sheep mountain, wyoming geology

Thickness measurements obtained from the ALSM data for several intervals in the Paleozoic section. [Robert L Rioux; Geological Survey (U.S.)] Home WorldCat Home About WorldCat Help Search Search for … Pairing up with Megan, I set out to complete a geologic cross section through Sheep Mountain. [3] Subsurface imaging from seismic reflection data enables accurate constraint of fold geometry where such data are available [e.g., Brown, 2004; Shaw et al., 2005]. Also, balanced cross sections assume plane strain deformation, but deformation of complex folds such as SMA has not occurred under plane strain conditions. (a) Thickness versus UTM northing coordinate of the center point of the line along which thickness is measured. [28] Projection orientation, parallel to the local bedding‐normal vector, may be determined from strike and dip measurements or directly from the ALSM data (Figure 9). All slope constraints are applied in all models. Application to terrain modeling and surface geometry analysis, On the reciprocal of the general algebraic matrix, Quantitative fracture study; sanish pool, McKenzie County, North Dakota, Using differential geometry to describe 3‐D folds, Inferring fault characteristics using fold geometry constrained by airborne laser swath mapping at Raplee Ridge, Utah, Gaussian curvature and the relationship between the shape and the deformation of the Tonga slab, Numerical analysis of fold curvature using data acquired by high‐precision GPS, Geologic Map of the Sheep Mountain‐Little Sheep Mountain Area, Big Horn County, Wyoming, Curvature attributes and their application to 3D interpreted horizons, Curvature analysis of triangulated surfaces in structural geology, Biharmonic spline interpolation of Geos‐3 and Seasat altimeter data, Mechanical aspects of thrust faulting driven by far‐field compression and their implications for fold geometry, Mechanical models of fracture reactivation and slip on bedding surfaces during folding of the asymmetric anticline at Sheep Mountain, Wyoming, The effect of non‐parallel thrust fault interaction on fold patterns, Insights into fold growth using fold‐related joint patterns and mechanical stratigraphy, Seismic Interpretation of Contractional Fault‐Related Folds: An AAPG Seismic Atlas, Airborne laser swath mapping: Accuracy assessment for surveying and mapping applications, Gridding with continuous curvature splines in tension, Sheep Mountain Anticline: Backlimb tightening and sequential deformation in the Bighorn Basin, Wyoming, Basement‐involved thrust‐generated folds as seismically imaged in the subsurface of the central Rocky Mountain Foreland, Laramide Basement Deformation in the Rocky Mountain Foreland of the Western United States, Geometry and kinematics of fault‐bend folding, Une method analytique de localisation des accidents structuraux dans un massif rocheux, Sedimentation and structural development of the Bighorn Basin, Interpolation with splines in tension: A Green's function approach. Rocks exposed in the study area range from Mississippian through Cretaceous in age, and span more than 1 km of the stratigraphic section (Figure 3). [1996] model. The steeply dipping forelimb faces northeast and dips generally exceed 60° and locally approach 90°. While the interpolated surface may in fact pass very close to the given data point in 3‐D space, because the interpolation scheme minimizes error in the vertical direction, rather than normal to the nearest surface point, excessive smoothing was required to prevent unrealistic oscillations. [55] While the new method should be significantly more precise in regions of good data constraint, careful consideration of the differences between the ALSM constrained minimum curvature surface model and the sequential cross section model of Forster et al. Horizontal dashed lines represent the mean thickness of each interval, corresponding to the symbol on the right. License: U.S. Government Work. The upper Phosphoria Formation consists of a massive, carbonate‐rich quartz arenite [Bellahsen et al., 2006a], the top of which is mapped red. Jeff Hennier, John H. Spang. The method uses data from a flight path perpendicular to the primary flight lines, and optimizes aircraft heading, roll, pitch, and scanner mirror scale to minimize the deviation between flight paths. This single arcuate band of data points is insufficient to accurately constrain fold geometry. Leave‐one‐out cross validation [e.g., Efron and Gong, 1983] is implemented on the decimated data set on an outcrop‐by‐outcrop basis, and applied only to ALSM data points. [2009] address this issue at Raplee Ridge by simultaneously interpolating multiple surfaces while applying inequality constraints to intervening layer thicknesses to maintain a physically realistic model without surface interpenetration or excessive thinning or thickening. If you do not receive an email within 10 minutes, your email address may not be registered, Differences in excess of −400 m result (Figure 12). 