The Vema Transverse Ridge (Central Atlantic)     

Kastens  Kim  Bonatti  Enrico  Caress  David  Carrara  Gabriela  Dauteuil  Olivier  Frueh-Green  Gretchen  Ligi  Marco  Tartarotti  Paola 《Marine Geophysical Researches》1998,20(6):533-556

Transverse ridges are elongate reliefs running parallel and adjacent to transform/fracture zones offsetting mid-ocean ridges. A major transverse ridge runs adjacent to the Vema transform (Central Atlantic), that offsets the Mid-Atlantic Ridge by 320 km. Multibeam morphobathymetric coverage of the entire Vema Transverse ridge shows it is an elongated (300 km), narrow (<30 km at the base) relief that constitutes a topographic anomaly rising up to 4 km above the predicted thermal contraction level. Morphology and lithology suggest that the Vema Transverse ridge is an uplifted sliver of oceanic lithosphere. Topographic and lithological asymmetry indicate that the transverse ridge was formed by flexure of a lithospheric sliver, uncoupled on its northern side by the transform fault. The transverse ridge can be subdivided in segments bound by topographic discontinuities that are probably fault-controlled, suggesting some differential uplift and/or tilting of the different segments. Two of the segments are capped by shallow water carbonate platforms, that formed about 3–4 m.y. ago, at which time the crust of the transverse ridge was close to sea level. Sampling by submersible and dredging indicates that a relatively undisturbed section of oceanic lithosphere is exposed on the northern slope of the transverse ridge. Preliminary studies of mantle-derived ultramafic rocks from this section suggest temporal variations in mantle composition. An inactive fracture zone scarp (Lema fracture zone) was mapped south of the Vema Transverse ridge. Based on morphology, a fossil RTI was identified about 80 km west of the presently active RTI, suggesting that a ridge jump might have occurred about 2.2 m.a. Most probable causes for the formation of the Vema Transverse ridge are vertical motions of lithospheric slivers due to small changes in the direction of spreading of the plates bordering the Vema Fracture Zone.  相似文献   

Grey Prediction of Siltation in North Channel of Yangtze Estuary     

Yu Cimei Shanghai Waterways Design & Research Institute  Shanghai 《中国海洋工程》1994,(2)

-The North Channel in the Yangtze Estuary is one of sea-leading waterways of Shanghai Harbour, in which yearly dredging volume reaches over ten million cubic meters, and it tends to increase year by year. Based on the channel regime similarity and through the relational grade, a GM (2, 1) is set up. It reveals the course of development of channel regime similarity under the action of various factors, and predicts the siltation volume in the nearest future which is the basis of dredging planning for relevant dredging departments.  相似文献   

Estimating mortality rates from tag recoveries: incorporating over-dispersion, correlation, and change points     

Kitada  Shuichi; Hiramatsu  Kazuhiko; Kishino  Hirohisa 《ICES Journal of Marine Science》1994,51(3):241-251

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Prediction of Load Carrying Capacity of Corroded Reinforced Concrete Beam     

范颖芳  周晶冯新 《中国海洋工程》2004,18(1):107-118

A novel method for prediction of the load carrying capacity of a corroded reinforced concrete beam (CRCB) is presented in the paper. Nine reinforced concrete beams, which had been working in an aggressive environment for more than 10 years, were tested in the laboratory. Comprehensive tests, including flexural test, strength test for corroded concrete and rusty rebar, and pullout test for bond strength between concrete and rebar, were condueted. The flexural test results of CRCBs reveal that the distribution of surface cracks on the beams shows a fractal behavior. The relationship between the fractal dimensions and mechanical properties of CRCBs is then studied. A prediction model based on artificial neural network (ANN) is established by the use of the fractal dimension as the corrosion index, together with the basic intbrmation of the beam. The validity of the prediction model is demonstrated through the experimental data, and satisfactory resuits are achieved.  相似文献   

