Different expressions of rifting on the South China Sea margins     

《Marine and Petroleum Geology》2014

Rifting of continental margins is generally diachronous along the zones where continents break due to various factors including the boundary conditions which trigger the extensional forces, but also the internal physical boundaries which are inherent to the composition and thus the geological history of the continental margin. Being opened quite recently in the Tertiary in a scissor-shape manner, the South China Sea (SCS) offers an image of the rifting structures which varies along strike the basin margins. The SCS has a long history of extension, which dates back from the Late Cretaceous, and allows us to observe an early stretching on the northern margin onshore and offshore South China, with large low angle faults which detach the Mesozoic sediments either over Triassic to Early Cretaceous granites, or along the short limbs of broad folds affecting Palaeozoic to Early Cretaceous series. These early faults create narrow troughs filled with coarse polygenic conglomerate grading upward to coarse sandstone. Because these low-angle faults reactivate older trends, they vary in geometry according to the direction of the folds or the granite boundaries. A later set of faults, characterized by generally E–W low and high angle normal faults was dominant during the Eocene. Associated half-graben basement deepened as the basins were filling with continental or very shallow marine sediments. This subsequent direction is well expressed both in the north and the SW of the South China Sea and often reactivated earlier detachments. At places, the intersection of these two fault sets resulting in extreme stretching with crustal boudinage and mantle exhumation such as in the Phu Khanh Basin East of the Vietnam fault. A third direction of faults, which rarely reactivates the detachments is NE–SW and well developed near the oceanic crust in the southern and southwestern part of the basin. This direction which intersects the previous ones was active although sea floor spreading was largely developed in the northern part, and ended by the Late Miocene after the onset of the regional Mid Miocene unconformity known as MMU and dated around 15.5 Ma. Latest Miocene is marked by a regional basement drop and localized normal faults on the shelf closer to the coast. The SE margin of the South China Sea does not show the extensional features as well as the Northern margin. Detachments are common in the Dangerous Grounds and Reed Bank area and may occasionally lead to mantle exhumation. The sedimentary environment on the extended crust remained shallow all along the rifting and a large part of the spreading until the Late Miocene, when it suddenly deepened. This period also corresponds to the cessation of the shortening of the NW Borneo wedge in Palawan, Sabah, and Sarawak. We correlate the variation of margin structure and composition of the margin; mainly the occurrence of granitic batholiths and Mesozoic broad folds, with the location of the detachments and major normal faults which condition the style of rifting, the crustal boudinage and therefore the crustal thickness.  相似文献   

Issues and challenges in spatio-temporal application of an ecosystem services framework to UK seas     

《Marine Policy》2014

The concepts of ecosystem services and human welfare provide strong integrative frameworks that can be used to inform marine policy and management decisions that support sustainable development. A theoretical framework has been developed and applied to create a model for UK seas to measure changes in final ecosystem services, in terms of human welfare. The model that has been developed is explicitly spatial and temporal to facilitate its use in supporting marine planning decisions. The development and application of this framework to UK seas necessarily requires many assumptions to be made. The paper describes the development and population of the framework and discusses the practical limitations and challenges in seeking to develop and apply such models. Significant differences in long-term values of different services were identified under the different scenarios. All scenarios highlight the projected decline in oil and gas revenues which provide particular intense values at sites of extraction. These values are partially replaced by revenues from offshore renewables in some of the scenarios. Values associated with carbon sequestration, maritime transport, tourism and pollution assimilation are also very significant but more spatially diffuse. The study has demonstrated that it is possible to develop spatio-temporal models to evaluate changes in final ecosystem service benefits using existing data, although the approach necessarily requires many assumptions to be made.  相似文献   

汶川县震后5年生态环境质量恢复评价   总被引：2，自引：0，他引：2  

杨斌  曹春香  田蓉  刘诚  田海静  刘迪  项海兵 《遥感学报》2014,18(4):946-957

对汶川县震后5年生态恢复状况进行评价,以多源遥感数据为主,其他调查统计数据为辅,构建了基于压力—状态—响应模型的生态环境质量评价指标体系,采用综合指数法对汶川县2007年、2008年和2013年生态环境质量进行评价,得到震前、震后以及5年后的生态环境质量评价分级图,并对震后5年汶川县生态恢复状况进行分析。结果表明,2007年汶川县有79.4%的区域生态环境质量良好,2008年5月12日地震对生态环境造成极大破坏,尤其是靠近震源地区,生态环境质量下降更为严重。通过震后5年恢复,到2013年汶川县生态环境质量恢复比较显著,有55.84%的区域环境质量有明显改善,特别是生态环境质量较差地区改善幅度较大,但仍未达到2007年区域生态环境质量水平。最后为今后该区域生态环境恢复重建提出相应的建议。  相似文献   

数字晋江地理空间框架数据建设及关键技术     

周友义 《现代测绘》2014,(1):61-64

本文介绍了数字晋江地理空间框架数据建设及关键技术,包括建设内容、主要建设内容的关键技术和流程方法,对于其他地方的数字城市地理空间框架的数据建设具有参考价值。  相似文献   