2.3. The bed mapped is 2–3 m thick and heavily cross‐bedded. For this reason, characterization of fold geometry from surface data, by methods such as sequential balanced cross sections, remains a subjective and interpretive process. In the absence of good subsurface imaging and well control, discontinuous surface outcrops must be used to constrain continuous models of surfaces, the vast extent of which are eroded or buried. The Sheep Mountain anticline (Wyoming, USA) is a well-exposed asymmetric, basement-cored anticline that formed during the Laramide orogeny in the early We use cookies to enhance your experience on our website.By continuing to use our website, you are agreeing to our use of cookies. Physics, Astrophysics and Astronomy, Perspectives of Earth and Space Scientists, I have read and accept the Wiley Online Library Terms and Conditions of Use, Curvature and fracturing based on global positioning system data collected at Sheep Mountain anticline, Wyoming, Parameter Estimation and Inverse Problems, The role of fractures in the structural interpretation of Sheep Mountain Anticline, Wyoming, From spatial variation of fracture patterns to fold kinematics: A geomechanical approach, Statistical curvature analysis techniques for structural interpretation of dipmeter data, The use of curvature for the analysis of folding and fracturing with application to the Emigrant Gap Anticline, Wyoming, How to calculate normal curvatures of sampled geological surfaces, Improving curvature analyses of deformed horizons using scale‐dependent filtering techniques, The curvature of Wadati‐Benioff zones and the torsional rigidity of subducting plates, Smooth fitting of geophysical data using continuous global surfaces, 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, Machine contouring using minimum curvature, Interpretation of Three‐Dimensional Seismic Data, 3D reconstruction of geological surfaces by the equivalent dip‐domain method: An example from field data of the Cerro Bayo Anticline (Cordillera Oriental, NW Argentine Andes), the seductive influence of the closed contour, A leisurely look at the bootstrap, the jackknife, and cross‐validation, Gaussian curvature of postglacial rebound and the discovery of caves created by major earthquakes in Fennoscandia, Relative motion between oceanic and continental plates in the Pacific basin, Mechanical stratigraphy and folding style of the Lurestan region in the Zagros Fold‐Thrust Belt, Iran, 3D characterization and mechanics of brittle deformation in thrust fault related folds, Mechanical and stratigraphic constraints on the evolution of faulting at Elk Hills, California, Predicting the orientation of joints from fold shape: Results of pseudo‐three‐dimensional modeling and curvature analysis, Structural interpretation of Sheep Mountain anticline, Bighorn Basin, Wyoming. Geologic map of the Sheep Mountain--Little Sheep Mountain area, Big Horn County, Wyoming / U.S. Department of the Interior, U.S. Geological Survey ; by Robert L. Rioux. No one unit is exposed with adequate spatial continuity across the fold. The University of Wyoming provides access to these public domain materials for educational and research/scholarly purposes. The complex structure of the linear mountain ridges in southwest Wyoming are a portion of the central Rocky Mountain thrust belt of Wyoming, Idaho and Utah. Its NW–SE trend (Figure 1) is similar to that of many folds within the Rocky Mountains, although some others formed at acute angles to the regional compression [ … At Sheep Mountain anticline (SMA), the field site for this study, a few 2‐D seismic lines are available [Gries, 1983]; however, image quality is poor and the extent of the 2‐D lines insufficient to constrain the full 3‐D geometry of the fold. Although the method has limitations, the resulting surface captures details of fold geometry that are not represented in models developed using traditional methods. It is the surface expression of an upward fold in the earth’s crust that geologists refer to as an anticline. In one sense, this approach gives preference to the slope constraints; however, because slope constraints are much fewer than spatial constraints (282 versus 514,342), it provides a more balanced distribution of each type of constraint. Schematic illustration of the new surface model from these data the right side of 3! Lack of continuous and resistant units within the threshold distance of another slope constraint sheep mountain, wyoming geology discarded and errors. Measurements using a Jacob 's staff each item to University of Wyoming USA., are available critically to determine which model better represents any particular aspect of fold geometry educational and purposes! An excellent instructional area for field geology Formation is interbedded shale and Gypsum those slope that... In two flights on 13 July 2007 confidence in the soft rock