⁴⁰Ar/³⁹Ar step-heating data and preferred-age calculations for the northeastern Carajás Province, Amazonian Craton, Mendeley Data
Description
Complete ⁴⁰Ar/³⁹Ar incremental step-heating dataset for the northeastern Carajás Province, southeastern Amazonian Craton, Brazil, with the source data underlying the figures of the associated article. The dataset comprises 536 step-heating analyses of 14 samples (31 aliquots) plus a hornblende standard, and a further 85 analyses of four grains of the hydrothermal reference sample Serra Verde-01. Dated minerals are hornblende, actinolite, anthophyllite, tremolite, biotite and white mica, hand-picked from mapped tectonic fabrics or from well-defined hydrothermal assemblages along a north–south transect crossing Mesoarchean basement, Neoarchean supracrustal and intrusive rocks of the Itacaiúnas Supergroup, and Paleoproterozoic cover. Analyses were performed by laser incremental heating at the Argon Geochronology in Earth Sciences laboratory, The University of Queensland. Samples were irradiated for 14 h at the B-1 CLICIT facility, Oregon State University, with Fish Canyon sanidine monitors at 28.201 Ma (Kuiper et al., 2008). Ages use the decay constants of Min et al. (2000) and an atmospheric ⁴⁰Ar/³⁶Ar of 298.56. For every analysis the data include measured and corrected Ar isotope intensities with uncertainties; ⁴⁰Ar/³⁹Ar, ³⁷Ar/³⁹Ar, ³⁸Ar/³⁹Ar and ³⁶Ar/³⁹Ar ratios; radiogenic ⁴⁰Ar*; ³⁹Ar moles and the fraction of ³⁹Ar released per step and cumulatively; Ca/K and Cl/K; apparent ages with analytical and J-propagated uncertainties; and the isotope-correlation parameters and error correlations needed to reproduce inverse-isochron regressions. Irradiation parameters, neutron-induced interference corrections, mass discrimination factors, decay constants, monitor age and atmospheric ratios are reported once in a dedicated metadata sheet rather than repeated on every row, following the reporting recommendations of Schaen et al. (2021). Exact step selections, regression statistics and selection status for the FT-009C inverse-isochron arrays are given in a separate sheet, and a sample key maps laboratory identifiers to the sample names used in the article. The data resolve a polyphase ca. 2.61–2.52 Ga hydrothermal amphibole record, ca. 2.20 Ga fluid-assisted re-equilibration, Rhyacian fabric recrystallization at ca. 2.08–2.05 Ga, an Early Orosirian event at ca. 2.01–1.96 Ga, and a ca. 1.88 Ga Uatumã hydrothermal overprint.