The year 2023 marks the 40th anniversary of active research in the Jack Hills, Western Australia. It commenced with detailed mapping and preliminary U/Pb zircon geochronology utilizing multigrain techniques, and evolved to ever more detailed work on individual zircon grains at the micro- and nanoscales. When coupled with contemporaneous advances in micro-analysis, this has led to a paradigm shift in how we view the utility of zircon, and also how we envisage the early Earth. Outstanding results include the discovery of the oldest known crystal formed on Earth (Wilde et al., 2001), elevated δ18O values indicating early continental crust and oceans and a cool early Earth (Valley et al., 2002), Lu-Hf data establishing the earliest crustal development back to 4.5 Ga (Harrison et al, 2008; Kemp et al., 2010), possible protolith development from a KREEP-like initial source (Kemp et al., 2010), and trace element and Hf data indicating the possibility of plate tectonics in the Hadean (Turner et al., 2020; Mitchell et al., 2022), amongst other advances. Jack Hills is therefore the site that keeps giving, with lead nanospheres recently identified in Hadean and Eoarchean zircon at the ‘discovery’ site (Kusiak et al., 2023). These, and other ‘firsts’ for Jack Hills, will be outlined, as too will the potential for further discoveries, including the possibility that discrete periods of activity can be recognized in the Hadean that may be traceable throughout the inner solar system.

Reference(s)

Harrison, TM, Schmitt, AK, McCulloch, MT, and Lovera, OM, 2008. Early (>4.5 Ga) formation of terrestrial crust: Lu-Hf, d18O, and Ti thermometry results for Hadean zircons. Earth and Planetary Science Letters, v. 268, p. 476-486.

Kemp, AJA, Wilde, SA, Hawkesworth, CJ, Coath, CD, Nemchin, A, Pidgeon, RT, Vervoort, and JD, DuFrane, SA, 2010. Hadean crustal evolution revisited: New constraints from Pb–Hf isotope systematic of the Jack Hills zircons. Earth and Planetary Science Letters, v. 296, p. 45-56.

Kusiak, MA, Wirth, R, Wilde, SA, and Pidgeon, R.T., 2023. Metallic lead (Pb) nanospheres discovered in Hadean and Eoarchean zircon crystals at Jack Hills. Scientific Reports, 13 (1) (2023), 895. DOI:10.1038/s41598-023-27843-6.

Mitchell, RN, Spencer, CJ, Kirscher, U, and Wilde, SA, 2022. Plate tectonic–like cycles since the Hadean: Initiated or inherited? Geology, v. 50, p. 827-831.

Turner, S, Wilde, S, Worner, G, Schaefer, B, and Lai, Y-L, 2020. An andesitic source for Jack Hills zircon supports onset of plate tectonics in the Hadean. Nature Communications (2020) 11:1241 | https://doi.org/10.1038/s41467-020-14857-1.

Valley, JW, Peck, WH, King, EM and Wilde, SA, 2002. A Cool Early Earth. Geology, v. 30, p. 351-354. Wilde, SA, Valley, JW, Peck, WH and Graham, CM, 2001. Evidence from detrital zircons for the existence of continental crust and oceans on the Earth 4.4Gyr ago. Nature, v. 409, p. 175-178.