Integrated gravity and seismic interpretation of duplex structures and imbricate thrust systems in the southeastern Pyrenees (NE Spain)

New insights into deformation mechanisms in the gravitationally driven Niger Delta deep-water fold and thrust belt

“…These models indicate that the mechanically incompetent layer does not undergo layer-parallel folding by flexural slip (as do the competent overburden units) but instead deforms internally either ductilely or brittlely through folding, faulting, penetrative vertical thickening, or combinations thereof ( Figure 12). The internal architecture of weak incompetent units that have been imaged within detachment folds have revealed that the incompetent unit commonly accommodates strain by forming compressional structures in a style analogous to the deformation style exhibited in overlying, competent units (Noack, 1995;Martínez et al, 1997;Couzens-Schultz et al, 2003;Plesch et al, 2007).…”

Fluid flow record from fracture-fill calcite in the Eocene limestones from the South-Pyrenean Basin (NE Spain) and its relationship to oil shows

“…The south-eastern sector of the Pyrenees consists of a stack of south-vergent units that include both sedimentary cover and basement (Martínez et al, 1997). Two distinct thrust systems can be distinguished; the upper thrust is comprised of mainly Mesozoic sediments with the detachment fault in the Keuper format group, and the lower thrust comprises the major Eocene units.…”

“…The study area is located in the Cadí thrust sheet (Fig. 1); this thrust sheet consists of a very thick Lower-Middle Eocene series and Paleocene sediments that are discordant on the basement (Martínez et al, 1997). The Lower-Middle Eocene sediments can be divided into several transgressive/regressive cycles (Vergés et al, 1998).…”

“…1). The lower part of the Armàncies Formation (up to 220m) is characterised by an important anoxic event (Permanyer et al, 1988;Permanyer, 2004) and the upper part by a carbonate platform facies (Martínez et al, 1997;Vergés et al, 1998). The upper part of the Armàncies Formation crops out in the Terrades area; there are many oil shows there that are related to fractures and vug porosity.…”

“…Though the presence of many oil shows and the existence of a good source rock (e.g., the Armàncies Formation) have attracted interest from oil companies in exploring the southeastern Pyrenees (Martínez et al, 1997;Permanyer, 2004), they have yet to discover any actual reservoirs. The Alpine Pyrenees consist of a narrow, asymmetrical, double-wedge mountain range that includes a relatively wide southern proforeland basin and a northern retroforeland basin; the combination of complex tectonic structure and basin evolution makes it difficult to apply successful exploration strategies.…”