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21.
马家沟灰岩(古)岩溶研究中的若干问题探讨 总被引:4,自引:0,他引:4
讨论了华北地区奥陶系马家沟组灰岩岩溶研究中的几个问题,包括沉积岩溶,暴露岩溶,埋藏岩溶,现代岩溶及陷落柱等,指出了沉积岩溶和暴露岩溶洞穴不能保存或保存甚少,但对后期的岩溶发育具有重要控制作用,最后,提出了今后奥陶系灰岩岩溶研究的基本思路。 相似文献
22.
AbstractThe transition from the Alpine tectonic assembly to the exhumation of the units in the Rhodope metamorphic province in northernmost Greece has been refined by 40Ar/39Ar laserprobe mica analyses. Preservation of pre-Alpine (~ 280 Ma and 145 Ma) muscovite cooling ages at the western margin of the Rhodope indicate that subsequent events failed to reset the argon system thermally in white mica in the outcropping basement of this region. The central and eastern Rhodope are characterized by white mica cooling ages of 40–35 Ma with ages gradually decreasing to ca. 15 Ma near the eastern margin of the Strymon Valley. The Eo-Oligocene ages reflect the regional exhumation of the metamorphosed units to shallow crustal levels, with corresponding temperatures below ca. 350 °C, by 40–35 Ma. The younger cooling ages are attributed to the initiation and subsequent operation of the Strymon-Thasos detachment system since ca. 30 Ma. This study provides a crucial contribution to future regional tectonic models for the Rhodope region as it recognizes an early stage of development of the Strymon-Thasos detachment system, and has constrained the regional exhumation of the Rhodope metamorphic province since 40 Ma indicating that the regionally observed amphibolite facies metamorphism had terminated by this time. © 2000 Editions scientifiques et médicales Elsevier SAS 相似文献
23.
The paper presents the evolution of the geographic environment imposed by sea-level changes in selected sites of the Aegean Sea region during the Upper Holocene. The changes are due, mainly, to paroxysmic phases of the actual neotectonic evolution and to differential—in time and space—block movements, and emerged or submerged coasts. The reconstitution of these coasts is presented and, in some cases, natural harbor morphology is revealed. The use and evolution of these sites is discussed. Other sites concern coastal or inland ancient settlements or constructions affected by submersion by the sea, by the rise of the groundwater table, or by uplift movements. A general discussion on engineering measures to be applied for protection of the antiquities affected by these geographic changes closes the presentation. 相似文献
24.
The ancient landslide has endured long-term slope evolution which results in its complicated material and special rock-soil properties. The risk of ancient landslide reactivation is substantially increasing due to the increase of intensified human engineering activities and the frequency of extreme weather events. Many ancient landslides have been reactivated all over the world and led to serious fatalities and severe damage to many important engineering facilities such as transportation and hydropower engineering projects. On the basis of the analysis of the research situation about the ancient landslides at home and abroad, the main research advances were summarized including the regional developing laws and recognizing of the ancient landslides, the mechanics properties of ancient landslide body and related sliding zone, reactivation mechanism of ancient landslides, reactivating process and modeling analysis of ancient landslides, early recognization of ancient landslide reactivation, etc. To meet the demands of disaster prevention and reduction, three key scientific issues were put forward to be solved: ①automaticaly establishing the methodology and identification criterions for recognition of ancient landslide; ②revealing the reactivation mechanism of ancient landslide based on a new strength theory; ③establishing the early rapid recognition method and predictive model for ancient landslide reactivation. Solving the above mentioned scientific theory and methodology will facilitate the planning and site selection of major projects as well as the disaster prevention and reduction in ancient landslide developing areas. 相似文献
25.
由俄罗斯科学院远东分院、美国地质调查局、蒙古科学院、中国吉林大学地球科学学院、朝鲜地质矿业学院、日本地质调查局合作建立的“东北亚地区矿产资源、成矿学和构造学地理信息系统”,整合了东北亚(包括俄罗斯远东地区、西伯利亚东部、中国东北部、蒙古、朝鲜半岛、日本等地区)地理学、地球动力学、原生矿床、外生砂矿床、成矿带等信息,为该地区区域矿产资源及地质找矿信息的存储、处理、分析、检索、共享和推广提供便利. 相似文献
26.
C. Papanicolaou N. Pasadakis D. Dimou S. Kalaitzidis S. Papazisimou A.E. Foscolos 《International Journal of Coal Geology》2009,77(3-4):401-408
Twenty-eight samples of peat, peaty lignites and lignites (of both matrix and xylite-rich lithotypes) and subbituminous coals have been physically activated by pyrolysis. The results show that the surface area of the activated coal samples increases substantially and the higher the carbon content of the samples the higher the surface area.The adsorption capacity of the activated coals for NO, SO2, C3H6 and a mixture of light hydrocarbons (CH4, C2H6, C3H8 and C4H10) at various temperatures was measured on selected samples. The result shows a positive correlation between the surface area and the gas adsorption. In contrast, the gas adsorption is inversely correlated with the temperature. The maximum recorded adsorption values are: NO = 8.22 × 10− 5 mol/g at 35 °C; SO2 = 38.65 × 10− 5 mol/g at 60 °C; C3H6 = 38.9 × 10− 5 mol/g at 35 °C; and light hydrocarbons = 19.24 × 10− 5 mol/g at 35 °C. Adsorption of C3H6 cannot be correlated with either NO or SO2. However, there is a significant positive correlation between NO and SO2 adsorptions. The long chain hydrocarbons are preferentially adsorbed on activated lignites as compared to the short chain hydrocarbons.The results also suggest a positive correlation between surface area and the content of telohuminite maceral sub-group above the level of 45%. 相似文献
27.
