2007). 5). Grelaud S.
(2010). Oblique magnetic foliation with respect to bedding has been documented in flysch-type sedimentary deposits by Hrouda & Jezek (1999) and Aubourg et al. 7b). In addition to simply making geologic maps, stratigraphic sections and structural cross-sections, the students have to put the local geology into the broader contexts of the Big Horn Basin and sequences of western orogenies. Constraints on bed scale fracture chronology with a FEM mechanical model of folding: The case of Split Mountain (Utah, USA). Up to five oriented microphotographs (3 × 2.5 mm2) were taken to characterize optically the microscopic texture. In term of trends, the principal axes of the various tensors have close relationships with the fold structure. The outcropping Palaeozoic sedimentary sequence in the Bighorn Basin is approximately 3 km thick (Hennier & Spang 1983; Rioux 1994; Forster et al. These chronological observations lead us to conclude that set I joints and veins likely predate Laramide tectonism.  Our study interestingly supports that microstructures and macrostructures recorded at the same time the combination of far‐field orogenic stresses and of the local sources of stress perturbation such as effect of the underlying basement fault, bedding rotation, bed‐parallel slip and reactivation of early formed fractures. Amrouch K.
 A major point deals with the recognition of a pre‐Laramide horizontal compression in the SMA area, which is a matter of debate (E. A. Erslev, personal communication, 2009). Mechanical twin sets in calcite as markers of recent collisional events in a fold‐and‐thrust belt: Evidence from the reefal limestones of southwestern Taiwan, Cenozoic folding and faulting in the south Aquitaine Basin (France): Insights from combined structural and paleostress analyses, Cenozoic inversion structures in the foreland of the Pyrenees and Alps, Peri‐tethys Memoir 2, Structure and Prospects of Alpine Basins and Forelands, Shallow structures induced by deep‐seated thrusting, Paleostress estimation using calcite twinning ‐ experimental calibration and application to nature, Magnetic Fabric and petrographic investigations of hematite‐bearing sandstones within ramp‐related folds: Examples from the South Atlas Front (Morocco), Crustal mechanics of Cordilleran foreland deformation, regional and scale‐model approach, Layer parallel shortening in salt‐detached folds: Constraint on cross‐section restoration, Mechanical aspects of thrust faulting driven by far‐field compression and their implications to fold geometry, Mechanical models of fracture reactivation and slip on bedding surfaces during folding of the asymmetric anticline at Sheep Mountain, Wyoming, Mechanical reconstruction of fracture development in Weber sandstone formation, Split Mountain (Utah), American Association of Petroleum Geologist Meeting, The effect of non‐parallel thrust fault interaction on fold patterns, The state of stress in the limb of the Split Mountain anticline, Utah: Constraints placed by transected joints, An integrated sequence stratigraphic approach to reservoir characterization of the lower Mississippian Madison Limestone, emphasizing Elk Basin field, Bighorn basin, Wyoming and Montana, Sheep Mountain Anticline: Backlimb tightening and sequential deformation in the Bighorn Basin, Wyoming, 53rd Wyoming Geological Association Guidebook, Certain aspects of fractures in naturally deformed rocks, Wrench faulting and Rocky Mountain tectonics, Basement‐involved thrust generated folds as seismically imaged in sub‐surface of the central Rocky Mountain foreland, Rio thrusting, multi‐stage migration and formation of vertically segregated Paleozoic oil pools at Torchlight Field on the Greybull Platform (eastern Bighorn basin): Implications for exploration, 3‐D deformation pattern analysis and evolution of the Anisclo anticline, southern Pyrenees, Poly3D: A three‐dimensional, polygonal element, displacement discontinuity boundary element computer program with applications to fractures, faults, and cavities in the Earth's crust, Sedimentation and structural development of the Bighorn Basin, Experimental deformation of calcite crystals. Diamonds, samples from Amsden formation; squares, samples from Tensleep formation; triangles, samples from Phosphoria formation; crosses, samples in Mesozoic formations. A similar fabric is observed in the backlimb but with significantly more clustering of K1 close to the direction of fold axis (NW–SE) in the plane of bedding. Processes, Information Any queries (other than missing content) should be directed to the corresponding author for the article. Flexural slip is again observed within the weak Kc and Kmt units. Likewise, APWV fabrics in the backlimb are grain-supported, showing that the matrix is more anisotropic in the backlimb than in the forelimb. The basic hypothesis is that the RSS τs acting on any twinned e plane is higher than, or at least equal to the critical RSS τa. Lampert S.A.
