Emplacement of the Cabezo María lamproite volcano (Miocene, SE Spain)

摘要: Lamproite volcanoes are uncommon in the geological record but exceptionally well preserved Betic Cordilleras of SE Spain, where they erupted during Late Miocene (Tortonian to Messinian stages). The parent melts thought have been channelled through major lithospheric faults erupt at or near faulted margins Neogene sedimentary basins. magmas be relatively CO2-poor (<1 wt %) and typically characterised by an effusive eruption style development lava lakes scoria cones. Cabezo Maria is a small (∼550 m diameter) lamproite volcano that was emplaced within shallow-water marine-influenced Vera Basin. lamproites compositionally similar those Roman Province generally less potassic (K2O<5 wt%) than other (ultra-) rocks Spain (e.g. Cancarix, Fortuna). initial stages were dominated explosive magma-water interactions formation peperites. These angular fragments glassy lavas (and isolated lobes) incorporated sediments, locally showing effects thermal metamorphism. Further, elutriation pipes ‘jigsaw-fit’ textures observed peperites overlain outward-dipping well-stratified deposits defining part cinder cone, which inferred emerged above sea level. Steep internal contacts with inward-dipping, structureless breccias likely represent inner wall central conduit. cross-cut late-stage dykes, supplied fissure eruptions geochemically capping cone. transition from behaviour may reflect decreased availability water, possibly due downward migration feeder conduit below level water-saturated sediments.