Identification of Perkinsus-like parasite in Manila clam, Ruditapes philippinarum using DNA molecular marker at ITS region   总被引：1，自引：0，他引：1  

ZHANG Xichang  LIANG Yubo  FAN Jingfeng  ZHANG Wei  PU Hongyu  LIANG Bin  CHEN Hongxing  SONG Lichao 《海洋学报(英文版)》2005,24(5):139-144

Genomic DNA was extracted from hypnospores of Perkinsus-like parasite of Manila clam Ruditapes philippinarum collected at the fishing grounds in Huanghai Sea coast Shicheng Island and East China Sea coast Ningbo, China. The internal transcribed spacer（ITS） in rDNA was PCR-amplified, cloned, sequenced, and compared with that of five Perkinsus species in GenBank. The fragment amplified from DNA of parasite of either Shicheng Island or Ningbo contained 649 bp, including partial ssrRNA（51 bp） and ITS（＋5.8 S） （598 bp） regions. The ITS（＋5.SS） sequences of Perkinsus-like parasite of both Shicheng Island and Ningbo were all 99% identical to those ofPerkinsis atlanticus, and were not more than 95% identical to those of other four Perkinsus species including P. marinus, P. andrewsi, P. qugwadi and P. medierraneus.The ITS （＋5.8S） sequence of Perkinsus-like parasite of Shicheng Island was 99% identical to that of Ningbo. These facts about nucleotide sequences suggested that the Perkinsus-like parasite in Manila clam, Ruditapes philippinarum collected from either the Huanghai Sea coast or the East China Sea coast was P. atlanticus, and might reflect P. atlanticus strains of distinct geographic distribution.  相似文献   

Super-deep CTD measurements in the Izu-Ogasawara trench and a comparison of geostrophic shears with direct measurements     

Keisuke Taira 《Journal of Oceanography》2006,62(5):753-758

CTD (Conductivity-Temperature-Depth) data at five stations across the Izu-Ogasawara Trench at 34°N were examined. Geostrophic velocity was in accordance with the directly measured currents. Above the trench floor, potential temperature increased at a rate of 0.6 m°C/1000 db from 8000 db to 9417 db, and salinity increased from 8300 db to the bottom. Potential density was almost constant at 7100–8700 db, and it increased to the bottom. Above the eastern and western flanks, inversion of potential density was indicated in the bottom layers with an increase of potential temperature and a decrease of salinity, suggesting geothermal heating and outflow of ground water.  相似文献   

Deep CTD Casts in the Challenger Deep,Mariana Trench   总被引：1，自引：0，他引：1  

Keisuke?TairaEmail author  Daigo?Yanagimoto  Shoji?Kitagawa 《Journal of Oceanography》2005,61(3):447-454

On 1 December 1992, CTD (conductivity-temperature-depth profiler) casts were made at three stations in a north-south section of the Challenger Deep to examine temperature and salinity profiles. The station in the Challenger Deep was located at 11°22.78′ N and 142°34.95′ E, and the CTD cast was made down to 11197 db or 10877 m, 7 m above the bottom by reeling out titanium cable of 10980 m length. The southern station was located at 11° 14.19′ N and 142°34.79′ E, 16.1 km from the central station, where water depth is 9012 m. CTD was lowered to 7014 db or 6872 m. The northern station was located at 11°31.47′ N and 142° 35.30′ E, 15.9 km from the central station, and CTD was lowered to 8536 db or 8336 m, 10 m above the bottom. Below the thermocline, potential temperature decreased monotonously down to 7300–7500 db beyond a sill depth between 5500 m and 6000 m, or between 5597 db and 6112 db, of the trench. Potential temperature increased from 7500 db to the bottom at a constant rate of 0.9 m°C/1000 db. Salinity increased down to 6020–6320 db, and then stayed almost constant down to around 9000 db. From 9500 db to the bottom, salinity increased up to 34.703 psu at 11197 db. Potential density referred to 8000 db increased monotonously down to about 6200 db, and it was almost constant from 6500 db to 9500 db. Potential density increased from 9500 db in accordance with the salinity increase. Geostrophic flows were calculated from the CTD data at three stations. Below an adopted reference level of 3000 db, the flow was westward in the north of Challenger Deep and eastward in the south, which suggests a cyclonic circulation over the Challenger Deep. Sound speed in Challenger Deep was estimated from the CTD data, and a relation among readout depth of the sonic depth recorder, true depth, and pressure was examined.  相似文献   