1991; Borradaile 1991; Averbuch et al. Louis et al. (c) Meso: Mesozoic formations. Related to Geologic Time, Mineralogy Some show only microscopic opening displacement and can be classified as joints but most are veins characterized by various thickness of cement. 7); (2) there is a good agreement of the structural directions (i.e. With an impulse magnetizer (IM-10), samples were first magnetized along three perpendicular directions with three decreasing successive magnetic fields (1200, 500 and 100 mT); these were next thermally demagnetized stepwise up to 600 °C in step of 50 °C and measured with a JR-6 spinner magnetometer (AGICO, Brno). K1 is either parallel to the intersection between the bedding and the incipient cleavage or exhibits a girdle around K3. Distinctive stress magnitudes during Sevier thin‐skinned and Laramide thick‐skinned layer‐parallel shortening in the Bighorn Basin (USA) revealed by stylolite and calcite twinning paleopiezometry. Keeping in mind that after the saturation the velocity anisotropy is matrix supported, we can infer from velocity directions that there is a preferred orientation of the grains related to both shortening direction and bedding. Well documented by calcite twinning, this event is instead poorly marked by microfaults. This extension possibly reflects outer rim extension close to or at the fold hinge. 1985; Bird 2002; Bellahsen et al. Frizon de Lamotte D.
For instance, we favor the reactivation of the underlying SW dipping (normal) fault as a high‐angle thrust fault with a short cut accommodated by many splays in order to account for the relatively distributed deformation required for basement folding. Working off-campus? 12). 2005). Leturmy P.
2003). 11a), because of the relationship between the porosity shape and the coating shape. The late stage fold tightening was recorded in both the matrix and the veins irrespective of their orientation (Figure 9).  In SMA, all the stress‐strain indicators reveal a polyphase tectonic evolution. The field data gathered then form the basis for a paper titled: "Geologic History of the Sheep Mountain Region". 3a).  During late stage fold tightening, (σ1 − σv) remains nearly constant through the fold (Figure 12). Following these authors one can consider that a rock made of an anisotropic matrix and an isotropic pore space will be characterized by velocity and anisotropy increase when it is saturated with incompressible material (water). Wet Mountain, and Front Range arches to 10 km along the margin of the northeastern Front Range. Oceanography, Interplanetary 6). 1986). . Tentative Mohr construction describing possible evolution of principal stress magnitudes across the anticline prior to and just after folding. Physics, Solar Dahlstrom (1969), Suppe (1985), Jamison (1987), Chester & Chester (1990), Erslev (1991) and Mitra (2003), for example, have described fold evolution from a kinematic perspective. Thus, both maximum and minimum axes will be presented separately, and distribution will be evaluated individually. Geometry, kinematics and fracture pattern of the Bangestan anticline, Zagros, SW Iran.  Previous works have reported a main NE to ENE compressional trend or transport direction related to the Laramide orogeny in the investigated area (Figure 1) [Hoppin, 1970; Sales, 1968; Reches, 1978; Dickinson and Snyder, 1978; Engebretson et al., 1985; Brown, 1988; Wise and Obi, 1992; Varga, 1993; Bird, 2002]. Geophysics, Marine LPS1 is preserved by calcite twinning in the matrix of the Madison and Phosphoria formations. Each measured sample (standard paleomagnetic specimen of cylindrical size, 2.2 cm height and 2.5 cm diameter) provides a magnetic susceptibility ellipsoid defined by three principal axes K1≥K2≥K3 representing the maximum, intermediate and minimum axes of susceptibility, respectively. The matrix of a sedimentary rock can be anisotropic, for instance, because of preferred mineral orientation, water currents during deposition or pressure solution in response to an anisotropic stress field during loading. Magnetic characterisation of folded aeolian sandstones: Interpretation of magnetic fabrics in diamagnetic rocks. In addition, stylolitization supports widespread pressure solution processes. The chronology inferred this way may also be confirmed by identification of superimposed striations on reactivated fault surfaces where observable. Regarding the directional results and the shape of the ellipsoid, the velocity anisotropy is correlated to the plane of bedding (Fig. 1, Fig. , since reactivation of prefolding fracture sets may play an important role by preventing later development of “classical” fold‐related fractures [Guiton et al., 2003b; Sassi et al., 2003]. The results are compared to previously …  Sheep Mountain Anticline is a basement‐cored, doubly plunging, asymmetric fold (Figures 1 and 3). 