We’re Saved! Massachusetts ‘to fight climate change with sweeping executive order’ – ‘Getting serious about meeting its climate goals’
Climate skeptic basher John Cook (promoter of 97% claim) joins George Mason U. – Morano’s alma mater!
Nature Geoscience. doi:10.1038/ngeo2800
Author: Alan Brandon
The composition of Earth's crust depends on the style of plate tectonics and of the melting regimes in the mantle. Analyses of the oldest identified rocks suggest that these styles and the resulting crust have changed over Earth's history.
Nature Geoscience. doi:10.1038/ngeo2786
Authors: J. R. Reimink, J. H. F. L. Davies, T. Chacko, R. A. Stern, L. M. Heaman, C. Sarkar, U. Schaltegger, R. A. Creaser & D. G. Pearson
Due to the acute scarcity of very ancient rocks, the composition of Earth’s embryonic crust during the Hadean eon (>4.0 billion years ago) is a critical unknown in our search to understand how the earliest continents evolved. Whether the Hadean Earth was dominated by mafic-composition crust, similar to today’s oceanic crust, or included significant amounts of continental crust remains an unsolved question that carries major implications for the earliest atmosphere, the origin of life, and the geochemical evolution of the crust–mantle system. Here we present new U–Pb and Hf isotope data on zircons from the only precisely dated Hadean rock unit on Earth—a 4,019.6 ± 1.8 Myr tonalitic gneiss unit in the Acasta Gneiss Complex, Canada. Combined zircon and whole-rock geochemical data from this ancient unit shows no indication of derivation from, or interaction with, older Hadean continental crust. Instead, the data provide the first direct evidence that the oldest known evolved crust on Earth was generated from an older ultramafic or mafic reservoir that probably surfaced the early Earth.
Nature Geoscience. doi:10.1038/ngeo2806
Authors: Miquela Ingalls, David B. Rowley, Brian Currie & Albert S. Colman