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Heavy mineral composition and texture of the recently formed fluvial delta sediment of Lake Nasser/Nubia, Egypt and Sudan
International Journal of Sediment Research ( IF 3.5 ) Pub Date : 2021-07-19 , DOI: 10.1016/j.ijsrc.2021.07.002
Omran E. Frihy 1 , Essam A. Deabes 1 , Abdelaleem A. Abudia 2 , Ahamed Adawi 1
Affiliation  

Surficial sediment samples collected from the recently formed fluvial delta in Lake Nasser/Nubia (Egypt and Sudan) in conjunction with data on bottom current and depth soundings are examined to interpret hydraulic-sorting processes and transport/depositional patterns. The ~500 km long northeastward-trending lake, lies within Egypt and Sudan, is created as a result of the construction of the Aswan High Dam in 1964. The original grain-size distribution and heavy mineral compositions of these samples help to characterize the classical depositional features of the recently formed underwater delta-front and prodelta depocenters. Starting from the south, those delta-front deposits, which floor most of the narrow-shallow basin of Lake Nubia, are characterized by thick coarse-grained sandy deposits, rich in heavy minerals (averaged 12.8%). This delta-front is followed to the northeast by thin layers of prodelta mud, poor in heavy mineral contents (averaged 0.6%). These layers cover the entire broad basin of Lake Nasser. The northeasterly downslope fining-trend, along with a continuous decrease in heavy mineral composition, along the length of the lake, are attributable to processes of grain sorting, which take place due to contrasting densities and grain sizes. These processes lead to the concentration of heavy mineral placer, mostly in the delta-front samples. The sorting mechanism, in turn, is controlled by the interplay of unidirectional-directed northeastward current, physiographic characteristics of the lake, including topographic configuration, geometry (cross-section), and floor topography (slope gradient). In terms of mineral exploration, the highest proportion of mineral grades in the delta-front sediments is likely to be considered as a viable source for economic placers that require more planning initiatives for industrial and commercial evaluation.



中文翻译:

最近形成的纳赛尔湖/努比亚、埃及和苏丹河流三角洲沉积物的重矿物组成和质地

从最近形成的纳赛尔湖/努比亚(埃及和苏丹)河流三角洲收集的地表沉积物样本结合底流和深度探测的数据进行了检查,以解释水力分选过程和运输/沉积模式。约 500 公里长的东北向湖位于埃及和苏丹境内,是 1964 年阿斯旺高坝建设的结果。这些样品的原始粒度分布和重矿物组成有助于表征经典最近形成的水下三角洲前缘和前三角洲沉积中心的沉积特征。从南部开始,这些三角洲前缘沉积物覆盖了努比亚湖窄浅盆地的大部分,其特征是厚厚的粗粒砂质沉积物,富含重矿物(平均 12.8%)。该三角洲前缘在东北部是薄薄的前三角洲泥层,重矿物含量低(平均 0.6%)。这些层覆盖了整个纳赛尔湖的广阔盆地。沿湖长度向东北下坡的细化趋势以及重矿物组成的持续减少可归因于由于密度和粒度大小不同而发生的谷物分选过程。这些过程导致重矿物砂矿的集中,主要集中在三角洲前缘样品中。分选机制反过来又受单向东北流与湖泊地貌特征的相互作用控制,包括地形配置、几何形状(横截面)和底面地形(坡度梯度)。在矿产勘探方面,

更新日期:2021-07-19
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