郯庐断裂带安徽太湖段第四纪新活动研究   总被引：1，自引：0，他引：1  

赵朋  郑海刚  姚大全  杨源源  黄显良  方震 《大地测量与地球动力学》2018,38(12):1251-1255

郯庐断裂带太湖段位于东大别的东侧，为东大别与山前盆地的构造界线，遥感影像上断层线性特征清晰。在太湖-桐城一带开展了多次野外地质调查和探槽工作，其中太湖小池镇殷家上屋探槽显示，断层带发育有较软的断层泥，断层向上延伸入中更新世棕红色蠕虫状亚粘土中，OSL和ESR样品测试结果表明，断层在中更新世有过较强的活动。桐城挂车河镇洪老屋断层剖面显示断层错断了早中更新世砾石层，断层下部发育有新鲜的断层泥，ESR样品测试结果同样表明断层在中更新世有过较强活动。综合分析认为，郯庐断裂带太湖段在早中更新世仍有过较强活动，最新活动时代为中更新世(Q2)，这或是该地区地震活动以中小地震为主的一个构造背景因素。  相似文献   

冻融作用对不同初始状态基坑稳定性的影响研究     

赵容舟  梁二雷  姚晓亮  余帆 《冰川冻土》2021,43(5):1480-1488

为研究季节冻土区冻融作用对基坑工程的影响,基于考虑冰-水相变的热传导理论、考虑黏聚力的修正剑桥模型和强度折减法,建立了适用于季节冻土区基坑稳定性分析的计算平台。在此基础上,结合具体的试验数据对不同初始状态的基坑算例进行计算,研究季节冻土区基坑冻融前后稳定性和位移的变化情况,并根据土体冻融前后的物理力学参数对上述变化规律作出分析。研究结果表明,冻融作用加剧季节冻土区基坑的局部变形,且土体的初始干重度对变形规律的影响较大,但基坑的整体安全系数并未受到冻融作用的显著影响。存在一个临界干重度γ_d0,基坑土体的初始干重度接近临界干重度时,围护桩水平位移在冻融前后的变化较小,随着土体初始干重度与临界干重度的差距增大,围护桩水平位移在冻融前后的变化量也随之增大。土体的初始干重度越小,基坑围护桩的竖向位移和坑底隆起位移在冻融前后的变化量越大,即土体初始干重度较小的基坑在经历冻融后,围护桩的竖向位移产生显著沉降,但坑底隆起情况有明显缓解。研究成果对季节冻土区基坑工程的设计和施工具有重要意义。  相似文献   

花东海盆综合地震探测及其重要的构造意义          下载免费PDF全文

赵明辉  王强  杨富东  张佳政  高红芳  孙龙涛  刘思青  张光学 《地球科学》2021,46(1):359-368

花东海盆位于欧亚板块与菲律宾海板块交汇处,是现今西太平洋俯冲体系中唯一遗留的早白垩纪洋盆,是研究西太平洋俯冲构造演化与动力学机制的一个关键区域.前期研究发现,关于花东海盆的基础科学问题迫切需要解决:花东海盆的性质、年龄及形成演化历史如何?南北走向的加瓜海脊是花东海盆的东部边界吗?其隆升机制和构造属性如何?花东海盆的西部边界是马尼拉俯冲带吗?其各构造单元流体作用及其与花东海盆的构造关系如何?为了解决上述科学问题,在花东海盆开展主动源与被动源的综合地球物理探测和地质采样是非常必要的.一方面,可以采用纵/横波联合反演方法获取花东海盆及其东/西边界的深达地幔的精细速度结构,为构建西太平洋俯冲构造体系跨圈层的构造演化模式提供重要的地质地球物理证据,另一方面,为中国未来在花东海盆大洋钻探计划提供重要的基础数据.   相似文献   

高分辨率遥感数据处理及其铀矿地质应用     

张杰林 《国外铀金地质》2010,(2):124-124

高光谱和高空间分辨率遥感技术在铀矿地质勘查中具有重要作用,遥感数据挖掘与知识发现、新方法研究则是各种铀成矿要素光谱信息和空间特征识别的关键技术手段。本文基于曲波变换技术,开发了卫星高光谱数据（Hyperion）和高空间分辨率（SPOT5）的影像融合方法,融合影像在数据噪声消除、信息增强与信息提取方面应用效果显著;利用离散小波变换技术,高精度提取了主要铀成矿要素的光谱参数,建立了典型四价和六价铀矿物的光谱识别谱系。另外,通过钻孔岩心和探槽工程的高光谱编录、地质编录和物探编录,建立了典型蚀变带的物谱关系模型,重点分析了赤铁矿化蚀变（Fe3＋）光谱特征与铀含量之间的相关关系。上述遥感数据处理新技术新方法在桃山地区铀矿地质勘查中取得了理想效果。  相似文献   

