medium-high rank (mean maximum vitrinite reflectance >0.5%) coal districts in China.

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TL;DR: In the Linxia Basin on the northeast margin of the Tibetan Plateau, the Cenozoic strata are very thick and well exposed, and abundant mammalian fossils are discovered in the deposits from the Late Oligocene to the Early Pleistocene as mentioned in this paper.
Abstract: 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. ne Hipparion fauna comes from the red clay of the Liushu and Hewangiia 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.

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TL;DR: A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China as discussed by the authors, which represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria.
Abstract: A new dinosaur of Early Cretaceous age was recently discovered from the Mazongshan area of northwestern Gansu Province, China. The new dinosaur represents a new genus and species of Sauropoda, and is among the most basal members of Titanosauria. Its finding also suggests that titanosaurs might have originated in Asia no later than the Early Cretaceous.

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TL;DR: Based on a mass of exploration wells and 2D seismic data of the shallow shelf region, a interpretation of sequence stratigraphy confirmed the existence of deep-water fans as discussed by the authors, and the cyclic falling of sea level, abundant detrital matter from the paleo Pearl River and the persistent geothermal subsidence in the Baiyun sag are the three prerequisites for the formation and development of deepwater fans.
Abstract: The shallow shelf delta/strand arenaceous-pelitic deposit region in the north of the Pearl River mouth basin, sitting on the northern continental shelf of the South China Sea, has already become an important oil production base in China. Recent researched has revealed that a great deal of deep-water fans of great petroleum potentiality exist on the Baiyun deep-water slope below the big paleo Pearl River and its large delta. Based on a mass of exploration wells and 2-D seismic data of the shallow shelf region, a interpretation of sequence stratigraphy confirmed the existence of deep-water fans. The cyclic falling of sea level, abundant detrital matter from the paleo Pearl River and the persistent geothermal subsidence in the Baiyun sag are the three prerequisites for the formation and development of deep-water fans. There are many in common between the deep-water shelf depositional system of the northern South China Sea and the exploration hotspots region on the two banks of the Atlantic. For example, both are located on passive continent margins, and persistent secular thermal subsidence and large paleo rivers have supplied abundant material sources and organic matter. More recently, the discovery of the big gas pool on the northern slope of the Baiyun sag confirms that the Lower Tertiary lacustrine facies in the Baiyun sag has a great potentiality of source rocks. The fans overlying the Lower Tertiary source rocks should become the main exploration areas for oil and gas resources.

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TL;DR: In this article, a disc-shaped macrofossil, Eoandromeda octobrachiata, characterized by eight spiral arms that were probably housed within an outer membrane was found.
Abstract: Shales of the Ediacaran Doushantuo Formation of South China contain a new disc-shaped macrofossil, Eoandromeda octobrachiata, characterized by eight spiral arms that were probably housed within an outer membrane. Although the presence of eight radiating structures entails a resemblance to cnidarian octocorals as well as to ctenophores, direct homologies with these extant groups are unlikely. Instead we bring attention to the helicospiral morphology of newly reported embryos from the Doushantuo Formation, suggesting that the long-sought adults of the Ediacaran embryonic metazoans have finally been found.

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TL;DR: The Vietnamese-Belgian Karst Project (VBEKAP) as discussed by the authors is an example of a multidisciplinary approach to karst-related problems, which aims to improve living conditions of local people and sustained protection and management of the karast environment and ecosystem.
Abstract: Karst in Vietnam covers an area of about 60,000 km2, i.e. 18 % of the surface of the country. The country has an annual average temperature of 24°C, an annual average rainfall of 2300 mm and a relative humidity of about 90%. Karst in Vietnam is typified by peak cluster-depression landscapes ranging in elevation from 200 to over 2000 m. Tower and coastal karst landscapes also exit. Because of naturally favourable conditions, karst ecosystems are diverse and very rich. Higher plants (cormophytes) are abundant. They are represented by approximately 2000 species, 908 genera, 224 families, 86 orders and 7 phyla. They form a thick vegetation cover of evergreen tropical rainforest. Knowledge about lower plants is limited. The fauna is rich and diverse. Phyla such as Protozoa, Vermes, Mollusca and Arthropoda are yet ill known. Preliminary results show that the phylum Chordata is represented by 541 species from 80 families, 40 orders and 5 classes. There exist many precious and rare mammals, in particular some endemic species such as Trachypithecus poliocephalus, T. delacouri, Rhinopithecus avanculus, Rhinolophus rouxi, Seotoma dineties and Silurus cuephuongensis. The class Insecta has about 2000 species. The fast population growth, particularly in the mountainous areas of the country, triggers an increasing demand for land and therefore threatens the ecosystem. To obtain land for farming, people have cut, burned and destroyed natural forest cover; resulting in occurrence of hazards such as soil-loss, water-loss, flash floods, mud-rock flows, rock-falls, severe drought, water logging and changes of karstic aquifers etc. Poaching precious animals and illegal logging are increasing. In contrast to other natural systems, karst ecosystems cannot be reestablished once damaged. Living karst landscapes will become rocky desert ones without life. Conservation of karstic environmental systems in general and karstic ecosystems in particular should not be the sole vocation of scientists but also a duty and responsibility of authorities and people from all levels. A good example of a multidisciplinary approach to karst-related problems is the implementation of the Vietnamese-Belgian Karst Project (VBEKAP): “Rural development in the mountain karst area of NW Vietnam by sustainable water and land management and social learning: its conditions and facilitation”. The aim of this project is to improve living conditions of local people and sustained protection and management of the karst environment and ecosystem.

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TL;DR: In this article, the U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed.
Abstract: Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton (NCC). The complex is composed of various high-grade and multiply deformed rocks, including gray gneiss, basic granulite, amphibolite, fine-grained gneiss and marble, metamorphosed to upper amphibolite or granulite facies. It can be divided into four rock units: the Fuping TTG gneisses, Longquanguan augen gneisses, Wanzi supracrustals, and Nanying granitic gneisses. U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed. The data on metamorphic zircon rims give ages of 1.82-1.84 Ga, corresponding to the final amalgamation event of the NCC, whereas the data for igneous zircon cores yield two age populations at ∼2.10 and ∼2.51 Ga, with some inherited ages scattering between 2.5 and 2.9 Ga. These results suggest that the Wanzi supracrustals were derived from the Fuping TTG gneisses (∼2.5 Ga) and the Nanying granitic gneisses (2.0–2.1 Ga) and deposited between 2.10 and 1.84 Ga. All zircons with ∼2.51 Ga age have positive initial ∍Hf values from +1.4 to +10.9, suggesting an important crustal growth event at ∼2.5 Ga through the addition of juvenile materials from the mantle. The Hf isotope data for the detrital zircons further imply that the 2.8 Ga rocks are important components in the lower crust, which is consistent with a suggestion from Nd isotope data for the Eastern Block. The zircons of 2.10 Ga population have initial ∍Hf values of −4.9 to +6.1, interpreted as mixing of crustal re-melt with minor juvenile material contribution at 2.1 Ga. These results are distinct from that for the Western Block, supporting that the Fuping Complex was emplaced in a tectonic active environment at the western margin of the Eastern Block.