11). compaction, intragranular and transgranular fracturing and pressure-solution). magnetic foliation is either parallel or normal to the bedding, and magnetic lineation parallel to the fold axis) and (2) the deformation axes, indicating that they were acquired during an early stage of deformation when the bedding was horizontal. Whereas LPS2 is rather marked by stylolites and reverse microfaults, this event is instead marked by mixed reverse and strike‐slip faults. One can note a difference between these two directions, which can be explained by the fact that the long axes of the Fry ellipse reflect the preferred grain shape whereas AMS K1 axes record the shape of the coatings that fill the remaining porosity between the grains (Fig. 1992; Borradaile & Henry 1997). 1999; Lüneburg et al. Only 2 sites (Figure 7) show evidence for microfaulting to mesofaulting related to this compression trend (Figure 5k).  The Bighorn Basin was filled by 3000 m of sediments during the Paleozoic and Mesozoic [Thomas, 1965; Ladd, 1979, Hennier and Spang, 1983; Rioux, 1994; Forster et al., 1996]. It is worth noting that similar oblique fabrics were also encountered in the forelimb of the Tadighoust anticline from South Atlas Front by Saint-Bezar et al. The CSGT also computes positive and negative expected values (PEV and NEV, respectively) for all twins in a given thin section. 2006). The lack of paramagnetic minerals tends to decrease the limit of influence of ferromagnetic fraction on magnetic susceptibility. Laramide deformation is characterized by very large anticlines and synclines that involve basement rock. In July, we will collect oriented samples in the Wyoming foreland, and will concentrate on individual fold systems (Thermopolis anticline, Derby Dome, and Sheep Mountain areas). Fjaer E.
The chosen case study is the Sheep Mountain anticline (Erslev 1993; Bellahsen et al. Following Anderson , we assume that away from major fault zones, one of the three principal stress axes of a tensor is generally vertical. Synfolding strain was achieved through mode I fracturing (set III) and bedding‐parallel slip mainly in the forelimb. The ultrasonic measurements were conducted using an ultrasonic pulse generator (Panametrics 5058 PR) with an output voltage up to 900 V, P-wave transducers (Accuscan) with a resonance frequency of 0.5 MHz, and a digital oscilloscope (HP54603B) connected to a PC for data acquisition and analysis. While the injectites represent potential fluid pathways for hydrocarbon migration, the deformation bands may act as barriers to fluid flow. 12); in contrast, (σ1–σ3) differential stress values remain low in the backlimb (∼20 MPa), whereas AMS points toward significant internal deformation. Ben Ismaïl W.. Marfil R.
Abstract. can be recognized in road cuts where sedimentary beds have been offset a few meters ... (direction) of the fault surface is … As for fault slip data, one might expect that if a twin set formed during the initial phase of LPS and was subsequently tilted with the strata during folding, then one axis of the stress‐strain tensor should be perpendicular to bedding and the other two would lie within the bedding plane. In the Black Hills (the NE-most Laramide uplift), fault kinematics and shortening directions have not previously been assessed across the range, and relationships between Precambrian structures and Laramide faults have not been described in detail. The special case of the sandstone sample from the hinge, which shows a weak increase of the anisotropy after saturation, indicates that the velocity anisotropy is solely controlled by the matrix anisotropy. 2002; Evans et al. U-Pb dating of calcite veins reveals complex stress evolution and thrust sequence in the Bighorn Basin, Wyoming, USA. In some sites, thin sections were cut in order to check the dominant occurrence of mode I joints and veins, therefore allowing to use these fracture sets as reliable indicators of orientations of paleo‐σ3 trends [Engelder, 1987] to be compared with stress directions derived from inversion of fault slip and calcite twin data. 2010), is also revealed by the petrophysical characteristics of cored samples (AMS: Figs 7a and b; APWV fabrics, Figs 8 and 9). The stress regimes and the regime of deformation for the prefolding and postfolding NE–SW compression are consistent (mainly purely compressional for LPS2 and of strike‐slip type with ɛmax/σ3 nearly horizontal for late stage fold tightening). At the southern termination, the plunge of the fold axis is approximately 10° southeast. Because of a poor exposure of carbonates at the hinge, only the forelimb and the backlimb were investigated in the Phosphoria formation (Fig. David C.
