Title

Correlating stacking patterns between fluvial and marginal marine environments of the Castlegate sandstone

Presentation Type

Poster

Abstract

The Castlegate is part of an upper-Campanian clastic wedge deposited in the Cretaceous Western Interior Seaway during the late Sevier Orogeny, approximately 79 million years ago. Studies have shown that controls on the sequence stratigraphic architecture are multifold, but they are most commonly interpreted to be driven by tectonics and eustatic changes in sea level. We hypothesize that eustatically-driven sequence stratigraphic changes will separate rock packages that express in-phase relative base level changes between proximal and distal positions. This also suggests that relatively small changes in depositional environment will be observed across sequence boundaries. In contrast, we hypothesize that tectonically-driven sequence boundaries will be expressed by out-of-phase changes in relative base level between proximal and distal positions and that large changes in depositional environment will be observed across sequence boundaries. To test these hypotheses, we will compare the outcrop expressions, stratigraphy, and sedimentology of deposits near Price, Utah with deposits near Green River, Utah. Amalgamated sheet sandstones characterize the fluvial environment (Price locality), while marginal marine- and tidally-influenced deposits characterize the coastal environment (Green River locality). We will compare the architecture of the fluvial environments to that of the coastal environments using photomosaics and measured stratigraphic sections, and we will use these techniques to attempt to relate stacking patterns between sequence boundaries in the two areas. We will use previously established sequence stratigraphic boundaries to compare the degree of amalgamation in the fluvial environment with the facies shifts in the marginal marine environment.

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Apr 13th, 11:00 AM Apr 13th, 12:00 PM

Correlating stacking patterns between fluvial and marginal marine environments of the Castlegate sandstone

UC Ballroom

The Castlegate is part of an upper-Campanian clastic wedge deposited in the Cretaceous Western Interior Seaway during the late Sevier Orogeny, approximately 79 million years ago. Studies have shown that controls on the sequence stratigraphic architecture are multifold, but they are most commonly interpreted to be driven by tectonics and eustatic changes in sea level. We hypothesize that eustatically-driven sequence stratigraphic changes will separate rock packages that express in-phase relative base level changes between proximal and distal positions. This also suggests that relatively small changes in depositional environment will be observed across sequence boundaries. In contrast, we hypothesize that tectonically-driven sequence boundaries will be expressed by out-of-phase changes in relative base level between proximal and distal positions and that large changes in depositional environment will be observed across sequence boundaries. To test these hypotheses, we will compare the outcrop expressions, stratigraphy, and sedimentology of deposits near Price, Utah with deposits near Green River, Utah. Amalgamated sheet sandstones characterize the fluvial environment (Price locality), while marginal marine- and tidally-influenced deposits characterize the coastal environment (Green River locality). We will compare the architecture of the fluvial environments to that of the coastal environments using photomosaics and measured stratigraphic sections, and we will use these techniques to attempt to relate stacking patterns between sequence boundaries in the two areas. We will use previously established sequence stratigraphic boundaries to compare the degree of amalgamation in the fluvial environment with the facies shifts in the marginal marine environment.