GNGTS 2013 - Atti del 32° Convegno Nazionale

Satriano C., A. Zollo and C. Rowe (2008). Iterative tomographic analysis based on automatic ref ined picking. Geophysical Prospecting, 56, 467–475, doi:10.1111/j.1365-2478.2008.00700.x. Tarantola, A. and B. Valette (1987). Generalized nonlinear inverse problems solved using the least-squares criterion. Rev. Geophys 20 , 219–232. Vidale John E. (1990). Finite-difference calculation of traveltimes in three dimensions. Geophysics, Vol. 55, No. 5 pp 521-526. Waldhauser, F. andW. L. Ellsworth (2000, Dec). A double-difference eartquake location algorithm: Method and application to the northern hayward fault, california. Bulletin of the Seismological Society of America , 1–16. Travertines as fault activity indicators: new data from the Southern Apennines A. Ascione 1 , A. Iannace 1 , P. Imbriale 1 , N. Santangelo 1 , A. Santo 2 1 Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse - DiSTAR, Università Federico II, Napoli, Italy I,2 Dipartimento di Ingegneria Idraulica, Geotecnica e Ambientale, Università Federico II, Napoli, Italy Introduction. It has been known since a long time that there is a worldwide association between travertines and tectonically active areas (Barnes et al ., 1978). Furthermore, according to Hanckock et al . (1999), late Quaternary travertines can reveal much about areas that are experiencing active faulting. The linkage between travertines and active faults may be envisaged in the key role played by active faults in the transport, and rise, of hydrothermal fluids (Sibson, 1996). Several travertine deposits occur in proximity of either step-over zones (relay ramps) or lateral tips of fault zones, i.e. in settings in which complex strains can lead to the development of networks of intersecting tensional fissures that enhance the sub-surface flow of hydrothermal fluids (Hanckock et al ., 1999). Italy is the homeland of travertines. The western slope of the northern and central Apennines enclose several huge outcrops quarried since Roman time, which are the type localities of the rock. Such travertines punctuate the area affected by Quaternary volcanism and by the occurrence of hydrothermal springs (Chiodini et al ., 2000; Minissale, 2004), and the role of deep-seated CO2 in their genesis is widely acknowledged (e.g., Brogi et al ., 2012). By contrast, calcareous deposits in the southern Apennines, which may be texturally classified as tufa, have long been associated with cool meteoric waters (D’Argenio and Ferreri, 1988; Ford and Pedley, 1996; Golubic et al ., 1993) discharging from the main aquifers of the region. Conversely, recent studies (Santo et al ., 2011; Ascione et al ., 2013a), based on comprehensive data sets including i) the regional scale distribution of the major (i.e. mappable on medium scale maps) tufa bodies, and of Quaternary extensional faults, ii) spring chemistry, and iii) petrographic and stable isotope (d 13 C and d 18 O) analyses of tufa/travertine deposits, provided evidence that geologically significant continental carbonates of southern Italy are related to CO2-rich water rising along active extensional faults (Ascione et al ., 2013a). As such large mappable travertine bodies may be considered as indicators of active tectonics, and hence they can be used to detect fault traces. In this study, we examine the role of travertines as tools in the reconstruction of the tectonic history of a region. This is based on comparative analysis of Quaternary time-space distribution of both large travertine bodies and extensional fault activity. Geological setting. The study region is the southern Apennines fold-and-thrust belt, which was formed from Miocene to Middle Pleistocene. Thrusting, with a general NE sense of transport, involved both ocean-derived units and deformed sedimentary successions of continental margin origin. These consist of carbonate platform/slope and pelagic basin successions, stratigraphically covered by Neogene foredeep and wedge-top basin sediments. Extensional tectonics affected the internal portion of the chain since the late Miocene, with the formation of the Tyrrhenian back-arc basin (Sartori, 1990, 2003). Since Early Pleistocene times, extension in the southern Tyrrhenian basin affected the southern Apennines with the formation of large peri-Tyrrhenian grabens, bounded by both NW-SE and NE-SW trending extensional faults (e.g., Milia and Torrente, 1999; Caiazzo et al ., 2006). Starting from the 11 GNGTS 2013 S essione 1.1