Plate kinematics, origin and tectonic emplacement of supra-subduction ophiolites in SE Asia   总被引：2，自引：0，他引：2  

Manuel Pubellier  Christophe Monnier  Ren Maury  R. Tamayo 《Tectonophysics》2004,392(1-4):9

A unique feature of the Circum Pacific orogenic belts is the occurrence of ophiolitic bodies of various sizes, most of which display petrological and geochemical characteristics typical of supra-subduction zone oceanic crust. In SE Asia, a majority of the ophiolites appear to have originated at convergent margins, and specifically in backarc or island arc settings, which evolved either along the edge of the Sunda (Eurasia) and Australian cratons, or within the Philippine Sea Plate. These ophiolites were later accreted to continental margins during the Tertiary. Because of fast relative plate velocities, tectonic regimes at the active margins of these three plates also changed rapidly. Strain partitioning associated with oblique convergence caused arc-trench systems to move further away from the locus of their accretion. We distinguish “relatively autochthonous ophiolites” resulting from the shortening of marginal basins such as the present-day South China Sea or the Coral Sea, and “highly displaced ophiolites” developed in oblique convergent margins, where they were dismantled, transported and locally severely sheared during final docking. In peri-cratonic mobile belts (i.e. the Philippine Mobile Belt) we find a series of oceanic basins which have been slightly deformed and uplifted. Varying lithologies and geochemical compositions of tectonic units in these basins, as well as their age discrepancies, suggest important displacements along major wrench faults.We have used plate tectonic reconstructions to restore the former backarc basins and island arcs characterized by known petro-geochemical data to their original location and their former tectonic settings. Some of the ophiolites occurring in front of the Sunda plate represent supra-subduction zone basins formed along the Australian Craton margin during the Mesozoic. The Philippine Sea Basin, the Huatung basin south of Taiwan, and composite ophiolitic basements of the Philippines and Halmahera may represent remnants of such marginal basins. The portion of the Philippine Sea Plate carrying the Taiwan–Philippine arc and its composite ophiolitic/continental crustal basement might have actually originated in a different setting, closer to that of the Papua New Guinea Ophiolite, and then have been displaced rapidly as a result of shearing associated with fast oblique convergence.  相似文献   

Minute members of Baissinae (Insecta: Hymenoptera: Gasteruptiidae) from the upper Mesozoic of China and limits of the genus Manlaya Rasnitsyn, 1980     

Junfeng Zhang  Alexander P. Rasnitsyn   《Cretaceous Research》2004,25(6):797-805

A brief review and discussion of baissine wasps of Gasteruptiidae, Hymenoptera is given. Eight fossil specimens of wasps from the Laiyang Formation in Laiyang, Shandong, China are described. One new genus, Mesepipolaea, and four new species, M. nanligezhuangica, Humiryssus specialis, H. cancellatus and H. vulgatus are established, and two new combinations are proposed: Humiryssus laiyangensis (Hong and Wang, 1990) (originally Aulocopsis laiyangensis Hong and Wang , 1990), H. oculatissimus (Rasnitsyn and Jarzembowski, 1998) (originally Manlaya oculatissima Rasnitsyn and Jarzembowski, 1998). Sinowestratia communicata Zhang and Zhang, 2000 is a junior synonym of Manlaya flexuosa (Ren et al.,1995) (originally Manlaya flexuosus Ren et al.,1995). Stratigraphic inferences from these finds are briefly discussed.  相似文献   

Ammonites from the Pawpaw Shale (Upper Albian) in northeast Texas     

W.J. Kennedy 《Cretaceous Research》2004,25(6):865-905

The lower part of the Pawpaw Shale in northeast Texas yields an abundance of diminutive limonitic ammonites, the assemblage being: Tetragonites sp. juv., Engonoceras serpentinum (Cragin, 1900), Conlinites wrighti gen. et sp. nov., Cantabrigites wenoensis (Adkins, 1920), Neophlycticeras (Neophlycticeras) sp., Neophlycticeras (Paradolphia) occidentalis sp. nov., Stoliczkaia (Stoliczkaia) clavigera Neumayr, 1875, Stoliczkaia (Lamnayella) worthense (Adkins, 1920), Stoliczkaia (Shumarinaia) asiatica Matsumoto and Inoma, 1975, Enigmaticeras riceae gen. et sp. nov., Flickia simplex Pervinquière, 1907, Ficheuria pernoni Dubourdieu, 1953, Ficheuria americana sp. nov., Anisoceras armatum (J. Sowerby, 1817), Hamites venetzianus Pictet, 1847, Mariella (Mariella) worthensis (Adkins and Winton, 1920), Mariella (Mariella) asper sp. nov., Lechites (Lechites) comanchensis (Adkins, 1920), Worthoceras worthense (Adkins, 1920), and Scaphites hilli Adkins and Winton, 1920.This assemblage is correlated with the Mortoniceras (Subschloenbachia) rostratum Subzone of the European sequence on the basis of the occurrence of that species in the underlying Weno Limestone, in the passage beds between the Pawpaw Shale and the succeeding Main Street Limestone, and the lower part of the Main Street.Some previous authors have interpreted the diminutive limonitic ammonites of the Pawpaw as being “dwarf” or “stunted”. The overwhelming majority of individuals are nuclei of much larger ammonites, with smaller numbers of adults of small species that occur in other facies and geographic locations, together with a smaller number still of paedomorphic dwarfs. The fauna is interpreted as a preservational one, where diagenetic pyrite formed in relatively small voids, either the early phragmocone chambers of larger ammonites, or the phragmocone and body chambers of genuinely diminutive species which oxidised to limonite during the weathering process.  相似文献   

