Boron Determination in Twenty One Silicate Rock Reference Materials by Isotope Dilution ICP-MS     

Massimo D'Orazio 《Geostandards and Geoanalytical Research》1999,23(1):21-29

The concentration of boron was determined in twenty one geochemical reference materials (silicate rocks) by isotope dilution inductively coupled plasma-mass spectrometry. Boron was extracted from the rocks using HF digestion, suppressing boron volatilisation through boron-mannitol complexation. Sample solutions, in a diluted HCl matrix, were analysed by ICP-MS without any separation of boron from the matrix elements. The results obtained were in agreement with the literature data and indicate that using the described procedure, trace amounts of boron can be very easily determined in complex matrices with rapidity and precision. With the instrumentation and reagents used in this study, this procedure can be used for the determination of 0.5 μg g⁻¹ boron in a 15 0 mg silicate rock sample. Replicate analyses of the twenty one geochemical reference materials (GRM), ranging in boron concentration from 1.35 to 15 7 μg g⁻¹, yielded precisions (relative standard deviation) varying between 0.9 and 9.8%.  相似文献   

Anatomy of the Holocene succession of the southern Venice lagoon revealed by very high-resolution seismic data     

Massimo Zecchin  Giuliano Brancolini  Luigi Tosi  Federica Rizzetto  Mauro Caffau  Luca Baradello 《Continental Shelf Research》2009

The southern portion of the Venice lagoon contains a relatively thick (up to 20 m) Holocene sedimentary body that represents a detailed record of the formation and evolution of the lagoon. New very high-resolution (VHR) seismic profiles provided a detailed investigation on depositional geometries, internal bounding surfaces and stratal relationships. These informations, combined with core analysis, allowed the identification of large- to medium-scale sedimentary structures (e.g. dunes, point bars), the corresponding sedimentary environment, and of retrogradational and progradational trends. In addition, the availability of dense seismic network produced a 3D reconstruction of the southern lagoon and the recognition of the along-strike and dip variability of the stratal architecture.  相似文献   

Isotope geochemistry (Sr–Nd–Pb) and petrogenesis of leucite-bearing volcanic rocks from “Colli Albani” volcano, Roman Magmatic Province, Central Italy: inferences on volcano evolution and magma genesis     

Elena Boari  Riccardo Avanzinelli  Leone Melluso  Guido Giordano  Massimo Mattei  Arnaldo A. De Benedetti  Vincenzo Morra  Sandro Conticelli 《Bulletin of Volcanology》2009,71(9):977-1005

The “Colli Albani” composite volcano is made up of strongly silica-undersaturated leucite-bearing rocks. Magmas were erupted during three main periods, but a complex plumbing system dominated by regional tectonics channelled magmas into different reservoirs. The most alkali-rich magmas, restricted to the caldera-forming period (pre-caldera), are extremely enriched in incompatible trace elements and display more radiogenic Sr (⁸⁷Sr/⁸⁶Sr?=?0.71057–0.71067), with slightly less radiogenic Pb with respect to those of the post-caldera period. Post-caldera volcanic activity was concentrated in three different volcanic environments: external to the caldera, along the caldera edge and within the caldera. The post-caldera magmas produced melilite- to leucitite-bearing, plagioclase-free leucitites. In contrast to the pre-caldera lavas, they are characterised by lower incompatible trace element abundances and less radiogenic Sr (⁸⁷Sr/⁸⁶Sr?=?0.71006–0.71039). Magmas evolved through crystal fractionation plus minor crustal assimilation in a large magma chamber during the pre-caldera period. The multiple caldera collapses dissected and partially obliterated the early magma chamber. During the post-caldera stage, magmas were channelled through several pathways and multiple shallow-level magma reservoirs were established. A lithospheric mantle wedge previously depleted in the basaltic component and subsequently enriched by metasomatic slab-derived component is suggested as the mantle source of Colli Albani parental magmas. Two different parental magmas are recognised for the pre- and post-caldera stages. The differences may be related to the interplay between smaller degrees of melting for the pre-caldera magmas and more carbonate-rich recycled subducted lithologies in the post-caldera magmas.  相似文献   

