Transverse jointing in foreland fold-and-thrust belts: a remote sensing analysis in the eastern Pyrenees

Abstract

Abstract. Joint systems in the eastern portion of the Ebro Basin of the eastern Pyrenees enjoy near continuous exposure from the frontal portion of the belt up to the external portion of its associated foredeep. Utilizing orthophoto mosaics of these world-class exposures, we have manually digitized over 30 000 joints within a 16 km×50 km study area. The mapped traces exhibit orientations that are dominantly perpendicular to the trend of the belt (transverse) and, subordinately, parallel to the belt (longitudinal). In particular, joints systematically orient perpendicular to the trend of the belt both in the frontal folds and in the inner and central portion of the foredeep basin. Longitudinal joints occur rarely with a disordered spatial distribution, exhibiting null difference in abundance between the belt and the foredeep. Joint orientations in the external portion of the foredeep become less clustered, with adjacent areas dominated by either transverse or oblique joints. Our data indicate that joints in the studied area formed in the foredeep in response to a foredeep-parallel stretching, which becomes progressively less intense within the external portion of the foredeep. There, the minimum stress direction becomes more variable, providing evidence of the poor contribution of the forebulge-perpendicular stretching on stress organization.

Polyphased brittle deformation around a crustal fault: A multi-scale approach based on remote sensing and field data on the mountains surrounding the Têt hydrothermal system (Eastern Pyrénées, France)

“…Low amount of N-S major and secondary normal faults suggests that N-S faulting is not the main process controlling the formation of N-S fractures (Figure 3e). N-S fractures have been described north of Conflent by Arthaud and Pistre [1993] and are commonly attributed to the N-S Pyrenean compression Mattauer, 1969, 1972;Ballas et al, 2012;Tavani et al, 2020]. Where N-S fractures clusters are observed (e.g.…”

Pre-folding fracturing in a foredeep environment: insights from the Carseolani Mountains (central Apennines, Italy)

“…A second possible explanation for crossjoints is that they accommodated along-foredeep stretching due to cross-sectional (e.g. Tavani et al 2020) and/or planar (e.g. Doglioni, 1995) arching of the foredeep.…”

“…The presence of joints and veins in the 'undeformed' foreland of fold-and-thrust belts (e.g. Dunne & North, 1990;Railsback & Andrews, 1995;Zhao & Jacobi, 1997;Billi & Salvini, 2003;Whitaker & Engelder, 2006;Martinelli et al 2019;Tavani et al 2020) suggests, however, that several joints and veins observed on anticlines of accretionary wedges might have developed before folding, i.e. during foreland deformation.…”

Fault Gouge Dating in the Spanish Pyrenees: Fault Ages, Thrust Propagation Sequence, Wall‐Rock Provenance, and Thermal Constraints

“…The narrow southeastern fold-thrust belt is propagated through primarily syn-orogenic Upper Cretaceous to earliest Oligocene strata of the flexural foreland Ebro basin (Muñoz et al, 1988;Tavani et al, 2020;Vergés et al, 1995;Verges et al, 1998) (Figure 4). The oldest synorogenic sediments found in the eastern portion of the Ebro basin, found only at the northern margin of the basin, are Maastrichtian-Paleocene Garumnian-facies continental siltstones and shallow marine carbonates.…”