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首页> 外文期刊>Quaternary Science Reviews: The International Multidisciplinary Review Journal >Causal links between Nile floods and eastern Mediterranean sapropel formation during the past 125 kyr confirmed by OSL and radiocarbon dating of Blue and White Nile sediments
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Causal links between Nile floods and eastern Mediterranean sapropel formation during the past 125 kyr confirmed by OSL and radiocarbon dating of Blue and White Nile sediments

机译：OSL和蓝色和白色尼罗河沉积物的放射性碳测年证实了过去125年内尼罗河洪水与地中海东部腐朽石形成之间的因果关系

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It has long been hypothesised that beds of highly organic mud or sapropels seen in marine sediment cores retrieved from the floor of the eastern Mediterranean accumulated during times of high Nile fluvial discharge. Our recent fieldwork in the valleys of the Blue Nile, the White Nile and the main Nile has for the first time revealed a sequence of extreme flood episodes synchronous with sapropel units S5 (124 kyr), S4 (102 kyr), S3 (81 kyr), S2 (55 kyr) and Si (13.5-6.5 kyr). There are more weakly defined links with Nile floods and sapropel units S9 (240 kyr), S8 (217 kyr), S7 (195 kyr), S6 (172 kyr), but the dating error terms are too large to allow us to be too definite. During times of extreme floods over the past 125 kyr, wide distributary channels of the Blue Nile flowed across the Gezira alluvial fan in central Sudan and transported a bed load of sand and gravel into the lower White Nile valley. The sands were reworked by wind to form source-bordering dunes, all of which contain heavy minerals of Ethiopian provenance. These source-bordering dunes were active at 115-105 kyr, 60 kyr and 12-7 kyr, all times of extreme Blue Nile floods. The flood and dune sediments were dated using a combination of optically stimulated luminescence (OSL) and radiocarbon analyses. The Quaternary record of Nile floods discussed here shows a precessional signal and reflects episodes of stronger summer monsoon and more northerly seasonal movement of the ITCZ, linked to times of higher insolation in northern tropical latitudes. Progressive aggradation of Holocene Nile channels in northern Sudan has had a profound influence upon human settlement in the last 8 kyr. (C) 2015 Elsevier Ltd. All rights reserved.
机译：长期以来一直有假设认为，在尼罗河河水排放量高的时期，从地中海东部海底取回的海洋沉积物岩心中发现了高度有机的泥浆或腐殖质床。我们最近在青尼罗河，白尼罗河和尼罗河主河谷进行的实地调查首次揭示了一系列极端洪水事件，与腐烂单位S5（124年），S4（102年），S3（81年）同步），S2（55千卡）和Si（13.5-6.5千卡）。与尼罗河洪水和Sappel单位S9（240年），S8（217年），S7（195年），S6（172年）的联系更加模糊，但是约会误差项太大，以至于我们无法做到定。在过去125年的极端洪水期间，青尼罗河的宽阔分布河道横渡了苏丹中部的Gezira冲积扇，并将一床沙子和碎石运到白尼罗河下游山谷。风将沙子重新加工形成边界沙丘，所有沙丘都含有埃塞俄比亚起源的重矿物。这些源边界沙丘活跃在115-105吉尔，60吉尔和12-7吉尔，这是青尼罗河特大洪水的所有时期。洪水和沙丘的沉积物是结合使用光激发发光（OSL）和放射性碳分析来确定年代的。此处讨论的尼罗河洪水的第四纪记录显示出一个进动信号，反映了ITCZ夏季风增强和北向季节性移动的发作，这与北部热带纬度的日照时间增加有关。苏丹北部全新世尼罗河河道的逐步聚集对最近8年的人类住区产生了深远的影响。 （C）2015 Elsevier Ltd.保留所有权利。

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