Palaeomagnetic dating of the Neostromboli succession Gilda Risica a,b,c, ⁎, Fabio Speranza b , Guido Giordano d , Gianfilippo De Astis b , Federico Lucchi e a Università degli Studi di Firenze, Dipartimento di Scienze della Terra, Via La Pira, 4, 50121 Firenze, Italy b Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata, 605, 00143 Roma, Italy c Università di Pisa, Dipartimento di Scienze della Terra, Via S. Maria 53, 56126 Pisa, Italy d Università degli Studi di Roma Tre, Dipartimento di Scienze, Largo San Leonardo Murialdo 1, 00146 Roma, Italy e Università di Bologna, Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Piazza di Porta S. Donato 1, 40126 Bologna, Italy abstract article info Article history: Received 21 October 2018 Received in revised form 22 December 2018 Accepted 22 December 2018 Available online 27 December 2018 The Neostromboli volcanic succession is characterized by packages of lava flow units and scoria beds erupted from the summit of the Stromboli volcano, and by scoria cones and lava flows poured out from lateral vents and fissures. Available radiometric ages constrain Neostromboli activity in the 14–4 ka BP age window, but the chronological relations of central vs. peripheral activity are still poorly understood. Furthermore, radiometric and palaeomagnetic ages for some of the peripheral eruptions are strikingly inconsistent. Here we report on the palaeomagnetic dating of thirty-four sites from Neostromboli products. Seventeen are new palaeomagnetic directions, while additional seventeen ages are recalculated - using published directions by Speranza et al. (2008) - with the recent SHA.DIF.14K palaeo-secular variation (PSV) field model. We show that the beginning of Neostromboli succession could be much younger than the commonly accepted ≈14 ka onset, providing our oldest data an age of ≈9 ka. The improved geochronological resolution allowed by palaeomagnetic dating sug- gests that the early stages of the Neostromboli activity occurred at 9–8 ka BP and were characterized by summit lava flow units blanketing both the SW and northern volcano flanks; after ≈7.5 ka lateral eruptions from periph- eral cones and fissures became dominant. We suggest that the intense flank activity enabled magma-water inter- action thus yielding explosive activity and repeated collapse events, leading to the Sciara del Fuoco formation. Our work confirms that PSV analysis of Holocene volcanics may yield eruption chronology definition with an ac- curacy unlikely to be achieved with other radiometric techniques. © 2018 Elsevier B.V. All rights reserved. Keywords: Palaeomagnetism Stromboli Palaeo secular variation of geomagnetic field Dating Neostromboli San Vincenzo scoria cone 1. Introduction The well-known activity of Stromboli volcano is characterized at present by the typical “Strombolian” small intermittent explosions af- fecting the summit area, punctuated every few tens of years by higher energy explosions (“paroxysms”), and by the emission of lava flow units within the Sciara del Fuoco scar (e.g. Barberi et al., 1993; Rosi et al., 2013). However, volcanic activity in the geological past also in- cluded peripheral and fissure Strombolian to effusive eruptions, and phreatomagmatic explosions associated with volcanic edifice destruc- tion and flank collapse (e.g. Rosi, 1980a, b; Gillot and Keller, 1993; Hornig-Kjarsgaard et al., 1993; Keller et al., 1993; Francalanci et al., 2013; Lucchi et al., 2013a; Vezzoli et al., 2014). The Neostromboli suc- cession is the product of the activity that preceded the actual one, and is characterized by both lavas and scoriae issued by the summit craters, and by lower altitude flank eruptions, yielding scoria cones and lava flow units often lacking or having unclear stratigraphic relations with other Neostromboli products (Fig. 1). Moreover, the final phases are marked by one or more phreatomagmatic eruptions (see Sections 2 and 5.3), represented in the field by several scattered pyroclastic surge and flow deposits, one of which is the Secche di Lazzaro Formation (hereafter Fm.), first described in the 1980s (Rosi, 1980a, b). Such explo- sive event(s) have been also related to different major flank collapses during the Holocene along the multi-stage Sciara del Fuoco collapse structure (Francalanci et al., 2013; Lucchi et al., 2018). The relative timing of summit vs. peripheral volcanic activity most likely arises from the interplay of regional tectonics, local instability processes, and magma feeding dynamics (e.g. Vezzoli et al., 2014). Thus, the absolute age framing of Neostromboli activity is indeed relevant to understand both past Stromboli evolution and to better constrain volcanic hazard. Absolute dates so far available tie the Neostromboli activity to a 14–4 ka BP (hereinafter ka) time window. Most of these ages were re- cently achieved by palaeomagnetic (Speranza et al., 2008), cosmogenic He (Foeken et al., 2009), 40 Ar/ 39 Ar (Calvari et al., 2011; Wijbrans et al., 2011), and 14 C(Francalanci et al., 2013) dating, that complemented two pioneer K/Ar dates gathered some 25 years ago by Gillot and Journal of Volcanology and Geothermal Research 371 (2019) 229–244 ⁎ Corresponding author at: Università degli Studi di Firenze, Dipartimento di Scienze della Terra, Via La Pira, 4, 50121 Firenze, Italy. E-mail addresses: gilda.risica@unifi.it (G. Risica), fabio.speranza@ingv.it (F. Speranza), guido.giordano@uniroma3.it (G. Giordano), gianfilippo.deastis@ingv.it (G. De Astis), federico.lucchi@unibo.it (F. Lucchi). https://doi.org/10.1016/j.jvolgeores.2018.12.009 0377-0273/© 2018 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Journal of Volcanology and Geothermal Research journal homepage: www.elsevier.com/locate/jvolgeores