The historic magmatic-hydrothermal eruption of the Breccia di Commenda, Vulcano, Italy

摘要: The historic Breccia di Commenda (BC) explosive eruption of Vulcano (Aeolian Islands, Italy) opened with a phase that generated gray fine ash layer dispersed to the northwest (phase 1). continued dilute pyroclastic density current (PDC) was east, followed by emplacement radially distributed, topographically controlled PDC deposits 2). last produced sequence accretionary lapilli and toward southeast 3). most impressive feature BC is its high lithic/juvenile clast ratio yellow color 2. Lithic fragments are mainly hydrothermally altered rocks, in silicic advanced argillic facies. Juvenile fragments, ranging from 20 % 40 % volume, confined component comprise rhyolitic trachyandesite, poorly non-vesicular fragments. fraction richer S, Cu, Zn, Pb, As than juvenile bombs, also components other La Fossa units, suggesting formed presence an anomalously amount S metals. Sulfur metals may have been carried as aerosols chloride- sulfate-bearing micro-crystals, derived condensation magmatic gas eruptive cloud. content lithic clasts suggests explosions involved fluid-saturated rocks residing conduit zone. However, supports idea this explosion triggered ascent new magma. We categorize magmatic-hydrothermal emphasize type phreatomagmatic external water active hydrothermal system. Rock magnetic temperatures non-altered lava indicate uniform deposit temperature for between 200 260 °C, maximum at 280 °C. These homogeneous, relatively low consistent 2 expansion abundant steam flashing In addition, recent paleomagnetic dating provides age 1000 1200 AD, younger reported previously published data, previous interpretations history Mt. Pilato require re-evaluation.