Issues

Cover: Exposure of part of the Torres del Paine intrusive complex (Patagonia, Chile) in the cliffs of Cerro Castillo, Valle del Frances. The vast glacier-polished outcrops of these cliffs provide a unique opportunity to study how such sheeted intrusions are built up. In this image, multiple distinct magmatic units of the Mafic Sill Complex are exposed in spectacular detail, and display ductile contacts between magmatic units, as exemplified by the flame structures visible in the image. Geologists for scale. Isotopic differences between the Mafic Sill Complex and other units of the Torres del Paine intrusive complex testify to the waning influence of subduction, after large-scale geodynamic changes resulted in the transient migration of arc magmatism into the retro-arc region (Ewing et al., this issue). See “The zircon Hf isotope archive of rapidly changing mantle sources in the south Patagonian retro-arc” by Ewing et al., p. 587–608.

Photo by: Tanya Ewing

Cover design by: Eric Christensen