From Dioctahedral to Trioctahedral Smectites: Where Volcanism meets Weathering, Sedimentation and Diagenesis
George E. Christidis, Technical University of Crete, Greece, gchristidis@tuc.gr
Manuel Pozo, Universidad Autónoma de Madrid, Spain, manuel.pozo@uam.es
Telma Musso, Universidad Nacional del Comahue, Argentina, telma.musso@probien.gob.ar
Smectites form in sedimentary environments by diagenetic processes often involving volcaniclastic deposits, by hydrothermal alteration of pyroclastic rocks and lavas, often associated with ore deposits, and during weathering. The smectite-rich rocks known as bentonites, are important industrial clays with numerous industrial applications. Both the dioctahedral and trioctahedral smectites display compositional heterogeneity within the microscale, that is related to paleoenvironmental conditions during formation and is very useful for industrial and environmental applications and exploration of bentonites. The session will present the research progress on the genesis of dioctahedral and trioctahedral smectites in different geological environments and will address the following topics: Compositional heterogeneity of smectites in various environments, detection of links between intrinsic properties of smectites and the mode of their formation, formation of smectites in soils and paleosoils, genesis of trioctahedral smectites with emphasis on the Li-bearing varieties, considering the recent energy transition trends, petrography as a tool for understanding formation and diagenetic modifications of smectitic clays, authigenic smectites in marine sediments and importance of smectites as paleoclimatic indicators. 
