T8-S1. Hydrothermal Systems in the Early Earth

Ewa Slaby (e.slaby@twarda.pan.pl)
Jacques Touret (ljtouret@orange.fr)
Mark van Zuilen (vanzuilen@ipgp.fr)

Keynote Speaker: Juan Manuel Garcia-Ruiz (Laboratorio de Estudios Cristalográficos, CSIC / University of Granada, Spain): Mineral self-organization in the early Earth

Hydrothermal systems, possibly the place where life has first appeared, have existed since water condensed on the surface of our planet. At the Earth’s surface, hydrothermal fluids are linked to volcanism or shallow intrusives. Massively released in mid-oceanic ridges, they play a major role in controlling the composition of terrestrial envelopes (hydrosphere and atmosphere). But hydrothermal fluids exist also in continents, either emitted by shallow intrusions (Cu-porphyry types) or associated to various types of metamorphism. Deep in the crust and upper mantle, their relationship with magmatic processes (cause or result) is a major problem, currently at the center of a great international interest.
The study of hydrothermal systems is truly multidisciplinary, involving a number of disciplines: mineral reactions and textures, isotope signatures (notably stable isotopes), fluid inclusions, rare gases, models of mass-transfer or fluid-rock interaction. Today, most fluids are recycled from the surface to the mantle by subduction. But the situation was possibly very different during the early history of the Earth. The aim of this session is to bring together researchers interested in ancient hydrothermal systems, in order to discuss key aspects of early fluid-rock interaction. We particularly welcome contributions that focus on the comparison between early and present time hydrothermal systems, fluid origin, characterization of metasomatic versus magmatic processes, remnants of hydrothermal fluids preserved in mineral inclusions, and the role of hydrothermal systems in the formation and evolution of the continental and oceanic crust.