Search results for "petrology"

Solubility of Monazite–Cheralite and Xenotime in Granitic Melts, and Experimental Evidence of Liquid–Liquid Immiscibility in Concentrating REE

2021

Abstract We provide new experimental data on monazite, xenotime and U–Th-bearing cheralite solubility in slightly peralkaline to peraluminous granitic melts using dissolution and reverse (i.e. recrystallization after dissolution) experiments in water-saturated and flux-bearing (P + F + Li) granitic melts, at 800 °C and 200 MPa. Although a positive correlation between rare earth element (REE) solubility and melt peralkalinity is confirmed, monazite solubilities reported here are much lower than the values previously published. We suggest that the presence of elevated phosphorus concentrations in our melts depresses monazite solubility, principally because phosphorus complexes with Al and alk…

Mean bulk densities of samples of dry atmospheric aerosol particles: A summary of measured data

1977

Mean bulk densities of various samples of dry atmospheric aerosol particles sampled at different sites and during different seasons and weather situations range between 1.8 and more than 3 gm cm3.

Pattern formation in 3-D numerical models of down-built diapirs initiated by a Rayleigh–Taylor instability

2015

SIGNIFICANCE AND IMPLICATIONS OF SHINGLING IN REFRACTION RECORDS *

1966

The occurrence of shingling in. long range refraction records often makes the task of the seismic interpreter heavier, especially when several refractors are encountered and the velocity contrasts are small. The explanation of the phenomenon given by the existing literature is examined and the theoretical results are compared with the observed data on field records. In field seismograms shingling must be separated from the effect of geological structures or lateral discontinuities. If an appropriate analysis of shingling is possible, this phenomenon can be related to the type of refracting layer, being a useful tool to a qualitative approach. On the other hand the implications of shingling …

COMPARATIVE CONSIDERATIONS ON THE ENERGY CONTENT OF SEISMIC WAVES IN CENTRAL AND LINEAR PATTERN SHOOTING*

1960

In continuation of a publication by Pierau and Mueller (1960), theoretical and experimental comparisons are made about the energy content of seismic waves for central and linear shotpoint arrangements. The following results are obtained: Using shotpoint arrangements as chosen for the investigation, the energy content of deep reflections is greater in linear than in central pattern shooting, provided that the total quantity of charge is the same in both cases. Furthermore the seismograms obtained with linear shotpoint arrays are less disturbed by surface waves than those obtained in central pattern shooting. Both effects are superimposed and improve considerably the signal-to-noise ratio, th…

MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems

2022

Prediction of stable mineral equilibria in the Earth's lithosphere is critical to unravel the tectonomagmatic history of exposed geological sections. While the recent advances in geodynamic modeling allow us to explore the dynamics of magmatic transfer in solid mediums, there is to date no available thermodynamic package that can easily be linked and efficiently be accounted for the computation of phase equilibrium in magmatic systems. Moreover, none of the existing tools fully exploit single point calculation parallelization, which strongly hinders their applicability for direct geodynamic coupling or for thermodynamic database inversions. Here, we present a new Mineral Assemblage Gibbs En…

Uncertainty in environmental and hydrological mathematical modelling

2012

Engineers are increasingly called to deal with practical problems related to water resources management, risk analysis, environmental engineering and water pollution. Providing a way forward to solve the above questions requires setting up mathematical models that are affected by uncertainty, that in many cases is relevant. In fact, the theories that are employed for providing solutions to engineer’s problems are not exact sciences: even if it is methodologically rigorous, it is incapable of producing precise results, for the presence of inherent randomness that translates in indeterminacy and therefore uncertainty. To cope with uncertainty is a challenge for scientists and practitioners, t…

New insights into magma dynamics during last two eruptions of Mount Etna as inferred by geochemical monitoring from 2002 to 2005

2006

Two distinct eruptive events characterize the volcanic activity at Mount Etna during the 2002 to 2005 period. We identified signals of magma ascent preceding these eruptions by geochemical monitoring of both chemical composition and He-isotope ratio of gas emissions from five locations in the peripheral area of the volcano. The geochemical signals are interpreted using the models proposed by Caracausi et al. (2003a, 2003b) and allow identification of episodes of magma ascent and estimation of the pressures of degassing magma. As observed for the 2001 eruption (Caracausi et al., 2003b), magma ascent probably triggered the onset of the 2002–2003 eruption, and minor events of magma ascent were…

Temporal evolution of the Fogo Volcano magma storage system (Cape Verde Archipelago): a fluid inclusions perspective

2023

The architecture of the magma storage system underneath Fogo Volcano (Cape Verde Archipelago) is characterised using novel fluid inclusion results from fifteen basanites, spanning the last 120 thousand years of volcanic activity, and encompassing a major flank collapse event at -73 ka. Fluid inclusions, hosted in olivine and clinopyroxene, are made of pure CO2, and based on their textural characteristics, are distinguished in early (Type I) and late (Type II) stage. Inclusions homogenize to a liquid phase in the 2.8 to 30.8 degrees C temperature range. Densities values, recalculated assuming an original 10% H2O content at the time of trapping, range from 543 to 952 kg center dot m(-3), and …

Constraints on mantle source and interactions from He-Sr isotope variation in Italian Plio-Quaternary volcanism

2008

[1] Helium isotope ratios of olivine and pyroxene phenocrysts from Plio-Quaternary volcanic rocks from southern Italy (seven Aeolian Islands, Mt. Vulture, Etna, Ustica, and Pantelleria) range from 2.3 to 7.1 Ra. Importantly, the phenocryst 3He/4He correlate well with whole rock Sr isotopic composition (0.70309–0.70711), reflecting the mixing of two sources. A significant contribution of He from crustal contamination is recorded only occasionally (e.g., pyroxenes from Vulcano). When merged with data from the Roman Comagmatic Province, a remarkably strong near-linear He-Sr isotope correlation is apparent. The general northward decrease in 3He/4He corresponds to an increase in 87Sr/86Sr (and a…