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141.
142.
Andrea D'Alpaos Stefano Lanzoni Simon Marius Mudd Sergio Fagherazzi 《Estuarine, Coastal and Shelf Science》2006,69(3-4):311
The evolution of the cross section of a salt-marsh channel is explored using a numerical model. Deposition on the marsh platform and erosion and deposition in the channel affect the tidal prism flowing through the cross section, such that the model captures the evolution of the stage–discharge relationship as the channel and marsh platform evolve. The model also captures the growth of salt-marsh vegetation on the marsh platform, and how this vegetation affects flow resistance and the rate of sedimentation. The model is utilized to study the influence of hydroperiod and vegetation encroachment on channel cross section. Numerical results show that a reduction in hydroperiod due to the emergence of the marsh platform causes an infilling of the channel. Vegetation encroachment on the marsh surface produces an increase in flow resistance and accretion due to organic and mineral sedimentation, with important consequences for the shape of the channel cross section. Finally, modeling results indicate that in microtidal marshes with vegetation dominated by Spartina alterniflora, the width-to-depth ratio of the channels decreases when the tidal flats evolve in salt marshes, whereas the cross-sectional area remains proportional to the tidal peak discharge throughout channel evolution. 相似文献
143.
Multistatic Sonar Localization 总被引:2,自引:0,他引:2
Stefano Coraluppi 《Oceanic Engineering, IEEE Journal of》2006,31(4):964-974
This paper develops bistatic contact-localization statistics as a function of source-target-receiver geometry, source and receiver location errors, sound-speed errors, time and bearing errors, and array-heading errors. We verify the analysis through Monte Carlo simulation and illustrate localization accuracy for some representative choices of source-target-receiver geometry and measurement error assumptions. We examine the improved localization accuracy of multistatic contacts that result from the fusion of multiple sonar contacts 相似文献
144.
Linking marine protected areas to integrated coastal and ocean management: A review of theory and practice 总被引:4,自引:0,他引:4
If managed in isolation, coastal and marine protected areas (MPAs) are vulnerable to natural resource development and exploitation occurring outside these areas—in particular, overfishing, alteration and destruction of habitats, and water pollution. Thus, protection of coastal and marine areas—of species, habitats, landscapes, and seascapes—should be integrated into spatial development strategies for larger areas, under the umbrella of integrated coastal and ocean management (ICM). This is typically easier said than done, since the actors involved in MPA networks and in ICM programs are often different, reflecting different cultures, networks of relationships, ministries, and goals and motivations.This article reviews the ecological, social and economic linkages between MPAs and the governance of broader ocean and coastal areas; sets forth nine guiding principles for managing MPAs within an ICM context; reviews work conducted under the Convention on Biological Diversity to operationalize the linkages between ICM and MPAs; and develops strategic guidance for addressing these linkages. The article ends with a call to bring together the diverse communities involved in marine protected areas, coastal and ocean management, and watershed management to collaborate in national-level ocean and coastal planning, including in the designation of networks of marine protected areas. 相似文献
145.
The oxidation and reduction that occur during early diagenesis of sediments has been studied in the interstitial waters of
a rapidly accumulating sedimentary sequence from the Mediterranean margin of Spain. A series of reactions that are mediated
by progressively lower free energy derived from oxidation of organic matter is evident in the sedimentary sequence. Iron and
manganese are rapidly reduced. Phosphate and alkalinity maxima at a subbottom depth of 15 m indicate maximal organic matter
degradation. Methane first appears at ∼20 m subbottom after sulfate is depleted, and its concentrations quickly climb.
Received: 27 October 1997 / Revision received: 4 March 1998 相似文献
146.
Conclusions The calibration by Blundy and Holland is not a calibration of the reaction albite + tremolite = edenite + 4quartz, because the AlIV content of amphiboles is a combined result of
substitutions.The requirements for a calibration of any of these substitutions are: (1) an amphibole-activity model unequivocally accounting for each substitution and (2) a data-set, wherein all amphiboles are buffered by the same assemblages. 相似文献
147.
Vinicio Manzi Rocco Gennari Frits Hilgen Wout Krijgsman Stefano Lugli Marco Roveri Francisco J. Sierro 《地学学报》2013,25(4):315-322
We propose a revised age calibration of the Messinian salinity crisis onset in the Mediterranean at 5.971 Ma based on the recognition of an extra gypsum cycle in the transitional interval of the Perales section (Sorbas basin, Spain) and the revision of the magnetostratigraphy of the Monticino section (Vena del Gesso basin, Italy). This age re‐calibration allows to state more accurately that: (i) the interval encompassing the MSC‐onset is continuous, thus ruling out any erosional feature or stratigraphic hiatus related to a major sea‐level fall affecting the Mediterranean; (ii) the first gypsum was deposited during the summer insolation peak at 5.969 Ma associated with an eccentricity minimum and roughly coincident with glacial stage TG32; (iii) the MSC‐onset was preconditioned by the tectonically‐driven reduction of the hydrological exchanges with the Atlantic Ocean and finally triggered by glacial conditions in the northern hemisphere and by arid conditions in northern Africa. 相似文献
148.
