scholarly journals Coarse-grained meandering distributive fluvial system of the basal Cedar Mountain Formation, U.S.A.

2021 ◽  
Vol 91 (11) ◽  
pp. 1188-1205
Author(s):  
Stephen P. Phillips ◽  
John A. Howell ◽  
Adrian J. Hartley ◽  
Magda Chmielewska
Keyword(s):  
Grain Size ◽  
Early Cretaceous ◽  
Foreland Basin ◽  
Fluvial System ◽  
Channel Migration ◽  
Fluvial Systems ◽  
Plan View ◽  
Cedar Mountain Formation ◽  
Lateral Channel ◽  
Net To Gross

ABSTRACT The analysis of downstream changes in ancient fluvial systems can better inform depositional models for foreland-basin systems. Herein we analyze the basal deposits of the Early Cretaceous Cedar Mountain Formation of Utah to better understand the variety of fluvial deposits present and to develop a depositional model for the Sevier foreland basin. We also evaluate the long-held interpretation of a braided origin for these deposits and document numerous examples of point-bar deposition in highly sinuous meandering rivers by analysis of large (20 to 60 km2) plan-view exposures. These plan-view exposures allow comparisons between planform and cross-sectional geometries. The study utilizes outcrop data, virtual outcrop models, and satellite imagery to develop a facies model and analyze the architecture of channel bodies in the Buckhorn Conglomerate and Poison Strip Sandstone of the Cedar Mountain Formation. We document downstream (west to east) decreases in lateral channel migration, sinuosity, channel amalgamation, grain size, and percent of fluvial channel facies (conglomerate and sandstone). Fluvial channel deposits occur arranged into larger stratal bodies: multistory–multilateral channel bodies that are dominantly composed of clast-supported conglomerate in the west to a mix of multistory, multilateral, and isolated channel bodies composed of matrix-supported conglomerate in the east. The median width of highly sinuous point bars is similar across the field area (344 m to 477 m), but the inclusion of narrower (median = 174 m), low-sinuosity bar elements in the east indicates an overall reduction in lateral channel migration and sinuosity downstream. Net-to-gross values range from 100% in much of the western outcrops to as low as 38% in the east. Paleocurrent analysis reveals a transverse (west to east) paleoflow for the study interval that merges with axial (south–north) paleoflow near the Utah–Colorado state line. We estimate 104 m3/s-scale discharge and 106 kilometer-scale drainage area for axial rivers based on paleohydraulic analysis which represents a significant part of the Early Cretaceous continental-scale drainage. The observed downstream trends in lateral channel migration, sinuosity, channel amalgamation, grain size, and net-to-gross for the basal Cedar Mountain Formation are consistent with expected trends for sinuous single-thread distributive fluvial systems and are similar to observed trends in the Jurassic Morrison Formation. Medial (Buckhorn Conglomerate) to distal (Poison Strip Sandstone) zones are preserved and span the forebulge to backbulge depozones of a foreland-basin system. Postulated deposits of the proximal distributive fluvial system have been removed during erosion of the foredeep depozone. The easternmost Poison Strip Sandstone and coeval Burro Canyon Formation represent deposits of an axial system at which western-sourced distributive fluvial systems end. Distributive fluvial systems dominate modern foreland basins, and this study suggests that they may constitute a significant proportion of ancient successions.

Tracking dinosaurs in BLM canyon country, Utah

2018 ◽  
Vol 3 ◽  
pp. 67-100 ◽  
Author(s):  
ReBecca K. Hunt-Foster ◽  
Martin G. Lockley ◽  
Andrew R.C. Milner ◽  
John R. Foster ◽  
Neffra A. Matthews ◽  
...  
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

Tracking dinosaurs in BLM canyon country, Utah

2016 ◽  
Vol 3 ◽  
pp. 67-100
Author(s):  
ReBecca Hunt-Foster ◽  
Martin Lockley ◽  
Andrew Milner ◽  
John Foster ◽  
Neffra Matthews ◽  
...  
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

The Lower Cretaceous in east-central Utah—The Cedar Mountain Formation and its bounding strata

2016 ◽  
Vol 3 ◽  
pp. 101-228 ◽  
Author(s):  
James Kirkland ◽  
Marina Suarez ◽  
Celina Suarez ◽  
ReBecca Hunt-Foster
Keyword(s):  
Colorado Plateau ◽  
Foreland Basin ◽  
Salt Tectonics ◽  
Initial Development ◽  
Paradox Basin ◽  
Cedar Mountain Formation ◽  
History Of ◽  
San Rafael ◽  
San Rafael Swell ◽  
Biological History

Although only recognized as a discrete stratigraphic unit since 1944, the Cedar Mountain Formation represents tens of millions of years of geological and biological history on the central Colorado Plateau. This field guide represents an attempt to pull together the results of recent research on the lithostratigraphy, chronostratigraphy, sequence stratigraphy, chemostratigraphy, and biostratigraphy of these medial Mesozoic strata that document the dynamic and complex geological history of this region. Additionally, these data provide a framework by which to examine the history of terrestrial faunas during the final breakup of Pangaea. In fact, the medial Mesozoic faunal record of eastern Utah should be considered a keystone in understanding the history of life across the northern hemisphere. Following a period of erosion and sediment bypass spanning the Jurassic–Cretaceous boundary, sedimentation across the quiescent Colorado Plateau began during the Early Cretaceous. Thickening of these basal Cretaceous strata across the northern Paradox Basin indicate that salt tectonics may have been the predominant control on deposition in this region leading to the local preservation of fossiliferous strata, while sediment bypass continued elsewhere. Thickening of overlying Aptian strata west across the San Rafael Swell provides direct evidence of the earliest development of a foreland basin with Sevier thrusting that postdates geochemical evidence for the initial development of a rain shadow.

