Author's personal copy Late Triassic tholeiitic magmatism in Western Sicily: A possible extension of the Central Atlantic Magmatic Province (CAMP) in the Central Mediterranean area? R. Cirrincione a , P. Fiannacca a , M. Lustrino b,c , V. Romano a, ⁎, A. Tranchina a a Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università degli Studi di Catania, C.so Italia, 57, 95129 Catania, Italy b Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, 00185 Roma, Italy c CNR — Istituto di Geologia Ambientale e Geoingegneria (IGAG) c/o Dipartimento di Scienze della Terra, Università degli Studi di Roma La Sapienza, P.le A. Moro, 5, 00185 Roma, Italy abstract article info Article history: Received 16 May 2013 Accepted 7 October 2013 Available online 18 October 2013 Keywords: Tholeiitic magmatism Lithospheric thinning Triassic Western Sicily Late Triassic basaltic rocks crop out in the Lercara area in Western Sicily. Major and trace element composition, as well as Sr–Nd isotopic ratios ( 87 Sr/ 86 Sr i = 0.7074 -0.7076; εNd i = from -0.69 to -1.09) of the Lercara rocks shows many similarities with Large Ion Lithophile Elements (LILE)- and Light Rare Earth Elements (LREE)-rich tholeiitic basalts of the Central Atlantic Magmatic Province (CAMP), that erupted during the Mesozoic fragmentation of the Pangea supercontinent and subsequent opening of the Central Atlantic Ocean. The geochemical features of the Lercara igneous rocks, together with the spatial distribution of the ~200 Ma old CAMP rocks are unlikely to be associated with the arrival of a thermal anomaly in the form of a mantle plume and are more compatible with adiabatic melting of passively upwelling sub-lithospheric mantle. The original melts variably interacted with lower crustal rocks before reaching the surface. AFC modeling suggests two distinct differentiation paths including either simple mixing or assimilation-fractional crystallization processes involving lower crustal rocks. These interactions with continental crust indicate that an ocean basement most probably had not yet formed. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Large amounts of magma are usually produced during the early stages of continental fragmentation (e.g., Paraná-Etendeka-Angola, Ethiopia-Yemen, Central and North Atlantic Magmatic Provinces). The elevated melt productivity is classically interpreted as being caused by thermal anomalies related to mantle plumes (e.g., Ewart et al., 1998; Riley et al., 2005; Wilson, 1997) assuming that the sub-lithospheric upper mantle (the so-called DMM = Depleted MORB Mantle) is geochemically homogeneous, isothermal, depleted and stiff and that the lithospheric mantle does not substantially participate in partial melting processes (e.g., McKenzie and Bickle, 1988). Alternative views, based on seismological, mineralogical, thermodynamic, geochemical and petrological constraints indicate the presence of geochemical, mineralogical and lithological heterogeneities in the shallow mantle, as well as differences in the thickness of the plates and their conductive heat transmission (e.g., Anderson, 2011; Coltice et al., 2007; Foulger et al., 2013; Rampone and Hofmann, 2012, and references therein). The study of magmas produced during the transition between the continental rifting stage and the formation of incipient oceanic crust represents an essential tool in the investigation of the mantle sources involved in these magmatic events. Western Sicily represents an example of one of these key areas, in that it shows the early stages of continental rifting recorded in the geochemical signatures of the erupted magmas. Here, Late Triassic–Early Jurassic magmatism mostly consists of hypabyssal and submarine volcanic rocks enclosed in the sedimentary sequences of the Apennine–Maghrebian Chain (Basilone et al., 2010; Catalano et al., 1984; Grasso and Scribano, 1985; Lucido et al., 1978). These igneous rocks were emplaced during the diachronic Pangea break-up that developed from the Late Paleozoic up to Jurassic, into the opening of the Neo-Tethys and the Alpine Tethys Oceanic systems (e.g., Frizon de Lamotte et al., 2011; Handy et al., 2010; Puga et al., 2011; Saccani et al., 2011, and references therein). In this study we use petrological, geochemical and isotopic data to investigate the mantle sources and the mechanisms of magma evolution during the transition from continental rifting to incipient ocean spreading, as recorded by subalkaline basalts and basaltic andesites cropping out in western Sicily. We also attempt to place these rocks in a larger geodynamic context by making comparisons with other Late Triassic– Early Jurassic volcanic rocks genetically related to the dismembering of Pangea and the Central Magmatic Atlantic Province (CAMP, e.g., Callegaro et al., 2014; Marzoli et al., 1999, 2004, and references therein). 2. Geological background Two main elements characterize the geology of Sicily: the approximately E–W oriented Sicilian fold-and-thrust belt, with a Lithos 188 (2014) 60–71 ⁎ Corresponding author. Tel.: +39 0957195786; fax: +39 0957195760. E-mail address: vanessa.romano@unict.it (V. Romano). 0024-4937/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.lithos.2013.10.009 Contents lists available at ScienceDirect Lithos journal homepage: www.elsevier.com/locate/lithos