Dataset for: Transitioning from subduction to asthenospheric slab window and the source of the volcanism at the Meseta del Lago Buenos Aires, Patagonia
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Dataset for manuscript entitled, "Transitioning from subduction to asthenospheric slab window and the source of the volcanism at the Meseta del Lago Buenos Aires, Patagonia " by Guest et al. to be submitted to Geochimica et Cosmochimica Acta. Here we report new major, minor and trace element contents, as well as Sr, Nd, Pb, and Hf isotopes of the Meseta del Lago Buenos Aires (MLBA) lavas. We also report estimated mantle equilibration temperatures and pressures of MLBA lavas after correction for olivine fractionation after Plank and Forsyth (2016). Additionally, we report new Hf and Pb isotopes of lavas erupted along the Chile Ridge.
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Whole rock samples were analyzed at the Peter Hooper GeoAnalytical Laboratory at Washington State University. The major elements were measured on a ThermoARL Advant'XP + sequential XRF spectrometer for both major and selected trace elements (Ni, Cr, V, Ga, and Zn) following the procedures given in Johnson et al. (1999). Rare-earth-elements and remaining trace elements (Sc, Rb, Sr, Y, Zr, Nb, Cs, Th, U, Hf, Ta, and Pb) were measured on Li-tetraborate fused beads by inductively coupled plasma-mass spectrometry (ICP-MS) using an Agilent 7700 quadrupole mass spectrometer at WSU following the procedures given in Knaack et al. (1994). 31 of the 63 MLBA samples have previously reported 40Ar-39Ar ages ranging from 0.07-11.03 Ma (Brown et al., 2004). Sr, Nd, Hf, and Pb isotopic compositions were measured on a Thermo Scientific NEPTUNE PLUS MC-ICP-MS at the Mass Spectrometer Analytical Facility, Brown University. 87Sr/86Sr, 143Nd/144Nd and 176Hf/177Hf were corrected for instrumental mass fractionation using an 88Sr/86Sr = 0.1194, 146Nd/144Nd = 0.7219 and 179Hf/177Hf = 0.7325 respectively with an exponential law. Sample Pb solution was spiked with NBS SRM-997 Tl standard prior to analysis with a Pb/Tl ~ 4 to correct for the mass fractionation using an exponential law with a 203Tl/205Tl = 0.418922. The 87Sr/86Sr, 143Nd/144Nd and 176Hf/177Hf of samples are reported relative to NBS SRM-987 87Sr/86Sr = 0.71024, JNd-i Nd standard 143Nd/144Nd = 0.512115 and JMC-475 Hf standard 176Hf/177Hf = 0.282160 respectively. 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb are reported relative to the NBS 981 standard 206Pb/204Pb= 16.9356, 207Pb/204Pb= 15.4891, and 208Pb/204Pb= 36.7006 (Todt et al., 1996). We estimated the pressure and temperature of mantle-melt equilibration in representative MLBA lavas accounting for the effects of water, CO2 and Fe3+/FeT ratios (Lee et al., 2009; Plank and Forsyth, 2016).