U-Pb dating of Triassic units from the Domeyko Range, northern Chile (II)

Published: 01-11-2020| Version 1 | DOI: 10.17632/rkf4js5xdd.1
Contributors:
mauricio espinoza,
Veronica Oliveros,
Luigi Solari

Description

This dataset covers the U-Pb dating of detrital and igneous samples from Triassic volcanic and sedimentary units across the Domeyko Range, northern Chile. It accompanies planned publication "Gondwanan inheritance on the building of the western Central Andes (Domeyko Range, Chile): Structural and thermochronological approach (U-Pb and 40Ar-39Ar)". The geochronology provides time constraints for the age of sources and maximum depositional ages of Triassic units (Quebrada del Salitre, Sierra de Varas, and La Ternera formations) as well as crystallization ages of some of these Triassic units and one age of the Paleozoic basement (Sierra Castillo batholith). Files comprise samples analyzed in the Laboratorio de Estudios Isotópicos (U-Pb_LEI) and Arizona LaserChron (U-Pb_ALC) laboratories. Each sample includes information about the zircons considered and discarded in the calculation of dates.

Files

Steps to reproduce

U-Pb zircon analyses were performed using laser-ablation inductively-coupled-plasma mass-spectrometry (LA-ICP-MS) in 10 detrital and 2 igneous zircon samples. Heavy minerals were separated by standard methods. Finally, zircon grains were handpicked under a binocular microscope, mounted in epoxy, and polished to expose grain centers for cathodoluminescence imaging. U-Pb analyses were performed at the Laboratorio de Estudios Isotópicos (Centro de Geociencias, UNAM) following the procedures reported in Solari et al. (2018), and the Arizona LaserChron Center (University of Arizona; e.g. Gehrels et al., 2008). Concordia and average ages were calculated using Isoplot v. 4.15 (Ludwig, 2011). We applied a discordance filter for igneous (< 5 %) and detrital (< 25 %) analyses, with a reverse discordance filter applied to both igneous and detrital analyses (> -5 %). Captions of tables: U-Pb zircon data measured in the Laboratorio de Estudios Isotópicos (LEI, Universidad Autónoma de México): Notes to table: ±2s abs: 2 sigma absolute error; Rho: According to Solari and Tanner (2011) it corresponds to the error correlation, which is defined as the ratio of the covariance to the product of the standard deviations (in %) of the two ratios 206Pb/238U and 207Pb/235U, that constitute the two axes of the conventional (or normal) Concordia of Wetherhill (e.g., Schmitz and Schoene, 2007; Paton et al., 2010); Best age (Ma): 206Pb/238U was picked when the zircon age is less than 1000 Ma or 207Pb/206Pb when the zircon age is more than 1000 Ma; Disc %: Degree of discordance of zircon ages [1/(1-(206Pb/238U age / 207Pb/235U age)*100)]. U-Pb zircon data measured in the Arizona LaserChron Center (ALC, University of Arizona): Notes to table: ± (%): Percentage error of isotopic ratios (206Pb/207Pb, 207Pb/235U and 206Pb/238U); Best age (Ma): 206Pb/238U was picked when the zircon age is less than 1000 Ma or 207Pb/206Pb when the zircon age is more than 1000 Ma; Disc %: Degree of discordance of zircon ages [1/(1-(206Pb/238U age / 207Pb/235U age)*100)].