气候变化领域集成服务门户(CCPortal): Anatomy and evolution of a dynamic arroyo system, Kanab Creek, southern Utah, USA

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DOI	10.1130/B35195.1
	Anatomy and evolution of a dynamic arroyo system, Kanab Creek, southern Utah, USA
	Townsend K.F.; Nelson M.S.; Rittenour T.M.; Pederson J.L.
发表日期	2019
ISSN	167606
起始页码	2094
结束页码	2109
卷号	131 期号:2021-11-12
英文摘要	Many alluvial valleys in the American Southwest are entrenched within continuous arroyos, and stratigraphic evidence indicates that these fluvial systems experienced repeated periods of entrenchment and aggradation during the mid- to late-Holocene. Previous research suggests arroyo dynamics were regionally quasi-synchronous, implying that they were driven by allogenic forcing due to hydroclimatic fluctuations. However, several of these interpretations rely on records with limited age control and include distal correlations across the American Southwest. While hydroclimatic variability must exert some role, autogenic mechanisms related to catchment- specific geomorphic thresholds are hypothesized to partially control the timing of arroyo dynamics. If driven by autogenic processes, episodes of arroyo cutting and filling may not be regionally contemporaneous. Recent improvements in dating methods permit more detailed reconstructions of the timing and evolution of arroyo dynamics, allowing for a more nuanced assessment of these competing hypotheses. Here we present a uniquely large and focused chronostratigraphic data set from two alluvial reaches of Kanab Creek, located in the Grand Staircase region of southern Utah. Episodes of prehistoric arroyo cutting and filling are reconstructed from 27 sites through recognition of soils and buttressed unconformities in the arroyo-wall stratigraphy, and age control derived from 54 optically stimulated luminescence (OSL) ages and 50 radiocarbon ages. Our chronostratigraphic data set indicates five periods of channel aggradation occurred since ca. 6.0 ka, with each interrupted by an episode of arroyo entrenchment. Repeated aggradation to a similar channel elevation suggests attainment of a threshold profile, and comparison of the pre-entrenchment longitudinal profile with the modern arroyo channel demonstrates that changes between end-member entrenched and aggraded states are expressed in channel concavity and slope. We propose that arroyo dynamics are partially driven by sediment supply and the rate of channel aggradation, and that these systems must approach complete re-filling before they become sensitive to incision. Entrenchment itself appears to be associated with rapid transitions from pronounced decadal-scale aridity to pluvial (wetter) periods. Not all such hydroclimatic fluctuations are associated with arroyo entrenchment, which highlights the importance of threshold controls on the behavior of these systems. The collective period of "dynamic instability" characterized by epicycles of arroyo entrenchment and aggradation did not initiate until the mid-Holocene, when a climatic shift toward warmer and drier conditions likely increased fine-grained sediment supply to the fluvial system. © 2019 Geological Society of America.
语种	英语
来源期刊	Bulletin of the Geological Society of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/184936
作者单位	Department of Geology, Utah State University, 4505 Old Main Hill, Logan, UT 84322-4505, United States; Utah State University Luminescence Laboratory, 1770 North Research Parkway, Suite 123, North Logan, UT 84321, United States; Department of Earth and Environmental Sciences, University of Michigan, 1100 North University Avenue, Ann Arbor, MI 48109-1005, United States
推荐引用方式 GB/T 7714	Townsend K.F.,Nelson M.S.,Rittenour T.M.,et al. Anatomy and evolution of a dynamic arroyo system, Kanab Creek, southern Utah, USA[J],2019,131(2021-11-12).
APA	Townsend K.F.,Nelson M.S.,Rittenour T.M.,&Pederson J.L..(2019).Anatomy and evolution of a dynamic arroyo system, Kanab Creek, southern Utah, USA.Bulletin of the Geological Society of America,131(2021-11-12).
MLA	Townsend K.F.,et al."Anatomy and evolution of a dynamic arroyo system, Kanab Creek, southern Utah, USA".Bulletin of the Geological Society of America 131.2021-11-12(2019).