SEDIMENTOLOGY OF TERRIGENOUS MUD FROM THE ORANGE RIVER DELTA AND THE INNER SHELF OFF NAMAQUALAND, SOUTH AFRICA
SEDIMENTOLOGY OF TERRIGENOUS MUD FROM THE ORANGE RIVER DELTA AND THE INNER SHELF OFF NAMAQUALAND, SOUTH AFRICA
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南非奥兰治河三角洲和纳马夸兰内陆架陆源泥的沉积学
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发表时间：
1997
期刊：
影响因子：
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通讯作者：
M. Meadows
中科院分区：
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作者：
M. E. Mabote;J. Rogers;M. Meadows
摘要利用射线照相和粒度分析技术对纳马夸兰大陆架外内陆架的沉积物岩心进行了研究。粒度-频率分布显示，沉积物为多模态，以8-4μm的极细粉砂模态为主，表明弱的、向极流动的De德克尔流导致橙子河口外的陆源泥向南扩散。看来，这股水流的强度不足以输送比非常细的淤泥更粗的物质。大于63微米的物质很罕见，但可能是风暴事件的标志。沉积物中的石英和云母与纳马夸兰的半干旱气候有关，在那里，它们被从内陆向近海移动的绝热贝格风夹带。海绵骨针表明存在滤食性动物（表层动物）。浮游有孔虫可能表明与营养丰富的上升流沃茨相关的相对较高的生产力，这支持了大量的浮游生物。F的存在…
ABSTRACT Sediment cores, from the inner shelf off the Namaqualand continental shelf have been examined using radiographic and grain-size techniques. Size-frequency distributions reveal that the sediments are poly modal, with a dominant very fine-silt mode being between 8-4μm, and suggest that the weak, poleward-flowing De Decker Current causes southward dispersal of terrigenous mud off the Orange River mouth. It appears that this current is not strong enough to transport material coarser than very fine silt. Material >63μm in size is rare, but may be indicative of storm events. Quartz and mica in the sediments are related to the semi-arid climate of Namaqualand, where they are entrained by adiabatic Berg winds moving offshore from the interior. Sponge spicules indicate the presence of filter-feeding animals (epifauna). Planktonic foraminifera may be indicative of relatively high productivity associated with nutrient-rich upwelling waters, which support an enormous population of plankton. The presence of f...