Climatic control of the late Quaternary turbidite sedimentology of Lake Kivu, East Africa: Implications for deep mixing and geologic hazards
Climatic control of the late Quaternary turbidite sedimentology of Lake Kivu, East Africa: Implications for deep mixing and geologic hazards
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DOI：
10.1130/g35818.1
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发表时间：
2014-09
期刊：
影响因子：
5.8
通讯作者：
Xuewei Zhang;C. Scholz;R. Hecky;D. Wood;H. Zal;C. Ebinger
中科院分区：
文献类型：
--
作者：
Xuewei Zhang;C. Scholz;R. Hecky;D. Wood;H. Zal;C. Ebinger
东非大裂谷的基伍湖流域遭受各种地质灾害，包括频繁的火山喷发、地震以及潜在的湖泊翻转和排气事件。高分辨率地震反射数据、14 C测年沉积岩芯和湖底测深数据的综合揭示了该湖东部盆地的大型轴向和横向浊积岩系统。浊积岩是特大洪水期间异重河水的来源，浊积岩的出现时间受到气候控制。过去~12 k.y.的浊积岩记录与热带东非的区域古水文记录相关。我们的研究表明，深湖中保存的洪水引入的浊积岩是水文变化的指标，基伍湖近期历史上的极端洪水可能引发了深度混合事件。这项研究对基伍湖目前的脱气工作也有影响；异常浊流可能引发潜在的地质灾害，在设计和部署天然气开采设施时需要考虑这一点。
The Lake Kivu catchment in the East African Rift is subject to various geologic hazards, including frequent volcanic eruptions, earthquakes, and potential limnic overturns and degassing events. Integration of high-resolution seismic reflection data, 14 C dated sediment cores, and lake-floor bathymetry reveals large axial and transverse turbidite systems in the eastern basin of the lake. The turbidites were sourced by hyperpycnal river flows during exceptional floods, and the temporal occurrence of the turbidites was climatically controlled. The turbidite record over the past ∼12 k.y. is correlated with the regional paleohydrologic records from tropical East Africa. Our study suggests that flood-introduced turbidites preserved in deep lakes are indicators of hydrological changes, and that extreme floods in Lake Kivu9s recent history may have triggered deep mixing events. This study also has implications for the current degassing efforts in Lake Kivu; potential geologic hazards may be triggered by extraordinary turbidity currents, and need to be considered in the design and deployment of gas extraction facilities.