桶形基础平台吊耳的设计及其应用     

刘孟家  陈学春  王丙玲 《海洋科学进展》2000,18(4):81-84

分析了桶形基础平台吊耳设计和施工过程中出现的问题及其原因,提出了导管架平台外侧吊耳的设计方案.  相似文献   

郯庐断裂带安徽段现代地震活动及应力场特征   总被引：13，自引：6，他引：7       下载免费PDF全文

刘东旺  夏瑞良  刘泽民  沈小七  李敏莉  闫素萍 《地质科学》2006,41(2):278-290

分析了郯庐断裂带安徽段地震活动特征,利用近震直达波最大振幅比方法反演了99次中-小地震震源机制,并作了统计和聚类分析。现代地震活动整体上继承了历史地震分布格局,未显示增强趋势;断裂带及邻区应力场P轴和T轴优势方位大致呈近东西向和近南北向分布,现今承受的作用力以近水平或斜向为主,但也存在部分其它方向的应力场和近垂直方向的作用力。震源断层的破裂类型,带内以逆冲(或正断),或近逆冲(或正断)型为主。带附近较明显地呈现出走滑型或近走滑型破裂的优势;北、南亚段应力场有明显差异,即北压南张,其分界大约在北纬32°附近,北西西走向的桥头集—东关断裂是两者间的构造变换带。  相似文献   

大直径环式组合潜孔锤及钻进工艺研究   总被引：6，自引：0，他引：6  

王茂森  殷琨  张晓光 《地质与勘探》2006,42(2):90-92,96

论述了大直径嵌岩桩孔钻进的现状、发展趋势,阐述了大直径环式组合潜孔锤的工作原理、结构设计、钻进工艺方法,对设计加工的HC-15型环式组合潜孔锤钻具进行了室内模拟试验,并对试验结果进行分析总结.  相似文献   

Seep mounds on the Southern Vøring Plateau (offshore Norway)     

Michael Ivanov  Adriano Mazzini  Valentina Blinova  Elena Kozlova  Jan-Sverre Laberg  Tatiana Matveeva  Marco Taviani  Nikita Kaskov 《Marine and Petroleum Geology》2010

Multidisciplinary study of seep-related structures on Southern Vøring Plateau has been performed during several UNESCO/IOC TTR cruises on R/V Professor Logachev. High-resolution sidescan sonar and subbottom profiler data suggest that most of the studied fluid discharge structures have a positive relief at their central part surrounded by depression. Our data shows that the present day fluid activity is concentrated on the top of these “seep mounds”. Number of high hydrocarbon (HC) gas saturated sediment cores and 5 cores with gas hydrate presence have been recovered from these structures. δ¹³C of methane (between −68 and −94.6‰ VPDB) and dry composition of the gas points to its biogenic origin. The sulfate depletion generally occurs within the upper 30–200 cm bsf and usually coincides with an increase of methane concentration. Pore water δ¹⁸O ranges from 0.29 to 1.14‰ showing an overall gradual increase from bottom water values (δ¹⁸O ∼ 0.35‰). Although no obvious evidence of fluid seepage was observed during the TV surveys, coring data revealed a broad distribution of living Pogonophora and bacterial colonies on sea bottom inside seep structures. These evidences point to ongoing fluid activity (continuous seepage of methane) through these structures. From other side, considerable number and variety of chemosynthetic macro fauna with complete absence of living species suggest that present day level of fluid activity is significantly lower than it was in past. Dead and subfossil fauna recovered from various seep sites consist of solemyid (Acharax sp.), thyasirid and vesicomyid (cf. Calyptogena sp.) bivalves belonging to chemosymbiotic families. Significant variations in δ¹³C (−31.6‰ to −59.2‰) and δ¹⁸O (0.42‰ and 6.4‰) of methane-derived carbonates collected from these structures most probably related to changes in gas composition and bottom water temperature between periods of their precipitation. This led us to ideas that: (1) seep activity on the Southern Vøring Plateau was started with large input of the deep thermogenic gas and gradually decries in time with increasing of biogenic constituent; (2) authigenic carbonate precipitation started at the near normal deep sea environments with bottom water temperature around +5 °C and continues with gradual cooling up to negative temperatures recording at present time.  相似文献   

