Age determination of sediment cores from the shelf off Mauretania, West Africa

The 60 km wide shelf off Mauritania is cut by several submarine canyons. Its water-circulation is controlled by the cool Canary current and upwelling.
Its Recent sediments show faunal associations remarkably related to the grain size distribution which in water depths between 40 and 80 m is strongly influenced by reworking of older coarse sand or sandstone. In this depth range a mixed biofacies originating from Pleistocene and Recent material is encountered. The present lateral faunistic and sedimentological facies change, including horizons of mixed provenance, can be recognized in vertical sequences taken by vibro-coring. This correlation combined with 14C-datations on molluscs enable the reconstruction of the history of the last glacial regression and transgression.
Due to the arid climate, the emerging calcareous shelf sediments are indurated and, therefore, protected from subaerial and submarine erosion. During low sea level eolian sand migrates over the shelf, but only about 1/10 of this material remains there and is later incorporated into the sandy shelf sediments. The calculated average rate of total sedimentation during Holocene is 15 cm, and the production rate of carbonate is 5 cm/1000 years.

毛里塔尼亚沿岸60千米宽的大陆架被数条海底峡谷切割。该区域的水循环受寒冷的加那利洋流（Canary Current）与上升流共同控制。
其现代沉积物中的生物群组合与粒度分布显著相关；在水深40至80米的区域，粒度分布强烈受到早期粗砂或砂岩再改造作用的影响。在此水深范围内，可见源自更新世与现代物质的混合生物相。当前的侧向生物组合与沉积相变化（包含多物源层位）可通过振动取芯获取的垂直沉积序列识别。结合软体动物的14C测年数据，该地层相关性可用于重建末次冰期的海退与海进历史。
由于气候干旱，出露的钙质大陆架沉积物发生固结硬化，因此免受陆上与海底侵蚀。在海平面低位时期，风成砂搬运至大陆架之上，但仅约1/10的物质留存于此，并最终混入砂质大陆架沉积物中。全新世时期的总沉积平均速率经测算为15厘米，碳酸盐生成速率为5厘米/千年。