Program

Clays play a dominant role in soils for contaminant fate and transport. Clays can act as carriers of contaminants and can facilitate transport, but also act as sorbents of contaminants, leading to contaminant immobilization. Global warming and extreme climate​ may influence the role of clays in contaminant fate and transport. ​Topics of this session include, but are not limited to:

• impact of global warming on clays and contaminant fate and transport
• interactions of clays with emerging contaminants (e.g., PFAS, pharmaceuticals, viruses, micro- and nanoplastics)
• interactions of clays with pyroplastics and biochar
• impacts of fires on surface properties of clays and oxides
• impact of seawater intrusion on clays and contaminant fate and transport
• eolian dust as mechanism for dispersion of clay-bearing contaminant and oxides in the environment

influence of geological parent material in the tropics on sediment enrichment in clay-bearing contaminant and oxides

Clayey sediments abound in many types of depositional settings, including fluvial deltaic, coastal, shallow and deep marine, and subglacial environments, as well as lahars and debris flows. Clayey sediments can damp turbulence, alter fluid rheology, and generate hindered or lubricated particle interactions. They also confer cohesiveness and inhibit erosion and hyporheic flow. The resulting complex sediment-fluid interactions affect largescale morphologic expressions and depositional patterns that are reflected in the stratigraphic record. Furthermore, clayey sediments often contain abundant organic matter and adsorb contaminants and pathogens and consequently play a critical role in water quality and the global carbon cycle. This session seeks contributions from studies exploring the movement of clayey sediment, the resulting depositional patterns, as well as its impacts on Earth and other planetary surfaces and on the global carbon cycle. We welcome field- and laboratory-based studies, numerical modeling, and theoretical contributions.

Clay minerals can significantly influence the frictional strength of rocks, impacting the behavior of natural faults and landslides. Frictional properties are contingent upon numerous factors, including mineral composition, preferred orientation, particle size and morphology, the presence of fluids, compaction, pressure, temperature, and sliding velocity. In this session, we welcome research encompassing observational studies, experimental investigations of deformation and friction, microphysical and molecular modeling, as well as innovative methodologies for exploring natural hazards and delving into the underlying physics and chemistry.

Recent studies of naturally occurring microbe-mineral interactions enhanced our understanding of mineral diagenesis, elemental cycling, and deep biosphere. While many chemical and physical processes potentially interact in these geological processes, the situation becomes more interesting when microbes engage redox reaction that may bypass the thermodynamic barriers of reactions. For example, such microbially mediated redox cycling has been known for decades to provide an important source of dissolved Fe to porewaters in ocean sediments, which may be derived from both oxide and phyllosilicate Fe(III) phases. Furthermore, recent studies indicate that microbial activity can dramatically accelerate oxidative transformation of highly stable Fe(II)-silicate minerals, and also promote oxidation of sedimentary iron-sulfide (e.g. pyrite, marcasite) at circumneutral pH. Electron transfer between electroactive microorganisms and redox-active minerals is a fundamental process that drives microbial energy conservation, mineral transformation and biogeochemical cycling of nutrients. These crucial interactions are directly linked to various major geological events and significantly influence the overall habitability of Earth.

In this session, we are looking for, but not limited to, 1) evidence for the microbially induced mineral alteration that could possibly suggest the new source of iron, 2) mechanisms of electron transfer and energy flow between minerals and microbes, and 3) laboratory and/or field studies which assess the impact of microbial-mineral interactions on in situ geochemical cycling processes.

Soils and sediments store a vast amount of organic carbon (OC), exchange C with the atmosphere and play a major role in regulating climate change. A large portion of the OC in soils and sediments is stabilized against microbial decomposition by interactions with minerals, primarily metal oxides and phyllosilicates, through adsorption reactions and particle aggregation. This so-called mineral‑associated OC has a turnover time of tens to thousands of years, and thus mineral-OC associations are a major mechanism for C storage and persistence in soils and sediments. Mineral-OC interactions also affect the formation and transformation of minerals. Despite being extensively studied, the current understanding of the mineral-OC reaction mechanisms and how these interactions affect the OC dynamics remain poorly understood. Mineral-OC interactions may vary in diverse environments and respond to environmental changes, such as permafrost thaw and sea level rise. Thus, this session is focused on 1) mechanistic understanding of mineral-OC interactions, and their impacts on the dynamics of OC and minerals, particularly using advanced analytical (e.g., spectroscopy, electron microscopy and mass spectrometry) and modeling techniques; 2) variations in mineral-OC interactions under diverse environmental conditions; and 3) responses of these interactions to environmental changes. Our session welcomes studies from both field and laboratory experiments. We encourage submissions from researchers with diverse backgrounds, in particular from early-career researchers and underrepresented communities.

