Title: ROCKY MOUNTAIN ASSOCIATION OF GEOLOGISTS - 1977 SYMPOSIUM
Abstract: The Uncompaghre uplift, as defined in the literature, is a buried tectonic feature, which separates the Paradox basin on the south from the Uinta basin on the north. The uplift covers an area of some 4500 square miles, trending northwesterly across the UtahColorado border at the general latitude of the Grand-Uintah County line in Utah, and is outlined on both the northeast and southwest by major zones of faulting which, in this paper, are called the Garmesa and Uncompaghre fault zones, respectively. The first recognizable tectonic activity on the Uncompaghre probably was initiated in late Precambrian time, with postulated left wrench movement along the Uncompaghre fault to the south and the Garmesa and other parallel fault zones to the north. This event was apparently followed by a period of relative quiescence, as no important tectonic activity is reflected in the preserved early Paleozoic marine rocks around the Uncompaghre periphery. The major uplift of the Uncompaghre took place during the Pennsylvanian and Permian, when some 10,000 feet or more of coarse Hermosa and Cutler arkose was dumped southward into the Paradox basin along the Uncompaghre fault zone. Pennsylvanian and Permian facies change from normal marine carbonates to non-marine red beds and clastics toward the central uplift along both Uncompaghre flanks, reflecting this tectonic event. Other periods of tectonic activity are recorded by late Permian, early Triassic, and Middle Triassic erosional unconformities. The Middle Triassic event is clearly expressed along the north side of the Uncompaghre, on the Douglas Creek arch and Seep Ridge antklinal nose, by southward truncation of all formations below the Shinarump Conglomerate. The central core of the ancestral uplift was ultimately stripped in Precambrian crystalline basement and buried beneath post-Shinarump Mesozoic and Tertiary sediments. During the Laramide orogeny, the uplift was regionally tilted to the northeast, and renewed movements on basement faults in the central area of the uplift produced the numerous drape folds on which Mesozoic gas accumulations are localized. Exploration potential appears to exist only for these younger rocks in the immediate Uncompahgre environs.
Publication Year: 1977
Publication Date: 1977-01-01
Language: en
Type: article
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Cited By Count: 13
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