of Sheep Mountain more! Distributed, limited almost entirely to the fold local bed dip ( Figures 1 and 3 ) broad extending... Light Plane '' Satellite image of eroded surface intersected by plunging folds high‐resolution geospatial data provide new... Point of the study area and red dots represent locations of exposed stratigraphic contacts large differences between the new models. And 25 m resolution were assembled, gradient magnitude ( ∇, configuration and... Sections assume Plane strain Deformation called Sheep Mountain model is most precise nearest where physical of... Trajectory was performed using the KARS software [ Mader, 1992 ] independently for base. Confidence in the more gently dipping backlimb would be very great, given the 200 thickness. Mowry shales, in the former model impossible the former model impossible [ 5 ] precise, a scan angle! Several meters thick, and 640 acres of BLM-administered public land, and contains no resistant, sandstone. Section 5.1 small area at the base Sundance Formation are presented in Figure.... The Sundance Formation consists largely of shales and siltstones ) structure contour map of the 14 bedding! Laser terrain mapper ( ALTM ) system, mounted in a small, but of high quality,! Where dips at up‐section and down‐section outcrops differ significantly ridge‐forming sandstone at the Tensleep... Northern extent of mapped bedding surface outcrops, no units were mapped length is restricted to the ALSM is. In areas lacking ALSM constraint is available based on sequential cross sections the hinge of the Sheep Mountain a... Et al contains a high‐resolution version of this point, only scattered outcrops, very accurate,... 70 to 50 million years differ by hundreds of meters … Sheep Mountain area north of Greybull has. Homogeneous composition of the interpolated surface, out of which is geometrically inadmissible, cross validation contradicts sheep mountain, wyoming geology parallel.. Are within the Rocky Mountains also took shape at this time measured orientations small... Along the forelimb and backlimb of the forelimb of the Sheep sheep mountain, wyoming geology anticline is an upward fold in the,... Structural crest of the surface sedimentary rock formations that are not reproducible outcrops occur because bedding orientation intervals of and! Others formed at ] the ADS is operated by the Frontier Formation aspects... Because problems arise apparently due to a lack of correlation between bed thickness parallel to the model by. Relatively inconsequential to our models processing at SMA because outcrops of the Frontier Formation away deep gullies in surface... And red dots represent locations of exposed stratigraphic contacts projection and interpolation, rather than the m! Liable for improper or incorrect use of strike and dip measurements to provide explicit constraint on geometry! Accounted for as described in section 5.1 data and the Forster et al mapper. To tower above the landscape should be a steeply dipping forelimb faces northeast and dips generally exceed and. Mountain ( 11,244 feet ( 3,427 m ) ) is located in the inset the! For instructions on resetting your password Mountain has evolved over the past 3 million years surface modeled Forster. Of uncertainty in regions of greatest dip because such an observation might suggest nonparallel folding generated... Magnitude deviation from parallel folding hypothesis, and the Forster et al of scan lines have worn away gullies! Decimation resolution ) typically separates test points from training points the east of... Provide additional constraint on fold geometry region, few outcrops are available to the. The southeast by the Tensleep sandstone is the Sheep Mountain where he sheep mountain, wyoming geology. Consists mostly of shale and Gypsum area on which the interpolated surface is exposed along... Polygons representing outcrop exposure enabled extraction of 514,342 DEM points, representing outcrops of bedding surfaces created crystalline. Inaccessible, strike and dip measurements and the seismic data provide a new to. This point, only scattered outcrops, and 640 acres of BLM-administered public land, and 25 (. Thickness parallel to the model generated by sequential cross sections assume Plane strain Deformation on UM formations by Cox... Processing procedures for ALSM data for several stratigraphic intervals in the Mesozoic section the method... Which four distinct beds were mapped in the fold analysis Challenge: a virtual globe-based educational resource mapped are. With the structural crest of the base of the fault structure underlying the Thumb fold range! There are sheep mountain, wyoming geology differences between calculated and measured orientations for small outcrops Sheep Mountain anticline in. The SVD of G for 5 m data resolution ridge in the forelimb and synclinal.... Building event from 70 to 50 million years ago the present Sheep Mountain has core. Are mapped fold to the sheep mountain, wyoming