1,721,160 research outputs found
Direct assessment of mantle boron and lithium contents and distribution by SIMS analyses of peridotite minerals
No full textSIMS investigation of nitrogen in tobelite. Constraints from EMPA and crystal chemical charge-balance
No full textPossibility to develope reference materials (standards) for quantitative SIMS
analysis of nitrogen in mica
Trace element redistribution in high temperature deformed gabbros from East Ligurian ophiolites (northern Apennines, Italy): Constraints on the origin of syndeformation fluids
No full textAbstract Mg‐gabbros from East Ligurian ophiolites (Northern Apennines, Italy) display a high‐temperature/low‐pressure recrystallization localized along ductile shear zones. In deformed gabbros, the igneous diopside is recrystallized into granoblastic aggregates of neoblastic diopside and minor red‐brown amphibole. The latter displays a pargasitic composition, with high amounts of AlIV Na(A) and Ti (± 1.8, 0.7 and 0.4 atoms per formula unit, respectively). Major element composition of neoblastic minerals highlight equilibration temperature conditions in the range 800–950° C. Red‐brown Ti‐pargasite also occurs as a minor interstitial constituent, presumably growing from a residual trapped liquid, in the differentiated lithologies (Fe‐Ti‐diorites) of the plutonic ophiolitic complex. By means of ion microprobe (SIMS technique), rare earth (La, Ce, Nd, Sm, Eu, Gd, Dy, Er, Yb) and selected trace elements (Sr, Y, Cr, V, Sc, Zr, Ti) have been analysed in igneous and neoblastic diopside, as well as in Ti‐pargasites. Ti‐pargasites have also been analysed for F and Cl, and compared with the halogen composition of the amphiboles, mainly hornblendes to actinolites, which are related to the subsequent low‐temperature brittle evolution. Neoblastic Ti‐pargasite from deformed Mg‐gabbros bears close compositional similarities with igneous Ti‐pargasite from undeformed Fe‐Ti‐diorites, whereas it is geochemically distinct from the amphiboles post‐dating the ductile event. In particular, Ti‐pargasites have relatively high contents of F, REE, Y, Zr and Sr, which are not consistent with crystallization in the presence of seawater‐derived hydrothermal fluids. High‐grade recrystallization probably developed in the presence of volatile‐rich igneous fluids, either trapped between the cumulus minerals or injected into the ductile shear zones from outside the local system. An alternative hypothesis comprises the absence of fluid phase and the development of ductile shear zones in Ti‐pargasite‐rich layers. The petrological features of deformed gabbros recovered from present‐day slow‐spreading ridges and fracture zones bear close similarities with the investigated ophiolitic metagabbros. In East Ligurian ophiolites, high‐grade ductile shear zones have been related to the initial stages of the uplift of the gabbro‐peridotite complex to the sea‐floor. Copyright © 1995, Wiley Blackwell. All rights reserve
Ti- and F-rich phlogopites from Mt. Vulture (Potenza, Italy): a combined EPMA, SIMS and SCXRD study
No full textMicroanalysis of hydrogen, boron and fluorine in vesuvianite by means of SIMS, EPMA and FTIR
No full textVesuvianite, a complex sorosilicate, often contains variable (from trace-to-minor-element) amounts of H, B and F. We describe a microanalytical study of H, B and F in vesuvianite by means of Electron Probe Microanalysis (EPMA), Secondary Ion Mass Spectrometry (SIMS), and single-crystal Fourier-Transform InfraRed (FTIR) spectroscopy. Most crystals investigated are B- (up to 3.67 wt% B2O3) and F-rich (up to 2.38 wt%); H2O ranges from 0.243 to 0.665 wt%. The H data obtained by SIMS allowed us to calibrate the quantitative analysis of H2O by FTIR spectroscopy. The resulting molar absorption coefficient (εi=100000±2000 L·mol-1·cm-2) is in excellent agreement with working curves available from the literature. Moreover, the SIMS data allowed us to obtain the calibration curve to estimate the B2O3 content on the basis on the FTIR absorbance:
ai=34000±1400·B2O3 (wt%)
A new application of SIMS to the analysis of nitrogen in mica minerals: tobelite.
No full textMuscovite, KAl2[AlSi3O10](OH)2, is a common rock-forming mineral in igneous and
metamorphic-rocks, sediments, hydrothermal alteration and ore deposits. The site between two
adjacent T-O-T (tetrahedral-octahedral-tetrahedral) layers is shared between K and NH4 in any
proportion leading to the building of the “ammonium micas”. Mica with: (i) NH4>K,
□ (vacancy); (ii) Si ≥ 3 apfu (atoms per formula unit); (iii) layer charge (T-O-T) less than one,
is named tobelite [Brigatti M F and Guggenheim S 2002 Rev. Mineral. Geochem. 46 1-97].
The NH4-analog of muscovite, i.e., tobelite, has been predominantly associated to two distinct
geological settings: a) diagenetic to low grade metamorphic shales from meta- anthracite and
anthracite coal fields; b) hydrothermal areas alteration [Ruiz Cruz M D and Sanz de Galdeano
C 2010 Clays Clay Miner. 58 558-572].
