Uplifted crust in parts of western India   总被引：1，自引：0，他引：1  

H. C. Tewari  G. Surya Prakasa Rao  B. Rajendra Prasad 《Journal of the Geological Society of India》2009,73(4):479-488

During northward movement of the Indian sub-continent, after its breakup from the Gondwanaland in the Late Cretaceous, the western part of India traversed over the Reunion plume. The Saurashtra peninsula and the Cambay Basin are two important geological regions in this part. Two and half dimensional density models, based on the crustal seismic structure, were generated to establish a relationship between these two regions. These models indicate that the crust is 32–33 km thick in the eastern Saurashtra and the northern part of the Cambay Basin. The shallower crust is in a triangular region formed by the extension of the western limb of the Proterozoic Aravalli trend in Saurashtra, its eastern limb and the Narmada fault in the south. Compared to 36–37 km thick crust to the west and 38–40 km to the east of this region the crust in the above triangular region is uplifted by 4 to 6 km. This uplift took place either after the deposition of Mesozoic sediments or was concomitant with the rise of Reunion plume prior to the extrusion of the Deccan volcanics as the region was close to the axis of the plume.  相似文献   

Long-term and short-term vertical velocity profiles across the forearc in the NE Japan subduction zone     

Tabito Matsu'ura  Akira Furusawa 《Quaternary Research》2009,71(2):227-377

We estimated the long-term vertical velocity profile across the northeastern Japan forearc by using the height distribution of late Quaternary marine and fluvial terraces, and we correlated the ages of the two marine terraces with marine isotope stages (MIS) 5.5 and 5.3 or 5.1 by cryptotephra stratigraphy. The uplift rate, estimated as 0.11-0.19 m ka^− 1 from the relative heights between the terrace surfaces and eustatic sea levels, was nearly equal to, or slightly slower than, the uplift rate farther inland (0.15-0.19 m ka^− 1), as determined from the relative heights of fill terrace surfaces. In contrast, the short-term vertical velocity profile, obtained from GPS observations, showed that the forearc is currently subsiding at a maximum rate of 5.4 ± 0.4 mm yr^− 1. Thus, the current short-term (geodetic) subsidence does not reflect long-term (geological) tectonic movement. Short-term vertical deformation is probably driven by subduction erosion or elastic deformation caused by interplate coupling, or both. However, long-term uplift is probably due not to moment release on the mega-thrust but to crustal thickening.  相似文献   

Geochronology and paleomagnetism of mafic igneous rocks in the Olenek Uplift, northern Siberia: Implications for Mesoproterozoic supercontinents and paleogeography     

Michael T.D. Wingate  Sergei A. Pisarevsky  Dmitry P. Gladkochub  Tatiana V. Donskaya  Konstantine M. Konstantinov  Anatoly M. Mazukabzov  Arkady M. Stanevich 《Precambrian Research》2009,170(3-4):256-266

We present a new, reliably dated Mesoproterozoic paleopole for Siberia, based on a combined geochronological and paleomagnetic study of mafic rocks within the Mesoproterozoic Sololi Group of the Olenek Uplift in northern Siberia. Ion microprobe (SHRIMP) U–Pb analysis yields crystallisation ages of 2036 ± 11 Ma for zircon from a basement granite and 1473 ± 24 Ma for baddeleyite from a large dolerite sill within the Kyutingde Formation. The baddeleyite result indicates that the lower Sololi Group is significantly older than was suggested by previous K–Ar results. Paleomagnetic analysis of the dolerite sill and related mafic intrusive rocks yields a paleopole at 33.6°N, 253.1°E, A₉₅ = 10.4°. A positive baked-contact test between the Kyutingde sill and sedimentary country rocks shows that the magnetisation is primary. Comparison of this paleopole with coeval results for Laurentia provides a revised reconstruction between Siberia and Laurentia, and implies that these two continents were parts of a single Mesoproterozoic supercontinent since at least 1473 Ma. We argue that Siberia, Laurentia, and Baltica belonged to the same supercontinent between 1473 Ma and mid-Neoproterozoic time.  相似文献   

