Crustal velocity structure off SW Taiwan in the northernmost South China Sea imaged from TAIGER OBS and MCS data     

Jia-Ming Deng  Tan K. Wang  Ben Jhong Yang  Chao-Shing Lee  Char-Shine Liu  Song-Chuen Chen 《Marine Geophysical Researches》2012,33(4):327-349

During TAiwan Integrated GEodynamics Research of 2009, we investigated data from thirty-seven ocean-bottom seismometers (OBS) and three multi-channel seismic (MCS) profiles across the deformation front in the northernmost South China Sea (SCS) off SW Taiwan. Initial velocity-interface models were built from horizon velocity analysis and pre-stack depth migration of MCS data. Subsequently, we used refracted, head-wave and reflected arrivals from OBS data to forward model and then invert the velocity-interface structures layer-by-layer. Based on OBS velocity models west of the deformation front, possible Mesozoic sedimentary rocks, revealed by large variation of the lateral velocity (3.1–4.8 km/s) and the thickness (5.0–10.0 km), below the rift-onset unconformity and above the continental crust extended southward to the NW limit of the continent–ocean boundary (COB). The interpreted Mesozoic sedimentary rocks NW of the COB and the oceanic layer 2 SE of the COB imaged from OBS and gravity data were incorporated into the overriding wedge below the deformation front because the transitional crust subducted beneath the overriding wedge of the southern Taiwan. East of the deformation front, the thickness of the overriding wedge (1.7–5.0 km/s) from the sea floor to the décollement decreases toward the WSW direction from 20.0 km off SW Taiwan to 8.0 km at the deformation front. In particular, near a turn in the orientation of the deformation front, the crustal thickness (7.0–12.0 km) is abruptly thinner and the free-air (?20 to 10 mGal) and Bouguer (30–50 mGal) gravity anomalies are relatively low due to plate warping from an ongoing transition from subduction to collision. West of the deformation front, intra-crustal interfaces dipping landward were observed owing to subduction of the extended continent toward the deformation front. However, the intra-crustal interface near the turn in the orientation of the deformation front dipping seaward caused by the transition from subduction to collision. SE of the COB, the oceanic crust, with a crustal thickness of about 10.0–17.0 km, was thickened due to late magmatic underplating or partially serpentinized mantle after SCS seafloor spreading. The thick oceanic crust may have subducted beneath the overriding wedge observed from the low anomalies of the free-air (?50 to ?20 mGal) and Bouguer (40–80 mGal) gravities across the deformation front.  相似文献   

2011年10月16日新疆精河县5.0级地震震害特征及原因   总被引：1，自引：0，他引：1  

陈建波  谭明  吴国栋  胡伟华  孙甲宁  张振斌 《震灾防御技术》2012,7(2):164-172

2011年10月16日新疆精河县5.0级地震震中位于博尔塔拉蒙古自治州精河县托里乡境内,极震区震中烈度为Ⅵ度.震害调查显示,灾区房屋主要以老旧的土坯房为主,地震使本身老旧的房屋裂缝加宽,破坏加重.其次,灾区房屋震害还具有明显的南北差异特性,场地条件差异是造成距离震中较远的部分房屋破坏较重的主要原因之一.  相似文献   

地震应急卫星通信系统的设计与应用.   总被引：6，自引：5，他引：1  

杨乐  曾薇  谭颖 《震灾防御技术》2012,7(1):100-109

地震应急通信是地震应急救援工作的基础和关键的组成部分.本文从地震应急卫星通信网络的组成及规模、站点配置、组网方式、工作模式、工作模式切换、通信方式、卫星信道规划、业务应用等方面,简要介绍了中国地震局“十五”期间建设并投入运行的地震应急卫星通信系统的设计以及在地震应急工作中的应用.  相似文献   

