4. Analy)cal apparatus and procedures In this chapter are described the analy1cal apparatus and procedures used during this PhD thesis.

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4. Analy)cal apparatus and procedures

In this chapter are described the analy1cal apparatus and procedures used during this PhD thesis.

4.1. X-‐ray diﬀrac)on

Mineral phases were iden1fied and studied through X-‐ray diffrac1on studies, using both single-‐crystal and powder techniques at Pisa University’s Dipar1mento di Scienze della Terra. Single-‐crystal data were collected through a Bruker Smart Breeze single-‐crystal diffractometer equipped with an air-‐cooled CCD detector and graphite-‐monochromated Mo Kα radia1on opera1ng at 50 KeV. Powder paOerns were collected using a Bragg-‐Brentano Philips with generator PW 1710, goniometer PW 1050/25 and Ni-‐filtered Cu Kα radia1on opera1ng at 40 KV and 20 mA.

4.2. Scanning electron microscope

Several polished sec1ons were inves1gated through scanning electron microscope Philips XL 30 opera1ng at 20 kV accelera1ng voltage and 15 μm beam diameter coupled with an energy-‐dispersive X-‐ray ﬂuorescence spectrometer EDAX PV 9900 at the Pisa University's Dipar1mento di Scienze della Terra.

4.3. Electron microprobe

Chemical analyses of skarn mineral phases were carried out using a JEOL-‐JXA-‐8600 electron microprobe (EMP) equipped with four WDS spectrometers at the CNR-‐IGG, Unit of Florence. Opera1ng condi1ons were set at 15 kV accelera1ng voltage, 10 nA beam current and variable peak coun1ng 1mes. X-‐ray counts were converted into oxides wt% using a PAP correc1on program (Pouchou and Pichoir, 1985).

4.4. Pb isotope

Pb isotope composi1on measurements were carried out using a Finnigan Mat 262 mul1-‐ collector Thermal Ioniza1on Mass Spectrometer (TIMS) at the CNR-‐IGG, Unit of Pisa. In order to correct isotope frac1ona1on repeated measurements of standard NIST SRM 981 were carried out together with unknown samples. Samples prepara1on and instrument set-‐up followed a standard procedure using in the TIMS laboratory (for further details see Agos1ni et al., 2005; internal report).

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4.5. H isotope

The hydrogen isotope composi1on of ilvaite samples were carried out using Thermo Fisher Delta XP Isotope Ra1o Mass Spectrometer with a TC/EA method (Sharp et al., 2001) at the CNR-‐IGG, Unit of Pisa. The calibra1on δD values were compared with those of 4 interna1onal standards (PB23, DS15, NBS30, BONSAL). The average reproducibility for standard and duplicate analyses is generally beOer than 5%.

4.6. O isotope

The 18_O/16_{O
ra1o
of
bio1te,
plagioclase,
ilvaite,
clinopyroxene
was
measured
by}

conven1onal laser ﬂuorina1on at the CNR-‐IGG, Unit of Pisa. The procedure was described by Sharp (1995). Pure F2 desorbed from K3NiF7 salt (Asprey, 1976) was used as reagent, and

O2 was the analyte measured with a Thermo Finnigan Delta XP Isotope Ra1o Mass

Spectrometer. Precision and accuracy of the analyses were monitored by measuring aliquots of laboratory quartz standards (QMS, δ18_{O
=
14.05
‰)
during
each
set
of
analyses,
yielding}

an average reproducibility of ± 0.14‰ (1s; n=12). The interna1onal standard used was a quartz standard NBS28 (δ18_{O=9.58
‰).
Another
standard
bio1te
NBS30
(δ}18_{O=5.24
‰)
was
also
used}

during the study and gave an average value of δ18_{O=5.22
±
0.16
‰

(1s;
n=7).}