Time-lapse zirconography: Imaging punctuated continental evolution

Abstract

The continental crust (CC) contains a 4.4 billion year record of Earth evolution (Armstrong, 1991; Bowring and Housh, 1995; Wilde et al, 2001; Harrison et al, 2005; Hawkesworth et al, 2010; Condie and Kroener, 2013). Understanding its growth is central to a broad range of research, including the geodynamics of the planet's interior (O'Neill et al, 2007; Korenaga, 2013), the evolution of the atmosphere (Barley et al, 2005) and even the evolution of life itself (Lowe and Tice, 2007). The growth of the continents is a competition between rates of crustal production and destruction (Armstrong, 1991; Hawkesworth et al, 2010), but which of these dominates the CC record is debated. Here I examine a large database of detrital zircon U-Pb ages (n > 200,000; Voice et al, 2011) as a function of the age of the sedimentary rock in which they are found. This provides snapshots of the Earth's CC age distribution through time; in essence, producing a time-lapse movie of CC evolution. The analysis strongly indicates that the growth of the CC was episodic.