Browsing by Subject "Delta progradation"
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Item Comparative paleoenvironmental and architectural analyses of the Anchor Mine Tongue to Upper Sego interval along the Book Cliffs of Utah and the Rangely Anticline of Colorado(2016-08) Jones, Rebecca Helen; Fisher, W. L. (William Lawrence), 1932-; Flaig, Peter Paul; Kerans, CharlesA recent, revised regional sequence stratigraphic correlation indicates that outcrop belts along the Rangely Anticline, Colorado contains strata that correlate with the Anchor Mine Tongue and upper Sego of the Book Cliffs, Utah. A detailed sedimentologic and ichnologic investigation of the Anchor Mine Tongue and upper Sego (Campanian) equivalent strata exposed the Rangely Anticline in the Piceance Creek Basin of Colorado revealed that these deposits record the evolution of a mixed fluvio-tidal deltaic system with a delta front significantly modified by tides. This system prograded over lower Sego tidal bars. Predominant structures that support this interpretation include combined flow ripples, trough cross-stratification, low-angle planar-lamination, mud drapes, mud rip-up clasts, mud balls, and trace fossils within sands that are interbedded with finer-grained bioturbated sediments. Ichnology was utilized to refine paleoenvironmental interpretations, and to distinguish between: tidally modified distal and proximal delta fronts and river-dominated deltas; subaqueous tidal channels and distributary channels; interdistributary bays and tidal flats; and marine mudstones and mud-rich paleosols. The Anchor Mine Tongue and upper Sego stratigraphy that is exposed along the Book Cliffs in the Uinta and Piceance Creek was also investigated using a combined sedimentologic and ichnologic approach. Deposits record a marine transgression followed by renewed progradation of tide-dominated deltas with wave-influence along the distal delta front. Paleoenvironments were similar to those of the Rangely area with the addition of marine shelf, wave-modified proximal prodelta, and tidally influenced, wave-modified distal delta front in the Book Cliffs region. The Anchor Mine Tongue and upper Sego in the Book Cliffs preserves the proximal and distal expressions of tide-dominated systems. The Anchor Mine Tongue and the upper Sego both along the Rangely Anticline and along the Book Cliffs are compared-contrasted. Deposits along the Rangely Anticline exhibit more fluvial-flood dominance than deposits along the Book Cliffs. The Rangely stratigraphy represents a mixed fluvio-tidal system whereas the Book Cliffs stratigraphy is tide-dominated. The distribution and variation of paleoenvironments supports a northwest-southwest trending shoreline during the Campanian.Item The depositional system for the Middle and Lower Wilcox in Houston Embayment, Northern Gulf of Mexico Basin(2016-08) Mercado, Lauren Kathleen; Olariu, Cornel; Steel, R. J.; Fisher, WilliamThe Paleocene-Eocene Wilcox formation has been a very oil and gas productive formation in the Gulf of Mexico. Recoveries are on the order of 40 to 500 million barrels of oil, but the potential exists to produce 3 to 15 billion barrels of oil. However, a number of technical and intellectual difficulties arise in economically producing the Wilcox Formation. Deep water Wilcox discoveries are located in low-permeability turbidite sandstones deposited in lower slope channels and basin floor fans in the Gulf of Mexico. The turbidite channels and fans are deep basin equivalents to the shelf delta systems located >250 miles updip, now below onshore Texas. It is important to understand the Paleocene-Eocene shelf depositional system dynamics as these are sediment feeders to the deep water turbidites and will provide a better understanding of the delivery system into the basin. This thesis focuses on the Middle and Lower Wilcox Formation specifically looking in the area of the Brazos and Colorado paleo-delta systems below the present day Texas coastal plain. The study areas represent shelf, shoreline and deltaic coastal deposits. The data used were well logs, such as gamma ray, spontaneous potential and resistivity. Using well log patterns the deposits have been broken down into six stratigraphic sequences on vertical logs, mapped, and analyzed. Signatures of log patterns also have been used to identify depositional systems from fluvial to coastal plain to the shelf in order to understand cycle stacking. The migration of the depocenters indicated a slight progradation, followed by retrogradation, followed by progradation caused by changes in accommodation and sediment supply. The analysis of the shelf and coastal depocenters suggest a possible complex link to the deep basin sediment transfer rather than a simple fluvial-delta-shelf-edge delta to deep water pathway.