Oliana anticline & Thrust sequences
The Oliana anticline is a 15-km-long, doubly plunging structure located in the footwall of the Segre thrust oblique ramp. Formed by stacking two slices of Paleogene strata, the anticline is an allochthonous structure that was transported 10 km to the south across a decollement situated within the Upper Eocene Cardona salt.
To the NW of the Oliana anticline and coeval with its growth, synorogenic conglomerates that overlap and are cut by thrusts demonstrate that the Mesozoic rocks of the South Central Unit in the hangingwall of the Segre thrust are deformed by break-back thrusts (i.e., a sequence of thrusting that becomes younger toward the hinterland) and related folds.
Link to: Oliana anticline location
Link to: Geozona-126 Anticlinal d'Oliana (Direcció General del Medi Natural, Generalitat de Catalunya).
The Cardona detachment uses the Late Eocene Cardona salt level to fold the Cardona, Súria and Oló-Callús detachment anticlines above it. The shortening was transferred from north across the Puig-reig ramp above which the Puig-reig-Oliana anticlines developed.
Structural cross-section between the backlimb of the Oliana anticline and the Montsec thrust sheet. Major structures within the Serres Marginals hangingwall developed following a hinterlandward sequence of thrusting synchronous to the displacement of the Oliana anticline towards the south (towards the foreland).
This is an excellent example of reconstruction of topography and related depositional systems during active thrusting.
Aerial view of the Oliana anticline from its NE termination (north to the right). Fields in the core of the anticline are middle Eocene marls. Cliff of the northern flank of the anticline is conglomeratic unit 1.
View of the front of the imbricate thrust system interrelated with 4 syntectonic growth units that permit to define the out-of-sequence thrusting in the back of the Oliana anticline. This hinterland sequence of imbricates developed to increase the taper of the South Central Unit during the coeval growth of the huge Olicana anticline.
NIce scenary shoeing the lowermost conglomeratic syntectonic units at the Ermita de Castellebre near the contact between the imbricate thrust system to the left and the Oliana NE termination towards the rigth.
Imbricate thrust system above the northern flank of the Oliana anticline (north to the right). The prominent limestones to the north of the photo are Mesozoic corresponding to the Montsec thrust sheet.
View to the NNW roughly parallel to the line of the above cross-section. In the frontal part of the photo the growth syncline related to syntectonic unit 2. In the intermediate part, a huge block of Mesozoic limestones is interbedded with growth strata unit 3. These fluvial strata are overthrusted by the Montsec thrust (the youngest of a hinterland sequence of thrusting).
References
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Puigdefàbregas, C., Muñoz, J.A., Vergés, J., 1992. Thrusting and foreland basin evolution in the southern Pyrenees. McClay, K. Thrust Tectonics. Chapman Hall, London, 247–254.
Vergés, J., 1993. Estudi geològic del vessant sud del Pirineu oriental i central. Evolució cinemàtica en 3D. PhD Thesis Univ. Barcelona 1–199.
Burbank, D.W., Vergés, J., 1994. Reconstruction of topography and related depositional systems during active thrusting. J. Geophys. Res. 99, 20281–20297.
Vergés, J., Burbank, D.W., Meigs, A., 1996. Unfolding: An inverse approach to fold kinematics. Geology 24, 175. doi:10.1130/0091-7613(1996)024<0175:UAIATF>2.3.CO;2
Vergés, J., Burbank, D.W., 1996. Eocene-Oligocene thrusting and basin configuration in the eastern and central Pyrenees (Spain). Friend, P.F. Dabrio, C.J. (Eds), Cambridge Univ. Press. World Reg. Geol. 6 Chapter E-11, 120-133.
Meigs, A.J., Vergés, J., Burbank, D.W., 1996. Ten-million-year history of a thrust sheet. Geol. Soc. Am. Bull. 108, 1608–1625. doi:10.1130/0016-7606(1996)108<1608:TMYHOA>2.3.CO;2
Vergés, J., Marzo, M., Muñoz, J.A., 2002. Growth strata in foreland settings. Sediment. Geol. 146, 1–9. doi:10.1016/S0037-0738(01)00162-2
Vergés, J., 2003. Evolución de los sistemas de rampas oblicuas de los Pirineos meridionales: fallas del Segre y Pamplona. Boletín Geológico y Min. España 114, 87–101.
Garcia-Castellanos, D., Vergés, J., Gaspar-Escribano, J., Cloetingh, S., 2003. Interplay between tectonics, climate, and fluvial transport during the Cenozoic evolution of the Ebro Basin (NE Iberia). J. Geophys. Res. Solid Earth 108, 2347. doi:10.1029/2002JB002073
Sussman, A.J., Butler, R.F., Dinarès-Turell, J., Vergés, J., 2004. Vertical-axis rotation of a foreland fold and implications for orogenic curvature: an example from the Southern Pyrenees, Spain. Earth Planet. Sci. Lett. 218, 435–449. doi:10.1016/S0012-821X(03)00644-7
Vergés, J., 2007. Drainage responses to oblique and lateral thrust ramps: a review. G. Nichols, C. Paola, E. Williams, eds., Sediment. Process. Environ. basins a Tribut. to Peter Friend, v. Int. Assoc. Sedimentol. Spec. Publ. vol. 38. Chapter 3, Blackwell Publ. p. 29-47. 38, 29–47.
Rushlow, C.R., Barnes, J.B., Ehlers, T.A., Vergés, J., 2013. Exhumation of the southern Pyrenean fold-thrust belt (Spain) from orogenic growth to decay. Tectonics 32, n/a-n/a. doi:10.1002/tect.20030