黄海、东海底栖生物的生态特点   总被引：12，自引：0，他引：12  

刘瑞玉  崔玉珩  徐凤山  唐质灿 《海洋科学集刊》1986,(27):153-174

黄海和东海，连同渤海，是面积广阔的陆缘海，绝大部分区域的深度不超过160m，超过200m的深水区范围很小，东海平均深度370m，黄海平均深度44m ，渤海只有18m。黄海、东海的海底地形、海流系统和水团结构都相当复杂。强大的高温高盐黑潮暖流水和以长江为主体的低盐冲淡水占主导地位。北部的黄海冷水则是在特殊的地理和气候条件下形成的夏季低温水团，而台湾暖流和黄海暖流对局部海域水文状况也有一定的影响。它们的存在及其相互作用决定了黄海和东海海域的底栖动物区系性质。此外，海底沉积物结构类型及其理化性质对底栖动物的组成和分布也有相当大的影响，不同种的分布式样明显地反映了粗、细、软、硬底质的分布轮廓；而有些底内动物的活动又对沉积物的物理纹层和化学特点产生一定的影响。 黄海、东海底栖动物种类很多，有的种数量很大，不少种(虾类)是具有经济价值的渔业捕捞对象，或是经济鱼虾的天然饵料，有些又可作为水团、海流的指示种，与生物资源的开发利用以及海洋生物科学的发展有密切关系。本文根据多年调查资料，系统反映中国东部近海大型底栖动物的概貌和生态特点，内容包括种类和群落组成、分布及其与水文和沉积环境的关系。  相似文献   

Fault Characteristics in Longmen Mountain Thrust Belt,Western Sichuan Foreland Basin,China   总被引：1，自引：0，他引：1  

万桂梅  汤良杰  杨克明  金文正  吕志洲  余一欣 《中国地质大学学报(英文版)》2008,19(6):611-624

Through field geological survey,the authors found that abundant thrust faults developed in the Longmen (龙门) Mountain thrust belt.These faults can be divided into thrust faults and strike-slip faults according to their formation mechanisms and characteristics.Furthermore,these faults can be graded into primary fault,secondary fault,third-level fault,and fourth-level fault according to their scale and role in the tectonic evolution of Longmen Mountain thrust belt.Each thrust fault is composed of several secondary faults,such as Qingchuan (青川)-Maowen (茂汶) fault zone is composed of Qiaozhuang (乔庄) fault,Qingxi (青溪) fault,Maowen fault,Ganyanggou (赶羊沟) fault,etc..The Longmen Mountain thrust belt experienced early Indosinian movement,Anxian (安县) movement,Yanshan (燕山)movement,and Himalayan movement,and the faults formed gradually from north to south.  相似文献   

柴达木盆地东部36～18kaB.P.期间的孢粉记录及其气候环境   总被引：1，自引：1，他引：0       下载免费PDF全文

万和文  唐领余  张虎才  李春海  庞有智 《第四纪研究》2008,28(1):112-121

对柴达木盆地察尔汗古贝壳堤剖面的沉积物进行孢粉分析,结果显示这个地区植被与气候在晚更新世中晚期经历以下几个阶段的变化:36.2～31.2kaB.P.(未校正14C年代,下同)期间,以禾本科、藜科、蒿属、莎草科为主,发育草原-草甸植被,气候温和湿润,盘星藻出现较多,反映淡水湖泊,水深在10m左右;31.2～27.6kaB.P.期间,松属、云杉属、桦属等为主的木本植物的含量增加,周围山地森林发育,表明气候温暖,降水量增多。但由于蒸发量大,有效湿度下降,荒漠成分柽柳属等增加,盘星藻在30kaB.P.以后消失,反映湖泊盐度增大;27.6～23.3kaB.P.期间,植被中荒漠成分显著增加,周围山地森林萎缩,气候趋向相对寒冷干旱,湖面积缩小;23.3～18.0kaB.P.,孢粉浓度很低,蒺藜科、藜科等荒漠成分明显增加,植被稀疏,已趋向荒漠化草原,反映气候寒冷干旱。从整个剖面来看,主要的陆生植物孢粉类型为禾本科、柽柳属、蒺藜科、麻黄属、松属、云杉属、柏科、胡桃属和桦属等,藜科和蒿属含量很少,这与柴达木盆地东部地区的表土分析结果完全不同,也与其他草原以及荒漠草原的表土花粉结果相异。这说明晚更新世中晚期柴达木盆地东部地区的植被和现在无法进行比较,气候环境与现在显著不同。  相似文献   

