冲绳海槽中部沉积物物质来源和沉积环境分析   总被引：1，自引：1，他引：0  

张丹丹  曾志刚  殷学博 《海洋学报》2017,39(7):92-101

本文基于AMS14C高精度测年,通过对柱状沉积物HOBAB2-S2的粒度、微量元素和稀土元素的分析,对冲绳海槽中部区5 300 a以来的物质来源和沉积环境进行了研究。通过对该孔的稀土元素与微量元素的研究发现研究区沉积物质具有陆源属性,并且通过不同物源区沉积物的稀土元素散点图表明5 300 a以来沉积物主要来自于台湾。文中将粒度特征作为研究区域沉积环境,尤其是水动力（黑潮）强弱的指示参数,根据粒度变化曲线,可将沉积过程分为4个阶段:第一阶段（5.30~3.81 ka BP）,粒径由粗变细,黑潮强度逐渐减小;第二阶段（3.81~2.70 ka BP）,粒径波动较大,无明显增大或减小趋势,表明沉积环境处于相对波动状态,水动力强弱不稳定;第三阶段（2.70~0.97 ka BP）,粒径变化较小,表明沉积环境处于相对稳定状态,研究区的水动力条件较稳定;第四阶段（从0.97 ka BP至今）,粒径逐渐变粗,水动力条件增强。  相似文献   

Target Deployment and Retrieval Using JIAOLONG Manned Submersible in the Depth of 6600 m in Mariana Trench     

GAO Xiang  DING Kang  REN Yu-gang  FU Wen-tao  DING Zhong-jun  ZHAO Sheng-y  LIU Bao-hua 《海洋工程》2017,31(5):618-623

China''s 7000 m manned submersible JIAOLONG carried out an exploration cruise at the Mariana Trench from June to July 2016. The submersible completed nine manned dives on the north and south area of the Mariana Trench from the depth of 5500 to 6700 m, to investigate the geological, biological and chemical characteristics in the hadal area. During the cruise, JIAOLONG deployed a gas-tight serial sampler to collect the water near the sea bottom regularly. Five days later, the sub located the sampler in another dive and retrieved it successfully from the same location, which is the first time that scientists and engineers finished the high accuracy in-situ deployment and retrieval using a manned submersible with Ultra-Short Base Line (USBL) positioning system at the depth more than 6600 m. In this task, we used not only the USBL system of the manned submersible but also a compound strategy, including five position marks, the sea floor terrain, the depth contour, and the heading of the sub. This paper introduces the compound strategy of the target deployment and retrieval with the practical diving experience of JIAOLONG, and provides a promising technique for other underwater vehicles such as manned submersible or Remote Operated Vehicle (ROV) under similar conditions.  相似文献   

Tectonics and sedimentation around Kashinosaki Knoll: A subducting basement high in the eastern Nankai Trough     

Toshihiro  Ike  Gregory F.  Moore  Shin'ichi  Kuramoto  Jin-Oh  Park  Yoshiyuki  Kaneda  Asahiko  Taira 《Island Arc》2008,17(3):358-375

Abstract   When seamounts and other topographic highs on an oceanic plate are subducted, they cause significant deformation of the overriding plate and may act as asperities deeper in the seismogenic zone. Kashinosaki Knoll (KK) is an isolated basement high of volcanic origin on the subducting Philippine Sea Plate that will soon be subducted at the eastern Nankai Trough. Seismic reflection imaging reveals a thick accumulation of sediments (∼1200 m) over and around the knoll. The lower portion of the sedimentary section has a package of high-amplitude, continuous reflections, interpreted as turbidites, that lap onto steep basement slopes but are parallel to the gentler basement slopes. Total sediment thickness on the western and northern slopes is approximately 40–50% more than on the summit and southeastern slopes of KK. These characteristics imply that the basal sedimentary section northwest of KK was deposited by infrequent high-energy turbidity currents, whereas the area southeast of KK was dominated by hemipelagic sedimentation over asymmetric basement relief. From the sediment structure and magnetic anomalies, we estimate that the knoll likely formed near the spreading center of the Shikoku Basin in the early Miocene. Its origin differs from that of nearby Zenisu Ridge, which is a piece of the Shikoku Basin crust uplifted along a thrust fault related to the collision of the Izu–Bonin arc and Honshu. KK has been carried into the margin of the Nankai Trough, and its high topography is deflecting Quaternary trench turbidites to the south. When KK collides with the accretionary prism in about 1 My, the associated variations in sediment type and thickness around the knoll will likely result in complex local variations in prism deformation.  相似文献   

