Ar-Ar dating for hydrothermal quartz from the 2.4 Ga Ongeluk Formation, South Africa: implications for seafloor hydrothermal circulation.

ABSTRACT: Fluid inclusions in hydrothermal quartz in the 2.4 Ga Ongeluk Formation, South Africa, are expected to partially retain a component of the ancient seawater. To constrain the origin of the fluid and the quartz precipitation age, we conducted Ar-Ar dating for the quartz via a stepwise crushing method. The obtained argon isotopes show two or three endmembers with one or two binary mixing lines as the crushing proceeds, suggesting that the isotopic compositions of these endmembers correspond to fluid inclusions of each generation, earlier generated smaller ⁴⁰Ar- and K-rich inclusions, moderate ⁴⁰Ar- and ³⁸Ar_Cl (neutron-induced ³⁸Ar from Cl)-rich inclusions and later generated larger atmospheric-rich inclusions. The K-rich inclusions show s

SUBMITTER: Saito T 

PROVIDER: S-EPMC6170566 | biostudies-literature | 2018 Sep

REPOSITORIES: biostudies-literature