Recycling and “re-hydration” of degassed magma inducing transient dissolution/crystallization events at Stromboli (Italy) |
| |
Authors: | Patrizia Landi, Nicole M trich, Antonella Bertagnini,Mauro Rosi |
| |
Affiliation: | aIstituto Nazionale di Geofisica e Vulcanologia, Sezione di Pisa, via della Faggiola, 32-56126 Pisa, Italy;bLaboratoire Pierre Süe, CEA-CNRS, CE-Saclay, 91191 Gif/Yvette, France;cDipartimento di Scienze della Terra, Universita’ degli Studi di Pisa, via Santa Maria, 53-56126 Italy |
| |
Abstract: | Intrusive degassing and recycling of degassed and dense magma at depth have been proposed for a long time at Stromboli. The brief explosive event that occurred at the summit craters on 9 January 2005 threw out bombs and lapilli that could be good candidates to illustrate recycling of shallow degassed magma at depth. We present an extensive data set on both the textures and the mineral, bulk rock and glassy matrix chemistry of the “9 Jan” products. The latter have the common shoshonitic–basaltic bulk composition of lavas and scoriae issued from typical strombolian activity. In contrast they differ by the heterogeneous chemistry of their matrix glasses and their crystal textures that testify to crystal dissolution event(s) just prior magma crystallization upon ascent and eruption. Comparison between mineral paragenesis of the natural products and experimental phase equilibria suggest water-induced magma re-equilibration. We propose that mineral dissolution is related to water enrichment of the recycled degassed magma, via differential gas bubble transfer and to some extents its physical mixing with volatile-rich magma blobs. However, all these features illustrate transient processes. Even though evidence of mineral dissolution is ubiquitous at Stromboli, its effect on the bulk magma chemistry is minor because of the subtle interplay between mineral dissolution and crystallization in magmas having comparable bulk chemistry. |
| |
Keywords: | mineral dissolution magma chemistry volatiles trace elements Stromboli |
本文献已被 ScienceDirect 等数据库收录! |
|