塔中83井区表生岩溶缝洞体系中油气的差异运聚作用   总被引：2，自引：0，他引：2       下载免费PDF全文

向才富  王建忠  庞雄奇  姜振学  刘洛夫  李素梅 《地学前缘》2009,16(6):349

叠合盆地海相碳酸盐岩介质油气运聚机理是油气勘探必须解决的关键科学问题之一,选择代表性储层介质进行系统油气运聚作用分析有利于为解决这一关键科学问题提供范例。塔中83井区鹰山组储层是典型的表生岩溶缝洞体系储层,油气主要分布在岩溶体系的水平潜流带中,油水关系复杂,油水界面倾斜。本区原油和天然气性质参数在NE向断层与NW向断层的交汇部位异常高,而随着远离断层交汇部位逐渐降低,并顺构造脊有规律的降低,说明断层交汇部位是本区油气的注入点,而油气运移的主输导通道沿本区的鼻状构造展布。这一认识为系统分析表生岩溶缝洞体系油气运聚机理奠定了地质基础。基于碳酸盐岩表生岩溶的相关研究成果,建立了表生岩溶缝洞体系的基本模型。在分析油气在表生岩溶缝洞体系运聚过程的基础上,认为复杂缝洞体系中油气的差异运聚原理是产生这种现象的关键。油气运移过程受储层含水程度控制,油气总是首先将临近充注点的孔隙或缝洞充满后,才能继续向远处运移,并沿油气运移路径顺次充满远处的孔洞缝体系。所形成的油气水分布规律受储层含水程度,储层中能导致油气侧向运移的侧向联通通道、局部缝洞单元与侧向联通通道的关系及其油气溢出点和晚期气侵强度的联合控制。岩溶缝洞体系中油气运聚过程及其所形成的油气分布规律对叠合盆地下构造层碳酸盐岩油气勘探具有重要的启发,油气勘探不仅要通过地球物理方法识别优质储层发育的部位,还应该尽量描述优质储层的孔洞缝结构,结合油气运移方向和主输导通道的空间展布规律指导油气勘探。  相似文献   

Effect of Arching on Uplift Capacity of Single Piles     

Amit Shelke  Nihar Ranjan Patra 《Geotechnical and Geological Engineering》2009,27(3):365-377

An analytical method has been proposed to predict the ultimate uplift capacity of single vertical piles embedded in sand considering arching effect. The present analysis takes into consideration of various pile and soil parameters such as length (L), diameter (d) of the pile, angle of internal friction of soil (ϕ), soil pile friction angle (δ) and unit weight of soil (γ). A modified value of coefficient of lateral earth pressure in uplift has been developed considering the arching effect of soil. A comparative assessment of the uplift capacity of piles predicted by using proposed theory and the existing available theories is made with the existing field and model test results. It has been observed that the present model considering the arching effect predicts the results closer.  相似文献   

黑龙江省东部佳木斯隆起多期隆升剥露历史的热年代学研究     

温泉波  刘永江  高飞  徐民  李伟民  冯志强  周建平  梁琛岳 《岩石学报》2017,33(6):1789-1804

黑龙江省东部佳木斯隆起是佳木斯地块重要组成部分,经历了多期板块碰撞闭合事件的影响,对其隆升剥露历史的热年代学研究有助于加深对东北各地块的碰撞拼贴历史以及古亚洲洋东端构造演化的认识。本文通过对黑龙江省东部佳木斯隆起老平岗花岗岩岩体中的锆石LA-ICP-MS、独居石Th-U-Pb化学法(CHIME)以及(钾长石、黑云母)~(40)Ar-~(39)Ar法同位素年龄的测定,恢复了佳木斯隆起多期隆升剥露的构造热演化历史。研究结果显示佳木斯隆起晚三叠世之前主要存在三个隆升阶段,分别为早古生代早期(511~494Ma)和晚二叠世-中三叠世早期(260~240Ma)的快速隆升阶段以及期间的相对慢速隆升阶段。511~494Ma快速隆升阶段,冷却速率为11.76℃/Myr,隆升速率为0.294mm/a,17Myr隆升总幅度达5.00km,代表了佳木斯地块与松嫩地块的碰撞拼贴事件;494~260Ma相对慢速隆升阶段,冷却速率为1.51℃/Myr,隆升速率为0.038mm/a,234Myr隆升总幅度仅有8.80km;260~240Ma快速隆升阶段,冷却速率平均为8.44℃/Myr,隆升速度平均为0.211mm/a,20Myr隆升幅度平均达4.22km,该事件应与佳木斯地块与华北板块在晚二叠世-中三叠世的碰撞拼接事件有关。  相似文献   

中国南方地区奥陶系热液-岩溶改造型白云岩储层发育机理——以黔中地区下奥陶统为例     

刘子豪  朱东亚  吴胜和  张殿伟  张荣强  周末 《海相油气地质》2017,22(2)

