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DOI	10.1073/pnas.1901642116
	Low-gradient; single-threaded rivers prior to greening of the continents
	Ganti V.; Whittaker A.C.; Lamb M.P.; Fischer W.W.
发表日期	2019
ISSN	0027-8424
起始页码	11652
结束页码	11657
卷号	116 期号:24
英文摘要	The Silurian-age rise of land plants is hypothesized to have caused a global revolution in the mechanics of rivers. In the absence of vegetation-controlled bank stabilization effects, pre-Silurian rivers are thought to be characterized by shallow, multithreaded flows, and steep river gradients. This hypothesis, however, is at odds with the pancontinental scale of early Neoproterozoic river systems that would have necessitated extraordinarily high mountains if such river gradients were commonplace at continental scale, which is inconsistent with constraints on lithospheric thickness. To reconcile these observations, we generated estimates of paleogradients and morphologies of pre-Silurian rivers using a well-developed quantitative framework based on the formation of river bars and dunes. We combined data from previous work with original field measurements of the scale, texture, and structure of fluvial deposits in Proterozoic-age Torridonian Group, Scotland—a type-example of pancontinental, prevegetation fluvial systems. Results showed that these rivers were low sloping (gradients 10−5 to 10−4), relatively deep (4 to 15 m), and had morphology similar to modern, lowland rivers. Our results provide mechanistic evidence for the abundance of low gradient, single-threaded rivers in the Proterozoic eon, at a time well before the evolution and radiation of land plants—despite the absence of muddy and vegetated floodplains. Single-threaded rivers with stable floodplains appear to have been a persistent feature of our planet despite singular changes in its terrestrial biota. © 2019 National Academy of Sciences. All rights reserved.
英文关键词	Cross-stratification; Neoproterozoic Era; Prevegetation alluvium
语种	英语
scopus关键词	article; biota; Embryophyta; floodplain; morphology; Neoproterozoic; nonhuman; radiation; river; Scotland; Silurian; stratification
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/158964
作者单位	Ganti, V., Department of Geography, University of California, Santa Barbara, CA 93106, United States, Department of Earth Science, University of California, Santa Barbara, CA 93106, United States; Whittaker, A.C., Department of Earth Science and Engineering, Imperial College London, London, SW7 2AZ, United Kingdom; Lamb, M.P., Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States; Fischer, W.W., Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, United States
推荐引用方式 GB/T 7714	Ganti V.,Whittaker A.C.,Lamb M.P.,et al. Low-gradient; single-threaded rivers prior to greening of the continents[J],2019,116(24).
APA	Ganti V.,Whittaker A.C.,Lamb M.P.,&Fischer W.W..(2019).Low-gradient; single-threaded rivers prior to greening of the continents.Proceedings of the National Academy of Sciences of the United States of America,116(24).
MLA	Ganti V.,et al."Low-gradient; single-threaded rivers prior to greening of the continents".Proceedings of the National Academy of Sciences of the United States of America 116.24(2019).