Mid-oceanic ridges (MORs) provide the unique opportunity to study two of the three plate boundaries: divergent plate boundaries along and across the ridge axis and tectonically dominated movements (e.g., transform faults). Our understanding of the active processes building and modifying the oceanic lithosphere has increased over the past 20 years due to advances in deep-sea research technologies and analytical and numerical modeling techniques. Increasingly, the processes inferred from the present oceanic lithosphere are also transferred into those operating in the Proterozoic and Archean. Yet, the relative role of magmatic, tectonic, and hydrothermal processes and their interaction in the formation and accretion of the oceanic lithosphere at the ridge, especially at slow and ultra-slow spreading ridges and along transform faults, remains poorly constrained. Transform faults and their extension into fracture zones have previously been considered as relatively cold and magmatically inactive; however, evidence for magmatism has recently emerged. The complex network of faults associated provide ideal pathways for hydrothermal percolation into the Earth’s lithosphere and may therefore play a significant role in the chemical and the thermal budget of the planet, as well as in the chemical exchange with the ocean (e.g., nutrients). Yet, little is known about fluid circulation in the lithosphere in these ultraslow settings.
This session objective is to favor scientific exchange across all disciplines and to share recent knowledge acquired along mid-oceanic ridge axes, transform faults, and fracture zones. We particularly welcome studies using modern deep-sea high-resolution techniques. The session also welcome contributions dealing with recent discoveries in hydrothermal systems, and which integrate geophysical, geochemical petrological and geological data with numerical modeling tools.