Kang Chen coauthored a reconstruction of ancient upper-crustal composition using elemental ratios in sedimentary rocks and igneous or metamorphosed igneous material. Ratios involving nickel, cobalt, chromium and zinc were used to infer a change from predominantly mafic toward more felsic crust.[ref]
Archean upper crust transition from mafic to felsic marks the onset of plate tectonics by Ming Tang and others. Abstract: elemental proxies and inferred compositional transition
The elemental measurements constrain composition through a proxy model; the proposed tectonic history is a subsequent interpretation.
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