Bruna B. Carvalho Omar Bartoli Fabio Ferri Bernardo Cesare Silvio Ferrero Laurent Remusat Luca S. Capizzi Stefano Poli 《Journal of Metamorphic Geology》2019,37(7):951-975
We investigate the inclusions hosted in peritectic garnet from metapelitic migmatites of the Kinzigite Formation (Ivrea Zone, NW Italy) to evaluate the starting composition of the anatectic melt and fluid regime during anatexis throughout the upper amphibolite facies, transition, and granulite facies zones. Inclusions have negative crystal shapes, sizes from 2 to 10 μm and are regularly distributed in the core of the garnet. Microstructural and micro‐Raman investigations indicate the presence of two types of inclusions: crystallized silicate melt inclusions (i.e., nanogranitoids, NI), and fluid inclusions (FI). Microstructural evidence suggests that FI and NI coexist in the same cluster and are primary (i.e., were trapped simultaneously during garnet growth). FI have similar compositions in the three zones and comprise variable proportions of CO2, CH4, and N2, commonly with siderite, pyrophyllite, and kaolinite, suggesting a COHN composition of the trapped fluid. The mineral assemblage in the NI contains K‐feldspar, plagioclase, quartz, biotite, muscovite, chlorite, graphite and, rarely, calcite. Polymorphs such as kumdykolite, cristobalite, tridymite, and less commonly kokchetavite, were also found. Rehomogenized NI from the different zones show that all the melts are leucogranitic but have slightly different compositions. In samples from the upper amphibolite facies, melts are less mafic (FeO + MgO = 2.0–3.4 wt%), contain 860–1700 ppm CO2 and reach the highest H2O contents (6.5–10 wt%). In the transition zone melts have intermediate H2O (4.8–8.5 wt%), CO2 (457–1534 ppm) and maficity (FeO + MgO = 2.3–3.9 wt%). In contrast, melts at granulite facies reach highest CaO, FeO + MgO (3.2–4.7 wt%), and CO2 (up to 2,400 ppm), with H2O contents comparable (5.4–8.3 wt%) to the other two zones. Our results represent the first clear evidence for carbonic fluid‐present melting in the Ivrea Zone. Anatexis of metapelites occurred through muscovite and biotite breakdown melting in the presence of a COH fluid, in a situation of fluid–melt immiscibility. The fluid is assumed to have been internally derived, produced initially by devolatilization of hydrous silicates in the graphitic protolith, then as a result of oxidation of carbon by consumption of Fe3+‐bearing biotite during melting. Variations in the compositions of the melts are interpreted to result from higher T of melting. The H2O contents of the melts throughout the three zones are higher than usually assumed for initial H2O contents of anatectic melts. The CO2 contents are highest at granulite facies, and show that carbon‐contents of crustal magmas are not negligible at high T. The activity of H2O of the fluid dissolved in granitic melts decreases with increasing metamorphic grade. Carbonic fluid‐present melting of the deep continental crust represents, together with hydrate‐breakdown melting reactions, an important process in the origin of crustal anatectic granitoids. 相似文献
149.
Zelia Dionnet Rosario Brunetto Alice Alon‐Toppani Stefano Rubino Donia Baklouti Ferenc Borondics Anne‐Ccile Buellet Zahia Djouadi Andrew King Tomoki Nakamura Alessandra Rotundi Christophe Sandt David Troadec Akira Tsuchiyama 《Meteoritics & planetary science》2020,55(7):1645-1664
In the near future, a new generation of sample return missions (Hayabusa2, OSIRIS‐REx, MMX, etc.) will collect samples from small solar system bodies. To maximize the scientific outcome of laboratory studies and minimize the loss of precious extraterrestrial samples, an analytical sequence from less destructive to more destructive techniques needs to be established. In this work, we present a combined X‐ray and IR microtomography applied to five Itokawa particles and one fragment of the primitive carbonaceous chondrite Paris. We show that this analytical approach is able to provide a 3‐D physical and chemical characterization of individual extraterrestrial particles, using the measurement of their 3‐D structure and porosity, and the detection of mineral and organic phases, and their spatial co‐localization in 3‐D. We propose these techniques as an efficient first step in a multitechnique analytical sequence on microscopic samples collected by space missions. 相似文献
150.
Coastal uplift rate at Matanzas (Cuba) inferred from MIS5e phreatic overgrowths on speleothems 下载免费PDF全文
Jo De Waele Ilenia M. D'Angeli Nicola Tisato Paola Tuccimei Michele Soligo Joaquín Ginés Angel Ginés Joan J. Fornós Igor M. Villa Esteban R. Grau González Stefano M. Bernasconi Tomaso R. R. Bontognali 《地学学报》2017,29(2):98-105
Many morphological elements in Cuba's landscape (e.g. marine terraces, tidal notches) demonstrate that coastal uplift has taken place, but the rate at which this occurs is not known. Carbonate phreatic overgrowths on speleothems have been found in a cave in Central North Cuba, ~1 km from the present coastline at 16 m asl. They form exceptional and unique mushroom‐shaped speleothems and balconies decorating the walls of the rooms. These phreatic overgrowths on speleothems (POS) formed at the oscillating air–water interface in sea‐level controlled anchialine lakes. U/Th dating of these overgrowths suggests ages that are compatible with the Marine Isotope Stage 5e (i.e. 130–115 ka). These POS have fixed this sea‐level highstand and demonstrate that this part of Cuba has been subjected to a much lower uplift rate than previously reported, that is, less than 0.1 mm/year since the last interglacial. 相似文献