one of the most recent eruptive events at Pantelleria (~6 ka). Enclaves range from mm-sized fragments todm-sized blocks with spheroidal to amoeboid shapes and characteristic globular surfaces; they are crystal-richwith ~30 vol% large anorthoclase, less abundant Fe-rich olivine, clinopyroxene and Fe–Ti oxides. Vesicles rangingfrom a fewmmto 1–2 cmin size are distributed throughout the enclave and are commonly filledwith microlitefreevesicular glass. The groundmass presents spectacular textures, including fine to coarse spherulites andhopper and skeletal microlites (mostly anorthoclase) with 10–35 vol% residual glass and 10–15 vol% smallvesicles (b50 μm to 200 μm). Residual glass has a pantelleritic composition with Na + K/Al N 2. Accordingly,the microlite composition is close to that of the host pantellerite.These textures were acquired during a magma mixing event prior to the eruption: (i) a vapor-saturatedcomenditic trachyte magma intruded the shallower, cooler pantellerite magma body, triggering a first degassingevent (first boiling) and rapid crystallization with a high degree of undercooling (ΔT = 100–150 °C); (ii) vaporexsolution induced by rapid crystallization (second boiling) produced the microvesicular groundmass; and(iii) vapor pressure forced the residual pantelleritic liquid to migrate into the large vesicles and/or outside theenclaves. Based on this interpretation, these enclaves can be used as a natural laboratory for identifying thechemical and physical processes driving the evolution of silicic magmas at Pantelleria. In particular, they canbe used to assess whether pantellerite melts can be obtained from comenditic trachytes after extensive crystallizationfollowed by gas-driven filter-pressing and consequent
|Numero di pagine||10|
|Rivista||Journal of Volcanology and Geothermal Research|
|Stato di pubblicazione||Published - 2015|
All Science Journal Classification (ASJC) codes
- Geochemistry and Petrology
Rotolo, S. G., Landi, P., & Rotolo, S. G. (2015). Cooling and crystallization recorded in trachytic enclaves hosted in pantelleritic magmas (Pantelleria, Italy): Implications for pantellerite petrogenesis. Journal of Volcanology and Geothermal Research, 301, 169-179.