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Updated: Dec 26, 2025

Kinematic History of a Salient-recess Junction Explored through a Combined Approach of Field Data and Analog Sandbox Modeling
Published on: August 5, 2016
An andesitic source for Jack Hills zircon supports onset of plate tectonics in the Hadean
Simon Turner1, Simon Wilde2, Gerhard Wörner3
1Department of Earth and Planetary Sciences, Macquarie University, Sydney, NSW, 2109, Australia. simon.turner@mq.edu.au.
Abstract:
The composition and origin of Earth's early crust remains hotly debated. Here we use partition coefficients to invert the trace element composition of 4.3-3.3 Gyr Jack Hills zircons to calculate the composition of the melts from which they crystallised. Using this approach, the average SiO2 content of these melts was 59 ± 6 wt. % with Th/Nb, Dy/Yb and Sr/Y ratios of 2.7 ± 1.9, 0.9 ± 0.2 and 1.6 ± 0.7, respectively. Such features strongly indicate that the protolith for the Jack Hills zircons was not an intra-plate mafic rock, nor a TTG (tondjhemite-tonalite-granodiorite) or a Sudbury-like impact melt. Instead, the inferred equilibrium melts are much more similar to andesites formed in modern subduction settings. We find no evidence for any secular variation between 4.3 and 3.3 Gyr implying little change in the composition or tectonic affinity of the Earth's early crust from the Hadean to Mesoarchaean.
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