Search results for "MINERALOGY"

Volcanic steam output directly measured in fumaroles: the observed variations at Vulcano Island, Italy, between 1983 and 1987

1992

The mass of steam emitted by the fumaroles of the crater of Vulcano (Aeolian Islands, Italy) was evaluated by using a direct measuring method. Measurements were effected with this method between 1983 and 1987 in nine field campaigns, the results of which are given in this paper. The steam flux measurements were performed by an instrument expressly designed for steam condensation. The estimates of the thermal energy transported daily by the steam gave values of up to 10E12 J. The sharp variations in the total mass outputs recorded in 1984 and 1985 are here interpreted as being a consequence of the probable accumulation of fluid pressure at depth, during the evolution of volcanic activity. Th…

Evolution of mica fish in mylonitic rocks

2003

Abstract Mineral fish are lozenge-shaped porphyroclasts, single crystals in a finer grained matrix, which occur in ductile shear zones and which are commonly used as shear sense indicators. Mineral fish of biotite, tourmaline, K-feldspar, garnet, hypersthene and quartz occur in mylonites but most common are white mica fish. These mica fish can be subdivided into six morphological groups that develop by different mechanisms determined by different initial shapes and orientations. The principal mechanisms of formation are intracrystalline deformation combined with rigid body rotation. Concomitant selective grain size reduction occurs by recrystallisation, cataclastic separation, pressure solu…

MPI-DING reference glasses for in situ microanalysis: New reference values for element concentrations and isotope ratios

2006

We present new analytical data of major and trace elements for the geological MPI-DING glasses KL2-G, ML3B-G, StHs6/80-G, GOR128-G, GOR132-G, BM90/21-G, T1-G, and ATHO-G. Different analytical methods were used to obtain a large spectrum of major and trace element data, in particular, EPMA, SIMS, LA-ICPMS, and isotope dilution by TIMS and ICPMS. Altogether, more than 60 qualified geochemical laboratories worldwide contributed to the analyses, allowing us to present new reference and information values and their uncertainties (at 95% confidence level) for up to 74 elements. We complied with the recommendations for the certification of geological reference materials by the International Associ…

2016

Abstract. To date, very little is known about the distribution of natural gas hydrates in sedimentary matrices and its influence on the seismic properties of the host rock, in particular at low hydrate concentration. Digital rock physics offers a unique approach to this issue yet requires good quality, high-resolution 3-D representations for the accurate modeling of petrophysical and transport properties. Although such models are readily available via in situ synchrotron radiation X-ray tomography, the analysis of such data asks for complex workflows and high computational power to maintain valuable results. Here, we present a best-practice procedure complementing data from Chaouachi et al.…

Rock paintings from Minas Gerais, Brasil, investigated by in-situ Mössbauer spectroscopy

2002

The archaeological site of Santana do Riacho is located at about 90 km northeastern of Belo Horizonte, in the “Serra do Cipo” region. The recent development of a miniaturised Mossbauer spectrometer opened the possibility of making in-situ measurements of the rock paitings, and the results of such pioneer work is presented in this contribution. The spectrometer MIMOS II operates in backscattering geometry measuring the scattered 14.41 keV Mossbauer radiation and the 6.4 keV Fe X-rays. The dimensions of the whole instrument are approximately 110 mm (long) × 80 mm (diameter). The paintings were selected based on their colours and apparent thickness, and six spots were measured. The analysis of…

In-situ Mössbauer Spectroscopy with MIMOS II at Rio Tinto, Spain

2010

The Rio Tinto, located in southwest Spain, exhibits a nearly constant, acidic pHvalue along its course. Due to the formation of sulfate minerals, Rio Tinto is considered a potential analogue site for sulfate-rich regions on Mars, in particular at the landing site of the Mars Exploration Rover Opportunity, where the ferric sulfate mineral jarosite was identified with Opportunity's Mössbauer spectrometer. Primary and secondary mineralogy was investigated in situ with portable Raman and Mössbauer spectrometers at four different Rio Tinto sampling sites. The two techniques analyse different sample portions due to their specific field of view and sampling depth and provide complementar…

Further characterisation of the 91500 zircon crystal

2004

This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodolumines…

On-Line and In-Situ Identification of Air Pollution

2002

The elemental, iron-phase, and oxidation state analysis of urban aerosol samples, collected from different sites in Vitoria metropolitan region, ES, Brazil, was carried out using Mossbauer (MB) Spectroscopy (MBS) and X-ray fluorescence (XRF) techniques. A portable XRF spectrometer for elemental analysis from Na to Fe, and the miniaturized MB spectrometer MIMOS-II have been installed together using a 100 mCi 57 Co(Rh) MB source for XRF excitation. Both measurements can be performed simultaneously. For continuous and fast characterization purposes a software package was developed for Mossbauer and XRF analysis. The software is based on genetic algorithm, fuzzy logic and artificial neural netw…

Ultrastructure of the Interlamellar Membranes of the Nacre of the Bivalve Pteria hirundo, Determined by Immunolabelling.

2015

The current model for the ultrastructure of the interlamellar membranes of molluscan nacre imply that they consist of a core of aligned chitin fibers surrounded on both sides by acidic proteins. This model was based on observations taken on previously demineralized shells, where the original structure had disappeared. Despite other earlier claims, no direct observations exist in which the different components can be unequivocally discriminated. We have applied different labeling protocols on non-demineralized nacreous shells of the bivalve Pteria. With this method, we have revealed the disposition and nature of the different fibers of the interlamellar membranes that can be observed on the …

In situ Laser Induced Breakdown Spectroscopy as a tool to discriminate volcanic rocks and magmatic series, Iceland.

2015

7 pages; International audience; This study evaluates the potentialities of a lab-made pLIBS (portable Laser-Induced Breakdown Spectroscopy) to sort volcanic rocks belonging to various magmatic series. An in-situ chemical analysis of 19 atomic lines, including Al, Ba, Ca, Cr, Cu, Fe, Mg, Mn, Na, Si, Sr and Ti, from 21 sampled rocks was performed during a field exploration in Iceland. Iceland was chosen both for the various typologies of volcanic rocks and the rugged conditions in the field in order to test the sturdiness of the pLIPS. Elemental compositions were also measured using laboratory ICP-AES measurements on the same samples. Based on these latter results, which can be used to ident…