Fossilisation of a silica diagenesis reaction front on the mid-Norwegian margin     

Raluca Cristina Neagu  Joe Cartwright  Richard Davies  Lars Jensen 《Marine and Petroleum Geology》2010

The diagenetic transformation of biogenic silica from opal-A to opal-CT was recognised on seismic reflection data over an area of 78 × 10³ km² on the mid-Norwegian margin. The opal-A/CT diagenetic boundary appears as a positive, high amplitude reflection that generally cross-cuts the hosting stratigraphy. We demonstrate that it is not a sea bottom simulating reflection (BSR) and also that is not in thermal equilibrium with the present day isotherms. We present arguments that three styles of deformation associated with the opal-A/CT reflection – polygonal faulting, regional anticlines and synclines and differential compaction folding – indicate that the silica diagenesis reaction front is fossilised at a regional scale. Isochore maps demonstrate the degree of conformity between the opal-A/CT reflection and three seismic horizons of Late Miocene to Early Pliocene age that potentially represent the paleo-seabed when ‘fossilisation’ of the reaction front took place. The seismic interpretational criteria for recognition of a fossilised diagenetic front are evaluated and the results of our study are integrated with previous studies from other basins of the NE Atlantic in order to determine if the arrest of silica diagenesis was diachronous along this continental margin.  相似文献   

The mystery of Pluto's mass     

C. Marchal 《Celestial Mechanics and Dynamical Astronomy》1993,56(1-2):13-26

After a short presentation of the Pluto-Charon system and the history of its mass determinations some first reasons are presented that support the existence of a ring of billions of small satellites about Pluto up to tenths of millions of kilometers.The stability, the shape and the dimensions of such an heavy ring are discussed.Finally a general review of advantages and drawbacks of this ring theory is presented as well as the possibilities of detection of the eventual Pluto's ring.  相似文献   

内磁层电流体系的地磁效应   总被引：2，自引：2，他引：2       下载免费PDF全文

徐文耀 《地球物理学报》1992,35(1):1-8

对Ⅱ区场向电流及其伴随的部分环电流和电离层电流组成的内磁层三维电流体系（PRFI电流系）的磁场效应进行了数值计算.这一三维电流体系在中低纬度地面产生的磁场呈现出特殊的纬度分布:X分量几乎不随纬度变化,Y分量随纬度增高近似呈线性变化.这些特征明显不同于对称环电流的磁场分布特征（X∝ cosφ,φ是纬度,Y=0）,也不同于DP2、S_q、L等电流体系的磁场分布特征.利用这一特征我们可以从地磁台子午链观测到的磁场扰动中分离出PRFI电流系的贡献.用1989年3月磁暴的实例检验了上述模型,观测结果与理论结果符合得很好.分析结果还表明,最大的D_st指数并不一定对应着最强的对称环电流.  相似文献   

The magnetospheric disturbance ring current as a source for probing the deep earth electrical conductivity     

Wallace H. Campbell 《Pure and Applied Geophysics》1990,134(4):541-557

Two current rings have been observed in the equatorial plane of the earth at times of high geomagnetic activity. An eastward current exists between about 2 and 3.5 earth radii (Re) distant, and a larger, more variable companion current exists between about 4 and 9 Re. These current regions are loaded during geomagnetic substorms. They decay, almost exponentially, after the cessation of the particle influx that attends the solar wind disturbance. This review focuses upon characteristics needed for intelligent use of the ring current as a source for induction probing of the earth's mantle. Considerable difficulties are found with the assumption thatDst is a ring-current index.  相似文献   

CTM-302型三分量高分辨率磁通门磁力仪的研制与应用   总被引：1，自引：0，他引：1       下载免费PDF全文

刘士忠  汤静波 《地球物理学报》1990,33(5):566-576

本文主要介绍CTM-302型三分量高分辨率磁通门磁力仪的技术指标与用途,仪器的结构与工作原理,技术指标的测试与对比以及应用情况;并通过国内外同类型产品的技术指标对比表提供了各项指标的水平。  相似文献   

多圆环柱域上解析函数边值问题再论     

王莉萍 《中国海洋大学学报(自然科学版)》2001,31(2):293-296

讨论多圆环柱域上多个复变量的解析函数的一般形式的 Riemann- Hilbert边值问题。通过函数的解析变换 ,导出了解析函数一般形式的 Riemann- Hilbert边值问题的可解性 ,并给出了解的积分表达式。  相似文献