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Maximum displacement (D) and trace length (L) data for a population of 97 normal faults from the Canyonlands Grabens region of SE Utah are presented. Values of L range from 100 to 6500 m, and of D from 1.5?155 m. The data exhibit a scatter between D and L of about half an order-of-magnitude. This is comparable to that exhibited in other published single population datasets. This magnitude of scatter cannot be attributed either to measurement errors or to variation in mechanical properties. We propose that a scatter of this magnitude can be explained by a general model for fault growth by segment linkage, whereby large incremental increases of length attained as fault segments link temporarily exceed incremental...
Faults and associated fracture networks can significantly influence regional flow of groundwater, hydrocarbons and other fluids. The distribution of CO2 springs and seeps along the Little Grand Wash fault and Salt Wash faults in central Utah is controlled by along-fault flow of CO2-charged groundwater from shallow aquifers (<1 km deep). The same faults are the likely conduits that charge the shallow aquifers with CO2 from depth. We document fault zone trace geometry and architecture, and evidence for palaeo-fluid flow within the footwalls of both faults. Evidence for palaeo-fluid flow consists of extensive bleaching of sandstones and some siltstones, mineralisation of carbonates and celestine veins and minor hydrocarbon...
The main aim of the discussion by McGill et al. is to clarify the geometry of the grabens in the Needles District of the Canyonlands National Park, Utah. The motivation for this paper is based on statements in Cartwright et al. (1995, 1996) pertaining to our interpretation of the cross-sectional geometry of the bounding faults of the grabens in this area, and the paper sets out to correct the record with regard to the conflicting views of these and earlier interpretations (by numerous authors). McGill et al. are certainly justified in correcting the impression given by Cartwright et al., 1995 J.A. Cartwright, B.D. Trudgill and C.S. Mansfield, Fault growth by segment linkage—an explanation for scatter in maximum...
Emplacement of the Proterozoic Gunnison annular complex, Colorado, involved brittle failure and both subhorizontal sheeting and steeply-dipping dyking. The annular complex consists of a central diorite body (1730 Ma), surrounded by a ring of metamorphosed supracrustal rocks, in turn ringed by tonalite and granodiorite (1721 Ma). The older central diorite was emplaced as sills parallel to bedding, prior to regional deformation of the Gunnison volcanic arc, 1730–1710 m.y. ago. This central body was deformed during regional shortening, into an upright bowl with inward-dipping walls. The surrounding country rocks were folded and locally transposed against the central body, forming an arcuate foliation, conforming...
A review of field observations reveals that faults in the upper crust initiate in one of three styles: linkage of pre-existing structures, linkage of precursory structures, or by localization of slip in a precursory shear zone. The first two styles can be characterized by three general stages. During stage 1, faults initiate by shear along pre-existing structures (formed during an earlier event), or by the initiation of precursor structures (formed earlier in the same deformation event). Stage 2 involves the pre-existing or precursor structures becoming linked by differently orientated structures, as stresses are perturbed within the developing fault zone. Linkage allows displacement to increase. A through-going...
The along-strike displacement variation of 20 well-exposed normal faults from the Canyonlands, Utah, is described and analysed. The displacement profiles of these faults are highly variable, and most irregularities can be related to fault segmentation. Many of the profiles are highly asymmetric, and this can be related to mechanical interaction in some cases. Linear displacement tapers are observed towards all the lateral tips, but the percentage of trace length over which this linear taper occurs is highly variable. Three distinct lateral tip geometries are recognised, referred to informally as types A, B and C. Type A tips have a simple Mode III displacement geometry, Type B tips are characterised by a zone of...
Maximum displacement (D) and trace length (L) data for a population of 97 normal faults from the Canyonlands Grabens region of SE Utah are presented. Values of L range from 100 to 6500 m, and of D from 1.5–155 m. The data exhibit a scatter between D and L of about half an order-of-magnitude. This is comparable to that exhibited in other published single population datasets. This magnitude of scatter cannot be attributed either to measurement errors or to variation in mechanical properties. We propose that a scatter of this magnitude can be explained by a general model for fault growth by segment linkage, whereby large incremental increases of length attained as fault segments link temporarily exceed incremental...
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Grabens in Canyonlands National Park, Utah, began extending above a layer of evaporites when the Colorado River cut through the overburden. Two-dimensional finite element models simulate the effects of geometry and rock properties on graben configuration and spacing. Only those models having a progressively increasing slope or no slope mimicked the natural upslope graben propagation. Typical rock properties produced the most realistic fault patterns: an initial friction angle of 31°, a cohesion of 1 MPa, and strain weakening comprising cohesion loss and decrease of friction angle to 26°. A tensile stress limit narrowed the grabens and reproduced the vertical upper portion of the natural faults. The viscous salt...
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Seismic refraction profiling and gravity measurements along the length of the northern Devils Lane graben in Canyonlands National Park reveal that the bedrock floor of the graben is buried beneath a sedimentary cover more than 90 m thick, at least four to ten times more fill than previously measured. This sediment thickness, when combined with exposed fault topography, yields a throw of ≥145 m on the master fault. We estimate that horizontal extensional strain across the graben is on the order of 2–3%, and if this is typical of grabens elsewhere in Canyonlands the maximum average strain rates across the region are about 1×10−14 s−1, or 2 mm year−1. Our results indicate that published length to displacement relationships...
Cartwright et al. (1995) have published an interesting and valuable study of fault growth by segment linkage based on field studies in the Needles District of Canyonlands National Park, southeastern Utah, where there is an unusually well exposed suite of grabens and associated valley anticlines (Harrison, 1927; Prommel and Crum, 1927; Baker, 1933; Lewis and Campbell, 1965; Potter and McGill, 1978; McGill and Stromquist, 1979; Huntoon, 1982; Trudgill and Cartwright, 1994; Cartwright et al., 1995, 1996; Schultz and Moore, 1996; Cartwright and Mansfield, 1998; Moore and Schultz, 1999). However, we disagree with the cross-sectional geometry assumed by Cartwright et al. The Canyonlands grabens have received much attention...
    map background search result map search result map Geophysical exploration within northern Devils Lane graben, Canyonlands National Park, Utah: implications for sediment thickness and tectonic evolution Modeling of grabens extending above evaporites in Canyonlands National Park, Utah Geophysical exploration within northern Devils Lane graben, Canyonlands National Park, Utah: implications for sediment thickness and tectonic evolution Modeling of grabens extending above evaporites in Canyonlands National Park, Utah