Fe and Mn are ubiquitous in aquatic-terrestrial environments. Their redox cycling and the solid phase transformation influence environmental processes (e.g., adsorption, precipitation, redox) of nutrients, heavy metals, and organic pollutants. This session will highlight state-of-the-art qualitative and quantitative investigations of the evolution of Fe- and Mn-(oxyhydr)oxide in the soil-water-sediment systems and their environmental impacts. We invite contributions on the aspects that include, but are not limited to:

- redox chemistry of Fe and Mn (oxyhydr)oxides in laboratory- to field-scale systems

- formation and transformation of Fe and Mn (oxyhydr)oxides

- environmental and geochemical impacts of Fe- and Mn-mineral phase evolution

- modeling of the Fe and Mn cycling that involves the mineral transformation

The geochemical behaviors of rare earth elements (REEs) in near-surface settings have received extensive attention during the past decade. REEs have been shown to be redistributed by many geochemical and chemical weathering processes such as the dissolution of primary REE minerals and REE-bearing minerals, complexation of REEs by organic and inorganic ligands, adsorption of REEs onto clay minerals and metal oxides in soils and regolith, and REE concentration by alluvial and coastal sedimentary processes. The study of the fractionation/redistribution of REEs can help understand important water-rock interactions acting at the nano- to mesoscale. The redistribution of REEs may attest to certain anthropogenic disturbances. Additionally, REEs are strategic resources and critical constituents for many important and strategic technologies used worldwide. Most REEs have been mined from hard rock deposits. New and diverse REE resources have been found in clay-rich regolith, deep-sea sediment, kaolin/bauxite deposits, and alluvial and heavy minerals beach sand placers. Understanding the geochemical and biogeochemical behaviors of REEs will shed new light on the formation of these new REE resources. The topics of this session are included but are not limited to i) New methods and technologies to study the geochemical and biogeochemical behaviors of REEs; ii) The study of the REEs in supergene, weathering, and sedimentary processes; (iii) Genesis and mining methods of these new sedimentary-regolith-hosted and other novel REE resources.

Clays and clay minerals are ubiquitous in sedimentary environments and most contain iron, either as part of the structure of clay minerals or as separate mineral phases in clays. Both biological and abiotic processes can lead to redox reactions of this clay-bound iron and dramatically change clay and clay mineral properties. Moreover, redox-activated iron in clays and clay minerals can, in turn, effect redox changes in other components such as contaminants, nutrients, or metals and, thus, affect their local distribution and global biogeochemical cycling.

This session welcomes contributions on recent developments that explore all aspects of iron redox processes in clays and clay minerals. We invite contributions ranging from fundamental and mechanistic investigations of iron redox processes and their effects on clays and clay minerals to their observation in natural environments and their application in engineered processes. We also welcome studies that use (computational) modelling approaches, laboratory-based experiments, and/or observations in natural and engineered environments.

Variable charge clays (VCC) are a dynamic class of secondary minerals that exhibit a range of properties based on external factors in the soil environment. VCC are important soil constituents, such as 1:1 clay minerals (kaolinite, halloysite), non-crystalline clays (allophane, imogolite), and oxides (Fe & Al), that drive many physical, chemical, and biological processes. Soil organic matter (SOM) is another important colloid with variable charge properties. In this session, we will honor Dr. Goro Uehara, whose foundational work in VCC systems in tropical Hawaiian soils helped researchers better understand soil behavior such as soil structure, aggregation, oxide cementation, water dynamics, sorption, fertility, nutrient availability, carbon sequestration, and microbial interactions. As Dr. Uehara taught us, understanding clay mineralogy is the first step in predicting soil behavior and properly managing soils. Therefore, this session focuses on findings that elucidate or predict VCC behavior.

We invite abstracts that address, but are not limited to, the following topics:

• Surface chemistry of VCC and SOM
• VCC influences on physical, chemical, and biological processes
• Non-crystalline clay research
• Oxide research
• Organo-mineral interactions
• Effects of VCC or SOM on microbial communities

Clay minerals and related low-dimensional compounds are recently focused as important nano-components to fabricate functional soft materials in the forms of colloids, gels, elastomers, and plastics for various applications of sensors, separation, energy conversion/storage, optical materials, medical materials, gas barrier packaging, etc. High-precision manipulation and hierarchical self-assembly of exfoliated nanosheets such as colloidal liquid crystal formation, macroscopic ordering by external-fields, and nano-compositing with polymers and functional molecules are important issues in this session.

