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Description
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This dataset accompanies the article "Geochemical signatures of forearc serpentinites from oceanic to continental subduction" in Geochimica Cosmochimica Acta. Here are given the location, major, trace and radiogenic isotope composition of studied meta-serpentinites. The dataset includes: Table S1. Locations and main assemblages of the studied ultramafic rocks. Table S2. Major and trace element compositions and Sr and Pb radiogenic isotopes of Ladakh serpentinites, blueschists and eclogitic metasediments. Table S3. Parameters used in the Sr and Pb isotope model
Major element analyses were carried out at SARM-CRPG (Service d'Analyses des Roches et des Minéraux – Nancy, France) by alkali rock fusion using LiBO2 and concentrations measured by inductively coupled plasma optical emission spectrometry (Thermo Scientific iCap6500 ICP-OES). Both total sulfur (SO4) and carbon (CO2) were quantified by infrared analysis of the loss on ignition components using a HORIBA EMIA 320V2 analyser. Results for the reference materials BHVO-2 (basalt, USGS) and UB-N (serpentinite, CRPG), analysed with the samples, were generally within 2% of the reported values and within the reported uncertainties for all major and volatile elements
Additional FeO analyses were performed by automated titration at the equivalent point with potassium dichromate after dissolution of the sample in a HF/H2SO4 mixture in the presence of H3BO3 and H3PO4. The error of the FeO analyses was less than 0.2 wt% (at two standard deviations) based on repeated analyses of the CRPG UB-N serpentinite standard.
Trace element contents were measured using an Agilent 7900 ICP-QMS at IPGP (France). The reproducibility is based on UB-N (1) analyses. It was better than 10% for Li, V, Co, Zn, As, Sr, Y, Zr, Ba, La, Ce, Pr, Nd, Sm, Eu, Tb, Tm, Hf, Pb, Th, U, between 10-15% for Ti, Cu, Gd, Dy, Ho, Er, Yb, Lu and of 25% for Sb when compared with published values. Boron concentrations were measured spectrophotometrically using an Agilent CARY60 and F was determined by an ion-selective electrode at SARM. For boron, the long-term reproducibility was between 10% and 20% at 100 ppm and 10 ppm, respectively.For fluorine, the long-term reproducibility was between 3% and 20% at 1000 ppm and 20 ppm, respectively. The reference material values for UB-N (B = 140 ppm; F = 96 ppm) and BHVO-2 (B = 2.5 ppm; F = 400 ppm) were consistent with previous studies.
Major element contents in weight percent, trace element content in parts per million unless otherwise stated.
Strontium isotope analyses were performed at SARM using a ThermoFisher Triton Plus thermal ionisation mass spectrometer (TIMS). The NBS987 was used as a reference standard with a reference value of 87Sr/86Sr = 0.710259 ± 0.000019. The isotopic composition of Pb was measured at IPGP on a Thermo Scientific Neptune Plus multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS). Reproducibility and accuracy were evaluated by measuring a procedural blank, replicate samples and reference material UB-N (208Pb/204Pb = 38.324 ± 0.002 ‰; 207Pb/204Pb = 15.623 ± 0.0005 ‰; 208Pb/204Pb = 18.311 ± 0.0005 ‰) of known composition.
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