Provenance record of the Jack Hills metasedimentary belt: Source of the Earth's oldest zircons

Detrital SHRIMP U-Pb results from four samples of metasediment show that the Jack Hills metasedimentary belt, Narryer terrane, Yilgarn craton, Western Australia contains two lithologically similar siliciclastic associations with discrete age and source characteristics. An older association only contains zircons with ages greater than 3000Ma and probably accumulated prior to 2700 Ma. Grains in the range 3600-3000 Ma are likely derived from granitic gneisses surrounding the metasedimentary belt. The older association was in part sourced from, and likely accumulated on, gneisses of the Narryer terrane, however, the source of the oldest (> 4000 Ma) grains is unknown. The younger association contains zircons with the bulk of the ages between 2800 and 2600 Ma, and detrital grains as young as 1800 Ma. It also shows ages in the range 3600-3000 Ma and a few grains as old as 4100 Ma. The younger association has a significant contribution of zircons derived from Yilgarn craton and Capricorn orogen and was deposited after similar to 1800 Ma, possibly in a foreland basin setting close to the older association with the two then tectonically interleaved. (c) 2005 Elsevier B.V. All rights reserved.