Session programme

Microstructures and crystallographic textures can be used to analyze the multi-dimensional, geometrical, physical and chemical properties of geo-materials, allowing the investigation of deformation, magmatic, metamorphic or sedimentaty processes evolved in their evolution.

These methods include, but are not limited to the quantitative assessment of particle shape properties, of grain and pore size distributions, spatial correlations, statistical pattern analysis, as well as the analysis of crystallographic orientation and misorientation data. Advances in analytical technology steadily increases the quality of data and thus allows a refinement of interpretations and new observations at unprocessed scales, dimensions and resolution. Advances in analytical procedures and algorithms provide the basics for faster, more precise and statistically sound analyses.

To celebrate the recent advancements in microstructural and texture analysis methods, resulting interpretations and refreshing new insights, we invite contributions related to new analytical methods or recent technical developments in well-established methods, such as EBSD, X-ray diffraction and topography, (S)TEM, SIMS, Atom probe, X-ray or Neutron tomographic techniques, AMS and light optical techniques. Novel attempts to data processing, analysis and interpretation are extremely welcomed.

We welcome discussions as well as demonstrations of methods of microstructure and texture analysis applied to geo-materials (including such difficult materials as ice and clay) from natural samples, deformation experiments and material sciences applications as well as stimulating results based on theoretical analyses or numerical simulations.

Shear zones as expressions of strain localization shape rocks from the micron- to the plate tectonic scale, influencing both viscous and brittle deformation systems. Strain localization across multiple scales is a complex process in any tectonic environment, and often still poorly understood. In many cases, strain localization involves feedback between mechanical, chemical and hydraulic processes that control the rheological evolution of deforming rocks. During strain localization, mylonites in shear zones evolve their fabrics, grain sizes and compositions, leading to changes in deformation mechanisms and mechanical properties. At one extreme, brittle fracturing and faulting may be coupled to shear zone processes, as evidenced by high-temperature fracturing, lower crustal earthquake nucleation, and deep fracture-controlled fluid pathways. Cyclical interplay between brittle and viscous deformation regimes may also occur. Whatever the deformation mechanism, shear zones constitute either barriers to or conduits for fluid flow, which emphasizes the significance of their dynamic transport properties.
This session seeks to illuminate deformation, metamorphic and transport processes in shear zones via a wide range of methodological approaches, including field- and microscale studies, numerical and analogue modelling approaches as well as rock deformation experiments and aims to present the latest advances in our understanding of shear zones and associated faulting. We particularly encourage early career researchers to present their findings.

In the continental crust, partial melting is now recognized as the main geological process responsible for the production of granites, crustal differentiation of major rheological changes. Many studies (geochemical, petrological, experimental, geodynamical modelling) have shown that partial melting occurring at the grain-scale has consequences at the crustal scale. During its long history heterogeneous continental crust has been through many tectonics cycles with synchronous partial melting and regional deformation. This pairing is critical: melt weakens the rocks allowing faster deformation within mountain building or rifting processes. Dilatant structural sites developed during orogenic deformation accumulate anatectic melt, which begins to crystallize there, before a subsequent shear-enhanced compaction event segregates highly fractionated melt with incredibly evolved compositions to higher crustal levels. These are mainly emplaced as pegmatites, which may be of considerable economic interest. Many interesting questions arise. How does the growth and progressive development of structures affect how melt migrate through the crust, on the grain and macroscales? Does it pump melt though the crust? What is the quantitative effect of partial melting on the effective viscosity of a migmatite? How fast can melt differentiate?
Studying such processes requires a multidisciplinary approach. Therefore we invite contributions to this session from structural analyses, geochemistry, petrology, experimental/rheological studies, field based observations, numerical modeling or geochronology that investigate partial melting at different scales in a heterogeneous and deforming continental crust.

Radioactive decay systems have been used to date rocks and minerals for over 100 years, but advances in the last 15-20 years have provided unprecedented improvements in our ability to constrain the rates and timescales of processes such as deformation, metamorphism and magmatism. The ultimate aim is to be able to answer questions such as "for how long was this shear zone active?", "what was the rate of deformation?", "how quickly did this metamorphic terrane heat up or cool down?", "was heating/cooling continuous or pulsed?", or "how long did it take this pluton to form?". This session aims to showcase the latest developments in chemical and textural techniques that allow ‘date’ to be linked to ‘process’ across all aspects of the evolution of the Earth’s lithosphere.

The goal of this session is to reconcile short-time/small-scale and long-time/large-scale observations, including geodynamic processes such as subduction, collision, rifting or mantle lithosphere interactions. Despite the remarkable advances in experimental rock mechanics, the implications of rock-mechanics data for large temporal and spatial scale tectonic processes are still not straightforward, since the latter are strongly controlled by local lithological stratification of the lithosphere, its thermal structure, fluid content, tectonic heritage, metamorphic reactions and deformation rates.

Mineral reactions have mechanical effects that may result in the development of pressure variations and thus are critical for interpreting microstructural and mineral composition observations. Such effects may fundamentally influence element transport properties and rheological behavior.
Here, we encourage presentations focused on the interplay between metamorphic processes and deformation on all scales, on the rheological behavior of crustal and mantle rocks and time scales of metamorphic reactions in order to discuss
(1) how and when up to GPa-level differential stress and pressure variations can be built and maintained at geological timescales and modelling of such systems,
(2) deviations from lithostatic pressure during metamorphism: fact or fiction?,
(3) the impact of deviations from lithostatic pressure on geodynamic reconstructions.
(4) the effect of porous fluid and partial melting on the long-term strength.
We therefore invite the researchers from different domains (rock mechanics, petrographic observations, geodynamic and thermo-mechanical modelling) to share their views on the way forward for improving our knowledge of the long-term rheology and chemo-thermo-mechanical behavior of the lithosphere and mantle.

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.

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"