Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1130/0016-7606(1997)109<0043:GWSPWD>2.3.CO;2 |
Ground-water sapping processes, Western Desert, Egypt | |
Luo, W; Arvidson, RE; Sultan, M; Becker, R; Crombie, MK; Sturchio, N; ElAlfy, Z | |
来源期刊 | GEOLOGICAL SOCIETY OF AMERICA BULLETIN
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ISSN | 0016-7606 |
EISSN | 1943-2674 |
出版年 | 1997 |
卷号 | 109期号:1页码:43-62 |
英文摘要 | Depressions of the Western Desert of Egypt (specifically, Kharga, Farafra, and Kurkur regions) are mainly occupied by shales that are impermeable, but easily erodible by rainfall and runoff, whereas the surrounding plateaus are composed of limestones that are permeable and more resistant to fluvial erosion under semiarid to arid conditions. Scallop-shaped escarpment edges and stubby-looking channels that cut into the plateau units are suggestive of slumping of limestones by ground-water sapping at the limestone-shale interfaces, removal of slump blocks by weathering and fluvial erosion, and consequent scarp retreat. Spring-derived tufa deposits found near the limestone escarpments provide additional evidence for possible ground-water sapping during previous wet periods. A computer simulation model was developed to quantify the ground-water sapping processes, using a cellular automata algorithm with coupled surface runoff and ground-water flow for a permeable, resistant layer over an impermeable, friable unit. Erosion, deposition, slumping, and generation of spring-derived tufas were parametrically modeled. Simulations using geologically reasonable parameters demonstrate that relatively rapid erosion of the shales by surface runoff, ground-water sapping, and slumping of the limestones, and detailed control by hydraulic conductivity inhomogeneities associated with structures explain the depressions, escarpments, and associated landforms and deposits. Using episodic wet pulses, keyed by delta(18)O deep-sea core record, the model produced tufa ages that are statistically consistent with the observed U/Th tufa ages. This result supports the hypothesis that northeastern African wet periods occurred during interglacial maxima. The delta(18)O-forced model also replicates the decrease in fluvial and sapping activity over the past million years, as northeastern Africa became hyperarid. The model thus provides a promising predictive tool for studying long-term landform evolution that involves surface and subsurface processes and climatic change. |
类型 | Article |
语种 | 英语 |
国家 | USA ; EGYPT |
收录类别 | SCI-E |
WOS记录号 | WOS:A1997WF33400003 |
WOS关键词 | EASTERN SAHARA ; MONSOON ; TOPOGRAPHY ; RAINFALL ; PLATEAU ; VALLEYS ; ORIGIN ; OASIS ; FLOW |
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/2XILL650/134227 |
作者单位 | (1)WASHINGTON UNIV, DEPT EARTH & PLANETARY SCI, MCDONNELL CTR SPACE SCI, ST LOUIS, MO 63130 USA;(2)ARGONNE NATL LAB, ARGONNE, IL 60439 USA;(3)EGYPTIAN GEOL SURVEY & MIN AUTHOR, CAIRO, EGYPT |
推荐引用方式 GB/T 7714 | Luo, W,Arvidson, RE,Sultan, M,et al. Ground-water sapping processes, Western Desert, Egypt[J],1997,109(1):43-62. |
APA | Luo, W.,Arvidson, RE.,Sultan, M.,Becker, R.,Crombie, MK.,...&ElAlfy, Z.(1997).Ground-water sapping processes, Western Desert, Egypt.GEOLOGICAL SOCIETY OF AMERICA BULLETIN,109(1),43-62. |
MLA | Luo, W,et al."Ground-water sapping processes, Western Desert, Egypt".GEOLOGICAL SOCIETY OF AMERICA BULLETIN 109.1(1997):43-62. |
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