In this work three crystals labelled Tob_M2, Tob_M3, Tob_3 were investigated by electron
probe microanalysis (EPMA) in terms of major constituents, and in terms of nitrogen by
secondary ion mass spectrometry (SIMS) in order to gain information on the presence and
amount of NH4. Nitrogen was detected as secondary positive ions by means of a Cameca IMS
4f ion microprobe installed at CNR-IGG, Pavia. SIMS analysis on 14N+ was performed with
16O- primary beam at a mass resolution (M/ΔM) of ~ 1250 required to discriminate the 28Si2+
and 12CH2
+ interferences at the nominal mass number 14 (a.m.u.).
In spite of the severe inhomogeneity of nitrogen in each crystal, the SIMS data put Tob_M2 as
the N-richest crystal of the set. The crystal, analyzed at different spots, is characterized by an
ion signal in the range 399 - 560 (c/s). For Tob_M3 the 14N+ average ion signal is 91 (c/s). In
Tob_3 the N content is likely the lowest in the sample set with an average count rate of
61 (c/s).
The lack of calibration standards did not allow so far to obtain quantitative results for N at the
ion microprobe. Nevertheless, our SIMS data agree qualitatively with constraints derived from
EPMA and charge-balance crystal chemical considerations, and point out that the ion probe is a
valuable tool for the investigation of N in mica minerals
Complementary Ti and Zr anomalies in orthopyroxene and clinopyroxene from mantle peridotites
No full textEPMA, SIMS and FTIR investigations on sodalites and haüynes from Somma-Vesuvius volcano (southern Italy). 14th European workshop EMAS, Modern Developments and Applications in Microbeam Analysis
No full textSodalite-group minerals (sodalite, tugtupite and danalite subgroups) commonly occur in
alkaline igneous rocks, and in some hydrothermal and metamorphic rocks. These minerals
present a zeolite-like cubic structure and two structural cavities per unit cell. Cationic and
anionic contents of SSG are of interest for the study of magmatic systems; in particular, their
volatile components can be useful because they can provide key information on the genetic
environment, like degassing dynamics, fluids behaviour during hydrothermal processes and so
on [1-4]. Besides, SSG are very promising in different fields of material science, since their
(ultra)microporous structures show high flexibility and versatility in hosting tetrahedral cations
and variable channels/cavities components. Hence, they can be suitable as advanced materials
and behave as models for many technological and commercial applications [5, 6], for instance
separation processing (i.e. hydrogen from gaseous macromolecules). The present study is
focused on crystal-chemical characterization of cationic and anionic components of SSG
occurring in various igneous to metamorphic rocks and ejecta from the alkaline-potassic
Somma-Vesuvius volcano (southern Italy), as revealed by using combined microbeam
techniques, i.e., EPMA, SIMS and μ-FTIR. Previous studies on sodalite-group minerals by
means of EPMA, Raman, and LA-ICP-MS techniques focussed on halogen- (Cl, Br) and
S-contents [2, 3, 8]. To the authors’ knowledge no studies on volatiles in SSG have been
performed so far by integrated SIMS-FTIR investigations. Compared to bulk analyses, SIMS
and μ-FTIR methods are particularly pivotal to probe trace to ultra-trace contents, speciations
and orientations of an absorber across the samples [1, 7]. Our investigations show that the
studied SSG correspond to sodalite sensu stricto, nosean (sulfatic sodalite) and haüyne. SIMS
measurements on H, F and C (quantified as H2O, F and CO2, respectively) show contents:
0.02 - 5.0 wt% H2O, 0.01 - 0.14 wt% F, and 0.69 - 2.95 wt% CO2. Within the single crystals,
the F and CO2 concentrations are virtually homogeneous, whereas in terms of H2O, samples
can vary from homogenous to strongly heterogeneous. Single-crystal FTIR spectra of SSG can
be grouped into sodalites and sulphatic sodalites/haüynes, according to the occurrence of the
12CO2 absorption at 2340 cm-1 [1, 9]. The absorption due to H2O and/or OH groups occurs as a
very broad band extending from 3700 cm-1 to 3000 cm-1. In all samples FTIR data show the
presence of CO32-. μ-FTIR focal plane array imaging shows a very heterogeneous and
antithetical distribution of CO2 and especially of H2O according to the SIMS data.
[ 1] Bellatreccia F, Della Ventura G, Piccinini M, Cavallo A and Brilli M 2009 Min. Mag.
73 399-413
[ 2] Hettmann K, Wenzel T, Marks M and Markl G 2012 Am. Mineral. 97 1653-1661
[ 3] Hammerli J, Spandler C, Oliver N H S and Rusk B 2014 Metam. Geol. 32 93-112
[ 4] Wang L X, Marks M A W, Keller J and Markl G 2014 Chem. Geol. 380 133-144
[ 5] Ferraris G and Merlino S 2005 Rew. Min., Geoch. MSA 57 448 pp.
[ 6] Riley B J, Pierce D A, Frank S M, Matyáša J and Burns C A 2015 J. Nuclear Mat. 459
313–322
[ 7] Ottolini L and Le Fèvre B 2008 Microchim. Acta 161 329-336
[ 8] Hammerli J, Rusk B, Spandler C, Emsbo P and Oliver N H S 2013 Chem. Geol. 337-
338 75-87
[ 9] Balassone G, Bellatreccia F, Mormone A, Biagioni C, Pasero M, Petti C, Mondillo N and
Fameli G 2012 Mineral. Mag. 76 191-21
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