The continental crust is the archive of Earth history. Although the oceanic crust provides a wealth of geologic information during the past ~280 million years, the subduction of the oceanic crust means that if we want to query Earth history beyond this point, we must rely on the continental crustal record. Understanding the rates and mechanisms of continental crustal growth is a fundamental question in Earth science with wide-reaching implications spanning natural resources to the evolution of life. However, the rate and mechanisms of continental growth along with the influence of plate tectonics on the processes of continental growth and destruction are hotly debated.
In general, models for the growth of continental crust fall into two broad categories, mantle-based and crustal-based (Korenaga, 2018). Mantle-based crustal growth models aim to constrain the net crust growth (i.e. all of the crust that has been extracted from the mantle) are generally based on tracking mantle chemistry through time. However, as subduction removes both oceanic and continental crust, these net crustal growth models do not account for this crustal recycling. Therefore, crustal-based growth models seek to quantify the timing and rate of extant continental crustal growth using the ages and isotopic compositions relative to the mantle. The difference between mantle and crustal growth models reflects the degree of recycling and reworking of material extracted from the mantle through multiple cycles of melting.
Outstanding questions still exist regarding the onset and rate of significant mantle extraction and whether continental growth occured in a steady state fashion or through episodic pulses. We approach these questions using large compiled isotopic datasets and newly developed statistical tests to constraining the rate and loci of continental growth and destruction.
Related Publications
Spencer, C. J., Roberts, N. M. W., & Santosh, M. (2017). Growth, destruction, and preservation of Earth’s continental crust. Earth-Science Reviews, 172, 87–106.
Roberts, N. M. W., & Spencer, C. J. (2015). The zircon archive of continent formation through time. Geological Society Special Publication, 389(1), 197–225.
Spencer, C. J., Cawood, P. A., Hawkesworth, C. J., Prave, A. R., Roberts, N. M. W., Horstwood, M. S. A., & Whitehouse, M. J. (2015). Generation and preservation of continental crust in the Grenville Orogeny. Geoscience Frontiers, 6(3), 357–372.
Spencer, C. J., Cawood, P. A., Hawkesworth, C. J., Raub, T. D., Prave, A. R., & Roberts, N. M. W. (2014). Proterozoic onset of crustal reworking and collisional tectonics: Reappraisal of the zircon oxygen isotope record. Geology, 42(5), 451–454.
Spencer, C. J., Hawkesworth, C., Cawood, P. A., & Dhuime, B. (2013). Not all supercontinents are created equal: Gondwana-Rodinia case study. Geology, 41(7), 795–798.