Understanding the roles of crustal growth and preservation in the detrital zircon record

Crustal evolution studies using detrital minerals must consider the potential for bias both during formation of the continental crust, and during later erosion and reworking of sedimentary material. To investigate the extent of these biases, and our ability to extract global information from local studies, this study presents in situ U-Pb, δ18O and εHf isotope date in detrital zircons from the Scottish Highlands for comparison with greater Gondwana and Laurentia. Zircon crystallisation ages between 3.8-1.1 Ga group into three episodes (at ~2.8, 1.7 and 1.2 Ga), coincident with the ages of known supercontinents (Superia, Nuna and Rodinia) and consistent with preservation due to continental collision and supercontinent stabilisation. Model ages between 4.2-1.4 Ga likewise group into three significant juvenile extraction events at ~3.3, 2.2 and 1.7 Ga, of which only the ~3.3 Ga peak has been observed elsewhere in Laurentia or Gondwana. Individual model ages appear to form continua within each crystallisation event, suggesting that the generation of new continental crust is a continuous process, but the record is then biased by the development of supercontinents.