Clay-based functional nanomaterials have found wide applications in various areas such as industry and agriculture. The versatile strategies for modification and functionalization of clays give large room to endow them with specific structured materials and physicochemical properties, improving their applicability in industry and agriculture. Topics of this session include, but are not limited to:

- modification and functionalization of clay to synthesize nanomaterials

- the applications of clay-based nanomaterials in various industrial areas

- the applications of clay-based materials in agriculture

This session will highlight recent advances in synthetic and natural clays for a wide range of biological applications such as nanomedicine and nanocosmetics. Contributions from all multidisciplinary areas of mineralogy, geosciences, chemistry, material sciences, biology, pharmacy, cosmetics, and toxicology are welcomed with an emphasis on work that includes the convergence between clay science and bio-medical applications. This session will deal with the utilization of natural clays and the engineering of clay materials for functionalizations not only to comprehend the physico-chemical interaction between clay minerals and biological substances but also to open a new applications field for clay materials. Topics within this theme include, but are not limited to:

1. Natural and synthetic clays and minerals in bio-medical applications
2. Surface and colloidal interaction between clay minerals and biological substances
3. Advanced materials containing clay minerals for nanomedicine and nanocosmetics
4. Chemical modification and functionalization on clay materials as bionanomaterials
5. Computational and experimental comprehension on of clay materials for advanced biological applications

The proposed session will cover the fundamentals and uses of tubular and fibrous clay minerals such as halloysite, palygorskite, sepiolite, and imogolite, among others. Clay scientists, material scientists, biomedical researchers, and engineers are particularly interested in the above-mentioned clay minerals because they enable the incorporation of multi-functionalities and their use as nano-containers, among other appealing properties for materials applications ranging from medical and environmental uses to energy and cultural heritage conservation. A fundamental understanding of the mineralogy, structure, and characteristics of various clay minerals is critical for targeting specific applications. This session intends to share the most recent achievements in the synthesis, functionalization, and application of tubular and fibrous clay minerals. The session also aims to connect scientists with diverse specializations in the following areas: (i) Mineralogy, geology, synthesis, modification, and characterization. (ii) Applications and future prospects in medicine and biology, (bio)nanocomposites, environmental protection, energy, and other advanced applications.

Clays and related low-dimensional nanostructures (e.g., layered silicates, layered double hydroxides) have been used as scaffolds (or precursors) to design advanced materials with excellent electronic and optical properties and have contributed to enrich clay science, in addition to materials chemistry. Even bare aluminosilicate or silicate sheets can tune the electronic properties of guest species attached on the sheets, revealed by advanced characterizations and calculations. This session aims at the discussions on recent advances of (photo)catalytic and optical properties of clays and related inorganics; advanced characterization techniques and theoretical studies on these materials.

Clays and clay minerals are critical components for building materials. For example, in brick raw materials, clay minerals not only comprise a large proportion but also provide the required plasticity so that the brick earth can be kneaded and moulded after being added with the proper amount of water. Vitrification under high temperatures means that glass phases are generated from collapsed clay minerals that help densify the brick body. In addition, clays are found to be promising uses in various construction binder systems, including Portland cement, geopolymer, limestone calcined clay cement, etc. As a prime example, metakaolin (2SiO₂·Al₂O₃) obtained from calcined kaolinite has been proven to be an excellent supplementary cementitious material (SCM) that can substitute cement in high percentages and contribute improved performance as well as lower carbon footprint to mortars and concretes. However, as weathering products from natural processes, clay minerals in different stratigraphic locations or geological settings have varying mineralogy and compositions; All these formation environments bring complexity to the building products and result in quality control difficulties if fundamental characteristics of clays and the clay mixes in hand are not understood. Trial-and-error and factory experience have been the norm for quality control, but such strategies tend to be inefficient.

This session will provide a good opportunity for researchers to discuss their local cases and experiences on clay/clay mineral-involved building materials. It is ultimately aimed to develop a specific and systematic understanding of key material structures and product properties and enable optimization of clay uses in building materials suiting all localities worldwide. Topics of this session include the following, but are not limited to:

- clays and clay minerals for LC³ (limestone calcined clay cement)

- clays and clay minerals in tiles and earth bricks (both unfired and fired)

- clays and clay minerals as additives to plasters (cement, gypsum, etc.)

- clays and clay minerals used for alkali activated materials

- clays and clay minerals in polymer-based building materials

Negative emission technologies need to be ensured if carbon neutrality is to be achieved by 2050. Clays and clay minerals are expected to play a significant role in negative emissions technologies such as especially enhanced rock weathering, soil carbon sequestration and geological sequestration.　And the modified clay materials has also high potential for carbon capturing in engineering processes. In this context, this session will provide a broad and comprehensive discussion of the role of clays and clay minerals on carbon dioxide removal in negative emission technology.

