Melilitolite intrusion and pelite digestion by high temperature kamafugitic magma at Colle Fabbri, Spoleto, Italy Francesco Stoppa a, ⁎, Victor V. Sharygin b a Dipartimento di Scienze della Terra, Università G.d'Annunzio, 66 100 Chieti, Italy b V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, pr. Koptyuga 3, Novosibirsk 630090, Russia abstract article info Article history: Received 16 April 2008 Accepted 2 March 2009 Available online 20 March 2009 Keywords: Leucite wollastonite melilitolite Kamafugite Melt inclusions Colle Fabbri Central Italy A subvolcanic body in Colle Fabbri (Umbria, Central Italy) intrudes sedimentary rocks and the overlaying extrusive breccia. The intrusive rock is melilitolite with essential leucite, kalsilite, and wollastonite plus accessory Ti-garnet, Ti–Al–Fe 3+ -clinopyroxene, magnetite, perovskite, rankinite, Si-bearing apatite, Fe–Ni sulphides, and carbonate/zeolite. Bulk chemistry of melilitolite indicates a strong SiO 2 -undersaturation, extremely high CaO composition, and strong initial potassic character. Sr and Nd isotopic ratios support a link with the source of kamafugites and carbonatites found in the same region. The igneous contact rock contains variable amounts of quenched clinopyroxene, anorthite, sanidine ±wollastonite, plus spinel and glass. Extremely high temperature melilitolite magma digested pelite country-rock, thus leading to a unique mineral composition. The homogenisation temperatures of mineral inclusions in contact rock demonstrate that crystallisation occurred well above 1230 °C. A large thermal aureole formed in a local clinker-like breccia, characterised by the association of felsic glass + indialite + tridymite ± Ti-magnetite, confirms high- temperature emplacement. Metasomatic/thermometamorphic phenomena favoured zone-specific miner- alisation of hydrated Ca-silicates, hydrated complex sulphates and zeolites in breccias and encasing rocks. © 2009 Elsevier B.V. All rights reserved. 1. Introduction An initial explosion in Colle Fabbri produced 4-meter-thick breccia, which currently covers paleosol on top of a sedimentary substratum. This extrusive breccia is intruded by sills and dykes, which are up to 50 cm thick (Fig. 1). A subsequent fine-medium grain holocrystalline stock intrudes breccia. The stock is 60 m wide, outcrops of approx. 500 m 2 , and has a conservatively estimated volume of 1000 m 3 . Contact with pelitic wall- rock shows strong mechanical deformation and thermal metamorphism. Stoppa (1988) used the name ‘euremite’ to describe a rock mainly composed of wollastonite, melilite, leucite, anorthite, and Ti magnetite. Leucite melilitolite ejecta can often be found in the Italian Pleistocene ultrapotassic provinces (Federico et al., 1994; Di Battistini et al., 1998; Schingaro et al., 2001, Stoppa et al., 2006). Moreover in situ leucite melilitolites can be found in the Pleistocene Intra-mountain Ultra-alkaline Province (IUP) of melilitites and carbonatites (Stoppa et al., 2003a). This province extends for about 400 km through the Umbria, Latium, Abruzzi, and Lucania regions along the Apennine graben systems and is characterised by kamafugitic melilitite and foidite, melilitolite, and Ca- carbonatite (Lavecchia et al., 2002 and references therein). Stoppa et al. (2005) and Capitanio (2005) have advocated a magmatic origin for Colle Fabbri rocks whereas Melluso et al. (2003) have proposed that they are paralavas. This paper provides an in- depth description of the mineralogy of the rocks, the melt inclusion composition and their homogenisation temperatures. Using these data we address the relationship between the igneous and non-igneous rocks in Colle Fabbri outcrop and discuss the effects of metamorphism and assimilation processes. 2. Analytical methods Double-polished rock sections (~50–100 μm in thickness) were used for optical examination of Colle Fabbri rocks in transmitted and reflected light. Back-scattered electron (BSE) imaging was performed using a JEOL 6380LA scanning electron microscope at the V.S. Sobolev Institute of Geology and Mineralogy, Novosibirsk, Russia. Electron microprobe analyses of Colle Fabbri minerals and glasses were performed at Lakehead University, Thunder Bay, Canada, V.S. Sobolev Institute of Geology and Mineralogy, Novosibirsk, Russia, and at the Department of Mineralogy, Natural History Museum, London, U.K. Elements were standardised according to combinations of well-charac- terised minerals, pure metals, and synthetic compounds. Operating conditions were selected according to the analytical sample. An accelerating potential of 15–20 kV, a beam current of 10–20 nA, and a beam diameter of 2–15 μm were used to analyse silicates. The analytical technique is described in Williams and Spratt (1995). The calculated lower detection limit is ~0.03 wt.%. A multi-method procedure was used by XRAL Laboratories (SGS Canada Inc) in Toronto, Canada, to analyse major and trace elements Lithos 112 (2009) 306–320 ⁎ Corresponding author. Tel.: +39 871 3556418; fax: +39 8713556454. E-mail address: fstoppa@unich.it (F. Stoppa). 0024-4937/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.lithos.2009.03.001 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos