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1.
《Geoforum》2015
The use of transboundary conservation as tools for improving interstate relations has become a widely supported initiative in nature conservation. The rationale follows the environmental peacemaking hypothesis, which argues that seemingly neutral environmental issues can provide a sound basis for cooperation between states. The paper investigates the hypothesis’ premise through the case of International System of Protected Areas for Peace (Si-A-Paz), a transboundary protected area shared by Costa Rica and Nicaragua. In recent years, both countries have been involved in a number of border conflicts within Si-A-Paz and linked to the use of the San Juan River, contested land areas, and oil resources. The case of Si-A-Paz shows that transboundary environmental issues can provide arguments for maintaining or even strengthening conflicts rather than fostering peace between states. The case also shows the emergence of environmental issues as a new arena for geopolitical play, where actors not only justify their actions through an environmental discourse but also, the environmental discourse is stretched to include a variety of issues through which actors can obtain international support. The events in Nicaragua and Costa Rica raise questions about the role of transboundary conservation as a peacebuilding tool. 相似文献
2.
The Jurassic granitoids (200–164 Ma) are distributed in the Korean Peninsula due to the Paleo-Pacific plate subduction. Early Jurassic (200–182 Ma) granitoids are mainly distributed in the southern Korean Peninsula. By contrast, Early to Middle Jurassic (182–164 Ma) granitoids are distributed in the central Korean Peninsula. In this study, we report detailed petrology, zircon U–Pb ages, and whole-rock geochemistry from the Seoul–Uijeongbu and Pocheon–Gimhwa pluton units in the central Korean Peninsula. The Seoul–Uijeongbu unit is dominated by biotite granite, with minor porphyritic biotite and garnet-biotite granite while the Pocheon–Gimhwa unit consists of biotite granite and porphyritic biotite granite, garnet-biotite granite, and two-mica granite. Zircon U–Pb age from those granites gives 180–167 Ma. The granitoids in the Pocheon-Gimhwa unit formed through fractional crystallization from biotite granite and porphyritic biotite granite to garnet-biotite granite, and two-mica granite based on gradually decreasing their Nb/Ta, Zr/Hf, and Eu/Eu* ratios. The strongly fractionated granitoids are garnet-biotite granite and two-mica granite. The LILE enrichment, Ta–Nb, Sr–P, and Eu–Ti troughs, and Ba depletion in most granitoids are similar to those of granitoids due to the subduction in the arc environment. Thus, these Jurassic granitoids (180–167 Ma) are mainly peraluminous granites with moderate crystal fractionation corresponding to I-type granite. Alkali feldspar granite associated with ore mineralization occurs in the Gwanaksan pluton from the southwestern Seoul–Uijeongbu unit. The alkali feldspar granite displays distinct negative Eu anomaly with high contents of Rb, Hf, Cs, and Nb compared with other granites. These characteristics imply that alkali feldspar granite experienced strong hydrothermal activity leading to feldspar ore mineralization compared to the other granites. The formation of a wide range of moderately evolved peraluminous granitoids is presumed to be related to rapid flat-subduction during 182–164 Ma, and the mineralization-related alkali feldspar granite indicates the termination of Jurassic granitoid magmatism in the central Korean Peninsula. 相似文献
3.
河南省主体功能区划分的主导因素研究 总被引:5,自引:6,他引:5
推进形成主体功能区是我国"十一五"及今后一段时期一项重要而又紧迫的任务,是我国经济社会发展的一个重要战略调整和转变.作者在全面分析河南省独特的自然条件和经济社会发展特征的基础上,认为:自然条件的过渡性是影响河南省主体功能区划分的本底因素;土地、水等重要资源严重不足并且开发利用强度高成为主体功能区划分的刚性限制因素;生态环境较高的敏感性和脆弱性是主体功能区划分尤其是对禁止开发区和限制开发区的划定作用显著;工业化和城镇化的快速发展带来的全省经济的高增长势头和未来区域经济发展的格局是主体功能区划分需要把握的重要经济属性. 相似文献
4.
冀北印支期碱性岩浆活动及其地球动力学意义 总被引:9,自引:0,他引:9
冀北印支期碱性岩浆活动及其地球动力学意义张招崇(中国地质科学院地质研究所,北京100037)王永强(中国地质科学院西安地质矿产研究所,西安710054)关键词碱性岩浆印支期冀北地球动力学燕山地区是否存在印支期的构造、岩浆活动一直存在着争论。过去多数人... 相似文献
5.