Annual Anthropogenic Carbon Transport into the North Pacific Intermediate Water through the Kuroshio/Oyashio Interfrontal Zone: An Estimation from CFCs Distribution     

Tsuneo Ono  Yutaka W. Watanabe  Katsuyuki Sasaki 《Journal of Oceanography》2000,56(6):675-689

Vertical distribution of anthropogenic carbon content of the water (exDIC) in the Oyashio area just outside of the Kuroshio/Oyashio Interfrontal Zone (K/O Zone) was estimated by the simple 1-D advection-diffusion model calibrated by the distribution of chlorofluorocarbons (CFCs). The average concentration of exDIC for = 26.60–27.00 is multiplied by the volume transport of Oyashio water into the North Pacific Intermediate Water (NPIW) to estimate the annual transport of exDIC into NPIW through K/O Zone. The estimated transport of exDIC was 0.018–0.020 GtC/y, which corresponds to 15% of the whole total exDIC accumulation in the temperate North Pacific. A simple assessment using the NPIW 1-box model indicates that the current study explains at least 70% of the total annual transport of exDIC into NPIW, and that small exDIC sources for NPIW still exists in addition to K/O Zone.  相似文献   

Instantaneous separable VPA (ISVPA)     

Kizner  Z. I.; Vasilyev  D. A. 《ICES Journal of Marine Science》1997,54(3):399-411

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威海地区高压岩石组合及其成因演化     

韩宗珠  王来明  张希道  毛振业 《中国海洋大学学报(自然科学版)》1993,(3)

利用矿物地质温压计估算变质高峰期温压条件、退变质作用温压条件。研究表明,本区为鲁苏构造带的北延部分,代表本区晚元古代华南陆块与华北陆块的碰撞及三叠纪华北陆块向华南陆块推覆事件的发生和演化。  相似文献   

国外渔具选择性研究进展   总被引：2，自引：1，他引：2  

梁振林  葛长字  刘英光 《中国海洋大学学报(自然科学版)》2001,31(6):835-841

为了保护和可持续利用渔业资源 ,渔具选择性的研究在国际上倍受重视。该文以比较作业法中渔具选择性曲线的推导 ,特别是利用扩张 SEL ECT模型推导渔具选择性曲线为例 ,介绍国外渔具选择性研究的最新进展 ,以期作为我国开展这方面研究工作的参考  相似文献   

福建深沪湾潮间带全新世有孔虫及其环境意义   总被引：2，自引：1，他引：2  

王绍鸿  俞鸣同  唐丽玉  赵希涛  王雪梅  黄向华 《台湾海峡》2002,21(1):6-11

本文对深沪湾西部潮间带表层沉积物和两个钻孔岩芯共30个样品的有孔虫组成进行了定性和定量分析。结果表明，表层沉积物中有孔虫群分布规律明显，随着离岸向海越远，水深越大，有孔虫娄量从1倍数上升到5位数，种数为9-69种，多变度V31-44，复合分异度H（s)3.25-3.25。从钻孔岩芯中的全新世有孔虫群特征可看出，中全新世以来海面升降和海洋环境可分为2个阶段：（1）海水初到钻孔位置，有孔虫数量和种数较少，分异度不高，海相性程度较低。（2）后期（埋深1.8m和2.0m以浅），海面有所升高，变为潮间带（高潮位→中潮位→低潮位）环境。  相似文献   

台风移速突变的诊断分析及路径预报     

仲荣根 《海洋湖沼通报》1994,(2):149-154

本文利用台风移动方程对作用在台风上的各力进行了诊断分析：主要力是气压梯度力和地转偏向力，二者同量级，其他各力约小１－３个量级；当台风加速移动时，气压梯度力小于地转编向力；减速移动时，气压梯度力大于地转偏向力。用预报方程计算得到的台风路径与实际台风路径在趋势上近于一致，预报误差约为２００ｋｍ。  相似文献