中国沉积盆地低熟油气形成机理与分布规律   总被引：1，自引：0，他引：1  

王敏芳 《江苏地质》2004,28(1):7-10

低熟油气是我国的一种重要资料，在我国陆相沉积，尤其是东部第三系盆地中较为富集。其生烃组分有树脂体、木栓质体、一些种类藻以及经细菌改造的有机质。总结了低熟油的成因与其分布规律，有利于低熟油气的进一步勘探。  相似文献   

库车坳陷白垩系储层的形成环境及成因分析   总被引：2，自引：3，他引：2  

刘建清  赖兴运  于炳松 《现代地质》2004,18(2):249-255

近年来 ,在中国新疆库车前陆盆地中发现了克拉 2等大型、特大型气田 ,并显示出良好的油气勘探前景。白垩系巴什基奇克、巴西盖组地层是克拉 2等气田的主力储层 ,研究其成因并建立科学合理的预测机制具有重大的理论和现实意义。在对库车盆地的构造背景、沉积物质来源、岩石结构特征、古生物、微量元素地球化学特征、粒度分析、沉积构造、沉积体系等多侧面进行综合研究的基础上 ,认为该区在下白垩系储层沉积时处于干旱氧化的古气候环境 ,储层岩石具低成分成熟度和结构成熟度的特征 ,储层自下而上具典型的沉积构造和完整的沉积序列 ,应属扇三角洲—辫状河三角洲—湖泊沉积体系。特别是粒度资料分析表明该区的储层多呈一个过渡性的特征 ,它既不同于典型的浊流 ,又不同于典型的曲流河特征 ,形成了该区以辫状河为主的显著沉积特点。  相似文献   

内蒙古东北部四五牧场浅成低温热液型金矿地质特征及成因讨论   总被引：6，自引：0，他引：6  

关继东  柴晓红 《地质与勘探》2004,40(2):36-40

大兴安岭火山岩区金矿的找矿突破是90年代后期实现的,目前发现的类型有HS型、LS型及硅化石英脉型3种浅成低温热液矿床.四五牧场金矿是产于海拉尔-根河中生代火山岩盆地边缘的HS型浅成低温热液金矿床,其形成与隐爆角砾岩体关系密切,隐爆角砾岩体的产出明显受构造控制并具成群分布的特点.岩石蚀变为典型的酸性硫酸盐型石英-高岭石(迪开石)-明矾石蚀变矿物组合.  相似文献   

藏北阿索构造混杂岩的发现及其地质意义     

唐峰林黄建村  罗小川黄传冠 《华东地质学院学报》2004,27(3):245-250

在藏北尼玛县西边阿索一带首次发现最宽约14km的阿索构造混杂岩带。该带西宽东窄，呈喇叭状，由复理石岩片、深海硅质岩、泥质岩岩片、蛇纹质岩片、火山岛弧岩片、碳酸盐岩岩片、大陆碎片岩片等组成。其中以复理石岩片为基质包含其它外来构造岩片。阿索构造混杂岩带所包含的蛇绿岩主要岩性单位有：蛇纹岩、辉石岩、英云闪长岩、似层状花斑岩和辉长岩、粒玄岩、辉长辉绿岩、枕状玄武岩、角斑岩、硅质岩、含铁锰粉砂岩、薄层灰岩、浊积岩等，属弧后盆地扩张一消减产物。根据硅质岩中放射虫、复理石岩片中孢粉时代及构造片岩中同位素年龄等资料，该弧后盆地扩张于晚侏罗世、闭合于早白垩世早期。空间上将狮泉河、永珠湖一纳木湖蛇绿岩带相连。  相似文献   