北秦岭东段二郎坪群火山岩锆石的LA-ICP-MS U-Pb定年及其地质意义   总被引：13，自引：0，他引：13  

赵姣  陈丹玲  谭清海  陈淼  朱小辉  郭彩莲  刘良 《地学前缘》2012,19(4):118-125

利用阴极发光（CL）技术和LA-ICP-MS原位分析方法,对北秦岭东段军马河、湾潭和湍河3个地区的二郎坪群基性火山岩进行了系统的锆石U Pb年代学研究。CL图像分析结果显示,三地火山岩中的锆石皆呈自形 半自形柱状形态和微弱的、宽的振荡环带结构。微量元素分析揭示,所有锆石都具有较高的稀土总量、重稀土和Th、U含量（ΣREE为(397.7~7 941.6)×10-6;ΣHREE为(376.7~7 774.2)×10-6;Th为(107.9~5 824.2)×10-6;U为(89.3~3 841.9)×10-6）以及轻稀土亏损、重稀土明显富集的左倾稀土配分曲线型式,所有锆石的Th/U比值皆大于0.4,显示典型岩浆锆石特征。LA-ICP-MS定年结果获得3地基性火山岩的形成年龄分别为(463±1.8) Ma、(475±1.5) Ma和(473±1.3) Ma,三者在误差范围内一致,表明北秦岭二郎坪群基性火山岩的形成时代为463~475 Ma。系统的岩石学和地球化学研究显示,二郎坪群火山岩具有弧后盆地火山岩的地球化学特征。研究获得的二郎坪基性火山岩463~475 Ma的结晶年龄明显晚于其南侧北秦岭超高压榴辉岩的原岩年龄(（791±6) Ma）以及变质年龄（(502±11) Ma）,而且榴辉岩的地球化学特征显示为板内玄武岩,也与二郎坪火山岩不同,因而指出北秦岭超高压榴辉岩与二郎坪火山岩没有直接成因联系。  相似文献   

构造电阻率差比值法识别火山岩裂缝地层天然气层     

谭锋奇  李洪奇  孙中春  欧阳敏  韩述一 《吉林大学学报(地球科学版)》2012,42(4):1199-1206

在基岩电阻率较高的硬地层中,除去泥质、孔隙和其他矿物等因素的影响后,地层电阻率与致密围岩电阻率的差异就被认为是裂缝以及地层孔隙中储存的流体性质引起的。选择相同岩性含气储层与致密围岩层的电阻率值,利用数值反演的方法确定出计算含气层段消除裂缝以及孔隙中流体性质影响以后的地层真电阻率公式,定义地层真电阻率和深侧向电阻率的差值与地层深侧向电阻率的比值为构造电阻率差比值,该参数主要反映裂缝以及孔隙中的流体性质对电阻率降低幅度的影响。因此,利用差比值法可以识别火山岩裂缝地层的流体性质,进而制作油层、气层和水层的判别图版,并结合其他测井曲线、油藏动态资料以及气测信息综合识别火山岩裂缝地层天然气层。该方法在准噶尔盆地研究区火山岩天然气层的识别中取得了很好的应用效果,解释结论与试油结果基本吻合。  相似文献   

The Emission Heights of Transition Region Lines in an Equatorial Coronal Hole and the Surrounding Quiet Sun     

Hui Tian Li-Dong Xia Jian-Sen He Bo Tan Shuo Yao 《中国天文和天体物理学报》2008,8(6)

Using the correlation between the radiance or Doppler velocity and the extrapolated magnetic field, we determined the emission heights of a set of solar transition region lines in an equatorial coronal hole and in the surrounding quiet Sun region. We found that for all of the six lower-transition-region lines, the emission height is about 4-5 Mm in the equatorial coronal hole, and around 2 Mm in the quiet Sun region. This result confirms the previous findings that plasma with different temperature can coexist at the same layer of transition region. In the quiet Sun region, the emission height of the upper-transition-region line Ne viii is almost the same that of the lower-transition-region line, but in the coronal hole, it is twice as high. This difference reveals that the outflow of Ne Ⅷ is a signature of solar wind in the coronal hole and is just a mass supply to the large loops in the quiet Sun.  相似文献   

