湖南会同寒武纪早期有机碳同位素地层学研究          下载免费PDF全文

王丹  凌洪飞  ULRICH Struck  姚素平  李达  卫炜  魏广祎 《高校地质学报》2016,22(2):274

寒武纪早期是地球海洋环境与生命演化的关键时期,但目前扬子东南缘深水相区的早寒武纪地层尚缺乏系统、精确 的地层对比工作。该文选取湖南省怀化地区会同钻孔剖面（深水相区） 的留茶坡组硅质岩、小烟溪组黑色页岩为研究对 象,进行了高分辨的有机碳同位素（δ13Corg） 地层对比,结果在会同剖面自下而上识别出四个正漂移（P1、P2、P3和P4） 与两个负漂移（N1和N2）,结合其他剖面的生物化石记录和锆石U-Pb年龄资料,将会同剖面有机碳同位素与湖南其他 剖面,以及和云南和三峡等地浅水相区剖面的有机碳、无机碳同位素曲线进行对比,认为扬子东南缘埃迪卡拉系-寒武 系界线在湖南深水相区可放置于留茶坡组上部较大的有机碳同位素负漂移（Basal Cambrian Carbon isotope Excursion, BACE） 出现的位置,但由于钻孔深度不够,所以该负漂移未在会同剖面获得,而P1、P2和P3分别对应于寒武系的ZHUCE （ZHUjiaqing Carbon isotope Excursion,第二阶）、CARE （Cambrian Arthropod Radiation isotope Excursion,第三阶） 和MICE（MIngxinsi Carbon Isotope Excursion,第四阶） 正漂移,N1 和N2 分别对应于寒武系的SHICE （SHIyantou Carbon isotope Excursion,第二阶） 和AECE（Archaeocyathid Extinction Carbon isotope Excursion,第四阶） 负漂移,因此会同剖面留茶坡组顶部至小烟溪组底部属于寒武系第二阶,小烟溪组下部属于寒武系第三阶,而小烟溪组中-上部属于寒武系第四阶,而顶 部是否达到第四阶顶部尚无法确认。碳同位素的负漂移可能是海侵时期上升流水体将底层富含12C还原水体带至浅水地区所 致,并分别与埃迪卡拉动物群、小壳化石动物群和古杯动物的灭绝密切相关;而在生物繁盛时期,海洋初级生产力升高, 有机质埋藏增加,导致碳同位素的正漂移。  相似文献   

日照港深水航道泥沙运移及航道选址研究     

吕海滨  刘刻福  王永吉  刘有刚  刘常乐 《海洋通报》2005,24(3):1-7

使用SP2100波潮仪和ADCP海流计等多种先进仪器在台风季节进行了波浪、海流和潮汐观测,在取得大量现场观测子料基础上,结合长期的岸站资料对该海域的水文特征及水动力特征进行了系统综合分析。通过2002年对日照港深水航道海域含沙量和水深测量等成果,进行断面输沙、航道冲淤量及航道海域泥沙数值模拟等方面的计算,并采用POM模式。选择了几种有代表性的风浪情况,分别对港口附近海域进行了“波浪掀沙、潮流输沙和海底演变”的数值模拟。通过上述方法,对1998年12月竣工的-11m水深的航道的淤积状况进行了探讨,并推荐方案1为深水航道的首选方案,方案5居次。  相似文献   

Numerical simulation of tidal current and erosion and sedimentation in the Yangshan deep-water harbor of Shanghai   总被引：2，自引：1，他引：1  

ZUO Shu-Hua  ZHANG Ning-Chuan  LI Bei  ZHANG Zheng  ZHU Zhi-Xia Ph.D c  idate  State Key Laboratory of Coastal  Offshore Engineering  Dalian University of Technology  Dalian  China  Key Laboratory of Engineering Sediment of Ministry of Communications  Tianjin Research Institute of Water Transport Engineering  Tianjin  China. Dr.  Prof.  China Research Scientist  Key Labor... 《国际泥沙研究》2009,24(3):287-298

