共查询到20条相似文献，搜索用时 500 毫秒
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Discussion on “A rapid loess flowslide triggered by irrigation in China” by D. Zhang,G. Wang,C. Luo,J. Chen,and Y. Zhou 总被引：1，自引：0，他引：1
Luciano Picarelli 《Landslides》2010,7(2):203-205
Catastrophic debris flows hit many areas in the world. Surprisingly, the features of the materials which are involved are
often very similar as well as the causes of rupture and the mechanics of resulting movement. A continuous exchange of ideas
among people involved in studies and investigations could be highly beneficial in the setting up of reliable criteria for
risk mitigation. 相似文献
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《Applied Geochemistry》1993,8(3):301-304
MacGowan and Surdam (1990a) suggested some modifications to the model of Lundegard and Land (1989) to make it more geologically and geochemically reasonable. The predictive power of such a geochemical model is wholly dependent on the species modeled and the constants used; any model that excludes important species or important thermodynamic data, or one that couples certain reactions in an unrealistic way, may produce results which are not geologically or geochemically reasonable (W. K. Harrison, pers. commun., 1988; Y. K. Kharaka, pers. commun., 1991). We have long recognized that, under early-burial diagenetic conditions, aluminosilicate hydrolysis generally controls formation water pH (Surdam and Eugster, 1976; Mariner and Surdam, 1970; Taylor and Surdam, 1981) and that, during intermediate burial, either aqueous CO2 or CAA species (in the absence of aqueous S species or other weak conjugate acid-base pairs) will dominate formation water alkalinity and control pH (Surdam et al., 1989c). We reassert that the model of Lundegard and Land (1989) does not take into account the relative importance of PCO2 and of concentrations of both Ca2+ and CAA and their relative organic metal complexes to carbonate mineral stability in sandstones in the zone of intermediate burial clastic diagenesis (cf. the models of Surdam et al., 1984 and Surdam and Crossey, 1985). The usefulness of such models is predicted on the completeness of the model and the use of the best, most accurate thermodynamic data. Also, geologically realistic concentrations of critical species are required for reasonable modeling to be done. Although their model is vigorously defended in the discussion of Lundegard and Land, 1989, Lundegard and Land, 1993, we continue to disagree that their analysis of their model conditions are either geologically or geochemically satisfying.We agree with the fundamental approach and philosophy of Lundegard and Land, 1989, Lundegard and Land, 1993. It is of the utmost importance to determine from experimental, geochemical, petrographic, and geological data what the controls on pH and alkalinity in formation waters are, as well as the exact thermodynamic speciation of aqueous moieties and the stability of detrital and authigenic minerals. Lundegard and Land (1993) raise an additional point about CAA reaction with carbonate minerals in shales, although Fisher and Lewan (1989), Lewan (1989) and MacGowan and Surdam (1990b) have demonstrated that CAA generated in shale likely migrate in the oil phase along incipient shale microfractures to the sandstone reservoir, and thus are likely to not react much with the shale. Finally, we agree with Lundegard and Land that these areas require much additional experimental and field analysis, and petrographic study. 相似文献
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Peter B. Kelemen 《Journal of the Geological Society of India》2009,74(2):280-282
Discussion
Paleoproterozoic Boninite-Like Rocks in an Intracratonic Setting from Northern Bastar Craton, Central India by D.V. Subba Rao, V. Balaram, K. Naga Raju and D.N. Sridhar. Jour. Geol. Soc. India, v.72, 2008, pp.373–380 相似文献16.
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《Gondwana Research》2013,24(4):1656-1658
The abundant and diverse assemblage of filamentous microbial fossils permineralized in the ~ 3465 Ma Apex chert of northwestern Australia — among the oldest records of life — are arguably the “best studied,” by the most workers using the most advanced techniques, in the history of science. Despite the extensive body of data establishing the biogenicity of the demonstrably cellular carbonaceous Apex fossils, Pinti et al. (2013) and Marshall and Marshall (2013) have raised issues regarding the interpretation of their studies of the Apex chert presented in our recent review article (Schopf and Kudryavtsev, 2012). We agree with the assessment of both of the relevant papers by Pinti et al. (2009, 2013): the observations they report do not apply to the bona fide microscopic fossils of the Apex chert. Similarly, like the minute objects reported by Pinti et al. (2009, 2013), the “quartz and haematite-filled fractures” discussed by Marshall and Marshall (2013) are mineralic pseudofossils that are not relevant to interpretation of the Apex fossil microbes and their suggestion that “multiple populations of carbonaceous material may be a wide-spread issue through out the Precambrian” is without merit. 相似文献
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