南海西沙海槽S14站位的地球化学异常特征及其意义   总被引：22，自引：6，他引：16  

祝有海  饶竹  刘坚  刘亚玲  白瑞梅 《现代地质》2005,19(1):39-44

西沙海槽具备良好的天然气水合物的形成条件,并已发现与其有关的地球物理标志--模拟海底反射层（BSR）。通过对西沙海槽S14大型活塞站位的孔隙水和沉积物样品进行化学组分、酸解烃和热释光等方面的分析测试,结果发现在海底之下4～5 m区间存在着较明显的高盐高烃异常,其中酸解烃中的甲烷、乙烷、丙烷含量及其热释光值均有所增高,孔隙水中的绝大部分离子及其盐度也存在着明显的升高,这一高盐高烃异常可能是下部与天然气水合物有关的孔隙流体沿着断层向上迁移所致。这些地球化学异常以及模拟海底反射层等地球物理标志显示该站位之下可能存在天然气水合物。  相似文献   

The sedimentation rates in the Okinawa Trough during the Late Quaternary   总被引：3，自引：0，他引：3  

XIONG Yingqian  LIU Zhenxi  LI Tiegang  LIU Yanguang  YU Hua 《海洋学报(英文版)》2005,24(4):146-154

On the basis of accelerator mass spectrometer radiocarbon （AMS ^14C） dating, sedimentation rates of 11 cores collected from the northern to southern Okinawa Trough are discussed. The sedimentation rates in the Okinawa Trough roughly range from 11 to 39cm/ka, and the average is 23.0cm/ka. China＇s continental matter is the main sediment source of the middle Okinawa Trough and has important contribution to the northern and southern Okinawa Trough. The sedimentation rates during the marine oxygen isotope （MIS） 2 are uniformly higher than those during MIS 1 in the northern and middle Okinawa Trough while they are on the contrary in the southern Okinawa Trough. Sedimentation rates in the Okinawa Trough can be one of the proxies of sediment source and an indicator of cooling events.  相似文献   

南海西沙海槽典型地震相识别与分析     

张志杰  于兴河 《海洋地质前沿》2005,21(1):40-44

西沙海槽区作为气水合物的可能聚集地越来越受到关注。浅析地震相分析方法,通过地震相标志的识别,归纳出自中中新世以来,西沙海槽发育有8种地震相：S形前积地震相、斜交前积地震相、下超型前积地震相、丘状地震相、杂乱地震相、空白地震相、透镜状地震相和席状地震相。较细致地描述了各种地震相的反射特征,并结合研究区的沉积背景,对不同地震相的沉积学特征做出了合理解释。  相似文献   

冲绳海槽岩浆物理化学性质及其地质意义     

黄朋  李安春  胡宁静 《海洋学报》2008,30(3):85-94

借助冲绳海槽火山岩地球化学分析结果,讨论了海槽不同区段岩浆的温度、压力、密度和黏度等物理化学参数,以确定海槽岩浆的物理性质及其对海槽不同区段岩浆演化过程的影响.海槽北段的岩浆相对于中段表现出高压力、低温度的特征.由于海槽岩浆挥发分含量较高,北段岩浆的密度和黏度要高于中段的.但总的来说,海槽岩浆具有低密度、低黏度的特点,因此岩浆更容易穿透岩石圈,而且有利于岩浆结晶分异作用的进行.对海槽岩浆相对运移速度的研究显示,在外部条件及含水量相同的前提下,在海槽中段岩浆上升速度要大于北段的,这从岩浆物理化学性质的角度解释了为何海槽中段火山活动要强于北段的.  相似文献   

