Temporal-spatial variations of euphotic depth of typical lake regions in Lake Taihu and its ecological environmental significance   总被引：5，自引：0，他引：5  

ZHANG Yunlin  QIN Boqiang  HU Weiping  WANG Sumin  CHEN Yuwei  CHEN Weimin 《中国科学D辑(英文版)》2006,49(4):431-442

Euphotic depth can be defined as the portion of wa- ter column that supports the net primary productivity. Its lower end is the critical depth, namely, the depth measured when the daily net primary productivity is zero[1]. In the ecosystems of oceans, lakes and rivers, phytoplankton live in the euphotic depth and euphotic depth is usually taken as the lower boundary, when studying the primary productivity and biomass of phytoplankton; therefore the corresponding depth is sometimes called the t…  相似文献   

TSP在隧道超前地质预报的应用研究          下载免费PDF全文

冯永  李永鸿  杜文哲 《地震工程学报》2006,28(4):348-351

由于隧道施工经常遇到严重的地质灾害,施工前进行超前地质预报是十分必要的。本文介绍了TSP超前地质预报系统的技术特点和基本原理,结合工程实例探讨了在使用TSP过程中的一些技术问题。结果显示利用工程地质调查结论可以确定合理的探测方案和提高TSP的预报精度。  相似文献   

相山铀矿田西北部与东南部地学信息对比研究     

张万良  刘德长 《铀矿地质》2007,23(5):316-320

文章通过对相山铀矿田西北部与东南部地学信息的对比分析,揭示了地质结构和矿床产出特征的不均一性和不对称性的主要影响因素,为相山矿田深部找矿及远景区扩大提供了新的依据。  相似文献   

地质档案原本立卷归档雏议     

张月蓉 《云南地质》2007,26(3):352-354

地质档案原本是地勘单位开展地质工作的重要基础资料,大多是孤本,非常宝贵,但原始资料的立卷归档工作往往不够重视。笔者结合本单位的实际,从存在问题、解决问题中进行分析探讨,并提出解决地质资料立卷归档的主要途径。  相似文献   

North-south transfer zones and paleo-morphological reconstruction of the Xylokastro area (Corinth Gulf, Greece)     

Joachim Place  Yves Graud  Marc Diraison  Laurence Warr 《Tectonophysics》2007,440(1-4):121-139

A large number of studies have documented the structural and sedimentary architecture of the Corinth Gulf, especially the major E–W trending normal faults important in accommodating the main extensional strain and associated growth of the Gilbert fan deltas. However, the role of several N–S oriented structures that crop out at the surface and are detectable at depth by seismic reflection and gravity surveys are not clearly understood. Based on new geological data, collected near Xylokastro, we describe the N–S oriented tectonic activity of this area. The mapped inland faults correspond to off-shore structures identified in re-interpreted seismic lines and appear to have acted as a major transfer zone during the opening of the Corinth Gulf. Reconstruction of the paleo-topography based on sedimentary facies and the environment of clay mineral formation suggest these transfer zones played an important role in controlling both local structural relief and depositional conditions of the Gilbert fan deltas.  相似文献   

Linking the Sulu UHP belt to the Korean Peninsula: Evidence from eclogite, Precambrian basement, and Paleozoic sedimentary basins   总被引：13，自引：0，他引：13  

Mingguo Zhai  Jinghui Guo  Zhong Li  Daizhao Chen  Peng Peng  Tiesheng Li  Quanlin Hou  Qicheng Fan 《Gondwana Research》2007,12(4):388-403

Considerable debate on whether and how the Sulu Orogenic Belt extends eastward to the Korean Peninsula has remained over the past decade. New results reported here include the following: (1) an eclogite and retrograded eclogite-bearing complex (Hongseong Complex) is discovered in South Korea, in which the eclogite occurs as lenses in circa  810–820 Ma granitic gneiss. SHRIMP zircon dating of the eclogite yields  230 Ma for the metamorphic age and  880 Ma for the protolith age; (2) The basement of the Rangnim, Gyeonggi and Yeongnam massifs have affinities to the basement of the North China Block (NCB). However the Gyeonggi Massif encloses a minor amount of large or small slabs of the Hongseong Complex that are similar to the rocks of the Sulu Belt. (3) Two main Paleozoic basins within the Rangnim and Gyeonggi massifs have a similar Paleozoic tectono-stratigraphy to the NCB. (4) The Imjingang and Ogcheon belts do not exhibit any metamorphic characteristics of collisional orogenic belts. Based on these facts, we propose a crustal-detachment and thrust model and suggest that the collision belt between the Yangtze Block (YB) and NCB (Sino–Korea Craton) is preserved along the western margin of the Korean Peninsula. The lower part of the UHP metamorphosed lithosphere of the YB was subducted under the Korean Peninsula and not uplifted to the surface. The lower crust of the YB (the Hongseong Complex) was detached from the subducted lithosphere and thrust over the Korean Peninsula, and inserted into the basement rocks of the Gyeonggi Massif. The upper crust of the YB possibly was detached from the lower crust and overthrusted along the Honam and Chugaryong shear zones. The Imjingang and Ogcheon belts possibly represent the detached upper crust of YB and their present occurrences are controlled by a Mesozoic strike–slip shear structure. All these detached lower and upper crustal slabs were strongly deformed during the Late Jurassic and Early Cretaceous tectonic event leading to their present geological distribution and characteristics.  相似文献   