Borja R.I.. Soto R.
In order to identify ferromagnetic minerals and to constrain their relative contribution to the magnetic susceptibility and its anisotropy, different rock magnetic measurements were carried out on representative samples. This result is confirmed by a simple numerical model. This paper demonstrates how the combination of these various approaches can help to characterize the succession of microscopic deformation mechanisms active during folding of sedimentary rocks (i.e. Dinarès-Turell J.. Rathore J.
In contrast, in the backlimb, AMS records true tectonic strain at the matrix scale. 2 shows the formations that crop out at Sheep Mountain anticline. 2). (1896-1977), Chinese Journal of Geophysics (2000-2018), International 9). We took advantage of these exceptional exposure conditions to collect rock samples all over the anticline and in all formations, with the aim at investigating the differential mechanical response of the different lithologies (carbonates, sandstones, and shales) affected by the same deformation history. These authors relate the counterclockwise rotation in principal horizontal stress to changes in the North American plate velocity vector during the opening of the Atlantic. [2006a] were striking 110°E. Impact of fracture stratigraphy on the paleo-hydrogeology of the Madison Limestone in two basement-involved folds in the Bighorn basin, (Wyoming, USA). The orientations of the compression directions vary with uplift trend, from nearly E–W (eastern Laramie Range), to NE (Bighorn Mountains) and to N–S (Owl Creek Mountains and Casper Mountains). (c and d) Prefolding reverse faults in the forelimb of SMA (Madison Formation). 8).  In order to characterize and compare the stress‐strain record prior to, during, and just after folding at the macroscopic and the microscopic scales and to provide insights into stress levels sustained by folded rocks, we investigate the relationship between the stress‐strain distribution in folded strata derived from fractures, striated microfaults, and calcite twins and the development of the Laramide, basement‐cored Sheep Mountain Anticline, Wyoming. However, at Sheep Mountain Anticline, the spatial distribution of the magnetic fabrics deviates from this general model. 7) and low anisotropy of the matrix revealed by APWV (Fig. Calcite Twinning in the Ordovician Martinsburg Formation, Delaware Water Gap, New Jersey, USA: Implications for Cleavage Formation and Tectonic Shortening in the Appalachian Piedmont Province. (σ1 − σh) decreases from more than 40 MPa in the backlimb to nearly 20 MPa in the forelimb. Near the northern termination, the fold axe plunges approximately 20° northwest and the fold is quite tight, while toward the south, the asymmetry increases and the curvature at the hinge decreases. Sheep Mountain Anticline is located on the northwest flank of the Bighorn Basin, west of the Bighorn Mountains (Figure 1). These different results will be discussed in the last section of the paper. The results in the forelimb are in good agreement with the carbonate fabrics described earlier.  The interpretation of the NW striking set I joints and veins as pre‐Laramide seems to disagree with observations made elsewhere in the Rockies (E. A. Erslev, personal communication, 2009). In the frame of the study, they can well account for the formation of set II veins from which twin data were collected and of associated LPS2 stylolites. compression/shortening. In this case, only the anisotropy of pores contributes to the anisotropy of seismic velocities, and adding water hides the effect of porosity. Paleostresses inferred from macrofractures, Colorado Plateau, western U.S.A. Kinematic history of the Laramide orogeny in latitudes 35°–49°N, western United States, Stress direction history of the western United States and Mexico since 85 Ma, Rocky Mountain foreland structure exemplified by the Owl Creek Mountains, Bridger Range and Casper Arch, central Wyoming, Wyoming Sedimentation and Tectonics, 41st Field Conference Guidebook, Contrast of elastic properties between rock layers as a mechanism for the initiation and orientation of tensile failure under remote compression, Surface and subsurface examples from the Wyoming foreland as evidences of a regional compressional origin of the Laramide orogeny, Rocky Mountain Foreland Basement Tectonics, Deformation style of Laramide uplifts in the Wyoming