以黔中地区下奥陶统为例,通过野外剖面观测、实验分析等工作,揭示了白云岩的热液-岩溶改造特征,并探讨了其发育机理。研究区下奥陶统红花园组和桐梓组以白云岩为主,在白云岩构造裂缝和溶蚀孔洞中见白云石、方解石、沥青的充填,具有典型的斑马纹状构造。充填白云石为粗晶粒状的鞍形白云石,具有弯曲晶面和波状消光的特征,阴极发光呈现较强的红色。充填白云石的碳同位素δ~(13)C在-2.2‰~-0.8‰之间,平均值为-1.47‰,氧同位素δ~(18)O在-12.2‰~-7.6‰之间,平均值为-9.4‰,与围岩白云石相比明显偏轻。充填白云石的稀土元素具有典型的Eu正异常特征,δEu最高达91.9。根据地质演化背景和流体作用类型,奥陶系白云岩储层发育过程为:早奥陶世沉积过程中发生同生/准同生白云石化作用;中晚奥陶世至早志留世,受都匀运动影响,白云岩暴露至地表遭受岩溶作用,形成岩溶孔洞型白云岩储层;中泥盆世遭受构造热液进一步对白云岩进行的溶蚀改造,所形成的溶蚀孔洞为天然气的主要储集空间。  相似文献   

Ore-forming Fluid Systems and Mineralization in the Eastern Jiangnan Uplift in the Border Area of Anhui and Jiangxi Provinces, China     

ZHOU Taof  YUAN Feng  HOU Mingjin  FAn Yu  DU Jianguo  ZHU Guang  YUE Shucang School of Resources  Environment Engineering  Hefei University of Technology  Hefei  Anhui  Academy of Geological Survery of Anhui Province  Hefei  Anhui 《《地质学报》英文版》2004,78(2):380-386

Obvious differences in mineralization characteristics exist between the southern and northern parts of the eastern part of the Jiangnan Uplift in northern Jiangxi Province and southern Anhui Province. The regional metallogeny is discussed, and the ore-forming fluid systems are classified in this article. It is proposed that the fluid ore-forming activities in the Jiangnan Uplift both in northern Jiangxi and southern Anhui have close relationships with the crust-mantle interaction and magmatic-tectonic activities. The types and scales of the mineralization on the both sides of the eastern Jiangnan Uplift were determined by fluid ore-forming systems and geological backgrounds.  相似文献   

藏东昌都地区侏罗纪岩石磁组构研究及其构造意义     

刘晨光  孙知明  李海兵  曹勇  叶小舟  吴百灵  曹新文  李成龙  裴军令 《地质学报》2019,93(10):2477-2485

本文对藏东昌都地区侏罗纪汪布组、东大桥组和小索卡组红层共71个采点开展了磁组构(AMS)研究。磁组构测试结果表明,早侏罗世汪布组岩石磁线理较磁面理发育,磁化率各向异性度较高,磁化率椭球最小轴K3散布于层面缩短方向,代表了与构造成因相关的磁组构;中侏罗世东大桥组和晚侏罗世小索卡组岩石则磁面理较磁线理发育,磁化率各向异性度较低,磁化率椭球最小轴K3与层面近垂直,指示了原生沉积磁组构。早侏罗世汪布组地层的磁组构揭示了其构造应力场方向为NE-SW向。中侏罗世东大桥组的磁组构指示了其沉积时的古水流方向为SE向(138.3°),而晚侏罗世小索卡组磁组构指示了其沉积时的古水流方向为NNW向(328.3°)。古水流方向的明显变化揭示了昌都地区从中侏罗世到晚侏罗世沉积物物源发生了相应的转变,表明昌都地区南早北晚的隆升过程。  相似文献   

合肥盆地圆筒山组物源分析及其地质意义：来自碎屑锆石的证据     

王勇生  田自强  胡召齐  白桥 《地学前缘》2019,26(2):179-193

合肥盆地位于华北板块东南缘,形成于华南、华北板块碰撞过程中。合肥盆地形成时表现为大别造山带向北逆冲形成的前陆挠曲盆地,早白垩世在区域伸展背景下转变为断陷盆地。中侏罗统圆筒山组是合肥盆地前陆挠曲阶段的沉积地层之一,主要表现为湖泊相沉积,与下伏的防虎山组典型的河流相沉积明显不同。为了获得圆筒山组更详细的物源信息,对肥西地区出露的圆筒山组紫红色粉砂岩开展了碎屑锆石LA-ICP MS U-Pb定年。定年结果显示,两个粉砂岩样品均获得了约2.0 Ga和约770 Ma两个主要峰值以及约2.4 Ga次要峰值。该特征与扬子板块锆石年龄分布特征几乎完全一致,指示圆筒山组物源应来自扬子板块。考虑到盆地地层的物源不应来自其周边隆起区分水岭的另一侧,因而推测圆筒山组物源应来自张八岭隆起中侏罗世时地表出露岩石。在燕山运动A幕影响下,下扬子地区发生逆冲褶皱活动,张八岭隆起发生明显隆升,上部岩石被剥蚀殆尽,仅保留现今出露的新元古代张八岭群及肥东杂岩,被剥蚀的岩石搬运沉积于合肥盆地内,形成圆筒山组。  相似文献