نتایج جستجو برای: tuff
تعداد نتایج: 1032 فیلتر نتایج به سال:
The Youngest Toba Tuff (YTT) eruption, which occurred in Indonesia 74,000 years ago, is one of Earth's largest known volcanic events. The effect of the YTT eruption on existing populations of humans, and accordingly on the course of human evolution, is debated. Here we associate the YTT with archaeological assemblages at Jwalapuram, in the Jurreru River valley of southern India. Broad continuit...
A phillipsite-faujasite tuff (faujasite) from Jordan has been activated and characterized to evaluate its efficiency in removing paraquat from synthetic wastewater and to specify optimum conditions with maximum efficiency of the faujasite tuff. Noticed variation in CEC is indicated and explained by selectivity of the faujasite to K(+) and Na(+). Removal of paraquat by using faujasite directly g...
Two strains were isolated from tuff, a volcanic rock that forms the walls of the Roman Catacombs of Saint Callixtus in Rome, Italy. A polyphasic approach using nutritional and physiological tests, reactions to antibiotics, fatty acid profiles, DNA base ratios, DNA-DNA reassociation and 16S rRNA gene sequence comparisons showed that the two isolates belong to a novel species within the genus Phy...
The distribution and compositions of chevkinite-group minerals (CGMs) in the pantelleritic Gold Flat Tuff, Nevada, USA, are used to examine three aspects evolution tuff, which we feel general significance peralkaline magmatism. First, both chevkinite-(Ce) perrierite-(Ce) occur certain facies, although normally these phases almost invariably different igneous lithologies. Their co-occurrence tuf...
This article reports the potential use of waste glass powder (GP) to improve the performance of concrete subjected to freeze-thaw (FT) cycling. Three GP contents were utilized in the study: 6%, 12%, and 18% by weight of cement. The other experimental parameters that were investigated in the study include: water to cement ratio (0.4 and 0.6) and aggregate type (limestone and tuff). Concrete pris...
Clay minerals from the three principal kinds of zeolitic sediments from the type area for zeolite facies alteration, the Triassic Murihiku Supergroup, Southland, New Zealand, have been studied by TEM. Bentonitic tuff consists largely of smectite and heulandite with minor illite; they occur as replacements of glass shards and are inferred to be direct alteration products of tuff alteration. Both...
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