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GEOREF RECORD

Autogenic modulation of fluvial channel fills in allogenically formed incised valleys; Cretaceous Blackhawk Formation, USA

Hiranya Sahoo and M. Royhan Gani
Autogenic modulation of fluvial channel fills in allogenically formed incised valleys; Cretaceous Blackhawk Formation, USA (in Autogenic dynamics of and self-organization in sedimentary systems, David A. Budd (editor), Elizabeth A. Hajek (editor) and Sam J. Purkis (editor))
Special Publication - Society for Sedimentary Geology (2016) 106: 163-175

Abstract

The stratigraphic fill of incised valleys has traditionally been interpreted to be primarily modulated by allogenic controls. The use of this concept has been so dominant that the possibility of autogenic mechanisms controlling fluvial organization of incised valley fills (IVFs) is largely overlooked, particularly in rock-record interpretations. This has been mainly due to the fact that deconvolving autogenic from allogenic signals remains challenging, especially for IVF deposits. Using integrated light detection and ranging (LiDAR), outcrop, and core data, we investigated the fluvial architecture of two IVFs in the lower Blackhawk Formation (Upper Cretaceous) of the Western Interior Seaway, Utah. Contrary to conventional interpretation, our analyses demonstrate that an autogenic signal linked to differential compaction of coal-precursor peats underlying IVFs likely exerted substantial control in both the vertical and lateral organization of sand-body architecture in these two IVFs, which are up to-15 to 20 m thick individually. Trends in vertical-amalgamation thickness, number of channel-story sand bodies stacked vertically, and width constraints of multilateral sand bodies (lateral amalgamation) of these two IVFs are correlated with thickness variation of underlying coal seams. Decompaction analysis of coal seams indicates that the magnitude of accommodation-creation by coal-precursor peat compaction was potentially much higher to overcome allogenic modulation. This is invoked as the principal reason for broad correlation between fluvial architecture of the IVFs and coal thickness in our data set. These findings contribute to isolating autogenic from allogenic signals in complex systems such as IVFs. They further provide insights on signal-shredding mechanisms in the depositional architecture of the Cretaceous Western Interior Seaway, and they supply evidence that paleovalley fluvial architecture should not be automatically attributed to allogenic processes.


ISSN: 1060-071X
EISSN: 2159-5755
Serial Title: Special Publication - Society for Sedimentary Geology
Serial Volume: 106
Title: Autogenic modulation of fluvial channel fills in allogenically formed incised valleys; Cretaceous Blackhawk Formation, USA
Title: Autogenic dynamics of and self-organization in sedimentary systems
Author(s): Sahoo, HiranyaGani, M. Royhan
Author(s): Budd, David A.editor
Author(s): Hajek, Elizabeth A.editor
Author(s): Purkis, Sam J.editor
Affiliation: University of New Orleans, Earth and Environmental Sciences, New Orleans, LA, United States
Affiliation: University of Colorado, Department of Geological Sciences, Boulder, CO, United States
Pages: 163-175
Published: 2016
Text Language: English
Publisher: Society for Sedimentary Geology (SEPM), Tulsa, OK, United States
Meeting name: SEPM research conference; Autogenic dynamics of sedimentary systems
Meeting location: Grand Junction, CO, USA, United States
Meeting date: 20140803Aug. 3-6, 2014
References: 41
Accession Number: 2017-082535
Categories: Stratigraphy
Document Type: Serial Conference document
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 1 table, sketch maps
N39°19'60" - N39°19'60", W111°15'00" - W111°15'00"
Secondary Affiliation: Western Kentucky University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 201743
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