However, it cannot be excluded that some of these tensors may be linked to the 135° LPS1 stage through a permutation of σ1 and σ2 axes. 2003; Robion et al. [67] In SMA, all the stress‐strain indicators reveal a polyphase tectonic evolution. Determining paleo-structural environments through natural fracture and calcite twin analyses: a case study in the Otway Basin, Australia. First, Laramide LPS2‐related set II veins clearly abut on the set I veins, as already reported by Bellahsen et al. Set IV corresponds to vertical joints oblique to the fold axis and striking 110° that may have developed in the backlimb in response to stress relaxation during fold exhumation. The CSIT applies to small twinning strain that can be approximated by coaxial conditions, so orientation of twinning strain can be correlated with paleostress orientation. Alternatively, tectonic force may be applied as a basal traction (as in the Laramide orogeny), in which case basal shear drives shortening and total shear force/deformational intensity grow with distance toward the foreland. This is confirmed by the postfolding compressional reactivation of set I veins (Figure 5i) and the offset of subvertical bedding by late strike‐slip faults (Figure 5f) in the forelimb. Contrary to all the other fabrics recorded in the fold, the carbonate rocks in the backlimb present a well-defined cluster of K3, which significantly deviates from the pole of bedding. Mapping permeable subsurface fracture networks: A case study on the Cooper Basin, Australia. In such a case, the fault system is interpreted after back tilting to its initial position by rotation along the local strike. 1999; Lüneburg et al. Impact of fracture stratigraphy on the paleo-hydrogeology of the Madison Limestone in two basement-involved folds in the Bighorn basin, (Wyoming, USA). Other stress indicators, such as veins and stylolites help to constrain extensional and compressional trends, respectively. Such information is of importance for inferring the microstructural characteristics and understanding the weak deformations in sedimentary rocks (Louis et al. Complex fault‐fold interactions during the growth of the Jabal Qusaybah anticline at the western tip of the Salakh Arch, Oman. Daniel J.M. The results demonstrate a very good agreement between the principal axes of the anisotropy of physical properties of rocks (AMS, APWV), Fry strain axes and principal stress–strain axes derived from calcite twinning (Fig. U-Pb dating of calcite veins reveals complex stress evolution and thrust sequence in the Bighorn Basin, Wyoming, USA. Natural fractures at depth in the Lower Cretaceous Kuqa Depression tight sandstones: identification and characteristics. The Laramide orogeny is modeled by applying a horizontal contraction in the NE direction of magnitude 0.1 (perpendicular to the fault strike) and an extension of magnitude 0.01 in the NW direction. At laboratory conditions (no confining pressure) the anisotropic behaviour of rocks with respect to the propagation of P waves will be mainly controlled by microstructures (at μm scale) leading to a reduction of the inter- or intragranular cohesion. However, whereas the correlation between the orientations of principal AMS axes and principal strain axes tends to be very consistent, the correlation between the magnitudes of principal AMS axes and corresponding principal strain axes is not (e.g. Varga [1993] concluded that the dominant Laramide trend was NE and that regionally local deviations may arise from strain partitioning with zones of dominantly compressional deformation and zones of dominantly strike–slip faulting along E–W trending structures oblique to the overall Laramide compression. These classical trends are generally explained by the fact that velocities range between the velocities of the mineral grains (intrinsically higher in calcite than in quartz) and those of the mineral–pore fluid filled (air or water) assemblage (Mavko et al. This increase is well identified on cooling curves where the susceptibility is systematically much higher than those of the heating curves (Fig. The locus of deformation was then transmitted laterally across both a hinterland that had attained maximum crustal thickness and the rigid Colorado Plateau, into the Laramide Rocky Mountain foreland. Rocky Mountain foreland uplifts: Products of rotating stress field or strain partitioning? At each site, 7–13 plugs were cored using a gasoline powered portable core-drill. These results question the origin and nature of the rock fabrics and should be compared to other independent microscopic and mesoscopic stress–strain indicators (see Bellahsen et al. Despite some slight changes in stress orientations marked for instance by shear reactivation of earlier formed set II joints [e.g., Fiore, 2006] and stress permutations, these local effects have poorly influenced stress orientations during LPS and late stage fold tightening; in contrast, they greatly influence differential stress magnitudes. But this plane is oblique to the bedding plane and K3 is tilted toward the south. The E-W trending Schoettlin Mountain fold, to the south of the CCF, indicates that N-S shortening is not constrained to the interchange zone, but occurs both in the N and S terminations of SMA. Determination of the tectonic evolution from fractures, faults, and calcite twins on the southwestern margin of the Indochina Block. This result is in good agreement with measurements of APWV, which indicate that the anisotropy is dominated by an anisotropic pore network embedded into an almost isotropic matrix. Transverse jointing in foreland fold-and-thrust belts: a remote sensing analysis in the eastern Pyrenees. Inversion of calcite twin data for paleostress orientations and magnitudes: A new technique tested and calibrated on numerically-generated and natural data. Swenen R. Frizon de Lamotte et al the other fractures finite element models which direction was laramide deformation when sheep mountain formed? contractional fault-related folding paleostress. 35 Ma on dry and saturated samples representing carbonate and sandstone lithologies ( Table 1 ) the plane of.. Migration of Laramide age the Delaney Butte–Sheep Mountain–Boettcher Ridge structure formations give quite different of. ] but additionally allows refining some of their orientation ( Figure 9 ) Implications: Insight from fault-propagation in... And Sage Hen anticline of related fracture sets in the forelimb of SMA forelimb the... 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