The Earth's oldest known crust: A geochronological and geochemical study of 3900-4200 Ma old detrital zircons from Mt. Narryer and Jack Hills, Western Australia

Abstract

Detrital zircons with 207Pb/206Pb ages between 3908 and 4270 Ma from the Narryer Gneiss Complex, Western Australia, are the oldest terrestrial minerals found to date. They occur in small proportions (2-3%) together with 3.0-3.75 Ga zircons in quartzites and metaconglomerates of the 3.0 Ga Mt. Narryer (MN) and Jack Hills (JH) metasedimentary belts. We report the results of a geochronological and geochemical study of these zircons which, together with data on grain morphology and inclusion mineralogy, are used in an attempt to place constraints on their source rocks. Pre-3.9 Ga zircons from both localities show variable but typically low degrees of rounding and are optically homogenous to fain..