Petroleum Geoscience, Vol. 18, 2012, pp. 17–31 DOI: 10.1144/1354-079311-017. 1354-0793/12/$15.00 © 2012 EAGE/Geological Society of London INTRODUCTION In sedimentary basins, deformation and fracturing processes influence the distribution of diagenetic episodes because they are discontinuities that can act as barriers or as conduits for fluid cir- culations and cause the mobilization of these fluids from reacti- vation in different episodes of tectonic activity (Sibson 1987; Agosta et al. 2007; Breesch et al. 2009). Knowing the distribu- tion of fractures, it is possible to predict the potential hydrocar- bon and aquifer reservoirs, as well as to assess their quality (Knipe & McCaig 1994; Labaume et al. 2004; Géraud et al. 2006; Bussolotto et al. 2007). The study of fracture-related car- bonate precipitates, coupling microstructural, petrological and geochemical analyses, allows one to unravel the origin and path- ways of the fluids (De Brit 1989; Muchez et al. 1995; Bitzer et al. 1997; Travé et al. 1998; 2004; 2009; Travé & Calvet 2001; Labaume et al. 2007; Micarelli et al. 2005; 2006; Benedicto et al. 2008; Vilasi et al. 2009; André et al. 2010). In addition, specific petrophysical properties of the fractured host-rock and the pressure, temperature, origin and behaviour of fluids will control the degree of fluid–rock interaction and precipitation of cements within the fractures. However, these processes depend not only on the lithology; the depth at which the deformation develops is also one of the main factors controlling the diagenetic behaviour of the fractured areas. For example, it is known that the development of fractures in carbonates at shallow crustal depths (<1–3 km) is a very complex process, because of the interaction of mechanical and chemical processes (Sibson 2000; Pili et al. 2002; Verhaert et al. 2009). The present study has been focused on characterizing the evolu- tion of fluids within a long basement-involved fault which shows a complex tectonic evolution due to the superposition of successive extensional and compressional events. The case study is the Vallès- Penedès Fault, located in the central part of the Catalan Coastal Ranges, in the northeastern part of Spain. The main aims followed are: (1) to characterize the distribution and chronology of fractures, the timing of diagenetic processes, the type of fault rocks and related cements and the fluids involved during different deformation events; (2) to characterize the differences between the Mesozoic and Neogene extensional events; and (3) to recognize the interference between karstic and tectonic processes. The interest in the study of the karst development and infilling is because the main hydrocarbon reservoirs in Spain are located offshore in the Mediterranean, in Mesozoic reservoirs, equivalent to those studied onshore. For this reason, the diagenetic study can be compared in both areas, and the studied outcrops can be used as analogues of the reservoirs present in the Valencia Trough. Geofluid behaviour in successive extensional and compressional events: a case study from the southwestern end of the Vallès-Penedès Fault (Catalan Coastal Ranges, NE Spain) V. Baqués * , A. Travé, E. Roca, M. Marín and I. Cantarero Geomodels Research Institute, Faculty of Geology, University of Barcelona, c/Martí i Franquès s/n, 08028 Barcelona, Spain *Corresponding author (e-mail: vbaques@ub.edu) ABSTRACT: The structural position of the Upper Jurassic–Lower Creta- ceous carbonates located in the central part of the Catalan Coastal Ranges corresponds to the southwestern end of the Vallès-Penedès Fault. This fault was reactivated at different times during successive extensional and compressional events and several generations of fractures and cementations were formed. Based on petrological and geochemical analyses of this cementation an evolution of the fluids related to the different tectonic stages can be deduced. (1) During the Mesozoic extension, the parent fluids resulted either from a mixing of trapped Upper Jurassic–Lower Cretaceous seawater and meteoric water, or from buffered meteoric waters. (2) Related to the Paleogene com- pression, the fluids came from the percolation of meteoric waters indicating shallow-depth deformation. (3) During the transitional phase between Pale- ogene compression and Neogene extension, a karstic dissolution took place and the porosities were infilled by different generations of sediments and cements deposited from meteoric fluids. (4) During the Neogene extension several episodes of meteoric percolations and fracturing processes occurred. The Neogene extensional faults used the earlier karstic system to develop and, later, during the late post-rift stage, a new karstic system occurred, cov- ering the walls of open fractures with speleothems. research-articleArticle 18 1 10.1144/1354-079311-017V. BaquésFluid behaviour in successive tectonic events 2012