Search results for "Inclusions"

Recycled crustal carbon in the depleted mantle source of El Hierro volcano, Canary Islands

2021

The Canary Islands, in the eastern Atlantic, are among the most enigmatic Oceanic Island provinces on Earth, as the mantle source feeding its volcanism exhibits wide spatial heterogeneity and a multiplicity of sources. Multi-isotope whole-rock studies have long revealed the presence of a recycled oceanic crust/lithosphere component in the mantle source. However, noble gas systematics have been more challenging to interpret, and the available carbon isotope data is limited and cannot support/dismiss this interpretation. Here, we present the very first isotopic characterisation of CO2 and noble gases (He-Ne-Ar) in fluid inclusions (FI) in minerals hosted in mantle xenoliths from El Hierro, th…

Interpretative model of shearband boudins internal evolution in HT ductile shear zones

2012

The internal structure of a shearband boudin resulting from an original igneous, hydrothermal or metamorphic segregation tabular rigid body is a subject of scientific interest. It allows understanding the deformation mechanisms acting on homogeneous quartz aggregate activated during simple shear progressive deformation. This work is focused on the characterization of the internal evolution of shearband boudins, using microtextural analysis, fluid inclusions studies, fractal and OCP analysis. The proposed interpretative model shows the several structural stages that can be well established during the process of the internal evolution of shearband boudin.

Internal Differentiation of the Archean Continental Crust: Fluid-Controlled Partial Melting of Granulites and TTG-Amphibolite Associations in Central…

2009

Fault bound blocks of granulite and enderbite occur within upper amphibolite-facies migmatitic tonalitic-trondhjemitic-granodioritic (TTG) gneisses of the Iisalmi block of Central Finland. These units record reworking and partial melting of different levels of the Archean crust during a major tectonothermal event at 2·6-2·7 Ga. Anhydrous mineral assemblages and tonalitic melts in the granulites formed as a result of hydrous phase breakdown melting reactions involving amphibole at peak metamorphic conditions of 8-11 kbar and 750-900°C. A nominally fluid-absent melting regime in the granulites is supported by the presence of carbonic fluid inclusions. The geochemical signature of light rare e…

A product space reformulation with reduced dimension for splitting algorithms

2021

AbstractIn this paper we propose a product space reformulation to transform monotone inclusions described by finitely many operators on a Hilbert space into equivalent two-operator problems. Our approach relies on Pierra’s classical reformulation with a different decomposition, which results in a reduction of the dimension of the outcoming product Hilbert space. We discuss the case of not necessarily convex feasibility and best approximation problems. By applying existing splitting methods to the proposed reformulation we obtain new parallel variants of them with a reduction in the number of variables. The convergence of the new algorithms is straightforwardly derived with no further assump…

Reaction between Cu-bearing minerals and hydrothermal fluids at 800 °C and 200 MPa: Constraints from synthetic fluid inclusions

2020

Abstract Transport and deposition of copper in the Earth's crust are mainly controlled by the solubility of Cu-bearing phases and the speciation of Cu in magmatic-hydrothermal fluids. To improve our understanding of copper mobilization by hydrothermal fluids, we conducted an experimental study on the interaction between Cu-bearing phases (metallic copper, Cu2O, CuCl) and aqueous chloride solutions (H2O ± NaCl ± HCl; with Cl concentrations of 0 to 4.3 mol kg-1). The experiments were run in rapid heat/rapid quench cold-seal pressure vessels at 800 °C, 200 MPa, and logfO2 ~ NNO+2.3. Either Cu or Au capsules were used as containers. The reaction products were sampled in situ by the entrapment o…

Volatile dilution during magma injections and implications for volcano explosivity

2016

Magma reservoirs underneath volcanoes grow through episodic emplacement of magma batches. These pulsed magma injections can substantially alter the physical state of the resident magma by changing its temperature, pressure, composition, and volatile content. Here we examine plagioclase phenocrysts in pumice from the 2014 Plinian eruption of Kelud (Indonesia) that record the progressive capture of small melt inclusions within concentric growth zones during crystallization inside a magma reservoir. High-spatial-resolution Raman spectroscopic measurements reveal the concentration of dissolved H2O within the melt inclusions, and provide insights into melt-volatile behavior at the single crystal…

The Magmatic to Hydrothermal Evolution of the Intrusive Mont Saint-Hilaire Complex: Insights into the Late-stage Evolution of Peralkaline Rocks

2017

The Cretaceous Mont Saint-Hilaire complex (Quebec, Canada) comprises three major rock units that were emplaced in the following sequence: (I) gabbros; (II) diorites; (III) diverse partly agpaitic foid syenites. The major element compositions of the rock-forming minerals, age-corrected Nd and oxygen isotope data for mineral separates and trace element data of Fe-Mg silicates from the various lithologies imply a common source for all units. The distribution of the rare earth elements in clinopyroxene from the gabbros indicates an ocean island basalt type composition for the parental magma. Gabbros record temperatures of 1200 to 800 degrees C, variable silica activities between 0 center dot 7 …

P4‐244: Progranulin (GRN), a protein mutated in frontotemporal dementia with ubiquitin‐positive inclusions (FTLD‐U), is abundantly expressed in human…

2009

Le comportement du soufre et les conditions d'oxydoréduction dans les basaltes hydratés de l'Etna inférés par des inclusions vitreuses et des verres …

2017

Sulfur is an important volatile component of magmas that presents different oxidation states, depending on the redox conditions and on the phase of occurrence: in silicate melts it is typically dissolved as S⁶⁺ and/or S²⁻ , in the gas phase it occurs principally as SO₂ (S⁴⁺ ) and H₂S (S²⁻). Mount Etna, in which magmatic redox conditions are poorly constrained, is used as a case study to investigate sulfur behavior in hydrous basaltic magmas during magma differentiation and degassing. This research integrates the study of natural olivine-hosted melt inclusions with an experimental study on S solubility in hydrous alkali basalts at magmatic conditions.Experimental results suggest the importan…

Melt inclusions track changes in chemistry and oxidation state of Etnean magmas

2017

Mount Etna (Italy) is a stratovolcano, located near the convergent boundary between African and European plates. Since its appearance, it was characterized by continuous variability of eruptive style and magma composition, though more subtle. Currently, its volcanic activity consists of effusive and explosive eruptions marked by high gas fluxes. Olivine hosted melt inclusions (MIs), belonging to products of the last 15 ky, were analysed for their chemical composition, volatiles contents and Fe speciation, in order to interpret the chemical variability and to evaluate the oxidation state of Etnean magmas and its eventual evolution. Olivine phenocrysts were selected from the most primitive Fa…