Research Article|April 01, 2018
Geochemical Perspectives (2018) 7 (1): VI.
The author is grateful to Jutta Zipfel for critically reading the manuscript. Comments by John Wasson, Klaus Mezger and Tim Elliott have substantially improved the manuscript. The editorial help of Marie-Aude Hulshoff and Alice Williams is gratefully acknowledged, as well as the remarkable work of Juan Diego Rodriguez Blanco on all the figures.