根据底栖有孔虫方解石的Mg/Ca推测新生代深海温度和全球冰体积     

Lear  CH  季福武 《海洋地质前沿》2001,17(8):16-18

通过深海底栖有孔虫方解石的Ｍｇ／Ｃａ比值已经获得５０Ｍａ以来的深海温度记录。该记录在形式上与相应的底栖氧同位素比值（δ１８Ｏ）记录非常相似 ,并且显示了深海温度的４个主要变冷时期 ,总体下降约１２℃。底栖δ１８Ｏ记录和Ｍｇ 温度记录的一起应用表明 ,南极冰首次快速地堆积于早渐新世（３４ＭａＢＰ） ,但未伴随有深海温度的降底。一般认为 ,在过去的１００Ｍａ中 ,即从所谓的白垩纪中期的“温室”到晚新生代的“冰库” ,地球的气候经历了巨大的变化。这一时期的长期寒冷被认为是由地球表面热量及其分布的影响因素共同引起。大…  相似文献   

墨西哥湾白恶纪—第三纪界面的底栖有孔虫     

LaiaAlegret  高莉玲 《海洋地质前沿》2001,17(12):16-18

自Ａｌｖａｒｅｚ等（１９８０）提出白垩纪—第三纪（Ｋ—Ｔ）分界期出现一次火流星撞击事件之后 ,发生大规模生物灭绝的这个时期便引起人们的关注。撞击的影响是 :浮游有孔虫和钙质超微浮游生物大规模灭绝、全球Ｉｒ异常、形成契克苏卢博撞击坑、撞击坑附近出现可疑碎屑沉积。麦斯特里希特末期和丹麦早期 ,Ｌａｒａｍｉｄｅ造出运动和ＳｉｅｒｒａＭａｄｒｅＯｒｉｅｎｔａｌ将细粒碎屑物质输送到墨西哥海盆东北部。坦皮科—米桑特拉海盆Ｋ—Ｔ界面碎屑沉积显示白垩系上统门德斯组近海泥灰岩和下第三系下统韦拉斯科组互层。此单元上方为年…  相似文献   

东太平洋深海沉积物元素地球化学特征及影响因素     

高素兰 《黄渤海海洋》1997,15(4):23-30

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A preliminary study on thermoluminescence characteristics of sediments from the North Pacific     

LV Huahu  SHI Xuef  WU Yonghu  YANG Gang  WEI Jianwei  REN Xiangwen 《海洋学报(英文版)》2007,26(3):56-72

Thirty-eight surficial deposit samples were collected from the equatorial North Pacific, and the natural thermoluminescence (TL) characteristics of both bulk and clay fraction samples (<2 μm fractions) were studied by the FJ427-A1 automatic TL Dosimeter for the first time. With the measurements of clay mineral composition, element composition by XRD and ICP, the correlations between TL intensity and sedimentary environment proxies were analyzed, such as water depth, ratio of FeO to Fe2O3 contents, LOI, and major clay mineral concentration, and it was found the bulk sample’s TL signal was stronger than the clay ones. Usually, increase in the clay components may result in the decrease of TL intensity. From the shape of TL curves, the pelagic sediments can be divided into two groups: the majority group has two glow peaks, in general, the first peak is broad and flat, but the second narrow and sharp; the minority group only has a single peak because the first is absent. The peak centers of TL curves are almost fixed, falling in the temperature sections 230~260 and 390~405 ℃ respectively. Lorentz model packed in the Origin 7.5 was chosen to deal with the TL curves. From the processing results, three parameters (H, C and A), corresponding to the height, center, and kurtosis of TL curve, were obtained to describe the curve characteristics. The correlations between TL curve parameters and sedimentary environment proxies were also calculated. On the basis of the above work, the relationship between TL characteristics and sediment type, mineral composition, sedimentary environment of surface sediments was discussed in the study area, and a conclusion is: sediments from the environment of shallower water, higher organic contents and weaker reductivity have stronger TL signals.  相似文献   

