Reinterpretation of the northern South China Sea pre-Cenozoic basement and geodynamic implications of the South China continent: constraints from combined geological and geophysical records     

Weilin Zhu  Yuchi Cui  Lei Shao  Peijun Qiao  Peng Yu  Jianxiang Pei  Xinyu Liu  Hao Zhang 《海洋学报(英文版)》2021,40(2):13-28

The pre-Cenozoic northern South China Sea(SCS) Basin basement was supposed to exist as a complex of heterogeneous segments, divided by dozens of N-S faulting. Unfortunately, only the Hainan Island and the northeastern SCS region were modestly dated while the extensive basement remains roughly postulated by limited geophysical data. This study presents a systematic analysis including U-Pb geochronology, elemental geochemistry and petrographic identification on granite and meta-clastic borehole samples from several key areas. Constrained from gravity-magnetic joint inversion, this interpretation will be of great significance revealing the tectono-magmatic evolution along the southeastern margin of the Eurasian Plate. Beneath the thick Cenozoic sediments, the northern SCS is composed of a uniform Mesozoic basement while the Precambrian rocks are only constricted along the Red River Fault Zone. Further eastern part of the northern SCS below the Cenozoic succession was widely intruded by granites with Jurassic-to-early Cretaceous ages. Further western part, on the other hand, is represented by meta-sedimentary rocks with relatively sporadic granite complexes. To be noted,the western areas derived higher-degree and wider metamorphic zones, which is in contrast with the lowerdegree and narrower metamorphic belt developed in the eastern region. Drastic collisions between the Indochina Block and South China continent took place since at least late Triassic, resulting in large-scale suturing and deformation zones. At the westernmost part of the northern SCS, the intracontinental amalgamation with closure of the Meso-Tethys has caused fairly stronger and broader metamorphism. One metamorphic biotite granite is located on the suturing belt and yields a Precambrian U-Pb age. It likely represents the relict from the ancient Gondwana supercontinent or its fringes. Arc-continental collision between the Paleo-Pacific and the southeast China Block, on the other hand, results in a relatively narrow NE–SW trending metamorphic belt during the late Mesozoic. Within the overall geological setting, the Cenozoic SCS oceanic basin was subsequently generated from a series of rifting and faulting processes along the collisional-accretionary continental margin.  相似文献   

南沙群岛海区沉积物中铀含量与冰期关系初探   总被引：2，自引：0，他引：2  

刘韶  温孝胜  余克服  赵焕庭 《海洋地质与第四纪地质》1999,19(2):49-54

运用研制国家铀系年龄一级标准物质的分析测试系统,精确的测定南沙群岛海区诸多柱样的铀含量、沉积物的平均沉积速率,结合相关科学资料综合整理,对比亚南极海等的岩心资料后认为,南沙群岛海域沉积物中自生铀含量（以下简称铀含量）高的层位为冰期,铀含量低的层位为间冰期  相似文献   

中国对虾(Penaeus chinensis)的白点综合征病毒(WSSV)的提纯和核酸提取   总被引：1，自引：1，他引：0  

汪岷  包振民  邵济钧  戴继勋  徐怀恕 《中国海洋大学学报(自然科学版)》1999,(3)

作者从发生白点综合征的中国对虾中,提取了一株白点综合征病毒,用电镜对纯化的病毒进行了形态学观察,并对病毒纯化过程中蛋白酶抑制剂的使用及离心速度的选择进行了探讨。经蔗糖密度梯度离心,分取各带负染后电镜观察,病毒条带位于４０％～５０％蔗糖梯度之间,其完整毒粒长２２５～２７０ｎｍ,直径７５～８８ｎｍ,有的完整毒粒带有很长的尾,病毒衣壳长２５０～３２０ｎｍ,直径６０～８０ｎｍ。在匀浆使用的缓冲液中加入蛋白酶抑制剂ＰＭＳＦ,可得到完整的带包膜的病毒颗粒,比不使用ＰＭＳＦ的提纯效果要好。经３０００ｒ／ｍｉｎ离心５ｍｉｎ,５０００ｒ／ｍｉｎ离心２５ｍｉｎ,去除大部分的组织碎片,经１００００ｒ／ｍｉｎ离心１ｈ,可使大部分病毒沉淀。并采用传统的方法对病毒核酸进行了提取,其基因组经初步分析为ｄｓＤＮＡ。  相似文献   

利用SAR图像监测海上石油污染的实验分析     

邵洁波  张汉德  吴强  张恒广  张杰 《海洋科学进展》1999,(4)

本文讨论了利用ＳＡＲ 图像监测海上石油污染的理论依据和环境条件,并根据ＲＡＤＡＲＳＡＴ 卫星装载的合成孔径雷达（ＳＡＲ）图像对渤海ＣＢ－６Ａ 井组发生的原油（气）泄漏事件进行了初步的研究和分析。  相似文献   

湖南煤层气资源及其分布特征     

肖正辉  邵龙义  鲁静  吉丛伟 《中国煤炭地质》2010,(3):17-20

为更好地开发利用湖南煤层资源,根据《新一轮全国油气资源评价》方案计算了湖南煤层气资源量、可采资源量和资源丰度,并探讨了其分布特征。经计算汇总,湖南煤层气地质资源量和可采资源量分别为780.80×108m3和325.94×108m3,煤层气资源丰度为0.30×108m3/km2。煤层气风化带~1 000m和1 000～1 500m的煤层气资源量分别为489.81×108m3和290.99×108m3。湖南煤层气资源主要分布在下石炭统测水组和上二叠统龙潭组中,分别为317.13×108m3和463.67×108m3,其中,下石炭统测水组煤层气资源主要分布在涟邵目标区的渣渡、金竹山、太平寺、冷水江等含煤向斜区域,上二叠统龙潭组煤层气资源主要分布在郴耒目标区的永耒、梅田、白沙、马田等含煤向斜区域。  相似文献   

