J.H. Clement, 1983. "North Flank of the Uinta Mountains, Utah", Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces, A. W. Bally
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The Uinta Mountains are an elongate, east to west trending range consisting entirely of metasedimentary and sedimentary rocks arched in a broad, asymmetrical anticline in northeastern Utah and adjacent northwestern Colorado. As Rocky Mountain ranges go, the Uintas are somewhat unique, trending east to west in a foreland region where most ranges strike generally north to northwest, and are cored by Precambrian crystalline basement complexes.
Late Precambrian quartzites, metaquartzites, sandstones, and shales comprise the broad core of the Uintas. These rocks make up the crest of the range and the broad interfluves that descend on both sides of the crest far down the flanks of the range. This Precambrian terrane is exposed for a distance of over 193 km (120 mi) in an east to west direction and an average of 29 km (18 mi) in a north to south direction. Cropping out along the topographically lower flanks of the range are Paleozoic and Mesozoic sedimentary rocks with an aggregate thickness of nearly 4,572 m (15,000 ft). The major flanking basins, Green River (north) and Uinta (south), are filled with Tertiary fluviatile and lacustrine sediments which lap on the flanks of the range.
A complex system of faults demarcating the boundary between the north flank of the uplift and the adjacent Green River basin has been mapped in exposed surface strata by geologists during the 115 years since Major John Wesley Powell first traversed the Range in 1868. The geometry of these boundary faults has been a matter of much controversy. W.R. Hansen's comprehensive works (1955-69), describe the reverse (30 to 70° nature of the observed flank faults, and Ritzman (1959), in a summation of faulting in the area, proposed that the Uinta fault is inclined at a very low angle (less than 10° to the south in some areas. However, the concept of normal faulting along the Uinta north flank persisted into the 1960s as evidenced by its depiction on the Tectonic Maps of the United States (1962) and North America (1969) which both show the Uinta Uplift bounded essentially by normal faults. This confusing interpretation may have been influenced by the existence of a number of vertical and high-angle, range-parallel faults that are mapped within the outcrop area of the Precambrian metasediments (see "crest fault" shown on geological section), but these are not the major boundary faults.
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Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces
Until a few decades ago, structural and regional geology were traditionally the preserve of field geologists. They usually mapped areas of outcropping deformed rocks and supplemented their work by laboratory studies of rock deformation and by theoretical work. Structural geology became tied to the geology of uplifts, folded belts, and underground mines, all of which were accessible to direct observation. Since World War II we have witnessed a tremendous development of geophysics in oceanography and in petroleum geology. Academic geophysicists in oceanography led their geological colleagues into modern plate tectonics and industry geophysicists developed reflection seismology into a superb structural mapping tool that penetrated the subsurface.
Today we are facing a situation where instruction and textbooks in structural geology are almost entirely dedicated to rock deformation, analytical techniques in detailed field geology and summaries of plate tectonics. Illustrations based on reflection seismic profiles are virtually absent in textbooks of structural geology. These texts illustrate only the parts of the proverbial elephant, together with some conjecture, but without ever offering a glimpse of the whole elephant.
Some of the reason cited for the relative scarcity of published reflection profiles are: 1) the confidentiality of exploration data; 2) difficulties in the photographic reduction and reproduction of seismic profiles for a book format; 3) the two-dimensional nature of vertical reflection profiles; and 4) the obvious distortions in reflection profiles that are typically recorded in time.
The AAPG leadership felt that it was time to attempt to correct the situation and to produce this picture and work atlas. The first volumes, of what may become a series of volumes, are addressing an audience that includes: petroleum geologists concerned with structural interpretations; exploration companies that provide in-house training; the AAPG continuing education program; and academic colleagues interested in updating their curricula in structural geology by inclusion of reflection profiles from the “real world” in their teaching.
The atlas is not meant to be a textbook in reflection seismology (instead we listed some at the end of this introduction) nor a text in structural and/or regional geology. Our intent is simply to provide a teaching tool.