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431.
Stefano Conti Daniela Fontana Claudio Corrado Lucente Gian Andrea Pini 《International Journal of Earth Sciences》2014,103(1):281-295
The Montardone mélange (Mm) is a chaotic, block-in-matrix unit outcropping in the Montebaranzone syncline in the northern Apennines. The Mm occurs in the uppermost part of the Termina Fm, the Middle–Late Miocene interval of a succession deposited in a wedge-top slope basin (Epiligurian succession). The Mm is closely associated with bodies of authigenic carbonates, characterized by negative values of δ13C (from ?18.22 to ?39.05 ‰ PDB) and chemosynthetic benthic fauna (lucinid and vesicomyid bivalves). In this paper, we propose that the Mm is a mud volcano originated by the post-depositional reactivation and rising of a stratigraphically lower mud-rich mass transport body (Canossa–Val Tiepido sedimentary mélange or olistostrome) triggered by fluid overpressure. We base our conclusion on (1) the Mm pierces the entire Termina Fm and older Epiligurian units and represents the direct continuation of the underlying Canossa–Val Tiepido mélange; (2) the geometry and facies distribution of the Montebaranzone sandstone body, which are compatible with a confined basin controlled by the rising of the Mm; (3) the systematic presence of large-scale (lateral extension 300–400 m) seep-carbonates associated with the mélange, suggesting a persistent gas-enriched fluid vent from the ascending overpressured mud; (4) blocks and clasts sourced from the Mm, hosted by the authigenic carbonates, conveyed by ascending mud and gas-enriched fluids. The Mm represents one of the few fossil examples of reactivation of a basin-scale sedimentary mélange (olistostrome); a three-stage model showing mechanisms of Mm raising is proposed. 相似文献
432.
Brian D. Smerdon Laura A. Smith Glenn A. Harrington W. Payton Gardner Claudio Delle Piane Joel Sarout 《Hydrogeology Journal》2014,22(8):1875-1887
A workflow is described to estimate specific storage (S s) and hydraulic conductivity (K) from a profile of vibrating wire piezometers embedded into a regional aquitard in Australia. The loading efficiency, compressibility and S s were estimated from pore pressure response to atmospheric pressure changes, and K was estimated from the earliest part of the measurement record following grouting. Results indicate that S s and K were, respectively, 8.8?×?10?6 to 1.2?×?10?5 m?1 and 2?×?10?12 m s?1 for a claystone/siltstone, and 4.3?×?10?6 to 9.6?×?10?6 m?1 and 1?×?10?12 to 5?×?10?12 m s?1 for a thick mudstone. K estimates from the pore pressure response are within one order of magnitude when compared to direct measurement in a laboratory and inverse modelled flux rates determined from natural tracer profiles. Further analysis of the evolution and longevity of the properties of borehole grout (e.g. thermal and chemical effects) may help refine the estimation of formation hydraulic properties using this workflow. However, the convergence of K values illustrates the benefit of multiple lines of evidence to support aquitard characterization. An additional benefit of in situ pore pressure measurement is the generation of long-term data to constrain groundwater flow models, which provides a link between laboratory scale data and the formation scale. 相似文献
433.
Luigi Germinario Siegfried Siegesmund Lara Maritan Claudio Mazzoli 《Environmental Earth Sciences》2017,76(21):739
Euganean trachyte is a subvolcanic porphyritic rock extracted in northern Italy with an age-old tradition of use as dimension stone, historically linked, in particular, to the fervent building activity brought by the Roman Empire and, later on, the Republic of Venice Serenissima. The results of a comprehensive petrophysical and mechanical characterization of Euganean trachyte from the most representative quarries are discussed here, involving the following properties: density, porosity, water absorption, capillary water uptake, hygroscopic water adsorption, hydric/hygric dilatation, water vapor diffusion, thermal expansion, and resistance to salt attack and abrasion. The different trachyte varieties, although belonging to the same quarry basin, exhibit a relatively wide array of technical performances, which are strongly dependent on pore volume, size, size distribution, shape, and degree of interconnection, controlling modes and rates of water transport and retention. Therefore, indications are provided for evaluating durability performance of the stone, with stress on water-driven weathering. Complementary information is finally given on the possible criteria followed in the antiquity for properly selecting the trachyte quarries to be exploited, and by a comparison with the properties of the most important trachytes extracted in Europe. 相似文献
434.
Acidification of solutions of oleate salts forms emulsions of oleic acid. It was found that these emulsions produce a different adsorption behaviour on different size fractions of the same mineral. At low oleate concentrations, for the finer fractions, adsorption at acid pH was higher than chemisorption at pH = 7.5; adsorption was lower for the coarser, flotation-size fractions. Therefore, the conclusions obtained in acid solutions for the adsorption of oleate on fine minerals cannot be applied to flotation-size minerals.At low oleate concentrations there is a good correlation between oleate adsorption and hematite flotation. This does not hold for oleate concentrations > 5· 10?5M, where there is poor flotability in the acid region, although the adsorption of oleic acid is very high. This is attributed to the disordered character of the layer of cooperatively adsorbed oleic acid. 相似文献