Granitoid events in space and time: Constraints from igneous and detrital zircon age spectra

The goal of this study is to evaluate the global age distribution of granitoid magmatism and juvenile continental crust production with U/Pb isotopic ages from igneous and detrital zircons, and with Nd isotopic data. Granitoid age peaks, which are largely defined by TIMS data, are narrow and precise in contrast to detrital peaks that are often broad and hump-shaped due to the larger uncertainties of SHRIMP and LAM-ICPMS data. Granitic age peaks do not always have detrital counterparts and vice versa. Possible contributing factors to this mismatch are removal of crustal sources by erosion, inadequate sampling of granitoids because of cover by younger rocks, or small age peaks hidden by large age peaks in detrital spectra. Seven igneous peaks are found on five or more cratons or continents (3300, 2700, 2680, 2500, 2100, 1900 and 1100 Ma) and seven detrital peaks occur on three or more continents (2785, 2700, 2600, 2500, 1900. 1650 and 1200 Ma). Nd isotope distributions suggest important additions of juvenile continental crust at 2700, 2500, 2120, 1900, 1700, 1650, 800, 570 and 450 Ma. Tight clusters of craton ages occur for Superior-Karelia, Sao Francisco-Nain, and Kaapvaal-Siberia in the early Archean and for Wyoming-Kaapvaal-Slave, Superior-Nain, and West Africa-Amazonia in the late Archean. The global 2700-Ma peak is not a simple spike, but involves several peaks between 2760 and 2650 Ma. Events older than 3700 Ma are limited to the Yilgarn, Slave, Nain and North China cratons, and events between 2600 and 2500 Ma are widespread only in East Asia, Central and East Africa, and India. Single, short-lived mantle plume events at 2700 and 1900 Ga (or any other time) cannot easily account for prolonged episodes of granitoid magmatism during the Precambrian. The causes of geographically widespread and geographically restricted events are probably not the same. Crown Copyright (C) 2008 Published by Elsevier B.V. on behalf of International Association for Gondwana Research. All rights reserved.