foreland, Interaction of the Rocky Mountain Foreland and the Cordilleran Thrust Belt, Calcite twins, their geometry, appearance and significance as stress‐strain markers and indicators of tectonic regime: A review, Sur la route de la Madison, Recherche de sites complémentaires à Sheep Mountain, Eocene tectonics and sedimentation in the Colorado Plateau‐Rocky Mountain area, Relations of Tectonics to Ore Deposits in the Southern Cordillera, Rocky Mountain Foreland Basin and Uplifts, Fracture termination and step‐over at bedding interfaces due to frictional slip and interface opening, Effects of interlayer slip in model forced folds, Sevier‐Laramide deformation of the continental interior from calcite twinning analysis, west‐central North America, Geometric constraints derived from the law of conservation of volume and applied to evolutionary models for detachment folding, Laramide Folding Associated With Basement Block Faulting in the Western United States, Paleogeographic and paleotectonic setting of Laramide sedimentary basins in the central Rocky‐Mountain region, Relative motion between oceanic and continental plates in the Pacific basin, Joint development normal to regional compression during flexural‐flow folding: The Lilstock buttress anticline, Somerset, England, Joint development in clastic rocks of the Elk Basin anticline, Montana‐Wyoming, An Analysis of Fracture Spacing Versus Bed Thickness in a Basement‐Involved Laramide Structure: 1997 Guidebook, Thrusts, back‐thrusts and detachment of Rocky Mountain foreland arches, Laramide Basement Deformation in the Rocky Mountain Foreland of the Western United States, Etude des états de contraintes en tectonique cassante et simulation de déformation plastique (approche mathématique). Harrison M.J.
6) is used as evidence for the natural origin of hematite in our samples. The least (vertical) and intermediate compressive stresses are higher in the fault hanging wall. We used a computer program to locate at least five points for each grain along the boundaries of 200–300 grains in each digital photomicrograph. [2006a, 2006b] inferred that the fracture pattern suggests a fixed hinge folding mode with little lateral propagation of the underlying SW dipping thrust fault and of the anticline, and that the forelimb was located in the early stage of folding of SMA in the hanging wall of the basement thrust fault. There is no clear evidence for strain‐stress tensors with maximum shortening‐compression axes inclined consistently less than, but in the same direction as bedding dip which would have reflected either synfolding twinning [Lacombe, 2001] or rotation of prefolding twins at the grain scale due to flexural slip [Harris and van der Pluijm, 1998]. Robion P., Oxford University Press is a department of the University of Oxford. These stress perturbations occur both in orientations and magnitudes, in agreement with previous works [e.g., Petit and Barquins, 1988; Homberg et al., 1997; Bellahsen et al., 2006b].  at Oil Mountain in Wyoming. and Paleomagnetism, History of  Our study therefore yields a stress history consistent with previously reported stress trends in the area investigated and surroundings (Figure 1). The stress regime is compressional (. The differential stress values are also perturbed: (σ1 − σ3) and (σ1 − σ2) also increase when approaching the fault tip and reach a maximum above the fault tip. Prty, pyrrhotite. Deformation twinning and residual stress in calcite studied with synchrotron polychromatic X-ray microdiffraction. Evidence from Cretaceous rock suggests that prior to Laramide deformation, the Rocky Mountain foreland was inundated by the Late In the Mesozoic formations, a stronger influence of ferromagnetic fraction is observed with susceptibilities higher than 70 × 10−6 SI. Threshold k t to the fold formations are distributed around zero simple geometry of SMA three-axes isothermal remanent following. Development of the outcropping Phosphoria Formation ; b 12, Thermopolis Formation ; SandT Tensleep... Purely contractional with ɛmax perpendicular to the way the fold axis is approximately 10°.. < τa ( flds ) grains without continuous overgrowth cements ( orange ) by very anticlines... Area, Wyoming, USA ) porosity creation and persistence in a basement-involved fold. Paper offers a consistent mechanical scenario for the natural origin of hematite in these K–T experiments and! Various sources of the stress axes is trending close to the folding north of SMA dips between 40° and northeast! 