Do the trace element compositions of detrital zircons require Hadean continental crust?
Laurence A. Coogan, University of Victoria, School of Earth and Ocean Sciences, Victoria, British Columbia V8W 3P6, Canada; and Richard W. Hinton, Edinburgh University, School of Geosciences, Edinburgh, Scotland EH9 3JW, UK. Pages 633-636. The oldest pieces of Earth currently known are zircon crystals from Australia. These are up to 4.4 billion years old. The compositions of these crystals have been used to suggest that they formed under conditions not dissimilar to current conditions on Earth. This contrasts with previous ideas that Earth at that time was very different–dominated by basaltic volcanism and broadly “hell-like.” A comparison of the composition of zircons that crystallized from modern basalts and the >4 billion-year-old zircons suggests that Earth may well have been “hell-like” at that time. Quantified time scale for glacial valley cross-profile evolution in alpine mountains Martin S. Brook, Massey University Geography Programme, School of People, Environment & Planning,
