Assessing the link between mantle source and sub-volcanic plumbing in the petrology of basalts from the 2001 and 2002/2003 eruptions of Mount Etna, Sicily: Evidence from geochemical and helium isotope data

Role of syn-eruptive plagioclase disequilibrium crystallization in basaltic magma ascent dynamics

“…The high plagioclase content of UV products requires a low water content, and implies that this shallow reservoir should be located a few hundred metres below the vent. This is consistent with the prevailing literature, in which it is suggested that LV were fed by a straight vertical conduit (‘eccentric' activity) whilst UV were fed a central conduit with a shallow horizontal dyke (‘central-lateral' activity)29303637383940414243444546. Furthermore, from petrological evidence, the shallow horizontal dyke should be located between 75 and 5 MPa (refs 29, 46), that is, between ∼2.5 km and the vent of the conduit.…”

An integrated P-T-H2O-lattice strain model to quantify the role of clinopyroxene fractionation on REE+Y and HFSE patterns of mafic alkaline magmas: Application to eruptions at Mt. Etna

“…This points out that the magmatic source might not have changed over the past 0.5 Ma and/or that subduction-related metasomatic fluids have minimal effect on helium isotope signature (Nuccio et al, 2008;Coulson et al, 2011). In other words, the petrological dissimilarity of 2001 and 2002-2003 flank eruptions does not necessarily correspond to significant variability in the mantle source, but rather may reflect the different evolutionary history of cogenetic magmas during crystal fractionation and degassing phenomena at different levels within the crust (Coulson et al, 2011). Importantly, a peculiar feature of 2002-2003 flank eruptions was the occurrence of lowpotassium oligophyric (LKO) magmas erupted only in the uppermost part of NERS.…”

“…In contrast, flank eruptions from the northern fissures (NF) share similarities with magmas feeding 2001 UV eruptions and the recent explosive activity at the summit craters (i.e., BN and NEC). NF products are more differentiated (MgO < 6 wt.%) and degassed trachybasalts to trachyandesites, showing porphyritic (plagioclase-phyric) textures that resemble those of trachybasalts erupted during the past decades at the summit craters (Clocchiatti et al, 2004;Ferlito et al, 2008;Corsaro et al, 2009;Coulson et al, 2011). In terms of incompatible trace elements, LILE, Sr-Nd isotopes, and radioactive disequilibria, both the 2001 UV and 2002-2003 NF products conform to the post-1971 volcanic activity (Clocchiatti et al, 2004).…”

“…Conversely, 2001LV and 2002 SF products are the most femic but also the most enriched in K, Rb, Ra, and 87 Sr (Clocchiatti et al, 2004), perhaps due to melting of a metasomatized mantle source containing hydrous phases (phlogopite/amphibole) or direct transfer to the melting region of fluid-mobile elements produced by dehydration of the subducting Ionian plate (Tonarini et al, 2001). It has been also suggested that LV and 2002 (Coulson et al, 2011), being also identical to the helium isotopes of products erupted during -2005(Nuccio et al, 2008 and in the last 0.5 Ma (Marty et al, 1994). This points out that the magmatic source might not have changed over the past 0.5 Ma and/or that subduction-related metasomatic fluids have minimal effect on helium isotope signature (Nuccio et al, 2008;Coulson et al, 2011).…”

“…It has been also suggested that LV and 2002 (Coulson et al, 2011), being also identical to the helium isotopes of products erupted during -2005(Nuccio et al, 2008 and in the last 0.5 Ma (Marty et al, 1994). This points out that the magmatic source might not have changed over the past 0.5 Ma and/or that subduction-related metasomatic fluids have minimal effect on helium isotope signature (Nuccio et al, 2008;Coulson et al, 2011). In other words, the petrological dissimilarity of 2001 and 2002-2003 flank eruptions does not necessarily correspond to significant variability in the mantle source, but rather may reflect the different evolutionary history of cogenetic magmas during crystal fractionation and degassing phenomena at different levels within the crust (Coulson et al, 2011).…”