Hydrothermal alteration of chlorite to randomly interstratified corrensite-chlorite: Geological evidence from the Oligocene Smrekovec Volcanic Complex, Slovenia

Chlorite, ordered mixed-layer chlorite-smectites, laumontite, quartz and albite are the most widespread alteration assemblage in cone-building and near-vent successions of lavas, autoclastic, pyroclastic and resedimented volcaniclastic deposits of the Oligocene Smrekovec Volcanic Complex, Slovenia. Randomly interstratified corrensite-chlorite with ~ 70–80% of corrensite layers (R0 Cr-Ch) is less common in occurrence and associated either with clinoptilolite and heulandite in fine-grained vitric tuffs, or with prehnite, laumontite, actinolite, analcime and albite in extensively altered and/or fractured host-rocks. The assemblage with clinoptilolite and heulandite indicates the temperatures of formation of