Title

Assessment of fluvial vs. wave-dominated processes in the formation of the lobate geometry of ancient Panther Tongue delta deposits, east-central Utah

Presentation Type

Poster

Abstract

The Cretaceous Panther Tongue of the Star Point formation in the Book Cliffs, Central Utah displays both a thickening and coarsening upward pattern and is interpreted as fluvial-dominated delta with significant gravity underflows forming the delta front. The facies associations suggest terminal distributary channel, channel mouth, and proximal delta-front and distal delta-front depositional environments. The Panther Tongue deposits range from a siltstone base to an overlying alternation of siltstone and sandstone beds to an amalgamation of thick sandstones at the top of the section. The sedimentary parasequences of the Panther Tongue sandstones suggest deposition from unidirectional currents, seaward-dipping clinoforms, and an overall lobate geometry. All of these observations are consistent with the Panther Tongue having been deposited in a river dominated delta. However, it has been observed that the sandstone beds thin to a greater degree in a dip direction than along strike, indicating a relatively strike-elongate geometry of the delta lobes. These characteristics are not typical of a fluvial-dominated delta lobe but rather are more suggestive of a wave-dominated delta. We hypothesize that analysis of sedimentary facies and paleocurrent indicators will provide a basis for interpreting the relative influence of fluvial vs. wave processes on the Panther Tongue. Specifically, in the case of a fluvial-dominated system we would expect to observe evidence of unidirectional currents, offshore-directed cross bedding and multiple distributary channels. In the case of a wave-dominated system we would expect to see evidence of wave ripples, hummocky-cross stratification and more amalgamation of sand bodies. In our field analysis both strike (lateral) parallel and dip parallel outcrops are examined. This will be assessed through measurements of vertical stratigraphic sections to document facies stacking patterns, and measurements of paleocurrent indicator directions with a geological Brunton compass. These observations are crucial in identifying potential hydrocarbon reservoirs in deltaic environments.

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Apr 13th, 3:00 PM Apr 13th, 4:00 PM

Assessment of fluvial vs. wave-dominated processes in the formation of the lobate geometry of ancient Panther Tongue delta deposits, east-central Utah

UC Ballroom

The Cretaceous Panther Tongue of the Star Point formation in the Book Cliffs, Central Utah displays both a thickening and coarsening upward pattern and is interpreted as fluvial-dominated delta with significant gravity underflows forming the delta front. The facies associations suggest terminal distributary channel, channel mouth, and proximal delta-front and distal delta-front depositional environments. The Panther Tongue deposits range from a siltstone base to an overlying alternation of siltstone and sandstone beds to an amalgamation of thick sandstones at the top of the section. The sedimentary parasequences of the Panther Tongue sandstones suggest deposition from unidirectional currents, seaward-dipping clinoforms, and an overall lobate geometry. All of these observations are consistent with the Panther Tongue having been deposited in a river dominated delta. However, it has been observed that the sandstone beds thin to a greater degree in a dip direction than along strike, indicating a relatively strike-elongate geometry of the delta lobes. These characteristics are not typical of a fluvial-dominated delta lobe but rather are more suggestive of a wave-dominated delta. We hypothesize that analysis of sedimentary facies and paleocurrent indicators will provide a basis for interpreting the relative influence of fluvial vs. wave processes on the Panther Tongue. Specifically, in the case of a fluvial-dominated system we would expect to observe evidence of unidirectional currents, offshore-directed cross bedding and multiple distributary channels. In the case of a wave-dominated system we would expect to see evidence of wave ripples, hummocky-cross stratification and more amalgamation of sand bodies. In our field analysis both strike (lateral) parallel and dip parallel outcrops are examined. This will be assessed through measurements of vertical stratigraphic sections to document facies stacking patterns, and measurements of paleocurrent indicator directions with a geological Brunton compass. These observations are crucial in identifying potential hydrocarbon reservoirs in deltaic environments.