Clay minerals and clay-bearing rocks are essential components in many design concepts for deep geologic disposal of spent nuclear fuel. This session invites contributions from basic research to applied repository design. Topics can include (but are not limited to) the following:

• Clay/shale host rock and engineered barrier systems
• Natural or artificial analogues of clay barriers
• Thermo-hydro-chemo-mechanical (THMC) properties
• Heavy metal and radionuclide sorption and transport
• Modeling across length and time scales, including artificial intelligence methods

Benchtop and underground research laboratory investigations

Clays and clayey nanomaterials, which are very small in size, have a large impact on a wide range of fields from our daily lives to the Earth's surface environment. To explore the structure, chemical composition, and properties of clayey materials, the use of electron microscopy has become indispensable in clay sciences. Furthermore, the recent development of electron microscopy techniques and its combination with related methods have contributed to the visualization of complex 3D structures and the understanding of the dynamic behavior of clayey materials. This session will be devoted to the application of microscopy, including electron/ion microscopy, EBSD, EELS and STEM, and to the new possibilities offered by combining with other methodologies (SIMS, X-ray microscopy, Autoradiography) in clay sciences. We also welcome advanced research, such as in-situ environmental and computational approaches to aim at investigating dynamic interactions of clayey materials.

***In recognition of his retirement from the University of Tokyo, we will be honoring Dr. Toshihiro Kogure, whose contributions to the atomic structure of clays using electron microscopy are well-known. We also welcome talks from his students and collaborators.

Molecular level simulation has proven powerful in studying microscopic properties of clay minerals and related phases. The physical and chemical information needed to understand these complex materials span many orders of magnitude from the atomic scale via the particle scale to macroscopic level representations. Translation between different scales requires detailed understanding and new modeling methods and thus remains a challenge. In recent years, novel approaches including machine learning, reactive force fields, and enhanced sampling, among others, have enabled significant advances in multi-scale modeling in materials science and technology. Applications of these methods in clay science are still emerging. In this session, we aim to highlight recent progress in computational modeling of clays and clay minerals. We particularly encourage contributions focused on (1) computational studies of clay properties using a wide variety of modeling techniques, including quantum mechanical, classical, multi-scale modeling, and other approaches, (2) development of new modeling techniques, and (3) combined computational modeling and experimental studies. Systems of interest include but are not limited to clay minerals, (hydr)oxides, zeolites, and their interfaces with water, organics, and other phases.

This session aims to characterize assemblages of phyllosilicate outcrops on Mars and at analog sites to constrain the martian environments where phyllosilicates formed and persisted. Smectites and other clay minerals are observed in a variety of locations on Mars, frequently associated with sulfates, iron oxides/hydroxides, or carbonates. Investigating these sites through orbital and surface missions provides information on the geochemical environment during their formation and on potentially habitable sites. Studies of phyllosilicates on Mars using orbital or rover data, geochemical modelling, and characterization of clay-bearing analogs or martian meteorites are encouraged.

Phyllosilicates have been identified and characterized on the asteroids Bennu, Ryugu, and the dwarf planet Ceres through spectroscopic remote sensing. Phyllosilicates in meteorites provide key constraints on understanding the phyllosilicates in asteroids. NH₄-phyllosilicates have been identified across much of the surface of Ceres, and lab studies of potential forms of these clays are enabling a more accurate understanding of the types and chemistries of these intriguing materials. Lab measurements performed on Ryugu returned samples show the presence of serpentine/saponite-type phyllosilicates. The additional presence of NH₄-related spectral signatures, carbonates, and organics reinforces the similarity of this asteroid to Ceres. The phyllosilicates observed on Bennu are also bringing exciting new insights to complement our understanding of the evolution of asteroids. Abstracts are requested characterizing phyllosilicates in asteroids and meteorites, as well as lab studies supporting our understanding of these data.

Remote detection and investigation of phyllosilicates and associated minerals has long been applied towards mining, industrial applications, and characterization of geochemical alteration. This includes airborne and handheld devices in the visible/near-infrared/short-wave infrared region for reflectance spectroscopy and the mid-infrared region for emission spectroscopy. Securing access to critical metals is essential for the transition of the fossil fuel-based energy sector to a sustainable, renewable energy future. However, exploring for phyllosilicates, critical metals and their extraction is very energy intensive, and remote sensing often provides a more effective technique. Example applications include the mapping of alteration haloes associated with porphyry copper deposits and characterizing the alteration of Li-host minerals. Lab studies of field samples are an integral component of accurate remote determinations, as are spectroscopic measurements of pure, well-characterized samples. For this session, we solicit abstracts on lab, field, and airborne spectroscopic studies of phyllosilicates and clay-bearing materials, such as geological case studies, or work on mineral reference libraries or fundamental vibrational spectroscopy.

This session will include all presentations not coming under one of the specific session categories.