Origin of old saline groundwater in the deep coastal formations of the Atacama Desert region: Consideration of lithium, boron, strontium and uranium isotopes contents

•Brines chlorine calcium type have been identified in deep coastal boreholes in the Atacama Desert.•The combined application of lithium, boron and strontium isotopes has made it possible to recognize an ancient marine origin of deep brines.•The combined application of the isotopes δ11B and δ7Li allows an indirect approximation of the age of groundwater of marine origin to be made.