Submarine canyons on the north of Chiwei Island: influenced by recent extension of the southern Okinawa Trough     

ZHAO Yuexi  LIU Baohu  LI Xishuang  LIU Chenguang  WU Jinlong  WANG Kuiyang 《海洋学报(英文版)》2008,27(4):63-72

Based on new multibeam bathymetric data and about 300 km long single seismic profiles, three topographic units were identified:the canyons, fractural valley and submarine terrace on the north of Chiwei Island where is a structural transition zone between the southern trough and the middle trough. The Chiwei Canyon and the North Chiwei Canyon are two of the largest canyons in the East China Sea (ECS) slope. Topographic features and architectures of them are described. The study shows that both of them are originated along faults. The evolution and spatial distribution of topographic units in the study area are controlled mainly by three groups of faults which were formed and reactive in the recent extensional phase of Okinawa Trough. The Chiwei Canyon was initiated during the middle Pleistocene and guided by F4 that is a N-S trending fault on the slope and F1, a large NW-SE trending fault on the trough. The pathway migration from the remnant channel to the present one of Chiwei Canyon is the result of uplift of tilted fault block that is coupled to the recent extension movements of the southern trough. The submarine terrace is detached from the ECS slope by the NEE-trending fault. The North Chiwei Canyon, developing during the late Pleistocene, is guided by F5, a N-S trending fault, diverted and blocked by the submarine terrace.  相似文献   

Geochemistry of pore waters from the Xisha Trough, northern South China Sea and their implications for gas hydrates   总被引：2，自引：0，他引：2  

Shao-Yong Jiang  Tao Yang  Lu Ge  Jing-Hong Yang  Hong-Fei Ling  Neng-You Wu  Jian Liu  Dao-Hua Chen 《Journal of Oceanography》2008,64(3):459-470

This paper reports all available geochemical data on sediments and pore waters from the Xisha Trough on the northern continental margin of the South China Sea. The methane concentrations in marine sediments display a downhole increasing trend and their carbon isotopic compositions (δ ¹³C = −25 to −51‰) indicate a thermogenic origin. Pore water Cl⁻ concentrations show a range from 537 to 730 mM, and the high Cl⁻ samples also have higher concentrations of Br⁻, Na⁺, K⁺, and Mg²⁺, implying mixing between normal seawater and brine in the basin. The SO₄ ²⁻ concentrations of pore waters vary from 19.9 to 36.8 mM, and show a downhole decreasing trend. Calculated SMI (sulfate-methane interfaces) depths and sulfate gradients are between 21 and 47 mbsf, and between −0.7 and −1.7 mM/m, respectively, which are similar to values in gas hydrate locations worldwide and suggest a high methane flux in the basin. Overall, the geochemical data, together with geological and geophysical evidence, such as the high sedimentation rates, high organic carbon contents, thick sediment piles, salt and mud diapirs, active faulting, abundant thermogenic gases, and occurrence of huge bottom simulating reflector (BSR), are suggestive of a favorable condition for occurrence of gas hydrates in this region.  相似文献   

西沙海槽沉积模式   总被引：1，自引：0，他引：1  

熊斌辉  刘春成  郭瑞 《海洋地质译丛》2009,(4):1-9

晚中新世琼东南盆地快速构造沉降，沉积欠补偿形成了西沙海槽。西沙海槽上部高陡带为悬浮沉积体系，下部低缓带为浊流滑塌沉积体系，槽底平缓带为河流沉积体系。不同于浊流沉积小而散，深海河流沉积为稳定的贯穿整个海槽的大储层。由于深海河流沉积体系稳、远、大的特点，其注定成为世界深水油气勘探的主要目标。  相似文献