塔里木盆地轮南奥陶系古潜山油气成藏与分布   总被引：24，自引：9，他引：15       下载免费PDF全文

刘静江  刘慧荣  谭琳  张春莲 《地质科学》2004,39(4):532-542

轮南奥陶系碳酸盐岩古潜山形成于晚加里东-海西期,经过多期构造运动的改造,形成了现今的构造格局;经过了多期成藏过程,形成了现今复杂的油气水分布特征.轮南奥陶系古潜山油气主要分布在潜山围斜部位,潜山面以下约150 m范围内,原油分布不受局部构造影响.总体看来,轮南奥陶系古潜山油气分布主要与储集空间的分布、水动力作用和差异聚集作用有关;轮南奥陶系古潜山油水界面是倾斜的,油气藏具有一定的水动力特征,可能是一个大型的水动力圈闭油气藏.  相似文献   

Geophysical monitoring technology for CO<Subscript>2</Subscript> sequestration     

Jin-Feng Ma  Lin Li  Hao-Fan Wang  Ming-You Tan  Shi-Ling Cui  Yun-Yin Zhang  Zhi-Peng Qu  Ling-Yun Jia  Shu-Hai Zhang 《应用地球物理》2016,13(2):288-306

Geophysical techniques play key roles in the measuring, monitoring, and verifying the safety of CO₂ sequestration and in identifying the efficiency of CO₂-enhanced oil recovery. Although geophysical monitoring techniques for CO₂ sequestration have grown out of conventional oil and gas geophysical exploration techniques, it takes a long time to conduct geophysical monitoring, and there are many barriers and challenges. In this paper, with the initial objective of performing CO₂ sequestration, we studied the geophysical tasks associated with evaluating geological storage sites and monitoring CO₂ sequestration. Based on our review of the scope of geophysical monitoring techniques and our experience in domestic and international carbon capture and sequestration projects, we analyzed the inherent difficulties and our experiences in geophysical monitoring techniques, especially, with respect to 4D seismic acquisition, processing, and interpretation.  相似文献   

Two-dimensional inversion of spectral induced polarization data using MPI parallel algorithm in data space     

Zhi-Yong Zhang  Han-Dong Tan  Kun-Peng Wang  Chang-Hong Lin  Bin Zhang  Mao-Bi Xie 《应用地球物理》2016,13(1):13-24

Traditional two-dimensional (2D) complex resistivity forward modeling is based on Poisson’s equation but spectral induced polarization (SIP) data are the coproducts of the induced polarization (IP) and the electromagnetic induction (EMI) effects. This is especially true under high frequencies, where the EMI effect can exceed the IP effect. 2D inversion that only considers the IP effect reduces the reliability of the inversion data. In this paper, we derive differential equations using Maxwell’s equations. With the introduction of the Cole–Cole model, we use the finite-element method to conduct 2D SIP forward modeling that considers the EMI and IP effects simultaneously. The data-space Occam method, in which different constraints to the model smoothness and parametric boundaries are introduced, is then used to simultaneously obtain the four parameters of the Cole—Cole model using multi-array electric field data. This approach not only improves the stability of the inversion but also significantly reduces the solution ambiguity. To improve the computational efficiency, message passing interface programming was used to accelerate the 2D SIP forward modeling and inversion. Synthetic datasets were tested using both serial and parallel algorithms, and the tests suggest that the proposed parallel algorithm is robust and efficient.  相似文献   

Three-dimensional forward modeling and inversion of borehole-to-surface electrical imaging with different power sources     

Ze Bai  Mao-Jin Tan  Fu-Lai Zhang 《应用地球物理》2016,13(3):437-448

Borehole-to-surface electrical imaging (BSEI) uses a line source and a point source to generate a stable electric field in the ground. In order to study the surface potential of anomalies, three-dimensional forward modeling of point and line sources was conducted by using the finite-difference method and the incomplete Cholesky conjugate gradient (ICCG) method. Then, the damping least square method was used in the 3D inversion of the formation resistivity data. Several geological models were considered in the forward modeling and inversion. The forward modeling results suggest that the potentials generated by the two sources have different surface signatures. The inversion data suggest that the low-resistivity anomaly is outlined better than the high-resistivity anomaly. Moreover, when the point source is under the anomaly, the resistivity anomaly boundaries are better outlined than when using a line source.  相似文献