FLUVIAL ARCHITECTURE OF EXHUMED AND INVERTED PALEOCHANNELS OF THE EARLY CRETACEOUS CEDAR MOUNTAIN FORMATION OF EAST-CENTRAL UTAH

2019 ◽  
Author(s):  
Michael C. Wizevich ◽  
◽  
Isabelle Kisluk ◽  
Willow R. Reichard-Flynn ◽  
Abby Keebler ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
East Central ◽  
Cedar Mountain Formation ◽  
Fluvial Architecture

scholarly journals A New Sequence Stratigraphic Framework of Terrestrial Fluvial

2017 ◽  
Vol 4 (1) ◽  
pp. 85 ◽  
Author(s):  
Zhipeng Lin ◽  
Le Chen ◽  
Jingfu Shan ◽  
Tan Zhang ◽  
Qianjun Sun ◽  
...  
Keyword(s):  
Deposition Process ◽  
Vital Role ◽  
Fluvial System ◽  
Fluvial Systems ◽  
Sequence Stratigraphic ◽  
Meandering River ◽  
River Types ◽  
Stratigraphic Framework ◽  
Different Characteristics ◽  
System Tract

Currently, the recognition and research on the classification of fluvial types mainly focus on the description and results of a series of indicators, such as the plane shape and sediment characteristics. However, there is limited literacy about how to demonstrate the fluvial types from the depositional process, especially less on sequence model of inland fluvial. Thus, this paper aims o propose a new kind of sequence stratigraphic framework, which is able to reflect the fluvial processes under the perspective of sequence stratigraphy. Accordingly, we use the principle of concrete analysis for concrete problems by comprehensively summing up the previous classification schemes of river types. With the research method of sedimentation process, new fluvial systems tracts for fluvial are presented here, including four parts: low fluvial system tract (LFST), advancing fluvial system tract (AFST), flooding fluvial system tract (FFST), receding fluvial system tract (RFST). Moreover, these could be applied to tackle the problem of the traditional division of fluvial. Various rivers have the different characteristics of systems tracts, then this may play a vital role in the discrimination of meandering river, braided river, anastomosing river and branched river. This study embodies the philosophical thought of Process Sedimentology and may contribute to revealing the deposition process of the fluvial system more profoundly from the aspect of genetic mechanism and evolution course. Most importantly, the fluvial classification system is definitely improved from the description stage to a complete rational stage.

scholarly journals The Quaternary Climatic and Tectonic Development of the Murat River Valley (Muş Basin, Eastern Turkey) as Recorded by Fluvial Deposits Dated by Optically Stimulated Luminescence

Quaternary ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 29
Author(s):  
Nurcan Avşin ◽  
Mehmet Korhan Erturaç ◽  
Eren Şahiner ◽  
Tuncer Demir
Keyword(s):  
Optically Stimulated Luminescence ◽  
Fluvial System ◽  
Middle Section ◽  
Alluvial Terrace ◽  
Last Glacial Period ◽  
Fluvial Systems ◽  
Tectonic Development ◽  
River Deposits ◽  
East Anatolia ◽  
The Last Glacial

The paper describes climatic and tectonic effects on fluvial processes of East Anatolia. This study from the Muş Basin contains three alluvial terrace levels (T3-T1) ranging from 30–35 m to 3–5 m above the present Murat River in its middle section. In order to provide a chronology for the evaluation of the significant, effects of climatic changes and tectonic uplift, we used optically stimulated luminescence (OSL) dating of the river deposits of the youngest (T3) and medium terrace (T2). The ages from these terrace deposits show that the T3 has formed approximately 6.5 ka ago, i.e., during the last part of the Holocene (MIS 1) and T2 has formed nearly 25 ka ago, i.e., during MIS 2 at the ending of the last glacial period. According to these results, it appears that the Murat River established its terrace sequences both in cold and warm periods. The variations in climate oriented fluvial evolution between the East Anatolia fluvial system and the temperate-periglacial fluvial systems in Europe may be the conclusion of different vegetation cover and melting thicker snow coverings in cold periods.

scholarly journals Palaeohydrological reconstruction of Siwalik Group in Surai Khola

1970 ◽  
Vol 31 ◽  
pp. 33-42 ◽  
Author(s):  
Prakash Das Ulak
Keyword(s):  
Grain Size ◽  
Gradual Change ◽  
Fluvial System ◽  
Sediment Grain Size ◽  
Upward Direction ◽  
Two Parameters ◽  
Siwalik Group

About 5 km thick Neogene Siwalik Group in the Surai Khola section of west Nepal comprises many fining-upward cycles, which are from several metres to tens of metres thick. However, the Siwalik sequence as a whole reveals a coarseningupward trend. The palaeohydrological reconstruction of the Siwalik Group was based mainly on two parameters: the sediment grain size and the thickness of individual fining-upward successions. The estimated palaeoflow velocity in the Siwalik Group varies from 0.32 to 4.76 m/s, palaeochannel gradient ranges from 5.29x10-5 to 9.59x10-4 m/m, and palaeodischarge fluctuates from 1 to 104 m3/s, in the stratigraphically upward direction. These palaeohydrological parameters indicate a gradual change in fluvial system, presumably owing to the southward propagation of thrusts.

Sign in / Sign up

Export Citation Format

Share Document