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Re-evaluating the paleogeography of the river-dominated and wave-influenced Ferron Notom Delta, southern central Utah; an integration of detailed facies-architecture and paleocurrent analysis

Li Yangyang, Janok P. Bhattacharya, Sumiyyah Ahmed and Daniel Garza
Re-evaluating the paleogeography of the river-dominated and wave-influenced Ferron Notom Delta, southern central Utah; an integration of detailed facies-architecture and paleocurrent analysis
Journal of Sedimentary Research (February 2018) 88 (2): 214-240

Abstract

This study re-evaluates the paleogeography of a river-dominated and wave-influenced deltaic system in a single parasequence (6a) of the Cretaceous Ferron Sandstone, south-central Utah, which was previously interpreted as a typical asymmetric delta. The conceptual asymmetric-delta model of Bhattacharya and Giosan (2003) has been widely applied to interpret ancient deltaic systems. However, reconstructed paleogeographies relying on this conceptual model are commonly not scaled to the architectural elements, which could possibly lead to inaccurate interpretations, especially when data are relatively sparse. The extensively exposed Ferron Sandstone outcrops provide an opportunity to demonstrate how detailed facies-architecture work can be integrated with regional facies relationships to elucidate a properly scaled paleogeography. Seven facies associations (FA) are identified in parasequence 6a and are arranged into two distinctively different successions. The river-dominated succession consists of prodelta, distal delta-front, proximal delta-front, and terminal-distributary-channel FA, while the wave- and storm-dominated succession comprises offshore-shelf, lower-shoreface, and upper-shoreface FA. The river-dominated succession is muddier and less bioturbated than the wave- and storm-dominated succession. Facies-architecture analysis shows that the river-dominated proximal delta-front facies consists of mouth-bar and terminal distributary-channel elements that are not seen in the wave- and storm-dominated facies. The scales of mouth bars and terminal distributary channels suggest that they are rather small features compared with the river-dominated delta lobe, which is incompatible with the simple bar-elongation asymmetric-delta model presented by Li et al. (2011). Instead, parasequence 6a is interpreted to be a valley-fed, river-dominated symmetric delta protected from waves by an updrift barrier system, which is analogous to the modern Mongky river delta on the west coast of Madagascar. The progressive change in orientation of west-directed mouth bars, to north-directed and east-directed lobes around the periphery of the river-dominated delta, indicates a highly radial Lafourche-type delta. Moving away from the protection of the barrier system, there is a gradual change from highly river-dominated facies to increasingly wave- and storm-influenced facies toward the southeast. Due to the entrenched nature of the feeder river associated with an incised-valley system, the parasequence 6a delta was bifurcation-dominated rather than avulsion-dominated. This study shows that it is critical to integrate detailed facies-architecture analysis in order to reconstruct properly scaled paleogeographies and hypothesizes that stable bifurcation-dominated deltas should be more common than avulsion-dominated deltas in a lowstand delta system due to the entrenched nature of the feeding trunk river, which inhibits avulsion.


ISSN: 1527-1404
EISSN: 1938-3681
Serial Title: Journal of Sedimentary Research
Serial Volume: 88
Serial Issue: 2
Title: Re-evaluating the paleogeography of the river-dominated and wave-influenced Ferron Notom Delta, southern central Utah; an integration of detailed facies-architecture and paleocurrent analysis
Affiliation: C&C Reservoirs, Houston, TX, United States
Pages: 214-240
Published: 201802
Text Language: English
Publisher: Society for Sedimentary Geology, Tulsa, OK, United States
References: 102
Accession Number: 2018-039802
Categories: Sedimentary petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 2 tables, sketch map
N38°19'59" - N38°19'59", W111°01'08" - W111°01'08"
Secondary Affiliation: McMaster University, CAN, CanadaOccidental Petroleum Corporation, USA, United StatesSanchez Oil and Gas, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by SEPM (Society for Sedimentary Geology), Tulsa, OK, United States
Update Code: 2018
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