Search results for " noble gases"

Noble gas magmatic signature of the Andean Northern Volcanic Zone from fluid inclusions in minerals

2021

Trace volatile elements like He are key for understanding the mantle source signature of magmas and to better constrain the relative roles of subduction and crustal processes to the variability of along-arc chemical and isotopic signatures of magmatic fluids. Here we report on noble gas abundances and isotopic data of Fluid Inclusions (FIs) in eruptive products and/or fumarolic gases from the Colombia-Ecuador segment of Andean Northern Volcanic Zone (NVZ). FIs in olivine phenocrysts from Ecuador (El Reventador, Cotopaxi and Tungurahua) yield air-normalized corrected He-3/He-4 ratios of 7.0-7.4 R-A, within the MORB range (8 +/- 1 R-A). With exception of the Cotopaxi lavas (opx = 50 km at the…

Relativistic coupled cluster calculations of the electronic structure of KrH+, XeH+ and RnH+

2012

Potential energy curves of NgH+ cations (Ng = Kr, Xe, Rn) were obtained by using four-component relativistic CCSD(T) coupled cluster calculations. Dissociation energies, equilibrium bond lengths, electronic properties, such as dipole moments and electric field gradients at the nuclei, and the related spectroscopic parameters of the electronic ground state have been determined. The results obtained for KrH+ and XeH+ are in good agreement with available experimental data, while those for RnH+ have been determined for the first time at this level of theory.

The composition of fluids stored in the central Mexican lithospheric mantle: Inferences from noble gases and CO2 in mantle xenoliths

2021

We present the first isotopic (noble gases and CO2) characterization of fluid inclusions coupled to Raman microspectroscopy analyses in mantle xenoliths from Central Mexico, a geodynamically complex area where the Basin and Range extension was superimposed on the Farallon subduction (terminated at 28 Ma). To characterize the isotopic signature of the Central Mexican lithospheric mantle, we focus on fluid inclusions entrapped in mantle xenoliths found in deposits of the Joya Honda maar (JH), a Quaternary monogenetic volcano belonging to the Ventura Espiritu Santo Volcanic Field (VESVF) in the state of San Luis Potosí (central Mexico). Thirteen ultramafic plagioclase-free xenoliths were selec…

Strongly SiO2-undersaturated, CaO-rich kamafugitic Pleistocene magmatism in Central Italy (San Venanzo volcanic complex) and the role of shallow dept…

2020

The Pleistocene (~460–265 ka) San Venanzo volcanic complex belongs to the IAP (Intra-Apennine Province) in central Italy, which comprises at least four small Pleistocene monogenetic volcanoes plus several unrooted pyroclastic deposits with peculiar mineralogical and whole-rock chemical compositions. San Venanzo products are strongly SiO2-undersaturated, CaO- and MgO-rich and show ultrapotassic serial character. The relatively common occurrence of calcite in the pyroclastic rocks and the overall high CaO content are interpreted in literature as primary mineral. The main rock facies at San Venanzo are calcite-rich scoria and lapilli tuffs, with minor massive lava flows, and a rare pegma…

The role of trapped fluids during the development and deformation of a carbonate/shale intra-wedge tectonic mélange (Mt. Massico, Southern Apennines,…

2020

Abstract Numerous studies exist on exhumed tectonic melanges along subduction channels whereas, in accretionary wedge interiors, deformation mechanisms and related fluid circulation in tectonic melanges are still underexplored. We combine structural and microstructural observations with geochemical (stable and clumped isotopes and isotope composition of noble gases in fluid inclusions of calcite veins) and U-Pb geochronological data to define deformation mechanisms and syn-tectonic fluid circulation within the Mt. Massico intra-wedge tectonic melange, located in the inner part of the central-southern Apennines accretionary wedge, Italy. This melange developed by shear deformation at the bas…

Petrological and noble gas features of Lascar and Lastarria volcanoes (Chile): Inferences on plumbing systems and mantle characteristics

2020

Lascar (5592 m a.s.l.) and Lastarria (5697 m a.s.l.) are Chilean active stratovolcanoes located in the Central Volcanic Zone (CVZ; 16°S to 28°S) that have developed on top of a 71 km thick continental crust. Independently of the similarities in their Plinian/Vulcanian eruptive styles, their complex magmatic feeding structures and the origins of their magmatic fluids still necessitate constraints in order to improve the reliability of geochemical monitoring. Here we investigate the petrography, bulk-rock chemistry, and mineral chemistry in products from the 1986–1993 explosive eruptive cycle at Lascar and from several Holocene eruptive sequences at Lastarria. These data are integrated with m…

Noble Gases Investigation on Etnean Volcanic Gases and on the Erupted Products During the 2001-2006 Period

2008

Data acquired during the last 20 years of geochemical monitoring of volcanic gases lead us to better understand how volcanoes work. According to theoretical and experimental investigations, both the chemical and isotopic changes in sampled volcanic gases have been interpreted in terms of magma ascent using the models proposed by Nuccio & Paonita, (2001) and Caracausi et al. (2003). On the basis of numerical simulations of volatile degassing, we have been able to recognize episodes of magma migration from deeper reservoirs of Mount Etna to the shallower storage volume, until magma is erupted. The 3He/4He isotope ratios of gas emitted at the periphery of Mount Etna volcanic edifice exhibit sy…

A TWO-COMPONENT MANTLE EXTENDING FROM MT. ETNA TO HYBLEAN PLATEAU (EASTERN SICILY) AS INFERRED BY AN INTEGRATED APPROACH WITH NOBLE GASES, TRACE ELEM…

2012

EVIDENCES OF ENRICHED MANTLE (EM-2) SOURCE CONTRIBUTION TO ETNEAN MAGMAS: A COMPREHENSIVE STUDY ON FLUID AND MELT INCLUSIONS OF 2001-2006 ERUPTIONS

2009

An overview of the geochemical characteristics of oceanic carbonatites: New insights from Fuerteventura carbonatites (Canary islands)

2021

The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This paper provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis. We present new data on trace elements in minerals and whole-rock, together with the first noble gases isotopic study (He, Ne, Ar) in apatite, calcite, and clinopyroxene from Fuerteventura carbonatites (Canary Islands). Trace elements show a similar trend as Cape Verde carbonatites, almost tracing the same patterns on multi-element and REE abundance diagrams. 3…