Textural-structural,mineralogical, isotopic,and age characteristics of Jurassic terrigenous rocks of the northwestern Caucasus (the Belaya River section)

Results of the comprehensive study of structural, lithological, mineralogical, and isotopic characteristics of Lower Jurassic rocks exposed in the Belaya River valley (Adygeya) in meganticlinorium of the Greater Caucasus are presented. Deformation microstructures were studied. Lithological and textural-structural changes in sequences related to intense secondary transformations should affect the state of isotopic systems of rocks. To reveal basic trends in the evolution of isotopic systems, investigation using the K-Ar method was carried out. Clay fraction (less than 1 μm) separated from rocks and bulk samples were analyzed. Cleavage development, approximate value of rock contraction, and isotopic characteristics are compared with the available data on alteration of clay mineral assemblages. Relationship between the degree of rock deformation at the microlevel and calculated K-Ar ages has been established. K-Ar systems of clayey rocks indicate the age of cleavage formation and correspond to the Bajocian-Bathonian contraction period.     

Corundum-group minerals in rocks of the Khibiny alkaline pluton,Kola Peninsula

Five minerals of the corundum group have been identified in the Khibiny pluton with certainty. Corundum proper and karelianite occur only in hornfels after volcanic and sedimentary rocks. Xenoliths of hornfels mark the ring faults that bound foidalite within the field of foyaite. Hematite occurs in hydrothermally altered nepheline syenite and crosscutting hydrothermal veins related to the ring faults. Minerals of the ilmenite-pyrophanite series are present in all rocks of the pluton, including veins. Accessory ilmenite in foyaite varies from the manganese variety and pyrophanite in the inner and outer parts of the pluton to manganese-free ilmenite in zone of the Main Ring Fault. In xenoliths of volcanic rocks and alkaline ultramafic rocks, ilmenite is enriched in magnesium. The zoning in distribution of the above-mentioned minerals and the character of variation in their compositions from margins of the pluton to its center are consistent with the petrochemical zoning formed as a result of foyaite alteration of near ring faults.     

Structure of ore fields and deposits: Current status and outlook for further development

The current status of investigations of the structure of ore fields and deposits in Russia is considered. The importance of traditional lines of research in this field and the great body of information acquired is emphasized. The changes in ideas of geodynamic and tectonic crustal evolution have made it necessary to alter concepts of the geological and structural position of ore fields and deposits. New challenges are caused by these changes and progress in the knowledge of ore deposits and the depth of their formation, as well as geodynamic, tectonophysical, and hydrodynamic processes in ore-bearing crustal blocks. The results of hydrodynamic modeling of deposit formation controlled by deeply penetrating fault zones are discussed. Various relationships between hydrodynamic and structural factors in ore formation are considered.     

生态屏障约束下的综合功能区划研究——以云南省昭通市为例(英文)

Ecological shelter zones reconstruction is an ecosystem restoration and conserva-tion project aimed to the ecological safety of nations,regions and basins. Reconstruction of ecological shelter zones of the upper reaches of the Yangtze River became one of the most important tasks of Western Development strategy. This article,taking Zhaotong as an exam-ple,studies the functional regionalization of ecological shelter zones. The study supplies a case for functional regionalization of small and medium regions whose main tasks are envi-ronment reservation. With the guidance of theories of functional regionalization,and based on the analysis of Zhaotong's natural,ecological and socioeconomic factors,the paper suggests five principles for factors selection. These principles include: (1) reversing order evaluation; (2) selecting main factors; (3) keeping the integrality of administrative regions of towns; and (4) making the products acceptable by local government. To analyze spatial status of selected factors,LUCC data in 2002,1:50,000 relief maps and town-unit socioeconomic statistical data in 2004 are used. RS and GIS tools are also applied to melt traditional and modern geo-graphical methods. This would be useful to functional regionalization research in mountain-ous areas. As a conclusion,the leading functional regions of ecological conservation or economic development are suggested,respectively. Zhaotong city is divided into two-level functional regions. The first-level includes three leading functional regions and they will lead developing direction of sub-regions. The second-level includes eight sub-regions,which are policy implemented regions,and will supply guidance to Zhaotong's ecological shelter zones reconstruction.     

Application of horizontal-to-vertical (H/V) Fourier spectral ratio for analysis of site effect on rock (NEHRP-class B) sites in Taiwan

The frequency-dependent amplification for rock (NEHRP-class B) sites was studied using earthquake ground-motion database collected in Taiwan during implementation of the Taiwan Strong Motion Instrumentation Program. The database used includes several hundred records from earthquakes of M_L 4.0–7.3 occurred between 1993 and 2004. The characteristics of amplification were evaluated using the well-known technique of horizontal-to-vertical Fourier spectral ratio (H/V) of the S-wave phase [Lermo J, Chavez-Garcia FJ. Site effect evaluation using spectral ratios with only one station. Bull Seism Soc Am 1993;83:1574–94]. The study allows us to analyze peculiarities of rock sites amplification in Northern and Eastern Taiwan. It was suggested to divide the NEHRP-class B site amplification into four types based on frequency of maximum amplification and the shape of amplification function. The applicability of the technique was also checked for a few stiff and soft soil sites (NEHRP-classes D and E).