Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/3320
AuthorsPappalardo, L.* 
Ottolini, L.* 
Mastrolorenzo, G.* 
TitleThe Campanian Ignimbrite (southern Italy) geochemical zoning: insight on the generation of a super-eruption from catastrophic differentiation and fast withdrawal
Issue Date2007
DOI10.1007/s00410-007-0270-0
URIhttp://hdl.handle.net/2122/3320
KeywordsCampanian Ignimbrite
Super eruption
Crystal size distribution
Partition coefficients
Subject Classification04. Solid Earth::04.04. Geology::04.04.04. Marine geology 
04. Solid Earth::04.04. Geology::04.04.05. Mineralogy and petrology 
04. Solid Earth::04.08. Volcanology::04.08.05. Volcanic rocks 
AbstractMore than ca 100 km3 of nearly homogeneous crystal-poor phonolite and ca 100 km3 of slightly zoned trachyte were erupted 39 ka during the Campanian Ignimbrite super eruption, the most powerful in the Neapolitan area. Partition coefficient calculations, equilibrium mineral assemblages, glass compositions and texture were used to reconstruct compositional, thermal and pressure gradients in the pre-eruptive reservoir as well as timing and mechanisms of evolution towards magma chamber overpressure and eruption. Our petrologic data indicate that a wide sill-like trachytic magma chamber was active under the Campanian Plain at 2.5 kbar before CI eruption. Thermal exchange between high liquidus (1199 C) trachytic sill and cool country rocks caused intense undercooling, driving a catastrophic and fast (102 years) in situ fractional crystallization and crustal assimilation that produced a water oversaturated phonolitic cap and an overpressure in the chamber that triggered the super eruption. This process culminated in an abrupt reservoir opening and in a fast single-step high decompression. Sanidine phenocrysts crystal size distributions reveal high differentiation rate, thus suggesting that such a sill-like magmatic system is capable of evolving in a very short time and erupting suddenly with only short-term warning.
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