北秦岭二郎坪群重晶石岩热水沉积地球化学证据及其成矿意义   总被引：10，自引：0，他引：10  

冯胜斌  邢矿  周洪瑞  燕长海  彭翼  赵吉梅  胡绍斌  任建光 《世界地质》2007,26(2):199-207

北秦岭二郎坪群中存在与地层整合产出的层状重晶石岩和铜多金属矿床。重晶石岩贫Al2O3、TiO2组分含量;富集热液组分As、Sb、Ba、Ag和Hg;微量元素U/Th>1;低ΣREE(平均值27.78×10-6)、富集轻稀土(LREE)、亏损重稀土(HREE)、具明显Eu正异常、Ce负异常及与大西洋TAG热液区热液沉积物相似的球粒陨石标准化的稀土元素配分模式特征。这些特征揭示研究区重晶石岩是热水沉积成因型。热水沉积重晶石岩与铜多金属矿床的紧密联系说明,研究区铜金属矿床是海底热液喷流沉积成岩成矿作用的产物。  相似文献   

北祁连造山带老虎山奥陶系硅质岩地球化学特征及古地理意义   总被引：5，自引：0，他引：5  

朱杰  杜远生 《古地理学报》2007,9(1):69-76

对北祁连造山带老虎山地区下奥陶统和中、上奥陶统硅质岩的沉积学和地球化学研究表明：下奥陶统硅质岩为生物化学作用成因，沉积于被动大陆边缘深海环境；中、上奥陶统下部与玄武岩共生的硅质岩显示热液成因，沉积于洋脊环境；中、上奥陶统上部硅质岩指示生物化学成因，形成于大陆边缘环境。上述特征表明老虎山地区在早奥陶世为相对稳定的被动大陆边缘构造环境，所含硅质岩和陆缘碎屑岩为大陆斜坡相浊流沉积。中、晚奥陶世柴达木板块向华北板块俯冲在弧后产生离散型活动大陆边缘，形成弧后盆地，硅质岩及其共生的枕状玄武岩和浊积岩应属于扩张弧后盆地的产物。  相似文献   

《翁同龢日记》中的冷暖感知记录及其对气候冷暖变化的指示意义     

张学珍方修琦  齐晓波 《古地理学报》2007,9(4):439-446

依据清代《翁同龢日记》（以下简称《日记》）中逐日的冷暖感知记录和同时期的器测月均温资料，采用相关分析和线性回归分析等统计方法，以月为基本统计单元，对《日记》中冷暖感知记录反演气候变化的能力进行了分析。结果说明，《日记》中的冷暖感知记录可以用于气候变化研究，但是最佳代用指标因气候变化的时间尺度和季节而异。总体而言，极热、偏热、偏凉、极冷日数对年内月到季时间尺度气候变化的代表性较好，其中尤以偏凉和极冷日数最佳。 对于年际尺度上的气候波动，从季节对比来看，冷暖感知日数反演夏季（6-8月份）月均温的能力最差；从冷暖感知类型对比来看，极冷日数是多个月份月均温的最佳代用指标，1、3、5、9和12月份的最佳代用指标均是极冷日数。并且，还可以依据极冷日数的多寡识别极端冷、极端热年。由此可见，古代私人日记中的冷暖感知记录可以用于反演历史时期气候的冷暖变化。  相似文献   

西昆仑柳什塔格峰西侧火山岩的特征、时代及地质意义   总被引：1，自引：0，他引：1  

李博秦姚建新  王炬川计文化　韩芳林 《岩石学报》2007,23(11):2801-2810

在西昆仑麻扎-康西瓦-苏巴什结合带的柳什塔格一带发现了一套火山岩建造,主要由强蚀变玄武岩、绿帘阳起石岩、阳起石岩(原岩为玄武岩)组成,上覆少量深水沉积岩。火山岩的岩石地球化学特征表明其主要来源于富集地幔玄武岩浆,形成于洋岛环境,因此它是一个古结合带大洋洋壳的残留。采样作Rb-Sr等时线年龄分析,时代为震旦纪(563±48Ma),说明麻扎-康西瓦-苏巴什结合带所代表的洋盆在震旦纪就已经存在。这个发现对重新认识麻扎-康西瓦-苏巴什结合带的演化时限具有重要意义。  相似文献