NW-oriented features on both sides of the Atlantic Ocean: evidence for a Paleozoic collision that formed the Labrador-Biscay wrench fault zone?
Lefort and Miller (1999) suggested that the northwest- to west-oriented wrench faults created pre-existing basement weaknesses, which were reactivated during Mesozoic rifting.
The southern boundary fault zone of Karachi Arc runs east west along the southern edge of Karachi - or through Karachi - and heads towards Makli-Thatha area where a small part of it is exposed as a wrench fault cutting through folded and brecciated Laki Limestone of Eocene age (Fig.
Both of these large folds are cut by numerous northwest trending wrench faults (such as the Sona Pass fault) between Monghopir and the southwestern tip of the map (Figs.
Right lateral movement and drag along this tectonic boundary - caused by eastward creep of Karachi Arc (red arrow) - could have modified folds like the southwest plunging Monghopir Anticline and induced all the wrench faults shown to the west of this large fold.
Many of the northwest trending wrench faults, cutting across the two folds, can be interpreted as modified Riedel shears showing enhanced offsets induced by drag along the southern tectonic boundary of the Karachi Arc.
Then they share findings of tests at specific locations, among them the role of wrench faults
and fractures in creating "sweet spots" in tight gas exploration and production in Rulison Field in Colorado, the fracture control of P-wave azimuthal anisotropy in a Laramide basement-cored anticline at Wyoming's Casper Arch, and natural fractures in folded sandstones of the Tensleep Formation in Wyoming.