Abstract Some significant geological sites are inaccessible. Among the most inaccessible sites are the hydrothermal vents and their associated biological communities located deep in the ocean. These prime geoheritage sites, hosting what may be the most primordial life on Earth, are vulnerable to mineral and fishing exploitation. Many lie in international waters, protected only by non-binding agreements with no clearly defined means of enforcement. The discovery of these vents in 1977 fundamentally altered scientists’ view of basic Earth processes and the extreme conditions under which life can exist. The discovery of the vents was a group effort and required technological accomplishments not available to previous generations of researchers. Often overlooked in the credits for this discovery was the persistence and determination of Kathleen Crane, a graduate student at Scripps Institution of Oceanography. Many women of her era faced significant challenges as they attempted to break into an often-unwelcoming field, marine geology. The challenges were not unique to geology; women were not welcomed in many other disciplines, both scientific and non-scientific. In spite of the obstacles, few people have made as remarkable a geoscience discovery as Dr Crane.

The footprints of mafic melts travelling from the depths to the surface are abundant in the mantle section of ophiolites. They constitute an important source of information about the melt migration mechanisms and related petrological processes in the shallowest part of the mantle beneath former oceanic spreading centres. In the field, these so-called ‘melt migration structures’ attract attention when they consist of mineral assemblages contrasting with that of their host peridotite. They therefore record a particular moment in the migration history: when the melt becomes out of equilibrium with the peridotite and causes a reaction impacting its modal composition, and/or when a temperature drop initiates the crystallization of the melt. The existence of cryptic effects of migration revealed by geochemical data shows that melts do not always leave a trail visible in the field. Although incomplete and patchy, the melt migration structures preserved in ophiolites are witnesses of processes that do actually occur in nature, which constitutes an invaluable support to the interpretation of geophysical data and inescapable constraints for numerical simulations and models of chemical geodynamics. Here we show how field observations and related petrological and geochemical studies allow us to propose answers to fundamental questions such as these: At which temperature is porous flow superseded by dyking? What are the factors governing melt trajectories? What is the nature of the ‘universal solvent’ initiating infiltration melting and making channelized porous flow the most common mode of transport of magmas through a peridotite matrix regardless the tectonic setting? A fundamental message delivered by ophiolites is that the shallow mantle behaves as a particularly efficient reactive filter between the depths and the surface of the Earth. Unexpectedly, the reactions occurring there are enhanced by the hybridization between mafic melts and a hydrous component, whatever its origin ( i.e. magmatic vs. hydrothermal). This hybridization triggers out of equilibrium reactions, leading to the formation of exotic lithologies, including metallic ores, and impacting the global geochemical cycle of a whole range of chemical elements.

Abstract On the eastern margin of the Panama Basin, the Nazca oceanic plate converges towards the continental plate of South America at approximately 53 mm a −1 . Subduction processes are accompanied by the presence of anomalous bathymetric elements including the Sandra Ridge. This east–west-orientated ridge is catalogued as an aborted rift derived from a magmatic spreading axis that was active between 12 and 9 Ma. Seismic activity within this structure is considered evidence of fault reactivation and tectonism. Once the structure reached the subduction trench several submarine landslides were triggered. Run-out lengths of these submarine landslides are perpendicular to the convergence of the structure with some units spreading and forming a wide fan that reaches tens of kilometres to the north and south of the trench. The area affected by the three main landslides varies between 130 and 300 km 2 approximately, with relatively superficial earthquakes (<33 km) and with magnitudes that reach up to M w 7.2. The morphology of the landslides suggests a retrogressive nature with younger events proximal to shore. This paper presents estimates of the age of these landslides and discusses sources of uncertainty regarding these times of occurrence.