胶州湾浮游生物群落NH₄⁺-N的吸收与再生通量   总被引：2，自引：1，他引：2       下载免费PDF全文

焦念志  王荣 《海洋与湖沼》1993,24(3):217-225

通过4个季节(1991年11月—1992年7月)的现场实验观测,初步研究了胶州湾表层浮游生物群落的NH_4~+-N吸收、再生通量的有关问题。结果表明,NH_4~+-N吸收、再生通量的季节变化为:夏季>春、秋季>冬季;周日变化为:吸收通量在白天大于夜间,再生通量夜间大于白天;全年平均,吸收通量为0.073μ mol/(L·h),再生通量为0.053μ mol/(L·h),再生通量始终小于吸收通量;NH_4~+-N的周转时间最长为16.34d(冬季),最短为0.68d(夏季);吸收通量主要来自Picoplankton(占总量的46％—57％);NH_4~+-N吸收具有光依赖性,不同粒级的光依赖顺序为:Netplankton>Nanoplankton>Picoplankton。  相似文献   

Adaptive Neural Network Control with Control Allocation for A Manned Submersible in Deep Sea     

俞建成张艾群  王晓辉吴宝举 《中国海洋工程》2007,21(1):147-161

This paper thoroughly studies a control system with control allocation for a manned submersible in deep sea being developed in China.The proposed control system consists of a neural-network-based direct adaptive controller and a dynamic control allocation module.A control energy cost function is used as the optimization criteria of the control allocation module,and weighted pseudo-inverse is used to find the solution of the control allocation problem.In the presence of bounded unknown disturbance and neural networks approximation error,stability of the closed-loop control system of manned submersible is proved with Lyaponov theory.The feasibility and validity of the proposed control system is further verified through experiments conducted on a semi-physical simulation platform for the manned submersible in deep sea.  相似文献   

Hybrid Model Testing Technique for Deep-Sea Platforms Based on Equivalent Water Depth Truncation     

张火明杨建民  肖龙飞 《中国海洋工程》2007,21(3):401-416

In this paper,an inner turret moored FPSO which works in the water of 320 m depth,is selected to study the so-called "passively-truncated numerical-simulation" type of hybrid model testing technique while the truncated water depth is 160 m and the model scale λ=80.During the investigation,the optimization design of the equivalent-depth truncated system is performed by using the similarity of the static characteristics between the truncated system and the full depth one as the objective function.According to the truncated system,the corresponding physical test model is made.By adopting the coupling time domain simulation method,the truncated system model test is numerically reconstructed to carefully verify the computer simulation software and to adjust the corresponding hydrodynamic parameters.Based on the above work,the numerical extrapolation to the full depth system is performed by using the verified computer software and the adjusted hydrodynamic parameters.The full depth system model test is then performed in the basin and the results are compared with those from the numerical extrapolation.At last,the implementation procedure and the key technique of the hybrid model testing of the deep-sea platforms are summarized and printed.Through the above investigations,some beneficial conclusions are presented.  相似文献   

赤潮期间藻类的化感效应   总被引：2，自引：1，他引：2       下载免费PDF全文

彭喜春  杨维东  刘洁生 《海洋科学》2007,31(2):84-88

海洋环境条件的变化导致浮游生物(微藻、原生动物或细菌)暴发性增殖或高度聚集使局部水体改变颜色产生赤潮.海洋浮游微藻是引发赤潮的主要生物,在4 000多种浮游微藻中有260多种能形成赤潮,中国沿海的赤潮生物有148种,其中43种曾引发过赤潮.  相似文献   

深海沉积物早期成岩作用的多元非线性稳定模型     

Dhak  SP 张丽洁 《海洋地质前沿》1996,(8):11-13

深海沉积物早期成岩作用的多元非线性稳定模型ＳｕｎｙａＰ．Ｄｈａｋａｒ等现代海洋沉积物中有机物氧化作用对Ｃ。Ｐ、Ｍｎ、Ｆｅ及其它金属元素的全球循环有着重要的影响。就此，业已提出了各种数学模型。虽然这些模型对有机物氧化作用做了较好的定量研究，但仍有其特定...  相似文献   

从戴威尔斯钻孔看米兰科维奇理论     

J．Imbrie李日辉  李国胜 《海洋地质前沿》1994,(1):6-8

1992年，Winograd等在美国《科学》杂志上撰文报道了南内华达州戴威尔斯钻孔(DH-11)的δ^18O记录．岩心采自覆盖一充水洞穴的方解石层，长36cm．其时间分辨率可与深海δ^18O的精度相媲美．包括了21个利用^230Th方法所做的精确的放射性数据(Ludwig，1992)．  相似文献