Analytical data of Ar/Ar sanidine dating of tephra SALAR T6 (20°59.862'S, 70°01.630'W). Sample was collected from Salar Grande site during the field campaign of March 2017. These data compliment and support the results presented in the journal article "Identification of humid periods in the Atacama Desert through hillslope activity established by infrared stimulated luminescence (IRSL) dating". Medialdea et al., 2019. Global and Planetary Change.

Volcanic horizon T6 was processed for using standard mineral separation procedures. After crushing and washing, heavy liquid mineral separation with densities of 2.54 and 2.59 g/cm3 was performed to obtain the sanidine from the sample. Mineral fractions were further purified by hand-picking under an optical microscope. The selected mineral separate was packed in a 6 mm ID AI packages and loaded together with Fish Canyon Tuff sanidine (FCs) standard in a 25 mm ID Al cup. Sample and standard were irradiated at the Oregon State University TRIGA reactor in the cadmium shielded CLICIT facility for 7 hours (irradiation code VU114). After irradiation, samples and standards were unpacked and loaded in a 185 hole Cu tray and baked overnight at 250 °C under vacuum. This tray was then placed in a doubly pumped vacuum chamber with Zn-Se window and baked overnight at 120 °C under high vacuum. This chamber was connected to a ThermoFisher NGPrep gas purification line equipped with a hot GP50, a cold finger (Lauda at -70 °C) and hot St707 getter. Sample (1-3 grains/fusion) and standards (1 grain/fusion) were fused using a 25W Synrad CO2 laser. Released gas was analysed on an ARGUS VI+ noble gas mass spectrometer at the Vrije Universiteit Amsterdam, The Netherlands, equipped with four Faraday cups at the H2, H1, AX and L1 positions and two compact discrete dynodes (CDDs) at positions L2 and L3. The system was equipped with a 1012 Ohm amplifier on H2 and 1013 Ohm amplifiers on H1, AX and L1 cups. Samples were run on H1-L3 collectors. Similar to Phillips and Matchan (2013) we did not apply bias corrections, but analysed samples and standards in the same tray (and thus at more or less the same time) alternating with air pipettes with intensities in the same range as the samples and standards. Line blanks were measured every 2-3 unknowns and were subtracted from succeeding sample data. Data reduction is done in ArArCalc (Koppers, 2002). Ages are calculated with decay constants from Min et al., 2000 and 28.201 Ma for FCs (Kuiper et al., 2008). The atmospheric 40Ar/36Ar air value of 298.56 is used (Lee et al., 2006). The correction factors for neutron interference reactions are (2.64 ± 0.02) x10-4 for (36Ar/37Ar)Ca, (6.73 ± 0.04) x10-4 for (39Ar/37Ar)Ca, (1.21 ± 0.003) x10-2 for (38Ar/39Ar)K and (8.6 ± 0.7) x10-4 for (40Ar/39Ar)K. Full analytical data is included in the table.