Non‐linear seismic analysis and vulnerability evaluation of a masonry building by means of the SAP2000 V.10 code     

Laurent Pasticier  Claudio Amadio  Massimo Fragiacomo 《地震工程与结构动力学》2008,37(3):467-485

The aim of the paper is to explore the possibilities offered by SAP2000^® v.10, a software package with user‐friendly interface widely used by practising engineers, for seismic analyses of masonry buildings. The reliability of the code was first investigated by carrying out static push‐over (SPO) analyses of two walls, already analysed by other researchers using advanced programs. The equivalent frame modelling was employed in all analyses carried out. The code was then used to investigate the seismic performance of an existing two‐storey building typical of the north‐east of Italy, with the walls being made of roughly squared stones. An SPO analysis was performed first on the most significant wall, followed by a number of time‐history analyses aimed to evaluate the dynamic push‐over curves. Finally, the seismic fragility curves were derived, considering the seismic input as a random variable. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Experimental Sensitivity Analysis of Oxygen Transfer in the Capillary Fringe     

Christina M. Haberer  Olaf A. Cirpka  Massimo Rolle  Peter Grathwohl 《Ground water》2014,52(1):37-49

Oxygen transfer in the capillary fringe (CF) is of primary importance for a wide variety of biogeochemical processes occurring in shallow groundwater systems. In case of a fluctuating groundwater table two distinct mechanisms of oxygen transfer within the capillary zone can be identified: vertical predominantly diffusive mass flux of oxygen, and mass transfer between entrapped gas and groundwater. In this study, we perform a systematic experimental sensitivity analysis in order to assess the influence of different parameters on oxygen transfer from entrapped air within the CF to underlying anoxic groundwater. We carry out quasi two‐dimensional flow‐through experiments focusing on the transient phase following imbibition to investigate the influence of the horizontal flow velocity, the average grain diameter of the porous medium, as well as the magnitude and the speed of the water table rise. We present a numerical flow and transport model that quantitatively represents the main mechanisms governing oxygen transfer. Assuming local equilibrium between the aqueous and the gaseous phase, the partitioning process from entrapped air can be satisfactorily simulated. The different experiments are monitored by measuring vertical oxygen concentration profiles at high spatial resolution with a noninvasive optode technique as well as by determining oxygen fluxes at the outlet of the flow‐through chamber. The results show that all parameters investigated have a significant effect and determine different amounts of oxygen transferred to the oxygen‐depleted groundwater. Particularly relevant are the magnitude of the water table rise and the grain size of the porous medium.  相似文献   

Gradual Fault Weakening with Seismic Slip: Inferences from the Seismic Sequences of L’Aquila, 2009, and Northridge, 1994   总被引：1，自引：0，他引：1  

Luca Malagnini  Irene Munafo’  Massimo Cocco  Stefan Nielsen  Kevin Mayeda  Enzo Boschi 《Pure and Applied Geophysics》2014,171(10):2709-2730

