Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1016/S0921-8181(02)00060-7 |
The coastal oasis: ice age springs on emerged continental shelves | |
Faure, H; Walter, RC; Grant, DR | |
通讯作者 | Faure, H |
会议名称 | Symposium on Global Carbon Cycle and Its Changes over Glacial-Intergiacial Cycles |
会议日期 | 1999 |
会议地点 | STRASBOURG, FRANCE |
英文摘要 | As ice caps expanded during each of the last five glaciations, sea level fell at least 120 m below current levels, exposing continental shelves worldwide to create vast areas of new land. As a result of this exposure, the ecology, climate, pedology, and geology of global shorelines were dramatically transformed, which in turn altered the carbon cycle and biodynamics of this new landmass. In this paper, we focus on a little-known hydrogeological phenomenon that may have had profound influences on biodiversity, human evolution, and carbon storage during periods of severe climatic stress of the Pleistocene Ice Ages. We propose that freshwater springs appeared on emerged continental shelves because falling sea level not only drew down and steepened the coastal water table gradient, thus increasing the hydrostatic head on inland groundwater aquifers, but also removed up to 120 m of hydrostatic pressure on the shelf, further enhancing groundwater flow. We call this phenomenon the "coastal oasis", a model based on three well-established facts. (1) In all coastal areas of the world, continental aquifers discharge a continuous flow of fresh water to the oceans, (2) Many submarine sedimentary and morphological features, as well as seepages and flow of fresh water, are known on and below the shelves from petroleum explorations, deep-sea drilling programs, and mariners' observations. (3) Hydraulic principles (Darcy's law) predict increased groundwater flow at the coast when sea level drops because the piezometric head increases by the equivalent depth of sea-level lowering. Sea level is presently in a relatively high interglacial position. Direct observation and verification of our model is difficult and must rely on explorations of terrain that are now deeply submerged on continental shelves. For this reason, we draw parallels between our predicted model and simple, well-exposed terrestrial hydrological systems, such as present-day springs that appear on the exposed shores of lakes whose free-air water levels fell during periods of aridity. Such modem examples are seen in the Caspian Sea and Dead Sea, the Afar Depression, and the Sahara Desert. These modem analogues demonstrate the likelihood that underground water will be more abundant on emerged shelves during sea-level fall, causing springs, oases, and wetlands to appear. Our model creates an apparent paradox: in tropical and subtropical arid lands, such as most of Africa, sea-level fall during hyperarid glacial phases would produce abundant fresh water flow onto emerged continental shelves as the continental interior desiccated. Thus, emergent shoreline springs provided new habitats for terrestrial vegetation and animals displaced from the interior by increasingly and conditions, shrinking ecosystems, and dwindling water supplies, Such a scenario would have had a profound influence on the vegetation that spreads naturally to colonize the emerged shelves during glacio-eustatic sea-level lowstands, as well as creating new habitats for terrestrial mammals, including early humans. (C) 2002 Elsevier Science B.V. All rights reserved. |
英文关键词 | global climate change glacial maxima sea-level change lake-level change continental shelf paleohydrogeology coastal oases coastal springs Sahara Quaternary carbon storage migrations human evolution Africa |
来源出版物 | GLOBAL AND PLANETARY CHANGE |
ISSN | 0921-8181 |
出版年 | 2002 |
卷号 | 33 |
期号 | 1-2 |
页码 | 47-56 |
出版者 | ELSEVIER SCIENCE BV |
类型 | Article;Proceedings Paper |
语种 | 英语 |
国家 | France;USA;Canada |
收录类别 | CPCI-S ; SCI-E |
WOS记录号 | WOS:000176800800005 |
WOS关键词 | SEA-LEVEL ; GROUNDWATER ; FLUCTUATIONS ; DEGLACIATION ; POCKMARKS |
WOS类目 | Geography, Physical ; Geosciences, Multidisciplinary |
WOS研究方向 | Physical Geography ; Geology |
资源类型 | 会议论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/293789 |
作者单位 | (1)Univ Mediterranee, Fac Sci, INQUA Commiss Carbon, F-13406 Marseille 09, France;(2)Franklin & Marshall Coll, Dept Geosci, Lancaster, PA 17604 USA;(3)Terracon Geosci Int, Prospect, NS B3T 2B3, Canada |
推荐引用方式 GB/T 7714 | Faure, H,Walter, RC,Grant, DR. The coastal oasis: ice age springs on emerged continental shelves[C]:ELSEVIER SCIENCE BV,2002:47-56. |
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