Climate and sea level induced turbidite activity in a canyon system offshore the hyperarid Western Sahara (Mauritania): The Timiris Canyon
Climate and sea level induced turbidite activity in a canyon system offshore the hyperarid Western Sahara (Mauritania): The Timiris Canyon
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DOI：
10.1016/j.margeo.2010.05.011
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发表时间：
2010-09
期刊：
影响因子：
2.9
通讯作者：
R. Henrich;Y. Cherubini;H. Meggers
中科院分区：
文献类型：
--
作者：
R. Henrich;Y. Cherubini;H. Meggers
研究毛里塔尼亚外海蒂米里斯峡谷沉积档案的一个主要成果是，撒哈拉腹地的气候变化不仅影响了近海远洋沉积过程，而且控制了峡谷系统的浊流活动。沉积物供应的斜坡，主要是由风成尘和再流动的风成沙，是最大的在超干旱的冰川和冰消期，由于整体增加贸易风强度，上升流引起的远洋生产力达到最高幅度。蒂米里斯峡谷的浊流活动对大陆坡周围沉积状况的这些变化迅速作出反应。在高冰期和早期冰消期，最高坡的支流冲沟被迅速和重复填充，随后浊流被释放，大湍流通过较低的蒂米里斯峡谷，导致溢出序列的堤坝。除了这种情况下，在MIS 3连续海平面上升暴露的外大陆架的部分洪水可能会导致重新动员巨大的风成沙丘领域，在冰川暴露期间扩大到接近大陆架边缘。在全新世期间，没有浊流活动记录在较低的Timiris峡谷，而从一个扩大的地区，在上Timiris峡谷核心揭示了一个有趣的气候控制的900年的周期性的碳酸盐和泥浊流事件在整个全新世。
A major outcome from studying the sedimentary archives of the Timiris Canyon off Mauritania is that climate shifts in the Saharan hinterland not only influenced offshore pelagic sedimentation processes, but also controlled turbidite activity in the canyon system. Sediment supply to the slope, predominantly by eolian dust and remobilised eolian sands, was greatest during hyperarid glacial and deglacial periods and, due to overall increased Trade wind strengths, upwelling induced pelagic productivity attained highest magnitudes. Turbidite activity in the Timiris Canyon responded rapidly to these shifts in the surrounding sedimentary regime on the continental slope. During high-glacial and early deglacial times, the tributary gullies on the uppermost slope were rapidly and repetitively filled, subsequently turbidity currents were released and large turbulent flows passed through the lower Timiris Canyon, leading to overspill sequences on its levees. In addition to this scenario, partial flooding of the exposed outer shelf during successive sea-level rises in MIS 3 may have caused re-mobilization of huge aeolian dune fields, that had expanded close to the shelf edge during glacial exposure. During the Holocene, no turbidite activity is recorded in the Lower Timiris Canyon, whereas a core from a widened area in the Upper Timiris Canyon reveals an interesting climate controlled 900-year cyclicity of carbonate- and mud-turbidite events throughout the Holocene.