Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1017/S001675681600025X |
Lateral accretion of modern unvegetated rivers: remotely sensed fluvial-aeolian morphodynamics and perspectives on the Precambrian rock record | |
Ielpi, Alessandro | |
通讯作者 | Ielpi, Alessandro |
来源期刊 | GEOLOGICAL MAGAZINE |
ISSN | 0016-7568 |
EISSN | 1469-5081 |
出版年 | 2017 |
卷号 | 154期号:3页码:609-624 |
英文摘要 | Modern unvegetated rivers flowing through aeolian-dune fields demonstrate potential as analogues for pre-vegetation fluvial landscapes. A prominent example is contained in the Lencois Maranhenses of Brazil, a coastal aeolian system hosting the semi-perennial Rio Negro. Remotely sensed images covering c. 45 years display the rhythmic expansion and wind-driven shift of single-threaded and sinuous fluvial trunks alternating with wider braided plains. Sinuous tracts feature mid-channel and bank-attached bars, including expansional point bars with subdued relief. The morphology, accretion and sediment transport of unvegetated point bars in the Rio Negro are compared to the morphodynamics of vegetated meandering rivers. Unvegetated point bars are composed of large coalescent unit bars, lack apparent scroll topography and are preferentially attached to channel banks located on the windward side of the river course. Unvegetated meanders have expansional behaviour related to downwind channel trailing. Point bars maintain an expansional planform despite spatial confinement induced by aeolian dunes. Channel-flow impingement onto cohesion-less banks favours scouring of deep pools along the bar tails, which host bank-collapse deposits subsequently reworked into new bars. Analogies to Precambrian rivers suggest that ancient unvegetated fluvial landscapes were not unequivocally featured by low sinuosity, especially if characterized by a low gradient and stable discharge. This inference is supported by ongoing studies on Proterozoic fluvial-aeolian systems in the Canadian Shield. Lack of scroll topography introduces overlap with low-sinuosity fluvial facies models, underscoring the value of observing ancient fluvial deposits in planform, or along 3D sections where the palaeodrainage of channel bodies and attached bars can be compared. |
英文关键词 | meander point bar Proterozoic pre-vegetation desert remote sensing Brazil |
类型 | Article |
语种 | 英语 |
国家 | Canada |
收录类别 | SCI-E |
WOS记录号 | WOS:000399394600013 |
WOS关键词 | NORTHWEST-TERRITORIES ; MEANDERING RIVERS ; SELF-ORGANIZATION ; POINT BARS ; BED RIVERS ; DEPOSITS ; VEGETATION ; CANADA ; MARS ; SEDIMENTATION |
WOS类目 | Geosciences, Multidisciplinary |
WOS研究方向 | Geology |
资源类型 | 期刊论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/199234 |
作者单位 | Laurentian Univ, Dept Earth Sci, Sudbury, ON P3E 2C6, Canada |
推荐引用方式 GB/T 7714 | Ielpi, Alessandro. Lateral accretion of modern unvegetated rivers: remotely sensed fluvial-aeolian morphodynamics and perspectives on the Precambrian rock record[J],2017,154(3):609-624. |
APA | Ielpi, Alessandro.(2017).Lateral accretion of modern unvegetated rivers: remotely sensed fluvial-aeolian morphodynamics and perspectives on the Precambrian rock record.GEOLOGICAL MAGAZINE,154(3),609-624. |
MLA | Ielpi, Alessandro."Lateral accretion of modern unvegetated rivers: remotely sensed fluvial-aeolian morphodynamics and perspectives on the Precambrian rock record".GEOLOGICAL MAGAZINE 154.3(2017):609-624. |
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