合肥—潢川盆地南缘中生代冲积沉积及其构造意义   总被引：4，自引：0，他引：4       下载免费PDF全文

李双应王道轩  刘因李任伟  孟庆任岳书仓 金福全 《地质学报》2005,79(4):465-474

合肥—潢川盆地南缘中生代地层被划分为4个年代体（Chronsome）。年代体Ⅰ包括早侏罗世防虎山组和中晚侏罗世圆筒山组下部，由辫状河、曲流河以及滨一浅湖沉积体系组成，局限于盆地东端；年代体Ⅱ包括中晚侏罗世三尖铺组、朱集组和圆筒山组上部，下部为冲积扇沉积，中、上部为辫状河沉积，早期属于横向水流系统（南北方向），晚期是纵向水流系统（东西方向），近EW向的信阳—金寨—舒城断裂是其南部边界；年代体Ⅲ包括早白垩世早期凤凰台组、段集组、周公山组，前两组为冲积扇沉积，后者为辫状河和越岸沉积，粗碎屑明显向盆进积达数公里，南部边缘发育横向水流，而往盆地方向发育纵向水流。年代体Ⅳ为早白垩世晚期黑石渡组和陈棚组，南部边界是磨子潭晓天断裂和桐柏-商城断裂，断裂以伸展走滑为主，东段早期为冲积扇-扇三角洲沉积，晚期为深湖浊积岩沉积。晚白垩世沉积仅发育在西段局部地区，其余处于隆升状态。平行于大别山造山带的近EW向纵向断裂控制着年代体的南部边界，NE向郯城庐江断裂和商城麻城断裂控制着年代体侧向相的变化。合肥潢川盆地南缘沉积从东往西逐渐超覆，揭示大别造山带折返具有自东而西的递进特征。郯城—庐江断裂和商城—麻城断裂对年代体的发育有明显影响，郯城—庐江断裂控制着早侏罗世沉积，表明构造活动至少始于早侏罗世。  相似文献   

The Upper Valanginian (Early Cretaceous) positive carbon-isotope event recorded in terrestrial plants     

Darren R. Gröcke  Gregory D. Price 《Earth and Planetary Science Letters》2005,240(2):495-509

Our understanding of the ancient ocean-atmosphere system has focused on oceanic proxies. However, the study of terrestrial proxies is equally necessary to constrain our understanding of ancient climates and linkages between the terrestrial and oceanic carbon reservoirs. We have analyzed carbon-isotope ratios from fossil plant material through the Valanginian and Lower Hauterivian from a shallow-marine, ammonite-constrained succession in the Crimean Peninsula of the southern Ukraine in order to determine if the Upper Valanginian positive carbon-isotope excursion is expressed in the atmosphere. δ¹³C_plant values fluctuate around − 23‰ to − 22‰ for the Valanginian-Hauterivian, except during the Upper Valanginian where δ¹³C_plant values record a positive excursion to ∼− 18‰. Based upon ammonite biostratigraphy from Crimea, and in conjunction with a composite Tethyan marine δ¹³C_carb curve, several conclusions can be drawn: (1) the δ¹³C_plant record indicates that the atmospheric carbon reservoir was affected; (2) the defined ammonite correlations between Europe and Crimea are synchronous; and (3) a change in photosynthetic carbon-isotope fractionation, caused by a decrease in atmospheric pCO₂, occurred during the Upper Valanginian positive δ¹³C excursion. Our new data, combined with other paleoenvironmental and paleoclimatic information, indicate that the Upper Valanginian was a cool period (icehouse) and highlights that the Cretaceous period was interrupted by periods of cooling and was not an equable climate as previously thought.  相似文献   

Flow behaviour and runout modelling of a complex debris flow in a clay‐shale basin     

Alexandre Remaître  Jean‐Philippe Malet  Olivier Maquaire  Christophe Ancey  Jacques Locat 《地球表面变化过程与地形》2005,30(4):479-488

Identification of debris‐flow hazard areas necessitates the knowledge of the flow thickness and the runout distance. Both have been investigated using a numerical runout model. On the Faucon stream (South French Alps), representative of clay‐shale basins, results of various rheological tests and numerical experiments are presented and discussed. The calibration of the model was undertaken using the results of both geomorphological surveys and sedimentological analyses. Rheological tests using either a parallel‐plate rheometer, a coaxial rheometer, slump tests, and an inclined plane were carried out on several samples. Results have shown that the flow behaviour could be described by an Herschel‐Bulkley constitutive equation. The rheological responses of several natural suspensions collected from surficial deposits (sandstones, moraines, weathered black marls) were also investigated. In order to model the runout of the flow, the model BING was used. The model describes well the influence of each type of sediment on the behaviour (runout distance, deposit thickness) of the flow, although the velocities were significantly overestimated. Different risk scenarios are tested and discussed. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献