Metamorphic minerals document the dynamic evolution of our planet, from the Archean to Present and from the grain- to plate-scale. Deciphering these records requires an approach that integrates petrology, geochemistry, chronology, structural analysis and modelling. Our ability to study our dynamic lithosphere through metamorphic geology continues to improve. At the same time, new analyses and approaches reveal issues and pitfalls that inspire future development.

This session aims to highlight integrated metamorphic geology and its use in elucidating the processes that shaped cratons and mountain belts through time. We welcome contributions in petrology, geo- and thermo-chronology, trace-element and isotope geochemistry, thermodynamic modelling, and structural geology—all with a specific focus on studying metamorphosed-metasomatised rocks. Part of the session will be devoted to novel developments and applications in geochronology and micro- to nano-analytical methods.

Invited speakers:
Robert Holder (Johns Hopkins University): "Monazite Eu anomalies revisited: beyond feldspar"
Pierre Lanari (Universität Bern): "An integrated modelling framework for tracing equilibrium relationships in metamorphic rocks"

Reactions between fluids and rocks have a fundamental impact on many of the natural and geo-engineering processes in crustal settings. Examples of such natural processes are localization of deformation, earthquake nucleation caused by high pressure fluid pulses, as well as metamorphic reactions and rheological weakening triggered by fluid flow, metasomatism and fluid-mediated mass transport. Moreover, the efficiency of many geo-engineering processes is partly dependent on fluid-rock interactions, such as hydraulic fracturing, geothermal energy recovery, CO2 storage and wastewater injection. All our observations in the rock record are the end-product of all metamorphic, metasomatic and deformation changes that occurred during the interaction with fluid. Therefore, to investigate and understand these complex and interconnected processes, it is required to merge knowledge and techniques deriving from several disciplines of the geosciences.
We invite multidisciplinary contributions that investigate fluid-rock interactions throughout the entire breadth of the topic, using fieldwork, microstructural and petrographic analyses, geochemistry, experimental rock mechanics, thermodynamic modeling and numerical modeling.

Supergene ore deposits, like bauxites, Ni-laterites and Zn-Pb-V, Cu nonsulfides, are commonly exploited for Al, Ni, Zn, V and Cu. However, they also contain several “critical” elements (REE, Sc, Co, Ge, Ga, In), which are not recovered from these ores because their amounts and deportment are not completely known, or economically viable extraction flowsheets are not available. This session is open to contributions on mineralogy and geochemistry of supergene ores, with particular attention to studies on critical elements distribution in these deposits.

Hydrothermal systems, mud volcanoes, hybrid environments such as sediment-hosted hydrothermal systems and piercement structures in general are among the most spectacular geological phenomena on Earth. Several studies demonstrated that these structures play a key role in the evolution of our planet and the cycles of life during several geological eras. Active piercements are usually characterized by deep-rooted plumbing systems and complex geochemical reactions where life can adapt to thrive in extremely harsh environments making them ideal targets for deep biosphere exploration. The geophysical signals associated to such environments are often ambiguous and difficult to interpret. The elevated pore pressures often encountered at depth and the high flow rates make these structures ideal natural laboratories to capture precursors of seismic events and dynamically triggered geological processes. Piercement structures have often been reported to respond to earthquakes and external forcing.

This session welcomes contributions from geophysical, geochemical, microbial, geological, numerical and laboratory studies to promote a better understanding of modern and palaeo piercement phenomena. In particular we call for studies related to 1) investigations controlling pre-existing geological structures; 2) the geochemical reactions occurring at depth and at the surface including microbiological studies; 3) the investigation of such systems with geophysical methods; 4) experimental and numerical studies; 5) the survey and the monitoring of these settings and environments to learn the dynamics of the extinct systems from the active ones; 6) the study of palaeo piercements as well as their effects on palaeo climate.

Geofluids (i.e. fluids located in the subsurface) are increasingly becoming of interest due to their significant role as natural resources. These fluids span a vast range of geological environments including groundwater drinking resources, shale gas and oil, deep/shallow geothermal resources and hydrothermal mineral resources. Despite being valuable resources, geofluids are both vulnerable to contamination or may themselves represent a potential source of contamination through externally-driven mechanisms, as in the case of shale gas extraction, CO2 leaking or land use for agriculture purposes. Ont he other hand geofluids themselves can be a source of natural contamination as in the geogenic contamination of groundwater resources containing elevated levels of trace elements including arsenic (As), chromium (Cr), iron (Fe), and uranium (U), amongst others. Strategic management of geofluids and protection of geological resources related to them is indispensable for the future sustainable development of these societal and economically important resources. The characterization of geofluids and their behaviour in natural or artificial (human-driven) circumstances requires a deep understanding of complex physical, geochemical and microbiological processes. They are influenced directly by geological setting, structural evolution, and fluid flow systems.