A discrete approach for anisotropic plasticity and damage in semi-brittle rocks     

D.W. Hu  Q.Z. Zhu  H. Zhou  J.F. Shao 《Computers and Geotechnics》2010

In this paper, we propose an anisotropic plastic damage model for semi-brittle geomaterials based on a discrete thermodynamic approach. The macroscopic plastic deformation is generated by frictional sliding of weakness planes. The evolution of damage is related to growth of such weakness planes. The local frictional sliding in each family of weakness planes is described by a non-associated plastic model taking into account material softening and volumetric dilatancy. The damage evolution is coupled with plastic deformation and modelled by an isotropic damage criterion. The proposed model is applied to modelling mechanical responses of typical sandstone under different loading paths. There is good agreement between numerical predictions and experimental data. Further, the anisotropic distributions of plastic deformation and induced damage are analysed and discussed.  相似文献   

A comparative micromechanical analysis of the effective properties of a geomaterial: Effect of mineralogical compositions     

A. Abou-Chakra Guéry  F. Cormery  J.-F. Shao  D. Kondo 《Computers and Geotechnics》2010

In order to provide a physical interpretation of the variation of the mechanical properties of Callovo-Oxfordian argillite with mineral composition, we implement three linear homogenization schemes. The argillite is modeled as a three phase material composed of a clay matrix and inclusions of quartz and calcite. It is shown that, unlike the dilute scheme and the self-consistent scheme, the Mori-Tanaka model describes the in situ experimental data well. The determined properties are finally used in a finite element computation. The aim is to evaluate the effect of mineral composition on the elastic response of the excavation of a vertical shaft in the context of the underground laboratory of Meuse/Haute Marne.  相似文献   

Coalescence of Fractures Under Uni-axial Compression and Fatigue Loading     

Y. L. Chen  J. Ni  W. Shao  Y. C. Zhou  A. Javadi  R. Azzam 《Rock Mechanics and Rock Engineering》2012,45(2):241-249

In this paper, white Portland cement was used as an experimental material. Prismatic specimens with pre-existing flaws at different angles of inclination (α) varying through 0°, 30°, 45°, 60°, 75° to 90° and cylindrical specimens with different numbers of pre-existing flaws (n) varying through 0, 1, 2 to 3 were tested under uni-axial compression tests. Crack initiation, propagation, coalescence, and failure were observed. The corresponding analytical expression for the stress intensity factor under uni-axial compression was derived, the coefficient of friction and the stress intensity factor of the specimens on the surfaces of the crack were analysed, and the corrective coefficient for the stress intensity factor was introduced. Fatigue tests with a loading frequency of f = 100 Hz were carried out on cylindrical specimens with constant amplitude of the cyclic load which is a proportion of the compressive load at failure (F _f) obtained from the uni-axial compression tests. The fatigue property of the specimens was analysed and the relationship (S _max − lg N _f) between the maximum stress and the number of loading cycles at failure for specimens with pre-existing flaws was proposed. The effect of pre-existing flaws on the fatigue life (N _f) and dynamic load (S _D) which can be applied was investigated.  相似文献   

青海省海西州德令哈地区近千年来年降水量变化特征分析   总被引：22，自引：17，他引：5       下载免费PDF全文

刘洪滨  邵雪梅  黄磊  梁尔源  方修琦  王丽丽 《第四纪研究》2005,25(2):176-183

试图揭示位于我国青藏高原东北部的青海省海西州德令哈地区近千年来世纪尺度年降水量变化规律。分析结果表明,该地区近千年年降水量变化存在显著的多尺度周期变化特征,其中以13～18世纪中的200年主控周期最为明显,并在15～17世纪达到最强,而近200年则以准120年的周期振荡为主,且在19世纪两种主要周期变化趋势相反,在近百年又趋向一致。年降水量序列的均值突变一般以30～100年尺度最为明显,世纪尺度的均值突变时段分别为公元1100～1111年、1403～1449年及1615～1661年,表现为年降水量的减少,以及公元1321～1348年、1497～1557年、1728～1743年及1885～1891年,表现为年降水量的增加。200年以上时间尺度的方差突变主要表现为序列的低频变化幅度,从公元1220年前后至1580年前后持续增大,且以15世纪的方差突变最为明显。  相似文献   

天然气水合物地热场分布特征   总被引：12，自引：0，他引：12       下载免费PDF全文

金春爽  汪集旸  王永新  何丽娟 《地质科学》2004,39(3):416-423,319

天然气水合物广泛分布于海底和永久冻土带。通过统计世界上已发现水合物或水合物标志的地区的热参数值,发现水合物分布区具有低热流的特征;由于水合物本身的低热导率特性,导致水合物分布区的热导率值较低;含水合物的沉积物由于水合物的分解,岩心温度也较低。通过研究南海的热场特征,发现南海的吕宋海槽、西沙海槽附近、湄公盆地和台西南盆地几个地区热流较低,可能是有利的水合物远景区。  相似文献