Space–time distribution of interplate moment release including slow earthquakes and the seismo-geodetic coupling in the Sanriku-oki region along the Japan trench     

I. Kawasaki  Y. Asai  Y. Tamura 《Tectonophysics》2001,330(3-4):267-283

Along the Japan trench where some Mw8 class interplate earthquakes occurred in the past century such as the 1896 Sanriku tsunami earthquake (M6.8, Mt8.6, 12×10²⁰ N m) and the 1968 Tokachi-oki earthquake (Mw8.2, 28×10²⁰ N m), the Pacific plate is subducting under northeast Japan at a rate of around 8 cm/year. The seismic coupling coefficient in this region has been estimated to be 20–40%. In the past decade, three ultra-slow earthquakes have occurred in the Sanriku-oki region (39°N–42°N): the 1989 Sanriku-oki (Mw7.4), the 1992 Sanriku-oki (Mw6.9), and the 1994 Sanriku-oki (Mw7.7) earthquakes. Integrating their interplate moments released both seismically and aseismically, we have the following conclusions. (1) The sum of the seismic moments of the three ultra-slow earthquakes was (4.8–6.6)×10²⁰ N m, which was 20–35% of the accumulated moment (18.6–23.0)×10²⁰ N m, in the region (39°N–40.6°N, 142°E–144°E) for the 21–26 years since the 1968 Mw8.2 Tokachi-oki earthquake. This is consistent with the previous estimates of the seismic coupling coefficient of 20–40%. On the other hand, the sum of the interplate moments including aseismic faulting is (11–16)×10²⁰ N m, leading to a “seismo-geodetic coupling coefficient” of 50–85%, which is an extension of the seismic coupling coefficient to include slow events. (2) The time constants showed a large range from 1 min (10² s) for the 1968 Tokachi-oki earthquake to 10–20 min (10³ s) for the 1896 Sanriku tsunami earthquake, to one day (10⁵ s) for the 1992 Sanriku-oki ultra-slow earthquake, to on the order of one year (10⁷ s) for the 1994 Sanriku-oki ultra-slow earthquakes. (3) Based on the space–time distribution, three “gaps of moment release,” (40.6°N–42°N, 142°E–144°E) 39°N–40°N, 142°E–143°E) and (39°N–40°N, 142°E–144°E), are identified, instead of the gaps of seismicity.  相似文献   

Seismic evidence for a mantle plume oceanwards of the Kamchatka–Aleutian trench junction     

A. Gorbatov  Y. Fukao  S. Widiyantoro †  E. Gordeev 《Geophysical Journal International》2001,146(2):282-288

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Cooling and inferred exhumation history of the Ryoke metamorphic belt in the Yanai district, south-west Japan: Constraints from Rb–Sr and fission-track ages of gneissose granitoid and numerical modeling     

Takamoto Okudaira  Yasutaka Hayasaka  Osamu Himeno  Koichiro Watanabe  Yasuhiro Sakurai  Yukiko Ohtomo 《Island Arc》2001,10(2):98-115

Abstract The Ryoke metamorphic belt in south-west Japan consists mainly of I-type granitoids and associated low-pressure/high-temperature metamorphic rocks. In the Yanai district, it has been divided into three structural units: northern, central and southern units. In this study, we measured the Rb–Sr whole-rock–mineral isochron ages and fission-track ages of the gneissose granodiorite in the central structural unit. Four Rb–Sr ages fall in a range of ca 89–87 Ma. The fission-track ages of zircon and apatite are 68.9 ± 2.6 Ma and 57.4 ± 2.5 Ma (1σ error), respectively. Combining the newly obtained ages with previously reported (Th–)U–Pb ages from the same unit, thermochronologic study revealed two distinctive cooling stages; 1) a rapid cooling (> 40°C/Myr) for a period (~7 Myr) soon after the peak metamorphism (~ 95 Ma) and 2) the subsequent slow cooling stage (~ 5°C/Myr) after ca 88 Ma. The first rapid cooling stage corresponds to thermal relaxation of the intruded granodiorite magma and its associated metamorphic rocks, and to the uplift by a displacement along low-angle faults which initiated soon after the intrusion of the magma. Uplift by the later stage deformation having formed large-scale upright folds resulted in progress of the exhumation during the first stage. The average exhumation velocity of the stage is ≥ 2 mm/yr. During the second stage, the rocks were not accompanied by ductile deformation and were exhumed with the rate of 0.1–0.2 mm/yr. The difference in the exhumation velocity between the first and second cooling stages resulted from the difference in the thickness of the crust and in the activity of ductile deformation between the early and later stages of the orogenesis.  相似文献