湘中地区奥陶系和震旦系含锰层中稳定同位素组成的沉积学新解释          下载免费PDF全文

杨振强  蒋德和  赵时久 《沉积与特提斯地质》1993,(2):25-36

湘中地区有中奥陶世和早震旦世两个重要的锰碳酸盐层。安化县附近的湘锰组含锰泥灰岩和锰白云岩的碳和氧同位素值分别为—2.69～—4.00‰PDB和—6.87～—14.04‰PDB。湘锰组MnCO_3有δ~(12)C值—7.44～—13‰PDB和δ~(18)O值—2.65～—13.03‰。磨刀溪组黑色页岩(中奥陶世)中的Mn-泥灰岩显示负的δ~(13)C值(—1.7～—6.56‰PDB)和δ~(18)O值(—11.67～—14‰PDB)。但结晶锰矿石有更高的负δ~(13)C(—4.70％～—17.79‰PDB)和δ~(18)O(—11.67～17.27‰)。本区存在三种锰碳酸盐岩C和O同位素演化趋势:(1)安化地区的锰灰岩为稳定的δ~(13)C趋势;(2)湘锰组黑色页岩中的MnCO_3具有同步趋势:(3)中奥陶世黑色页岩中的锰矿石具有强烈反向趋势。碳成岩作用对锰碳酸盐形成过程中C和O同位素组成影响很大。湘锰组碳酸盐来源为非生物成因的海洋CO_2和SR至Me带的有机碳加入有关。磨刀溪组结晶锰碳酸盐的主要来源是热解脱羧基带(D)。δ~(34)S也为生物来源(—8～—27.49‰CDT)。Mn(％)品位与δ~(13)C呈负相关关系。证据表明锰碳酸盐成因与海盆地缺氧事件和海底热水(喷气)沉积有关。  相似文献   

城市地下管线信息系统的建立与应用   总被引：3，自引：0，他引：3  

区福邦  陈顺清 《地球信息科学学报》1999,1(2):24-31

本文以广州市建立综合性地下管线信息系统为背景,针对中国城市地下管线勘测与管理的现状,提出了地下管线普查与信息系统建立的实施流程,强调了数据源保证、标准化质量监控、实时更新等关键技术问题.实现了“普查成图与监理入库相结合、全面普查与竣工测量相结合、规划审批与现状信息相结合”的建立具有空间决策支持系统或专家系统雏形的综合性管线信息系统模式,该模式适用于管线历史资料不完整、精度不高的发展中国家的广大城市.  相似文献   

A Similarity-Based Approach for Improving the Efficiency of Drawing Spatiotemporal Point Features     

Mingguang Wu  Kun Zhang 《The Cartographic journal》2020,57(1):57-69

ABSTRACT

The mapping of spatiotemporal point features plays an important role in geovisualization. However, such mapping suffers from low efficiency due to computational redundancy when similar symbols are used to visualize spatiotemporal point features. This paper presents a similarity-based approach to predict and avoid computational redundancy, which improves mapping efficiency. First, to identify computational redundancy, the similarity of point symbols is measured based on commonalities in symbol graphics and symbol drawing operations. Second, a similarity-enhanced method is proposed to comprehensively predict and avoid computational redundancies when mapping spatiotemporal point features. This approach was tested using two real-world spatiotemporal datasets. The results suggest that the proposed approach offers relatively large performance improvements.  相似文献   

Biogeochemical processes of incorporation, transformation and migration of organic matter at the marine water-sediment interface: Simulation by C labelled compounds     

R. Buscail 《Organic Geochemistry》1986,10(4-6)

The study of biogeochemical processes at the water-sediment interface must be able to explain the relatively small content of organic carbon in the sediment, compared to the calculated carbon flux in the oceans. The input of an organic molecule at the marine sediment surface (Gulf of Lion, France) was simulated by the injection of a ¹⁴C labelled molecule in the water of a preserved interface. A glutamic acid [¹⁴C(U)] simulated marine organic matter, whereas a catechol [¹⁴C(U)] represented continental organic material. The separation by successive acid and basic extractions of the remaining initial compounds and the resulting products showed the relative importance of biological (respiration, assimilation) and geochemical (adsorption on argillaceous particles and condensation in geopolymers) processes occurring at the water-sediment interface. The evaluation was supported by the determination of the geochemical (humic substances), hydrological (conditions of temperature and degree of oxygénation) and sedimentological characteristics of the environment studied and by the estimation of the benthic activity.  相似文献   

The　application　of　ultrasonic　seismic　model　experiment　in　quality　test　of　cement　mortar　injection　of　Yongjiang　river　submarine　tun－nel　tube　foundation     

杨钢宇  郭铁栓  李金龙  杨导声 《地震学报(英文版)》1996,9(4):665-670

ＴｈｅａｐｐｌｉｃａｔｉｏｎｏｆｕｌｔｒａｓｏｎｉｃｓｅｉｓｍｉｃｍｏｄｅｌｅｘｐｅｒｉｍｅｎｔｉｎｑｕａｌｉｔｙｔｅｓｔｏｆｃｅｍｅｎｔｍｏｒｔａｒｉｎｊｅｃｔｉｏｎｏｆＹｏｎｇｊｉａｎｇｒｉｖｅｒｓｕｂｍａｒｉｎｅｔｕｎ┐ｎｅｌｔｕｂｅｆｏｕｎｄ...  相似文献   