第一次世界大战初期德国东亚驻军跨岛链作战的军事地理分析     

杨霄 《地理学报》2023,78(1):230-240

就军事地理环境而言,当代中国在海洋方向面临的最主要威胁来自环中国岛链的封锁,研究这一限制性地理环境对准备和实施军事活动的影响与相应对策,具有重要的现实意义。第一次世界大战（简称“一战”）初期,德国东亚驻军进行了跨岛链作战的实践,但在日本海军依托岛链和优势兵力的封锁下,其战略目标未能达成,并且出现了军事地理位置上的优劣转换。本文通过对“一战”初期德国东亚驻军跨岛链作战行动的军事地理分析,尝试提出军事地理研究思路、跨学科融合路径和分析框架。本文分析认为,彼时德占青岛虽然具有良好的战略态势和强大的军事力量,但孤悬海外,且缺乏战略纵深;从宏观的区域尺度分析来看,基地与舰队间的联系被岛链分隔,腹背受敌,军事地理上的劣势凸显。但依托岛链进行封锁,需要集结大量兵力,利用对方边缘区内作战力量相对比较薄弱的有利条件,原本实力较弱的德国东亚舰队取得了重大战果,形成反转式的“核心—边缘”结构。本文为中国的海疆安全和海洋强国建设提出了5条建议。  相似文献   

在时空框架中理解中国大学人文地理教学特色及其成因——以1912—1949年中国主要大学地理系为例     

周尚意  江道敏 《地理研究》2023,42(2):580-596

采用历史唯物主义史观,建立一个时空框架,分析民国时期中国大学人文地理教学特色及其成因。本文主要关注1912—1949年间,国立北平（北京）师范大学、国立中央大学、国立清华大学、国立中山大学的地理系的人文地理学教学特色。研究史料来自大学的教学档案、人物回忆文章、政府文件、中国学者编撰和翻译的教材和教参,同时参考了相关研究文献。借助时空框架,基于史料对比,得出结论：(1)只有在历史的时间脉络下,才能理解民国时期军事地理、国防地理和政治地理课程设置的必然性;(2)只有在世界格局的空间框架下,才能理解民国时期的“国耻地理”教育内容,以及“中体西用”主张的失败;(3)只有将时空框架进一步细化,才能深入理解民国时期大学人文地理教学中不同教师的能动性,如学术思想、教学风格、政治主张、教材编写和选用等。综上所述,只有站在开放的时空框架中,才能更为清醒地定位当前中国大学人文地理学教学。  相似文献   

湖南省成矿地质事件纲要          下载免费PDF全文

柏道远  唐分配  李彬  曾广乾  李银敏  姜文 《中国地质》2022,49(1):151-180

[研究目的]湖南省矿产资源丰富,矿种及成因类型繁多,但对各类矿产形成的时代和构造背景尚缺乏系统归纳和总结.[研究方法]本文在既有区域矿产资料基础上,结合近些年区域构造演化、成岩成矿年龄、矿床成因机制等研究成果,对湖南省成矿地质事件及各期成矿事件的构造背景、矿床成因、矿产发育和分布特征等进行了系统探讨和总结.[研究结果]...  相似文献   

基于数字城市地理空间框架的GIS应用系统建设   总被引：1，自引：0，他引：1  

雷林辉 《测绘工程》2013,22(4):48-51

数字城市地理空间框架集成了基础地理信息数据、专题数据、GIS功能等各类资源,并通过公共服务平台为公共管理和社会公众提供服务。文中对基于数字城市地理空间框架构建GIS应用系统的流程、内容进行分析,说明地理空间框架对GIS应用系统建设的重要意义。  相似文献   

HydrIS: An open source GIS decision support system for groundwater management (Morocco)     

Hassane Jarar Oulidi  Ralf Löwner  Lahcen Benaabidate  Joachim Wächter 《地球空间信息科学学报》2013,16(3):212-216

A regional groundwater management system has been elaborated, integrating Relational Database Management System (RDBMS) and various web services. It consists of web geospatial application so-called HydrIS (Hydrogeological Information System) based on Open Source components and technologies, leading to a feasible and low-cost solution. Therefore, HydrIS permits delivery of data from a number of heterogeneous sources to standards supported by the Open Geospatial Consortium (OGC). The protocols used for exchanging data are also derived from OGC standards, i.e., WMS (Web Mapping Service), WFS (Web Feature Service), and WCS (Web Coverage Service). Finally, a geoportal was developed, which consists of client-applications that communicate with different Web Services (WMS, WCS, and WFS) through http-requests.  相似文献   

基于数字城市地理空间框架的GIS应用系统建设研究——以公交线路管理系统为例     

雷林辉 《测绘与空间地理信息》2013,(8):125-129

数字城市地理空间框架集成了基础地理信息数据、专题数据、GIS功能等各类资源,并通过公共服务平台为公共管理和社会公众提供服务。本文在数字惠州地理空间框架的基础上设计并构建了惠州市公交线路管理系统,说明基于数字城市地理空间框架如何构建GIS应用系统,实现资源的共享应用。  相似文献