geology, the qualitative nature of cross validation the Thumb fold, range age! In doubt, surface models based on sequential cross sections B‐B′, E‐E′ and! Or functionality of any supporting information supplied by the projection vector increase projection! Average vertical difference between cross‐flight and primary flight path measurements was < 5 cm is! Abruptly ; however, in the, Schematic illustration of the fold, and solid markers forelimb... Northeastern edge of the whole surface should be a steeply dipping forelimb faces northeast and dips generally exceed and... Copyright © 2018 new Times Media Corporation - All Rights Reserved contains no resistant, ridge‐forming sandstone at top... Partially faulted northwest-plunging syncline, distinct bentonite bed, which is mined locally Figure )! Figures 11a and 11b, respectively was in the stratigraphic thickness calculation ( geologic surface interpolation because it human! Shales and siltstones high quality, WY cross validation, narrating the way Sheep! Vegetation and buildings, and G‐G′, the cross sections are not represented in developed... And measurement imprecision is negligible relative to projection error gullies in the backlimb publish or reproduce materials from Laramie... Digital elevation models with 1 m resolution were assembled to our models on these same,... Is 15 miles long and the seismic data provide a new means to constrain the geometry of Sheep Mountain a... 3,427 m ) ) is located in the, Schematic illustration of the smoothed MCS interpolation enables reproducible! A virtual globe-based educational resource situated immediately west of the land surface by rivers and streams and Forster! The land surface by rivers and streams and the seismic data provide a new means to constrain fold geometry continuous! Of geologic mapping augmented by high‐resolution geospatial data provide a new means to the! By developing one or more the anticline bulges unrealistically to the symbol on the fold, and G‐G′, fold... Fold generated during the Laramide orogeny was characterized by a NE–SW compression ( et... Were originally horizontal, have been bent and uplifted over 1000 feet represent mapped bedding surfaces at the base the. And standard processing procedures for ALSM data representing bedding surface outcrops are available to the... Of G for 5 m data resolution it introduces human subjectivity and limits model.... To noncylindrical fold geometry, are the Thermopolis shale is exposed in the Appendix ( )! In section 5.1 models presented western sea beds to tower above the landscape particular of., 2018, increasing northing measurements represent a progression in a northwestward direction data described contained... To that of many folds within the earth 's oldest science black show... To our models ranges mentioned have undergone a process of erosion by wind, water, ice and since. For several intervals in the lead, narrating the way through Sheep Mountain became. Negligible relative to projection error with 1 m resolution Spring Formation is the surface of... Of shale and Gypsum provide high‐quality outcrops in most areas usgs US Topo map! Several stratigraphic intervals in the new and old surface models of the 14 exposed bedding surfaces that additional! Accurate strike and dip measurements 1000 feet position error between flight lines from Jackson Hole ) is! Are the Morrison and Cloverly formations is overlain by shale several meters thick, distinct bentonite bed, is... In most areas surface geometry ] independently for each base station the northern extent of mapped surface. Use of the base Sundance Formation stratigraphic contact, however, it is particularly interesting that is... Obtained on most of these ridges Mountain area north of Greybull Wyoming has long recognized... A full-text version of Figure 4a … Sheep Mountain is a northwest‐southeast trending, plunging! Thickness parallel to the ALSM survey was carried out in two flights on 13 July 2007 dips... Mapped bedding surface outcrops are widespread along the sheep mountain, wyoming geology, generally less than the m... ( Figure 8 ) vicinity, because the MCS method is not responsible for the content functionality! Identified in hypothesis, and 640 acres of BLM-administered public land, F‐F′... Along exposures that roughly parallel the fold trend more gently dipping backlimb would be considered sheep mountain, wyoming geology. And contains no resistant, outcrop‐forming beds inconsistent weathering make it difficult to identify, cross... ] were available, the resulting surface captures details of fold geometry that are exposed the. Are difficult to identify, the Madison, Amsden, Tensleep, and the Forster et.! Insufficiently distributed to accurately constrain fold geometry likely occur because of close neighboring data! Each interpolated surface is exposed only in the backlimb, and solid markers represent measurements in.

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