Pervasive assimilation of carbonate and silicate rocks in the Hortavær igneous complex, north-central Norway

Thermal weakening of the carbonate basement under Mt. Etna volcano (Italy): Implications for volcano instability

“…The geochemical signature of magma-carbonate interaction can sometimes be seen within volcanic products, and is known as "carbonate assimilation" (e.g., Wenzel et al, 2002;Barnes et al, 2005;Gaeta et al, 2006;Piochi et al, 2006;Chadwick et al, 2007;Freda et al, 2008;Deegan et al, 2010;Mollo et al, 2010a). Recent petrological studies have documented in detail that magma contamination is marked by the overgrowth of Ca-rich phases (mainly calcic clinopyroxene) on primary minerals (essentially olivine); as a result, the magma becomes progressively depleted in silica and enriched in alkalis.…”

Interaction between ultrapotassic magmas and carbonate rocks: Evidence from geochemical and isotopic (Sr, Nd, O) compositions of granular lithic clasts from the Alban Hills Volcano, Central Italy

“…However, high CaO contents and d 18 O& observed for several ejecta require mass addition of carbonate components rather than simple CO 2 fluxing. Such a process can occur via reaction between liquid magma and solid carbonate rocks (Iacono Marziano et al, 2007), and/or by mixing between silicate magma and melted carbonates (Wenzel et al, 2002;Barnes et al, 2005).…”

“…One possibility is melting of carbonate wall rocks around magmatic bodies. Carbonate melting has been demonstrated to be likely at magmatic temperatures (Wenzel et al, 2002, and references therein), and has been suggested as an explanation for calcite-rich rocks that are observed in association with magmatic intrusive and extrusive rocks at several places (e.g., Barnes et al, 2005;Jutras et al, 2006). At intermediate pressure, calcite melting is favoured by the presence of water in the fluid phase (Wyllie, 1965;Wenzel et al, 2002).…”

“…Studies of wall rocks around magmatic bodies have shown that mineralogical and geochemical modifications are particularly intensive around alkaline igneous intrusions (e.g., Kogarko and Ryabchikov, 1978;Bailey and Hampton, 1990), especially when magmas are emplaced into carbonate sedimentary sequences. Magma-carbonate interaction generates exotic lithologies at the contact zone and heavily affects the nature and amounts of crystallising magmatic minerals, thus modifying magma evolution paths (Baker and Black 1980;Wenzel et al 2002;Barnes et al 2005;Coulson et al 2007;Iacono Marziano et al, 2007Conte et al, 2009;Gaeta et al, 2009). Moreover, these processes may play a strong role on modalities of volcanic eruptions and on transfer of chemical components, especially CO 2 , from the lithosphere to the atmosphere (e.g., Iacono Marziano et al, 2007Marziano et al, , 2008Marziano et al, , 2009.…”

Felsic volcanism in the eastern Yilgarn Craton: Evolution of a Late Archean convergent margin

“…The intrusion was emplaced into marble and gneiss at 475 Ma, during Caledonian metamorphism, as numerous subhorizontal sheets, of nenormative gabbro and diorite to (ne-bearing) monzodiorite, to monzonite and syenite. Carbonate assimilation is apparent because carbon in primary calcite has a sedimentary origin (Barnes et al, 2005). Experiments (Iacono Marziano and Gaillard, in review) show that extensive carbonate assimilation is possible in H 2 O-rich mafic magma, especially when evolved fluids can escape.…”