从地球系统科学角度浅析中国地貌若干问题研究的新进展   总被引：10，自引：3，他引：7       下载免费PDF全文

杨小平  师长兴  李炳元  朱秉启 《第四纪研究》2008,28(4):521-534

以地球系统中各圈层的相互作用为主线,分析总结了我国沙漠地貌过程、流水地貌过程、冰川地貌过程及风沙地貌过程等领域研究的部分进展。由于我国沙漠地理位置的特殊性,其形成和演变与岩石圈构造变动即青藏高原隆升有着紧密的联系,所以,对我国沙漠形成、演变的研究能为探讨青藏高原隆升历史提供重要佐证。近30年来,有关我国沙漠形成时代的认识更新较快。新的沉积记录显示,我国西北地区的沙漠在中新世时就已经出现了,但沙漠沙丘大规模扩展可能是在中更新世才开始的。既使在晚更新世以来,我国沙漠地区的气候也有过明显波动、沙漠地貌的特征也发生过显著变化。沙漠通过为沙尘暴提供物源,对全球变化产生驱动作用。从地表过程来看,风沙地貌的形成演变不仅受风力作用,而且受流水、湖泊等多种地貌动力过程的影响,地貌类型是各种动力过程共同作用的缩影。古冰川地貌曾是最早发现的第四纪气候变化的证据。随着新的测年技术的出现,学术界对我国第四纪古冰川地貌演化过程有了较系统、全面的认识。流水地貌过程应该是地球上作用区域最广的一种地貌动力过程,对流水地貌过程的认识目前正在向微观和宏观深入。  相似文献   

Application of Spectral Decomposition to Detection of Fracture-Cavity Carbonate Reservoir Beds in the Tahe Oiifieid, Tarim Basin, NW China     

Liu Xiaoping  Yang Xiaolan  Zhang Yazhong  Han Long 《《地质学报》英文版》2008,82(3):530-536

Ordovician fracture-cavity carbonate reservoir beds are the major type of producing formations in the Tahe oilfield, Tarim Basin. The seismic responses of these beds clearly changes depending on the different distance of the fracture-cavity reservoir bed from the top of the section. The seismic reflection becomes weak or is absent when the fracture-cavity reservoir beds are less than 20 ms below the top Ordovician. The effect on top Ordovician reflection became weaker with deeper burial of fracture-cavity reservoir beds but the developed deep fracture-cavity reservoir beds caused stronger reflection in the interior of the Ordovician. This interior reflection can be divided into strong long-axis, irregular and bead string reflections, and was present 80 ms below the top Ordovician. Aimed at understanding reflection characteristics, the spectral decomposition technique, which uses frequency to ＂tune-in＂ bed thickness, was used to predict Ordovician fracture-cavity carbonate formations in the Tahe oilfield. Through finely adjusting the processing parameters of spectral decomposition, it was found that the slice at 30 Hz of the tuned data cube can best represent reservoir bed development. Two large N-S-trending strong reflection belts in the mid-western part of the study area along wells TK440- TK427-TK417B and in the eastern part along wells TK404-TK409 were observed distinctly on the 30 Hz slice and 4-D time-frequency data cube carving. A small N-S trending reflection belt in the southern part along wells T403-TK446B was also clearly identified. The predicted reservoir bed development area coincides with the fracture-cavities connection area confirmed by drilling pressure testing results. Deep karst cavities occur basically in three reservoir bed-development belts identified by the Ordovician interior strong reflection. Spectral decomposition proved to be a useful technique in identifying fracture-cavity reservoir beds.  相似文献   

Regional yield estimation for winter wheat with MODIS-NDVI data in Shandong, China   总被引：3，自引：0，他引：3  

Jianqiang Ren  Zhongxin Chen  Qingbo Zhou  Huajun Tang   《International Journal of Applied Earth Observation and Geoinformation》2008,10(4):403

