Tsunami sedimentary facies deposited by the Storegga tsunami in shallow marine basins and coastal lakes, western Norway
Tsunami sedimentary facies deposited by the Storegga tsunami in shallow marine basins and coastal lakes, western Norway
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DOI：
10.1046/j.1365-3091.1997.d01-63.x
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发表时间：
1997-12-01
期刊：
影响因子：
3.5
通讯作者：
Mangerud, J
中科院分区：
文献类型：
--
作者：
Bondevik, S;Svendsen, JI;Mangerud, J
位于挪威西海岸距今7000年前的海岸线以上0-11m的小型滨海湖泊中的沉积序列含有一种独特的沉积物，与上面和下面的沉积物非常不同。据解释，这一沉积物是海啸淹没沿海湖泊的结果。侵蚀不整合位于海啸相之下，并在整个盆地中被追踪，最大的侵蚀发生在湖泊的临海部分。最低的海啸相是局部含有海洋化石的分级或块状沙子。砂子向陆地方向变薄，粒度变小。上面是带有撕裂碎屑的粗有机碎屑，在这里被称为“有机砾岩”，以及较细的有机碎屑。海啸单元通常会被罚款并变薄。较高的盆地(距海岸线7000年以上6-11m)显示一个砂层，而7000年前更接近海平面的盆地可能显示由有机碎屑隔开的几个砂层。较低盆地中的这些交替可能反映了海水反复进入湖泊的浪潮。在距今7000年时低于海平面约几米的盆地中，海啸沉积的成矿性更强，通常以分级砂层的形式存在，但在一些浅海盆地中，砂层之间也存在富含有机物质的相。在大多数研究地点，海啸沉积物的总厚度为20-100厘米。建立了海啸相的侵蚀和沉积模式。
Sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year BP shoreline along the western coast of Norway, contain a distinctive deposit, very different from the sediments above and below. The deposit is interpreted to be the result of a tsunami inundating the coastal lakes. An erosional unconformity underlies the tsunami facies and is traced throughout the basins, with most erosion found at the seaward portion of the lakes. The lowermost tsunami facies is a graded or massive sand that locally contains marine fossils. The sand thins and decreases in grain size in a landward direction. Above follows coarse organic detritus with rip-up clasts, here termed 'organic conglomerate', and finer organic detritus. The tsunami unit generally fines and thins upwards. The higher basins (6-11 m above the 7000 year shoreline) show one sand bed, whereas basins closer to the sea level 7000 years ago, may show several sand beds separated by organic detritus. These alternations in the lower basins may reflect repeated waves of sea water entering the lakes. In basins that were some few metres below sea level at 7000 years BP, the tsunami deposit is more minerogenic and commonly present as graded sand beds, but also in some of these shallow marine basins organic-rich facies occur between the sand beds. The total thickness of the tsunami deposit is 20-100 cm in most studied sites. An erosional and depositional model of the tsunami facies is developed.