We estimate seismological fracture energies from two subsets of events selected from the seismic sequences of L’Aquila (2009), and Northridge (1994): 57 and 16 selected events, respectively, including the main shocks. Following Abercrombie and Rice (Geophys J Int 162: 406–424, 2005), we postulate that fracture energy (G) represents the post-failure integral of the dynamic weakening curve, which is described by the evolution of shear traction as a function of slip. Following a direct-wave approach, we compute mainshock-/aftershock-source spectral ratios, and analyze them using the approach proposed by Malagnini et al. (Pure Appl. Geophys., this issue, 2014) to infer corner frequencies and seismic moment. Our estimates of source parameters (including fracture energies) are based on best-fit grid-searches performed over empirical source spectral ratios. We quantify the source scaling of spectra from small and large earthquakes by using the MDAC formulation of Walter and Taylor (A revised Magnitude and Distance Amplitude Correction (MDAC2) procedure for regional seismic discriminants, 2001). The source parameters presented in this paper must be considered as point-source estimates representing averages calculated over specific ruptured portions of the fault area. In order to constrain the scaling of fracture energy with coseismic slip, we investigate two different slip-weakening functions to model the shear traction as a function of slip: (i) a power law, as suggested by Abercrombie and Rice (Geophys J Int 162: 406–424, 2005), and (ii) an exponential decay. Our results show that the exponential decay of stress on the fault allows a good fit between measured and predicted fracture energies, both for the main events and for their aftershocks, regardless of the significant differences in the energy budgets between the large (main) and small earthquakes (aftershocks). Using the power-law slip-weakening function would lead us to a very different situation: in our two investigated sequences, if the aftershock scaling is extrapolated to events with large slips, a power law (a la Abercrombie and Rice) would predict unrealistically large stress drops for large, main earthquakes. We conclude that the exponential stress evolution law has the advantage of avoiding unrealistic stress drops and unbounded fracture energies at large slip values, while still describing the abrupt shear-stress degradation observed in high-velocity laboratory experiments (e.g., Di Toro et al., Fault lubrication during earthquakes, Nature 2011).  相似文献   

Guest Editorial     

Alessandro Amato  Massimo Cocco 《Journal of Seismology》2000,4(4):5-6

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On the scale dependence of earthquake stress drop     

Massimo Cocco  Elisa Tinti  Antonella Cirella 《Journal of Seismology》2016,20(4):1151-1170

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The earliest open conduit eruptive center of the Etnean region: evidence from aeromagnetic,geophysical, and geological data     

Iacopo Nicolosi  Francesca D’Ajello Caracciolo  Stefano Branca  Carmelo Ferlito  Massimo Chiappini 《Bulletin of Volcanology》2016,78(7):50

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Understanding mass fluvial erosion along a bank profile: using PEEP technology for quantifying retreat lengths and identifying event timing          下载免费PDF全文

A. N. Thanos Papanicolaou  Christopher G. Wilson  Achilles G. Tsakiris  Tommy E. Sutarto  Fabienne Bertrand  Massimo Rinaldi  Subhasish Dey  Eddy Langendoen 《地球表面变化过程与地形》2017,42(11):1717-1732

This study provides fundamental examination of mass fluvial erosion along a stream bank by identifying event timing, quantifying retreat lengths, and providing ranges of incipient shear stress for hydraulically driven erosion. Mass fluvial erosion is defined here as the detachment of thin soil layers or conglomerates from the bank face under higher hydraulic shear stresses relative to surface fluvial erosion, or the entrainment of individual grains or aggregates under lower hydraulic shear stresses. We explore the relationship between the two regimes in a representative, US Midwestern stream with semi‐cohesive bank soils, namely Clear Creek, IA. Photo‐Electronic Erosion Pins (PEEPs) provide, for the first time, in situ measurements of mass fluvial erosion retreat lengths during a season. The PEEPs were installed at identical locations where surface fluvial erosion measurements exist for identifying the transition point between the two regimes. This transition is postulated to occur when the applied shear stress surpasses a second threshold, namely the critical shear stress for mass fluvial erosion. We hypothesize that the regimes are intricately related and surface fluvial erosion can facilitate mass fluvial erosion. Selective entrainment of unbound/exposed, mostly silt‐sized particles at low shear stresses over sand‐sized sediment can armor the bank surface, limiting the removal of the underlying soil. The armoring here is enhanced by cementation from the presence of optimal levels of sand and clay. Select studies show that fluvial erosion strength can increase several‐fold when appropriate amounts of sand and clay are mixed and cement together. Hence, soil layers or conglomerates are entrained with higher flows. The critical shear stress for mass fluvial erosion was found to be an order of magnitude higher than that of surface fluvial erosion, and proceeded with higher (approximately 2–4 times) erodibility. The results were well represented by a mechanistic detachment model that captures the two regimes. Copyright © 2017 John Wiley & Sons, Ltd.  相似文献