Yangshan near-shore sea area is the multi-island and multi-channel area with strong flow velocity and high suspended sediment concentration. Based on the characteristics of tidal currents, waves, and sediment in the Yangshan area, a two-dimensional numerical model of tidal currents, sediment transport, and sea bed deformation is developed. In the model, the effects of tidal currents and wind waves on sediment transport are considered. According to characteristics of the study area, unstructured grids are applied to fit the boundaries of the near-shore sea area. The results show that the calculated values are in good agreement with the measured data. The field of tidal currents, suspended sediment concentrations, and the deformation of the seabed can be successfully simulated.  相似文献   

Diversity history of Ordovician graptolites and its relationship with environmental change     

Zhang YuanDong  Chen Xu 《中国科学D辑(英文版)》2008,51(2):161-171

Statistical analysis based on global data indicated that the planktonic graptolites presented a distinguished pattern from that of benthic communities during the great Ordovician biodiversification. The graptolites started to diversify from the beginning of Ordovician and reached an acme in the early Middle Ordovician, but subsequently underwent a steady decline to the end of Ordovician. During the Ordovician, many clades of the graptolites made their originations, flourishing and replacements. However, in different regions and distinct environments across the world, graptolites may presumably display distinct patterns of radiation and evolution, a hypothesis to be tested. Herein a study of the graptolite diversity in the Early to Middle Ordovician in the Upper Yangtze Region (Platform) and Jiangnan Region (Slope), South China, is conducted. The results indicate that graptolites underwent a remarkable increase in both regions, but with distinct magnitude, scope, process and patterns. The diversification of graptolites in the Upper Yangtze Region, though less prominent, is divided into four stages and includes two peaks. In the Jiangnan Region, the graptolite diversification is far more prominent and includes three stages and one peak. Based on the distinct diversity histories and composition of graptolites in the two representative regions, a 'deep-water origin and shallow-water dispersal' model is proposed for the Ordovician graptolite faunas. According to the model, the major graptolite faunas of Ordovician originated in the deep-water region on the continental slope, the source of the graptolite novelties, and subsequently spread into shallow-water region on the shelf. Besides, we also conduct a comparison study of the Ordovician graptolite diversity in South China and other major regions. The results display that the graptolites diversified globally in the Early and Middle Ordovician. At the beginning of Ordovician, graptolites underwent a significant ecological innovation of graptolites: planktonic forms were derived from their benthic ancestors. This derivation resulted in the great guild expansion of graptolites. In late Early Ordovician (Floian), the global expansion of graptolites commenced. From the Floian to the end of Middle Ordovician, the graptolites diversity increased remarkably and displayed three peaks for all the regions. However, the peaks are somewhat distinct in magnitude and timing among regions. The Darriwilian peak is prominent in both South China and Baltic region, but inconspicuous in Australasia. No close relationship between the graptolite diversification and the palaeolatitudes are supported herein. Instead, the graptolite diversification seems to coincide with the global sea-level rises, suggesting a possible intrinsic relationship between them.  相似文献   

新疆塔里木板块西北缘早二叠世深水遗迹化石的发现及意义   总被引：3，自引：0，他引：3  

《沉积学报》2000,18(4)

