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Sequence Stratigraphy of Basal Oquirrh Group Caronates (Bashkirian) Thorpe Hills, Lake Mountain, Wasatch Front, UtahDerenthal, Andrew D. 10 November 2011 (has links) (PDF)
The Early Pennsylvanian (Bashkirian/Morrowan) Bridal Veil Limestone of north-central Utah was deposited in the eastern portion of the rapidly subsiding Oquirrh basin. The 420 meter-thick Bridal Veil Limestone displays distinct cyclicity formed by stacked, meter to decameter scale high-frequency sequences and their constituent parasequences. Though no one ideal cycle may be defined for the Bridal Veil Limestone, each high-frequency sequence and parasequence contains a general shallowing upward trend that ranges from anaerobic to dysaerobic mudstone at the base to skeletal wackestone to mud-dominated packstone, capped by heterozoan grain-rich carbonates or siliciclastic tidalites. Cycles bounded by exposure surfaces, indicated by micro-brecciation, rhizoliths, laminated calcite or silica crusts, rip-up clasts, centimeter-scale teepee structures, and/or pronounced erosional relief are termed high-frequency sequences. Those bounded by marine flooding surfaces are defined as parasequences. Thusly defined, the Bridal Veil Limestone is divided into 25 high-frequency sequences designated BVL-1 through BVL-25. Overall, two distinct sets of high-frequency sequences may be observed in the Bridal Veil Limestone. Sequences comprising the lower half of the formation (BVL-1 through BVL-12) are thicker, muddier, and less sand-prone than sequences in the upper half of the formation (BVL-13 through BVL-25), indicating an overall change in oxygenation, depositional texture, and accommodation upward in the section. Tracing of key beds and surfaces between the Thorpe Hills, Lake Mountain, and the Wasatch Range (spanning a distance greater than 50 miles) reveals that deposition was remarkably uniform across the southeastern part of the Oquirrh basin which we herein designate the Bridal Veil sub-basin and distinct from coeval formations in the southern Oquirrh basin, Ely basin, and Wyoming shelf. Mudstone and wackestone textures comprise a large portion of the formation by volume. Grain-rich carbonates are almost exclusively heterozoan in composition, indicating that the sub-basin was subphotic to aphotic through Early Pennsylvanian time.
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Sequence Stratigraphy of the Bridal Veil Falls Limestone, Carboniferous, Lower Oquirrh Group, on Cascade Mountain, Utah: A standard Morrowan Cyclostratigraphy for the Oquirrh BasinShoore, David Joseph 21 March 2005 (has links) (PDF)
The Bridal Veil Falls Limestone (lowest 400 meters of the Permo-Carboniferous Oquirrh Group) is well exposed on the flanks of Cascade Mountain (Wasatch Front and adjacent mountain ranges) near Provo, Utah. Because of its excellent exposure and location in the heart of the Oquirrh depocenter, this area was selected to develop a sequence stratigraphic framework for Morrowan rocks that may be applied throughout the Oquirrh basin (NW Utah and southern Idaho) as well as the adjacent Ely and Bird Springs troughs. Eleven partial to complete sections of the Bridal Veil Falls Limestone were measured along the west and north flanks of Cascade Mountain and the south end of Mt. Timpanogos. There the limestone is comprised principally of mud-rich carbonate lithofacies punctuated by thin, and sometimes discontinuous quartzose sandstone beds. The predominance of muddy to grain-rich heterozoan limestone microfacies suggests deposition on a west-dipping low energy carbonate ramp that prograded westward throughout Morrowan time. Sandstones reflect transport of siliciclastics from the incipient Weber shelf (located to the NE) during episodes of sea-level lowstand. The Bridal Veil Falls Limestone is subdivided into 21, third and fourth order depositional sequences ranging in thickness from 3 to 60 meters, and 62 parasequences. Parasequences are commonly asymmetrical, reflecting rapid flooding followed by protracted shoaling and/or sea level drop. Selected cycles are recognized in the Lake Mountains, Thorpe Hills, and the southern Oquirrh Mountains to the west of Cascade Mountain indicating that Parasequences delineated at Cascade Mountain are regionally extensive over an area of at least 300 square kilometers.
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