The significance of crop yield estimation is well known in agricultural management and policy development at regional and national levels. The primary objective of this study was to test the suitability of the method, depending on predicted crop production, to estimate crop yield with a MODIS-NDVI-based model on a regional scale. In this paper, MODIS-NDVI data, with a 250 m resolution, was used to estimate the winter wheat (Triticum aestivum L.) yield in one of the main winter-wheat-growing regions. Our study region is located in Jining, Shandong Province. In order to improve the quality of remote sensing data and the accuracy of yield prediction, especially to eliminate the cloud-contaminated data and abnormal data in the MODIS-NDVI series, the Savitzky–Golay filter was applied to smooth the 10-day NDVI data. The spatial accumulation of NDVI at the county level was used to test its relationship with winter wheat production in the study area. A linear regressive relationship between the spatial accumulation of NDVI and the production of winter wheat was established using a stepwise regression method. The average yield was derived from predicted production divided by the growing acreage of winter wheat on a county level. Finally, the results were validated by the ground survey data, and the errors were compared with the errors of agro-climate models. The results showed that the relative errors of the predicted yield using MODIS-NDVI are between −4.62% and 5.40% and that whole RMSE was 214.16 kg ha⁻¹ lower than the RMSE (233.35 kg ha⁻¹) of agro-climate models in this study region. A good predicted yield data of winter wheat could be got about 40 days ahead of harvest time, i.e. at the booting-heading stage of winter wheat. The method suggested in this paper was good for predicting regional winter wheat production and yield estimation.  相似文献   

基于MODIS数据的雪面温度遥感反演(英文)     

Ji Zhou  Yunhao Chen  Jing Li  Yan Tang 《地球空间信息科学学报》2008,11(4):247-251

On the basis of simplification of the Planck function in a low temperature range, this paper revises the practical split-window algorithm and presents a method for retrieving snow surface temperature （Ts） based on MODIS data in the middle-latitude region. The application of this method in Qinghai Lake region reveals that it is feasible for the retrieval of Ts. Results of correlation analysis indicate that there was strong negative relationship between Ts and altitude. By analyzing three typical areas in which land cover was relatively homogenous, this paper discusses the relationship between Ts and normalized difference snow index （NDSI） and then presents a new concept named ＂NDSI-Ts space＂.  相似文献   

澜沧江某水电站右坝肩工程边坡倾倒变形问题的数值 模拟研究   总被引：1，自引：0，他引：1  

赵小平  李渝生  陈孝兵  林富财 《工程地质学报》2008,16(3):298-303

澜沧江某水电站处于青藏高原东部边缘地带,属于高山峡谷地形地貌,高地应力环境,岩体卸荷裂隙很发育,使得倾倒变形和岩体质量、断裂活动及地震构造一样成为影响工程边坡岩体稳定的主要因素。针对工程边坡的大变形问题可采用离散元的数值模拟分析方法。通过建立理论开挖和工程边坡开挖离散元模型,可分别得出倾倒变形破坏机理发展过程为初期弱倾倒变形岩体的层内剪切错动、强倾倒变形岩体的层内拉张变形、强倾倒变形岩体的切层张-剪破裂及极强倾倒破裂岩体的折断张裂(坠覆)破裂和工程边坡的变形范围、确定开挖面及加固方式等。通过工程边坡模型的计算结果和现场地质调查成果的比较表明,计算结果和实际情况基本吻合。  相似文献   

软弱夹层几何参数对试样力学行为影响颗粒元模拟研究   总被引：2，自引：0，他引：2  

张晓平  吴顺川  张兵  潘文 《工程地质学报》2008,16(4):539-545

基于离散元理论的颗粒元程序,采用颗粒接触连接模型和滑动模型,建立了含软弱夹层试样的颗粒元模型。通过数值模型实验,对不同软弱夹层几何参数试样进行加载模拟,探讨了不同夹层厚度及不同倾角条件下试样的破坏过程和破坏形式,并分析其对试样强度的影响。模拟结果表明,裂隙首先产生于软弱夹层处,随着荷载的增加,再逐渐扩展,呈现渐进性破坏特征;夹层越厚,倾角越大,试样沿软弱夹层呈现较强的滑动特征,如果夹层薄且缓,软弱夹层成为试样破坏的非控制因素;软弱夹层厚度和夹角对试样的峰值强度都有影响,随软弱夹层厚度和夹角的增大,试样的峰值强度降低。  相似文献   

底摩擦重力试验在倾倒变形岩体稳定性研究中的应用   总被引：2，自引：0，他引：2  

陈孝兵  李渝生  赵小平 《地学前缘》2008,15(2):300-304

底摩擦重力试验(底摩擦试验)是利用相似理论分析原理,将研究原形按几何比例和各种物理力学参数,制作相似模型及确定相应的边界条件。然后按照相似边界条件进行加载试验,再现曾经发生过或今后将会出现的物理力学现象,进而了解其发展演化规律及其对工程的影响。澜沧江某水电站坝肩主要为典型的倾倒变形岩体,为探讨倾倒变形岩体在天然重力场条件的变形破裂发展趋势。试验采用模拟重力场条件的岩体底摩擦模型试验技术模拟分析岩体倾倒变形进一步发展演变过程及特征。  相似文献