The aim of this session is to foster scientific discussion between those with interest in a range of geofluid systems to better understand the role which these fluids have as socio-environmental and economic resources. The session emphasises the importance of lithological & mineralogical characterizationof various systems including in aquifers for a range of geogenic contaminants in groundwater, specifically addressing the source pathways and mobilisation mechanisms. The session also welcomes work including fluid flow, hydrology, geochemistry, environmental tracers, microbial investigations and both numerical and statistical modelling in support of fluid and resource management.

The session is supported by the RGFC-IAH (‘Regional Groundwater Flow Commission’ of International Association of Hydrogeologists) and the EU H2020 ENeRAG (‘Excellency Network Building for Comprehensive Research and Assessment of Geofluids’) project.

Mineral nucleation and growth processes are well studied for material science and industry applications under controlled laboratory conditions, but our understanding of these complex multistage pathways in natural environments is still rather incomplete. Monitoring precise and quantitative environmental parameters over long time periods is often difficult, imposing great uncertainties on growth processes and physicochemical properties of minerals used to reconstruct Earth’s history, such as microbialites, speleothems, or authigenic cements. Recent findings suggest that nano-clusters, colloidal particles, organic matter or microbes may be fundamental to nucleation and growth processes, especially if kinetics are sluggish at Earth surface temperatures. Thus, it is imperative to investigate mineral formation at the nano- and micro-scale within a broad, interdisciplinary perspective.
In this session we welcome oral and poster presentations from multiple fields including sedimentology, mineralogy, geochemistry, physical chemistry, biology and engineering that contribute to a better understanding of mineral nucleation and growth processes. Contributions may include process-oriented studies in modern systems, the ancient rock record, experiments, computer simulations, and high-resolution microscopy and spectroscopy techniques. We intend to reach a wide community of researchers sharing the common goal of improving our understanding of the fundamental processes underlying mineral formation, which is essential to read our Earth’s geological archive.

Transform faults form major active plate boundaries and are intrinsic features of plate tectonics and plate accretion. Submarine transforms are likely to be fundamental pathways for fluid circulation in depth, thus significantly contributing to the exchange between the lithosphere and the hydrosphere. This implies serpentinization and weathering that affect the mechanical properties in the deformation zone. An open question is the influence of the elemental exchange between the crust and ocean water on these processes, as well as the interactions with the biosphere, both at the surface and at depth. Continental transforms and strike-slip faults are often a site of major earthquakes, representing major hazards for the population. Here too, the role of weathering in the deformation zone is still unconstrained. Both types of faults are still poorly known in terms of structure, rheology and deformation. These features are seismically active zones, with large earthquakes often being recorded on the largest faults. Yet, little is known about the rupture process, seismic cyclicity and active deformation of transform faults. Recent works have shown that fracture zones, supposedly inactive features, can be reactivated and be the site of large earthquakes and deformation. Additional open questions are the way transform faults deform under far-field stresses, such as plate kinematic changes, and under more local stresses, what are the time constants of the processes and what are the primary controls of the tectonic and magmatic styles of the response. The tectonic and magmatic response of large offset transforms, particularly, is still largely unknown.

This session aims to present recent results on studies of these large features, especially on the rheology, deformation patterns, rupture processes, fluid circulation and physical properties of transform faults. We welcome observational studies on strike-slip and transform faults, both continental and oceanic, on fracture zones and on transform continental margins (structural geology and tectonics, geophysical imaging of the crust and lithosphere, petrology and geochemistry, seismology, fluid circulation and rock alteration, geodesy) as well as modelling studies, both analogue and numerical. Cross-disciplinary approaches are encouraged. The submission of abstracts divulging on-going international projects (drilling sites, seismic reflection imaging along strike-slip faults) are also welcome. This session is promoted by the Oceanic Transform Faults working group of InterRidge.