Author : Keri Leigh Belcher
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (134 download)
Book Synopsis Evolution of a Complex Tidally-modified to Wave-modified Deltaic Reservoir Analog by : Keri Leigh Belcher
Download or read book Evolution of a Complex Tidally-modified to Wave-modified Deltaic Reservoir Analog written by Keri Leigh Belcher and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The (Campanian) Blair Formation (Fm), along the Rock Springs Uplift (a N-S, doubly plunging anticline) near the city of Rock Springs, Wyoming, comprises a stratigraphic 3rd order sequence set that included lowstand, transgressive, and highstand deposits. The Blair Fm was emplaced in shallow marine depositional settings (less than 100m of water) and contains deposits of offshore, prodelta , fluvial-dominated delta front, tidally-influenced delta front , wave-influenced delta front, and subaqueous terminal distributary channels. Delta deposits coarsen and thicken upward with variable degree of reworking by tidal(t) currents or waves(w) indicated by: sigmoids(t), single and double mud drapes(t), mud chips(t), and hummocky cross-stratification(w). No evidence of deep-water basin floor or slope deposits is present in the Blair. Additionally, the Blair is similar to other shallow marine deposits of the Cretaceous Western Interior Seaway (CWIS) that display a preferential tidal dominance during lowstand and preferential wave dominance during highstand. The Blair Fm evolves from lowstand, tidally-influenced deltaic deposits to transgressive offshore and prodeltaic deposits, and ultimately into highstand wave-influenced deltaic deposits. Local embryonic Laramide uplift and differential subsidence led to changes in the basin floor slope and geometry, likely steepening the formerly gentle, ramp-style geometry of the retroarc foreland basin, and inducing high sediment supply near local uplifts. Presence of delta-front turbidites to the north and prodeltaic mudstones in the south are indicative of the locally high sediment supply to the north. The changes in basin floor topography and/or steepening of the basinal slope are evidenced by the successive, meter-scale slumped intervals and a thickness anomaly within the middle Blair, along with amplification of tidal signatures in the lower Blair. This incipient uplift during the emplacement of the Blair may have occurred earlier (82 Ma) than the postulated earliest timing of uplift at around 80 Ma suggested by other workers. The Blair Fm is considered an unconventional (tight), heterolithic reservoir that produces mainly gas in hydrocarbon fields near the Rock Springs anticline. The lower Blair, heterolithic, tidally-influenced lowstand wedge deposits may serve as an analog for other lowstand tidal reservoirs of the CWIS, including the Frewens sandstone of the Frontier Fm