Pollen and Spores in Marine Sediments from the East Atlantic -A View from the Ocean into the African Continent
Pollen and Spores in Marine Sediments from the East Atlantic -A View from the Ocean into the African Continent
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东大西洋海洋沉积物中的花粉和孢子——从海洋到非洲大陆的视野
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发表时间：
1999
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通讯作者：
L. Dupont
中科院分区：
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作者：
L. Dupont
介绍了西非地区海洋孢粉学研究的选定结果。重点是花粉粒从大陆到海洋的风和河流运输。从大陆到海洋的运输过程的相对重要性因地区而异。风成花粉输送到大西洋的花粉占西北非海洋沉积物中发现的花粉的主要部分。在几内亚湾和安哥拉盆地沿岸的陆架上，特别是在河口附近，花粉的传播主要是河流。东北信风将花粉从地中海南部和撒哈拉北部吹向西南和南部。非洲东风急流将花粉从撒哈拉南部和萨赫勒地区输送到东大西洋。由于冰期南向信风输送量大幅增加，西向非洲东风急流输送量保持纬度稳定。覆盖过去 150ka 的从北纬 30° 到南纬 12° 的岩心横断面提供了邻近非洲大陆植被历史的信息。在第6和第1冰期期间，地中海西南部地区的地中海森林急剧减少或完全消失，并被开阔的草原状植被所取代。撒哈拉-萨赫勒边界在北纬 15°（第 6,2 阶段和第 5d 阶段期间）和北纬 23°（第 5e 阶段期间）之间迁移。在第 1 和第 5 阶段，雨林分布广泛，但在第 3 和第 4 阶段，尤其是在第 2 和第 6 阶段，雨林面积大幅减少，此时开阔、草木茂盛的植被盛行。冰川雨林保护区位于几内亚山脉西南部和几内亚湾东海岸。 Miombo 林地在第 5 阶段扩大。Afromontane 罗汉松森林在第 5d 和 5b 阶段出现最大的扩张。第五阶段之后，几内亚山区不再出现罗汉松。
Selected results of marine palynological studies for the West African region are presented. Emphasis is laid on the aeolian and fluvial transport of pollen grains from the continent to the ocean. The relative importance of transport processes from the continent to the ocean varies from region to region. Aeolian pollen transport to the Atlantic accounts for a major proportion of the pollen found in marine sediments off Northwest Africa. On the shelves along the Gulf of Guinea and the Angolan Basin, particularly in the vicinty of river mouths, pollen transport is predominantly fluvial. NE-trade winds drift pollen from the southern Mediterranean and the northern Sahara southwest- and southwards. The African Easterly Jet transports pollen from the southern Sahara and the Sahel to the eastern Atlantic. As the southward trade-wind transport strongly increased during glacial stages, the westward African Easterly Jet transport stayed latitudinally stable. A transect of cores from 30°N to 12°S covering the last 150 ka provides information of the vegetation history of the adjacent African continent. During glacial Stages 6 and 1, the Mediterranean forest strongly declined or disappeared completely from the southwest Mediterranean area and was replaced by an open steppe-like vegetation. The Saharan-Sahelian boundary migrated between 15°N (during Stages 6,2 and Substage 5d) and 23°N (during Substage 5e). The rain forest was widespread during Stages 1 and 5, but strongly reduced during Stages 3 and 4 and especially during Stages 2 and 6 when open, grass-rich vegetation prevailed. Glacial rain forest refuges are found in the southwest of the Guinean mountains and along the eastern coast of the Gulf of Guinea. Miombo woodland expanded during Stage 5. Afromontane Podocarpus forests had their largest expansion during Substages 5d and 5b. Podocarpus did no longer occur in the Guinean mountains after Stage 5.