The zircon archive of continent formation through time

Abstract

The strong resilience of the mineral zircon and its ability to host a wealth of isotopic information make it the best deep-time archive of Earth's continental crust. Zircon is found in most felsic igneous rocks, can be precisely dated and can fingerprint magmatic sources; thus, it has been widely used to document the formation and evolution of continental crust, from pluton-to global-scale. Here, we present a review of major contributions that zircon studies have made in terms of understanding key questions involving the formation of the continents. These include the conditions of continent formation on early Earth, the onset of plate tectonics and subduction, the rate of crustal growth through time and the governing balance of continental addition v. continental loss, and the role of preservation bias in the zircon record.

Oxygen isotope and trace element geochemistry of zircons from porphyry copper system: Implications for Late Triassic metallogenesis within the Yidun Terrane, southeastern Tibetan Plateau

“…The incorporation of overlying pelagic sediments during partial melting of the subducted oceanic slab, or the partial melting of mantle wedge peridotites with higher δ 18 O due to prolonged subduction history (N 5.9‰; Roberts and Spencer, 2014), could also responsible for the elevated δ 18 O values for the PDL zircons. However, several lines of evidence were disagreeing with these two scenarios.…”

Continent formation through time

“…These zircons provide the only direct evidence of potential crustforming processes at this time, and the interpretation of such limited evidence is highly debated. Nebel et al (2014) recently reviewed the evidence from the Hadean zircons (see also Roberts & Spencer 2014), and provided a model that aimed to encapsulate all of the available evidence. Their model (see Fig.…”

“…Gastil 1960; Condie 1998; Kemp et al 2006;Parman 2007; see Fig. 1, Roberts & Spencer 2014). Modelling of growth rates based on these compilations has led many to the conclusion that the current volume of continental crust was achieved very early on in Earth history (e.g.…”

“…2). This balance will change through orogenic cycles (Collins et al 2011;Roberts 2012;Roberts & Spencer 2014, see Fig. 9), and through supercontinent cycles (Hawkesworth et al 2009;Spencer et al 2013).…”

“…The described setting and processes of continent formation lack any contrasts from those occurring in the Phanerozoic. Roberts & Spencer (2014) present a review of the major contributions that zircon-based studies have had on our understanding of continental evolution. Topics covered include the style of continent formation in the Hadean and Archaean, the onset of plate tectonics and subduction, the rate of crustal growth and the preservational bias that may exist in the zircon record.…”