Cooling and crystallization recorded in trachytic enclaves hosted in pantelleritic magmas (Pantelleria, Italy): Implications for pantellerite petrogenesis

Abstract

This study focuses on the comenditic trachyte enclaves hosted in pantelleritic lava and pumices emplaced during one of the most recent eruptive events at Pantelleria (~. 6. ka). Enclaves range from mm-sized fragments to dm-sized blocks with spheroidal to amoeboid shapes and characteristic globular surfaces; they are crystal-rich with ~. 30. vol% large anorthoclase, less abundant Fe-rich olivine, clinopyroxene and Fe-Ti oxides. Vesicles ranging from a few mm to 1-2. cm in size are distributed throughout the enclave and are commonly filled with microlite-free vesicular glass. The groundmass presents spectacular textures, including fine to coarse spherulites and hopper and skeletal microlites (mostly anorthoclase) with 10-35. vol% residual glass and 10-15. vol% small vesicles (<. 50. μm to 200. μm). Residual glass has a pantelleritic composition with Na. +. K/Al. >. 2. Accordingly, the microlite composition is close to that of the host pantellerite.These textures were acquired during a ma...