Tectonic versus diagenetic origin of fractures in a naturally fractured carbonate reservoir analog (Nerthe anticline, southeastern France) Arthur P. C. Lavenu, Juliette Lamarche, Arnaud Gallois, and Bertrand D. M. Gauthier ABSTRACT Field analogs allow a better characterization of fracture net- works to constrain naturally fractured reservoir models. In analogs, the origin, nature, geometry, and other attributes of fracture networks can be determined and can be related to the reservoir through the geodynamic history. In this article, we aim to determine the sedimentary and diagenetic controls on fracture patterns and the genetic correlation of fracture and diagenesis with tectonic and burial history. We targeted two outcrops of Barremian carbonates located on both limbs of the Nerthe anticline (southeastern France). We analyzed frac- ture patterns and rock facies as well as the tectonic, diagenetic, and burial history of both sites. Fracture patterns are deter- mined from geometric, kinematic, and diagenetic criteria based on field and lab measurements. Fracture sequences are de- fined based on crosscutting and abutting relationships and compared with geodynamic history and subsidence curves. This analysis shows that fractures are organized in two close- to-perpendicular joint sets (i.e., mode I). Fracture average spacing is 50 cm (20 in.). Fracture size neither depends on fracture orientation nor is controlled by bed thickness. Nei- ther mechanical stratigraphy nor fracture stratigraphy is ob- served at outcrop scale. Comparing fracture sequences and subsidence curves shows that fractures existed prior to folding and formed during early burial. Consequently, the Nerthe fold induced by the Pyrenean compression did not result in any new AUTHORS Arthur P. C. Lavenu  Aix-Marseille Uni- versity, Centre Européen de Recherche et d’En- seignement des Géosciences de l’Environne- ment (CEREGE) UM 34, 3, place Victor Hugo (case 67), 13331 Marseille Cedex 3, France; arthur.lavenu@total.com Arthur Lavenu is working for Total as a Ph.D. candidate, at Aix-Marseille University (Centre Européen de Recherche et d’Enseignement des Géosciences de l’Environnement [CEREGE]), France. He is currently completing his thesis, which focuses on relating fractures to rock properties and geodynamics in carbonates. He earned an M.Sc. degree (2009) in geologic reservoirs from the University of Montpellier 2, France. Juliette Lamarche  Aix-Marseille Univer- sity, CEREGE UM 34, 3, place Victor Hugo (case 67), 13331 Marseille Cedex 3, France; lamarche@cerege.fr Juliette Lamarche has been an assistant professor in structural geology at the Aix-Marseille Uni- versity (CEREGE), France, since 2003. She re- ceived her Ph.D. in structural geology from Paris VI University in 1999. Then, she did a post- doctoral research on three-dimensional (3-D) basin modelling at the GeoForschungsZentrum Potsdam (Germany). Her present-day research focuses on fractured reservoir analogs in car- bonates and 3-D structural basin modelling. Arnaud Gallois  Royal Holloway Univer- sity of London, Queens Building, Department of Earth Sciences, Egham Hill, Egham, Surrey TW20 0EX, United Kingdom; arnaud.gallois.2012@live.rhul.ac.uk Arnaud Gallois has been studying for a Ph.D. at Royal Holloway University of London since September 2012. Through outcrop study, facies modeling, and pore system analysis, he is studying nonmarine carbonates cropping out in Dorset (southeast England, United Kingdom) where microbialite mounds are developed. He obtained his M.Sc. degree (2010) in carbonate sedimentology and diagenesis in Aix-Marseille University, France. Copyright ©2013. The American Association of Petroleum Geologists. All rights reserved. Manuscript received December 13, 2012; provisional acceptance February 21, 2013; revised manuscript received March 14, 2013; final acceptance April 4, 2013. DOI:10.1306/04041312225 AAPG Bulletin, v. 97, no. 12 (December 2013), pp. 2207 – 2232 2207