输气管线中天然气水合物形成的地球化学控制因素   总被引：2，自引：2，他引：2  

徐文新  陈多福  陈光谦 《矿物岩石地球化学通报》2002,21(4):261-265

对于纯气体形成水合物，甲烷形成的温压条件最高，丁烷最低，乙烷和丙烷介于二之间。在甲烷-乙烷和甲烷-丙烷的二元混合体系中，形成水合物时随甲烷含量增高，形成温度降低、压力增高；对于自然产出天然气的多组分混合体系，随丙烷 丁烷含量增加，水合物形成压力降低，温度增高。增高水合物体系的盐度或加入阻凝剂，水合物的形成压力增高，温度降低。在确定的环境温度条件下，根据天然气成分可以确定天然气形成水合物的最大压力，从而能最大限度地提高输气设备的工作效率；加入阻凝剂或提高体系的盐度也可大大提高输气设备的工作效率。  相似文献   

西藏甲马铜多金属矿床金的叠加成矿   总被引：2，自引：0，他引：2  

任云生  粟登逵  张金树 《吉林大学学报(地球科学版)》2002,32(3):225-228

甲马铜多金属矿床各类矿石中金含量普遍较高。层次主矿体中金主要以细小的自然金形式包裹于斑铜矿和黝铜矿中。矿区多底沟组大理岩（层状主矿体顶板）中的构造破碎带内有独立金矿（化）体产出。喜山期中酸性，酸性岩脉也有不同程度的金矿化。不同产状金矿化持征，矿石ω（Au)/ω（Ag)比值等综合分析后认为：甲马矿区存在两期金矿化，即燕山期海底喷流积成矿作用中的伴生金矿化和与喜山期岩浆作用密切相关的热液型金矿化。  相似文献   

场地沉陷埋地管道反应分析方法   总被引：8，自引：1，他引：8  

高惠瑛  冯启民 《地震工程与工程振动》1997,17(1):68-75

场地的不均匀沉陷是导致埋地管线破坏的重要原因之一，至今，国内外对这一问题的研究甚少。本文提出了一个新的方法，用以分析受沉陷作用的埋地管道的反应，该方法选取跨越非沉陷区和沉陷区的埋地管道为研究对象，用三次曲线模拟沉陷区管道的几何大变形，推导出沉陷区段管道在几何大变形条件下的受力平衡方程的内力递推公式，用弹性地基梁模型模拟非沉陷区的管道变形，并用学陷区和非沉陷区交界面处的变形及力学协调条件给出了交界点  相似文献   

Anatomy of a submarine pyroclastic flow and associated turbidity current: July 2003 dome collapse, Soufrière Hills volcano, Montserrat, West Indies     

JESSICA TROFIMOVS  R. STEPHEN JOHN SPARKS  PETER J. TALLING 《Sedimentology》2008,55(3):617-634

The 12 to 13 July 2003 andesite lava dome collapse at the Soufrière Hills volcano, Montserrat, provides the first opportunity to document comprehensively both the sub‐aerial and submarine sequence of events for an eruption. Numerous pyroclastic flows entered the ocean during the collapse, depositing approximately 90% of the total material into the submarine environment. During peak collapse conditions, as the main flow penetrated the air–ocean interface, phreatic explosions were observed and a surge cloud decoupled from the main flow body to travel 2 to 3 km over the ocean surface before settling. The bulk of the flow was submerged and rapidly mixed with sea water forming a water‐saturated mass flow. Efficient sorting and physical differentiation occurred within the flow before initial deposition at 500 m water depth. The coarsest components (～60% of the total volume) were deposited proximally from a dense granular flow, while the finer components (～40%) were efficiently elutriated into the overlying part of the flow, which evolved into a far‐reaching turbidity current.  相似文献   

鄂尔多斯盆地西峰油田主要储层砂体的成因与演化   总被引：1，自引：0，他引：1  

刘自亮  王多云  李凤杰  孟祥化 《地质科技情报》2008,27(2):68-72

以鄂尔多斯盆地西峰油田上三叠统延长组为例,利用层序地层学理论对辫状河三角洲前缘沉积体系中以水下分流河道和河口坝两种储油砂体为主的多种成因组合进行了研究,将其划分为水下分流河道组合区、水下分流河道与河口坝混合区和河口坝组合区.详细刻画了辫状河三角洲前缘中主要储油砂体的成因类型,将水下分流河道成因砂体划分为叠加式水下分流河道砂体和完整式水下分流河道砂体两类;将水下分流河道与河口坝复合成因砂体划分为坝上河和河上坝砂体两类;将河口坝成因砂体划分为叠加式河口坝和孤立式河口坝砂体.讨论了各类成因砂体的形成机制.  相似文献