28.
虚拟地理环境研究进展与理论框架 总被引:3,自引:0,他引:3
阐述虚拟地理环境的形成、发展与研究现状,并从"虚拟现实技术"与"虚拟现实"的相互关系探讨虚拟地理环境基本概念.从基本思想、系统结构、在线参与者社会组织水平、与GIS/数字地球的关系等角度,分析虚拟地理环境的特征.从数据、模型、表现以及协同4个方面,讨论了虚拟地理环境系统建设的关键技术与研究前沿.尝试建立了一个虚拟地理环境基本理论初步研究框架,认为在地理哲学思想层次应该重点研究复杂性人地系统、地理虚/实关系论、地理/遥感信息本体论,在地理/地理信息科学层次需要重点研究地理认知与思维、地理相似原理、地理计算模拟;同时讨论虚拟地理环境与面向"人"的地理信息科学、基于虚拟地理环境地理科学方法论,以及可计算人地关系的相关理论问题. 相似文献
29.
Diego Perugini Giampiero Poli George Christofides George Eleftheriadis Antonis Koroneos Triantafyllos Soldatos 《Geological Journal》2004,39(1):63-80
Two distinct groups of subduction‐related (orogenic) granitoid rocks, one Jurassic and the other Tertiary, occur in the area between the Vardar (Axios) Zone and the Rhodope Massif in northern Greece. The two groups of granitoids differ in many respects. The first group shows evolved geochemical characters, it is not associated with mafic facies, and evidence of magmatic interaction between mantle‐ and crustal‐derived melts is lacking. The second group has less evolved geochemical characters, it is associated with larger amount of mafic facies, and magmatic interaction processes between mantle‐derived and crustal melts are ubiquitous as evidenced by mafic microgranular enclaves and synplutonic dykes showing different enrichment in K2O, Ti, and incompatible elements. This kind of magmatism can be attributed to the complex geodynamic evolution of the area. In particular, we suggest that two successive subduction events related to the closure of the Vardar and the Pindos oceans, respectively, occurred in the investigated area from Late Jurassic to Tertiary. We relate the genesis of Jurassic granitoids to the first subduction event, whereas Tertiary granitoids are associated with the second subduction. Fluids released by the two subducted slabs induced metasomatic processes generating a ‘leopard skin’ mantle wedge able to produce mafic melts ranging from typical calc‐alkaline to ultra‐potassic. Such melts interacted in various amounts with crustal calc‐alkaline anatectic melts to generate the wide spectrum of Tertiary granitoids occurring in the study area. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
30.
Evidence for Neotethys rooted within the Vardar suture zone from the Voras Massif, northernmost Greece 总被引:2,自引:0,他引:2
Three conflicting models are currently proposed for the location and tectonic setting of the Eurasian continental margin and adjacent Tethys ocean in the Balkan region during Mesozoic–Early Tertiary time. Model 1 places the Eurasian margin within the Rhodope zone relatively close to the Moesian platform. A Tethyan oceanic basin was located to the south bordering a large “Serbo-Pelagonian” microcontinent. Model 2 correlates an integral “Serbo-Pelagonian” continental unit with the Eurasian margin and locates the Tethys further southwest. Model 3 envisages the Pelagonian zone and the Serbo-Macedonian zone as conjugate continental units separated by a Tethyan ocean that was sutured in Early Tertiary time to create the Vardar zone of northern Greece and former Yugoslavia. These published alternatives are tested in this paper based on a study of the tectono-stratigraphy of a completely exposed transect located in the Voras Mountains of northernmost Greece. The outcrop extends across the Vardar zone, from the Pelagonian zone in the west to the Serbo-Macedonian zone in the east.Within the Voras Massif, six east-dipping imbricate thrust sheets are recognised. Of these, Units 1–4 correlate with the regional Pelagonian zone in the west (and related Almopias sub-zone). By contrast, Units 5–6 show a contrasting tectono-stratigraphy and correlate with the Paikon Massif and the Serbo-Macedonian zone to the east. These units form a stack of thrust sheets, with Unit 1 at the base and Unit 6 at the top. Unstacking these thrust sheets places ophiolitic units between the Pelagonian zone and the Serbo-Macedonian zone, as in Model 3. Additional implications are, first, that the Paikon Massif cannot be seen as a window of Pelagonian basement, as in Model 1, and, secondly, Jurassic andesitic volcanics of the Paikon Massif locally preserve a gneissose continental basement, ruling out a recently suggested origin as an intra-oceanic arc.We envisage that the Almopias (Vardar) ocean rifted in Triassic time, followed by seafloor spreading. The Almopias ocean was consumed beneath the Serbo-Macedonian margin in Jurassic time, generating subduction-related arc volcanism in the Paikon Massif and related units. Ophiolites were emplaced onto the Pelagonian margin in the west and covered by Late Jurassic (pre-Kimmeridgian) conglomerates. Other ophiolitic rocks formed within the Vardar zone (Ano Garefi ophiolite, Unit 4) in latest Jurassic–Early Cretaceous time and were not deformed until Early Tertiary time. The Vardar zone finally sutured in the Early Tertiary creating the present imbricate thrust structure of the Voras Mountains. 相似文献