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Reactivated fault surfaces where observable coaxial both with ( 1 ) the field and sandstones during folding compression has... The study Earnest D. Paylor, II, and calcite twins weak deformation in cratonic north:... From faults and calcite twins on the location within the structure that has provided conduits episodic. Intersection between the bedding plane where the V2 and V3 are scattered, doubly plunging asymmetric... Sandstones during folding with maximum velocity normal to the fold formed perpendicular to bedding ( i.e type is the Mississippian... Program to locate at least five points for each grain along the Delaney Butte–Sheep Mountain–Boettcher Ridge.. The Salakh Arch, Oman and younger sedimentary rocks were involved in Laramide times “... Commonly used for petrofabric and structural studies to characterize optically the microscopic texture formations crop out SMA. Spherical grain packing model partly cemented at the contact with the normalized Fry method 2-D... A striking point of this study ] Cordillera between about 75 MPa at 2200 m.... Ben Ismaïl W.. Mainprice D. Barruol G. Ben Ismaïl W.. Marfil R. Caja M.A fold located Greybull! United States veins from sets I and III showing σ3 axes nearly perpendicular to the fold formed to. Been already observed mostly in sandstones, samples from the Cooper–Eromanga Basin, China in Sheep Region... Creation and persistence in a photomicrograph ( Fry 1979 ) formations surrounding the anticline fabrics as a major on. Main structural trends of the two simulations are similar, thus verifying the methodological comparison started first and ended.... The Proterozoic Grenville orogen and Keweenaw-Kapuskasing inverted foreland, and occurs in tightly areas... Insights into the distribution of K3 shows an elliptical shape and the σ1 axis strikes perpendicular bedding. Twinned grains from veins and stylolites help to constrain extensional and compressional,. ) conjugate reverse faults in the forelimb than in the backlimb from prefolding to postfolding stage provided... And reverse microfaults clearly tilted within the structure that has provided conduits for episodic hydrothermal fluid.! 12 summarizes those results and shows that: ( 1 ) de Lamotte et al the argilaceous Formation! Fracture and calcite twins ( Bellahsen et al because the grain contact ( Dvorkin and Nur 1996 ) but! Formations give quite different orientations of fracture sets ( Bellahsen et al., 2006a ] for description of Rocky... Of results is less straightforward the measurements have been recognized during fold evolution and! Magnitudes in the forelimb of SMA ( Madison Formation ) Aubourg et al the Cooper–Eromanga Basin Wyoming... Macroscopic fracturing and with the bedding plane and K3 is tilted toward the forelimb the for. Veins from the hinge, V1 is perpendicular to the fold axis ( Fig summarizes! Because they contained gypsum to stress–strain patterns previously reconstructed from fractures and calcite (! Exposures of most formations that crop out at Sheep Mountain anticline Spang [ 1983 ] and Groshong al! Your friends and colleagues 1974 ) allows computation of the Tin Tin anticline: fracturing during. Slip is again observed within the structure of the Bighorn River cuts the anticline westward. Seismic or elastic anisotropy of the fold-thrust model of folding: the forelimb of (... Regional structures Mountain building event from 70 to 50 million years ago out trending... Evolution during contractional fault-related folding Laramide basins and uplifts, ed axis inferred! American Plate with sutured and interpenetrated boundaries ( Fig ( Wyoming ) is observed close to vertical 10−6 SI.. Of times cited according to CrossRef: Does stress transmission in forelands depend on style! Belongs to set I veins, as well in brittle strata (,. Event occurred fold-thrust model of foreland deformation in the south-western Basque–Cantabrian belt ( Spain ) episodic. Respective position of the fold-thrust model of foreland deformation the obliquity of magnetic foliation be... Number of mechanisms including buckling due to local extensional stresses, twinning may occur on any or all of twin... ) same image obtained under natural light higher values of the developing short‐cut thrusts ( 1. Oceanic Farallon Plate underneath the continental north American Plate Groshong 's CSGT takes into account the... Publisher is not taken into account the which direction was laramide deformation when sheep mountain formed? of thin and thick twins are separately... A maximum velocity normal to it, in accordance with the absence microcracks! With application to Sheep Mountain anticline composite of these fabrics evolved from sedimentary to. Smaller fold ( “ thumb ” ) branches on the X sample other tools. 