在新疆塔里木板块西北缘下二叠统比尤勒提群中部首次发现了大量深水遗迹化石,主要包括Glockeria Ksiazkiewicz 1968,Helminthoida sp., Megagrapton sp., Paleodictyon sp., Paleodictyon (Glenodictyum) Croaticum Ulchman 1995, Planolites sp., Protopaleodictyon sp., Scalarituba missouriensis Weller 1899, Spirophycus sp.等,代表典型深海环境的Nereites遗迹相。根据对温古尔剖面的研究,比尤勒提群下部为浅海陆棚相砂泥质灰岩、粉砂质泥岩、粉砂岩、泥晶灰岩等;而含丰富遗迹化石的比尤勒提群中部为一套深海海底扇沉积的浊积岩系夹少量硅质岩,并且在浊积扇的不同位置所产遗迹组合类型也明显不同,扇根以觅食迹为主,含大量穿相分子,扇中开始出现牧食迹,扇梢则出现特征的耕作迹;比尤勒提群上部为浅海陆棚－滨海相沉积的硅质灰岩、泥晶灰岩和砂质灰岩及粉砂质泥岩、钙质砂岩等。该套遗迹化石组合与深海浊积事件密切相关,同时表明塔里木板块西北缘早二叠世时期存在一个陆棚浅海－深海盆地沉积环境,晚二叠世时期海水向西退去形成陆相沉积。  相似文献   

Fatigue reliability analysis in time domain for inspection strategy of fixed offshore structures   总被引：2，自引：0，他引：2  

T. M. Madhavan Pillai  A. Meher Prasad 《Ocean Engineering》2000,27(2):264

The paper describes a methodology for estimation of reliability of fixed offshore structures with respect to fatigue and extreme stress. The failure criteria for fatigue are formulated using fracture mechanics principle and that for extreme stress using API Code. Advanced Second Moment method is used to find the reliability index. The total life of the structure is divided into a set of stationary sea-states, occurring during storms and described by directional power spectrum. The method has been illustrated through application to a typical jacket platform. Usefulness of the methodology for planning in-service inspections has been highlighted.  相似文献   

“埕岛二号”中心平台非灌浆腿导管架结构设计   总被引：7，自引：0，他引：7  

路国章  刘锦昆 《海岸工程》2000,19(1):8-11

结合“埕岛二号”生活平台介绍了非灌浆腿导管架的结构分析的细部构造设计计算,将其受力性能与常规导管架作了对比总结了该结构型式的导管架在结构设计时应注意的问题。  相似文献   

考虑结构-桩-土相互作用的导管架平台优化设计   总被引：11，自引：4，他引：7  

宋玉普  封盛  康海贵 《海洋工程》2000,18(2):18-23

首先建立了多设计准则、多约束条件的面向结构-桩-土相互作用的导管架海洋平台优化设计模型,然后给出了此模型与结构分析软件及优化算法软件相结合进行优化设计的方法,并以胜利油田埕北11#井单井采油平台为例进行优化设计.结果显示所建模型既不依赖于优化算法,也不依赖于初始设计值,目标函数值均收敛于同一极小值且收敛速度较快、减小幅度可观,从而说明了此模型的合理性.  相似文献   

Age estimation, growth, maturity, and distribution of the bluemouth rockfish Helicolenus d. dactylopterus (Delaroche 1809) from the Rockall Trough     

Kelly  C. J.; Connolly  P. L.; Bracken  J. J. 《ICES Journal of Marine Science》1999,56(1):61-74

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浮筒辅助大型导管架结构整体拆除上浮过程动力响应特征研究     

吕泽宇  车巨鹏  王树青  宋宪仓 《海洋工程》2023,41(3):37-47

浮筒辅助大型导管架结构整体拆除作业是一个连续过程,作业过程中拆除系统的动力荷载及动力参数均会发生显著变化,传统基于某一稳定状态的结构动力响应分析方法不能准确预测拆除系统上浮过程中的动力响应。通过建立浮筒辅助大型导管架结构整体拆除上浮过程动态分析模型,对拆除系统上浮过程的动力响应特性进行研究。结果表明,整体拆除动态分析模型可以准确描述拆除系统上浮过程中浮筒及导管架浮力变化对上浮高度的影响机制,拆除系统上浮高度约为不考虑浮筒和导管架浮力变化时的90%。此外,浮筒辅助大型导管架整体拆除方法的动态稳定性较强,四级海况下拆除系统的最大偏移量仅为4.2 m,有较好的工程应用前景。  相似文献