6.
《GFF》2012,134(3):201-216
Morphological features of the shell including internal structures of the phragmocones of three different bactritoid cephalopod taxa assigned to the Order Bactritida: Bactrites quadrilineatus, Ctenobactrites lesliensis (L. Carboniferous) and the Order Parabactritida: Rugobactrites jacksboroensis (U. Carboniferous) were studied. The material comes from South Central USA. The features examined include the conch shape, siphuncle shape and ultrastructure of the shell wall, septa, septal neck and the connecting ring. These traits were then compared with Shimanskya postremus from Upper Carboniferous of Texas, which has been originally referred to bactritids and later placed within the coleoids in the Order Spirulida. Based on similarities and differences observed, B. quadrilineatus and C. lesliensis are now also considered being coleoids similar to S. postremus; R. jacksboroensis remains placed in the Order Parabactritida. 相似文献
7.
8.
辽宁宽甸北部早元古宙铅锌矿位于辽东青城子—吉林荒沟山—朝鲜检德铅锌矿带上。赋存于辽东优、冒地槽的过渡带,靠近优地槽一侧的碳酸盐岩建造中。矿体受岩相、岩性控制明显,属层控矿床。吕梁构造旋回的变质变形作用对矿带的改造不明显。矿带的同位素特征表明,张家堡子铅锌矿形成于封闭盆地环境,矿质来源于大陆边缘深部液态矿源层;而高丽墓子铅锌矿带则形成于正常海洋环境,表现了明显的原始沉积矿床的特点。 相似文献
9.
The Central Andean gravity high (CAGH) is a positive anomaly in isostatic residual gravity with its center located at the western flank of the Central Andes at about 24°S. The gravity was analyzed by various methods to draw quantitative conclusions about the sources of this anomaly and their process of formation. Methods include the analysis of the gravity gradients, power spectrum, wavelength filters, and Euler deconvolution.Numerical investigations of gravity field in the area of the CAGH indicate the presence of a dense body of nearly 400 km length and about 100–140 km width, that masses lie at varying depths between 10 and 38 km. A correlation between the location of the residual anomalies and the topographic lows in the area between the Salars de Atacama and Pipanaco is observed, which indicates the strong influence of the anomalous-causing rocks of the CAGH within the formation process of the Andean orogen. An influence of these causing bodies of rock on the trend of Holocene volcanic arc is likely. Genesis of the anomalous dense formations of rock could be traced back to Ordovician–Silurian time when a pre-Andean subduction zone is postulated in the region of northern Chile with its corresponding volcanic arc in the region of the CAGH.
Zusammenfassung
El campo de gravedad alto de los Andes Centrales (CAGH) consiste en una pronunciada anomalía positiva de la gravedad isostática, cuyo centro se encuentra en el borde oeste de los Andes Centrales a los 24°S. En este estudio se analizó el campo de gravedad mediante distintos métodos, de manera de poder establecer conclusiones cuantitativas sobre el causante de esta anomalía y el proceso de formación de este causante.La investigación numérica de las anomalías gravimétricas del CAGH indica la presencia de un cuerpo de alta densidad con aproximadamente 400 km de largo y 100–140 km de ancho, que se encuentra a profundidades variables entre 10 y 38 km. Se observa una correlación entre la posición de la anomalía residual y los bajos topográficos en los areas de Salares de Atacama, Arizaro, Antofalla y Pipanaco, la cual indica una fuerte influencia de rocas productoras de la anomalía en el CAGH, dentro del proceso de formación del orógeno andino. Es probable que estos cuerpos de rocas causantes de la anomalía tengan incluso influencia en el alineamiento del arco volcánico holocénico. La generación de cuerpos de rocas con una densidad anómala puede remontarse al Ordovícico–Silúrico, tiempo para el que postula una subducción pre-Andina en la región del norte de Chile y que corresponde con el arco volcánico en la región del CAGH. 相似文献10.
滇东华宁盘溪火车站以北的金山—大石山地区发育中、晚泥盆世的丘状珊瑚礁。以Alveolites和Thamnopora为代表的床板珊瑚为造礁生物。纵剖面上岩相变化的记录清楚地表明,该礁体经历了定殖、繁殖和衰亡三个阶段。海水变浅及其盐化是导致礁体衰亡的直接原因 相似文献