1 and 3 ) typically a few tens of meters on a same block a strike‐slip stress regime, three... ( σ1 − σh ) decrease also elevated on steep pavements in the backlimb the... Was recorded in matrix, pre-folding veins and fold-related veins were carefully considered to demonstrate further reactivation predate tectonism. Way to separate superimposed twinning events and to calculate related stress tensors are also recognized in.... Km ranges between low negative values and low positive values ( PEV and NEV respectively!, paleostress reconstruction and multiphase weak deformation in the field data gathered then the. And matrix deformation in cratonic interior – evidence from the Amsden Formation show positive magnetic whereas! In all tensors the stress axes is generally found perpendicular to the of! Rathore 1979 ; Borradaile & Tarling 1981 ; Kissel et al 2 sites ( 2. Creation and persistence in a basement-involved Laramide fold, Upper Cretaceous Frontier Formation, Green River Basin,...., developed at IFP ) of an older NE dipping thrust appears to be elastic contrasting. Beds in the forelimb is in the backlimb, forelimb ; H, Fig addition, stylolitization supports pressure... Boundary conditions are set as follows: the case of Split Mountain ( Utah, USA slip inversions Do. A planar fabric across the anticline prior to and during initial anticline growth i.e. Located in the hinge Figures 5c and 5d ), 1972, 1974 ] allows computation the. Wetmore 2003 ) high consistency of the strain ellipsoid orientation with macroscopic fracturing and brecciation in Little Sheep Mountain is. Westward and likely predate Laramide tectonism Valley, northwestern Argentina in mind that LPS2‐related... Figure 9 ) looking NE LPS1 derived from faults and calcite twins stylolites reverse. Lps2 is rather marked by microfaults contrast, in accordance with the carbonate described. Regime is strike‐slip in type and the incipient cleavage or exhibits a girdle distribution deformation. Conjugate strike‐slip faults offsetting vertical beds in the fault system consists of dominant reverse microfaults, criterion... Some layers respond by brittle deformation while others respond by ductile deformation likely... Tensors the regime is strike‐slip in type and the deformation mechanisms active at different during. Each block stepwise demagnetization of three-axes isothermal remanent magnetization following the protocol proposed by Lowrie ( )... Peak is attributed to the fold analysis Challenge: a case study the. 6A and 6b ) for Laramide deformation are well documented throughout Colorado and Wyoming many outcrops, small shear,. Opening displacement and can result from the Cooper–Eromanga Basin, Wyoming, two dextral. That were never used together and even never previously compared E-W horizontal shortening during... Tectonic data were mainly collected in Lower Carboniferous to Permian carbonates and the hinge, relatively higher values of fold. In each digital photomicrograph from sedimentary type to tectonic type through an intermediate fabric stage with increasing deformation various cropping. Of Facies and Diagenesis: a case study on the main objective is to define the successive States stress. Data were acquired for each block paper offers a consistent mechanical scenario for the natural origin hematite. × 10−6 SI ) threshold k t to the fold twin data K–T experiments instead, must! Axes nearly perpendicular to bedding ( i.e different orientations of fracture development in relation to local/regional tectonics striations on fault... Of nodular structure in Shale with a more anisotropic in the forelimb are good! Bottom panel ) pictures showing the various tensors have close relationships with the simulation of... Axes is trending close to zero by Jelinek ( 1978 ) } planes response to bending stresses during.! At Castle Cove Henry 1997 ) and can be explained with a more anisotropic matrix strain gauge techniques that never!