Coexistence of low-angle normal and high-angle strike- to oblique-slip faults during Late Miocene mineralization in eastern Elba Island (Italy) Domenico Liotta a, ⁎, Andrea Brogi a , Marco Meccheri b , Andrea Dini c , Caterina Bianco a , Giovanni Ruggieri d a Department of Earth and Geoenvironmental Sciences, University of Bari “Aldo Moro”, Via Orabona 4, Bari, Italy b Department of Physics, Earth and Environmental Sciences, University of Siena, Via Laterina 8, Siena, Italy c CNR-IGG National Council of Research, Geosciences and Georesources Institute, Pisa, Italy d CNR-IGG National Council of Research, Geosciences and Georesources Institute, Florence, Italy abstract article info Article history: Received 2 April 2014 Received in revised form 26 May 2015 Accepted 24 June 2015 Available online xxxx Keywords: Extensional tectonics Fractures Mineralization Northern Apennines In this paper we deal with the kinematic and chronological relationships among low angle normal faults and high angle strike- to oblique-slip faults in an exhumed mineralized area, where shear veins and minor associated structures filled with the same mineral assemblage has been interpreted as indicators of coeval fault activities. The study area is located in the eastern Elba Island, where a mineralized late Miocene-early Pliocene low-angle normal fault (Zuccale fault) and high-angle strike- to oblique-slip faults extensively crop out, the latter giving rise to the Capoliveri-Porto Azzurro shear zone. The field study highlighted that: (a) the damage zones of both fault sets are mineralized by syn-kinematic tourmaline, graphite, Fe-oxides and/or Fe-oxyhydroxides shear veins, thus indicating their coeval activity during the hydrothermal event (5.9–5.4 Ma); (b) the Capoliveri- Porto Azzurro shear zone is constituted by a network of fractures, whose geometry and kinematics display the evolution of a NE-trending left-lateral oblique-slip transtensional shear zone; (c) its internal architecture is de- fined by tourmaline and Fe-oxides and/or Fe-oxyhydroxides mineralized veins, framed in the same kinematic field characterizing the Zuccale fault evolution; for this reason, the Capoliveri–Porto Azzurro shear zone is interpreted as a transfer zone active during the low-angle fault activity; (d) the Capoliveri–Porto Azzurro shear zone played the role of a significant normal fault during the Late Pliocene–Pleistocene, therefore favouring the deepening of the Tyrrhenian Basin with respect to the uplift and exhumation of the mid-crustal rocks of the Elba Island. It is finally argued that the interaction between the low-angle normal fault and the almost vertical shear zone determined an increase of permeability, favouring the mineralizing fluid flow during the hydrother- mal stage and, reasonably, the previous emplacement of the Porto Azzurro magmatic body. © 2015 Elsevier B.V. All rights reserved. 1. Introduction In rifting environments, extension is often accommodated by coexisting normal faults and nearly orthogonal strike- to oblique-slip faults (Bally et al., 1981; Ebinger, 1989; Gibbs, 1989; Lister et al., 1986), the latter playing the role of transfer zones. By this way, the con- temporaneous extension of adjacent crustal sectors is permitted, overstepping the mechanical differences that properly characterize the brittle crust (Peacock, 2003). Transfer zones are therefore significant regional structures accompanying thinning of the crust, such as the case of divergent margins (Ben-Avraham, 1992; Bosworth, 1985; Fantozzi, 1996) and/or intraplate rifting environments (Duebendorfer and Black, 1992; Larsen, 1988; Milani and Davison, 1988; Nelson et al., 1992). This framework is largely documented for those areas where ex- tension is characterized by high-angle normal faults and nearly orthog- onal strike- to oblique-slip faults (Gibbs, 1984, 1989, 1990). Differently, studies on the relationships between low-angle normal faults and contemporaneous high-angle strike- to oblique-slip faults are scarce, since only those areas where uplift is accompanied by exhu- mation can offer the possibility to investigate their relations. A further complication derives from the fact that the vertical structures are good candidates to be reactivated (e.g.: Sibson, 1990; Collettini et al., 2005; Nortiel et al., 2011; Alçiçek et al., 2013; Ghalayini et al., 2014) during the latest stage of deformation, thus resulting the youngest structures. This implies that the vertical structures mainly show the effects of the youngest deformation, often hiding the evidences of their original con- temporaneity with the low-angle normal fault activity. In such a context, syn-kinematic hydrothermal mineralization in fault zones can contribute to define the chronological relationships among faults with different spatial and kinematic features, since the hy- drothermal mineralization is a transient geological event, at local scale (Pirajno, 2009). For this reason, the Eastern Elba Island is an ideal region to address this topic (Fig. 1). In fact it represents an exhumed sector of the inner Northern Apennines where coexisting of low-angle normal faults Tectonophysics xxx (2015) xxx–xxx ⁎ Corresponding author. Tel.: +39 0805442573. E-mail address: domenico.liotta@uniba.it (D. Liotta). TECTO-126670; No of Pages 18 http://dx.doi.org/10.1016/j.tecto.2015.06.025 0040-1951/© 2015 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Tectonophysics journal homepage: www.elsevier.com/locate/tecto Please cite this article as: Liotta, D., et al., Coexistence of low-angle normal and high-angle strike- to oblique-slip faults during Late Miocene mineralization in eastern Elba I..., Tectonophysics (2015), http://dx.doi.org/10.1016/j.tecto.2015.06.025