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[en] Mount Taftan is a double-peaked stratovolcano, located in southeast of Iran. This volcano constructed a number of calderas among which one of the most important is Anjerk. The magmas erupted from this multi-caldera complex range from andesi-basalt to dacite, but are dominated by andesite and dacite. Two terminal cones, Narkuh and Matherkuh, culminate at 4100 m and 3950 m, respectively. There are three evolutionary stages in the history of the volcanic complex (stage 1: Palaevolcanism, 6.95±0.72Ma, stage 2: Mesovolcanism, 6.01±0.15Ma and stage 3: Neo volcanism, 0.71± 0.03Ma). The eruptive products consist of lava flows, iguimbrites and pyroclastic rocks. The later include tuffs, nuees ardents, breccias and sometimes reworked as lahars. Textural and mineralogical data suggest that both magma mixing and fractional crystallization were involved in the generation of the andesites and dacites. The magmas erupted from this volcano show a calc-alkaline trend. The corresponding lavas are calk-alkaline with a potasic tendency.
[en] In support of the Waste Package Task within the Nevada Nuclear Waste Storage Investigation (NNWSI), experiments on hydrothermal rock/water interaction, corrosion, thermomechanics, and geochemical modeling calculations are being conducted. All of these activities require characterization of the initial bulk composition, mineralogy, and individual phase geochemistry of the potential repository host rock. This report summarizes the characterization done on samples of the Bullfrog Member of the Crater Flat Tuff (Tcfb) used for Waste Package experimental programs. 11 references, 17 figures, 3 tables
[en] A regional model that can predict groundwater movement through the reference repository location and surrounding area is essential to assessing the site suitability for a nuclear waste repository. During the last two decades, several models have been developed to handle complicated flow patterns through complex geologic materials. The basic problem, however, is obtaining the data base needed to apply these models. The hydrological data needed include the spatial distribution of effective porosity, the hydraulic conductivity tensor and its variation in space, values of specific storage, the hydraulic head distribution, and the fluid properties. In this report, we discuss conventional methods of obtaining vertical hydraulic conductivity and examine their applicability to the BWIP site. 39 references, 12 figures, 4 tables
[en] Investigations of Rb-Sr systematics of basalts from the Afar depression (Ethiopia) indicate the presence of a heterogeneous mantle source region. The Sr isotopic compositions of the basalts from the Afar axial and transverse ranges identify source regions which are enriched in LIL elements and radiogenic Sr (axial ranges) and others which are relatively depleted (transverse ranges). Sr isotopic composition of basalts from the Red Sea, Gulf of Aden and Gulf of Tadjoura, which range from 0.70300 to 0.70340 are also reported and compared with the more radiogenic Afar region, which is characterized by 87Sr/86Sr ranging from 0.70328 to 0.70410. Available geochemical and isotopic data suggest that a relation exists between magma composition and the advancement of the rifting process through progressive lithosphere attenuation leading to continental break-up. However, the petrogenetic process is not simple and probably implies a vertically zoned mantle beneath the Afar region. Sr isotopic evidence suggests that the vertically zoned mantle is more radiogenic and enriched in LIL elements in its upper part. (orig.)