GNGTS 2016 - Atti del 35° Convegno Nazionale

142 GNGTS 2016 S essione 1.1 Petrosino et al. , 2014, 2016) and this multi-method approach has enormously improved the tephrochronology potential, making it a really robust and reliable geochronological tool. Case studies. The tephrochronological method has been already successfully applied in different sectors of the Apennines, supporting and constraining the geological investigation aimed at defining the fault activity and the Quaternary tectonic evolution of the basins. For instance, the Sulmona Basin (Abruzzo), bounded to east by the Mt. Morrone Fault system, hosts one of the most rich tephra succession with tens of layers dated directly and indirectly between 800 and 14 ka (e.g. Regattieri et al. , 2016; Giaccio et al. , 2015). Here the Mt. Morrone Fault crosses and displaces the apical portion of an alluvial fan system containing at its top a peculiar blackish reworked tephra layer, the chemically composition of which matches that of the products of the most recent eruption of the Colli Albani dated to ~36 ka (Galli et al. , 2015). This widely dispersal tephra (Giaccio et al. , 2013) allowed thus date the top of the alluvial fan and to evaluate the slip rate of the fault system over the last 36 ka which is of ~0.5 mm/yr. Moreover, the recognition of the C-22 tephra (a Tyrrhenian marker that dated at ~92 ka; Giaccio et al. , 2012a) in the underlying lacustrine sediments, both in the footwall and in the hanging-wall of the fault, allowed to extend the evaluation of the slip rate back to 92 ka, which resulted again on the order of ~0.5 mm/yr (Galli et al. , 2015). In the area of the 2009 L’Aquila earthquake (Abruzzo), the identification of several Middle Pleistocene tephra in the sedimentary infill of the Paganica-San Demetrio-Castenuovo Basin provided reliable chronological constrain to evaluate the long-term slip rate of the seismogenic fault and the overall Quaternary tectonic-sedimentary evolution of the basin (Galli et al. , 2011; Giaccio et al. , 2012b). Finally, in the Bojano Basin (Molise), the recognition of several tephra layers spanning the wide temporal interval of ~580-14 ka, most of which directly dated by 40 Ar/ 39 Ar method, allowed the characterization of the tectonic basin sedimentary-tectonic evolution since the early Middle Pleistocene. The tephrochronological constraints evidenced an uneven rate and distribution of tectonic strain for the fault segments composing the ~28 km-long N-Matese fault system over time. Briefly, following a strong tectonic activity occurred after ~580 ka along the presently buried fault segments bounding the Bojano plain, at least since 310 ka slip rates progressively decreased, dying out during the Late Glacial-Holocene. Conversely, the piedmont fault system, paralleling the northern Matese flanks, after an activity slowdown during the 480-110 ka time span, speed up with a consistent slip rate >0.5 mm/yr and up to >1 mm/yr, at least for the last 110 kyr (Peronace et al. , 2015; Galli et al. , submitted). From the above, and In the light of the systematic occurrence of pyroclastics in theApennine Chain, this method has a great, currently still barely exploited, potential as key tool  for improve our knowledge of the active tectonic of this region, and its enhanced application is warmly recommended.  References Bourne, A., Lowe, J.J., Trincardi, F., Asioli, A., Blockley, S.P.E., Wulf, S., Matthews, I.P., Piva, A., Vigliotti, L. 2010. Distal tephra record for the last ca. 105,000 years from core PRAD 1-2 in the central Adriatic Sea: implications for marine tephrostratigraphy. Quaternary Science Reviews 29, 3079–3094. Bourne, A.J., Albert, P.G., Matthews, I.P., Trincardi, F., Wulf, S., Asioli, A., Blockley, S.P., Keller, J., Lowe J.J. 2015. Tephrochronology of core PRAD 1–2 in the Adriatic Sea: insights into Italian explosive volcanism for the period 200–80 ka. Quaternary Science Reviews 16, 28–43. Galadini F. & Galli P., 2000. Active tectonics in the central Apennines (Italy) – Input data for seismic hazard assessment, Natural Hazards, 22, 202-223. Galli P., Galadini F., Pantosti D., 2008. Twenty years of paleoseismology in Italy, Earth Sciences Reviews, 88, 89-117, doi:10.1016/j.earscirev.2008.01.001. Galli P., Giaccio B., Peronace E., Messina P., 2015. Holocene Paleoearthquakes and Early-Late Pleistocene Slip-Rate on the Sulmona Fault (Central Apeninnes, Italy), BSSA, 105(1), 1-13. Galli P., Giaccio B., Messina P. and Peronace E.; 2011: Paleoseismology of the L’Aquila faults (central Italy, 2009 Mw 6.3 earthquake). Clues on active fault linkage. Geophysical Journal International, 187, 1119-1134, doi: 10.1111/ j.1365-246X.2011.05233.x.