Coarse-Clastic Facies and Stratigraphic Sequence Models from Lakes Malawi and Tanganyika, East Africa: Chapter 9
Coarse-Clastic Facies and Stratigraphic Sequence Models from Lakes Malawi and Tanganyika, East Africa: Chapter 9
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发表时间：
1990
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通讯作者：
C. Scholz;B. Rosendahl
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作者：
C. Scholz;B. Rosendahl
东非裂谷系西支马拉维湖和坦噶尼喀湖的地震反射数据揭示了多种粗粒沉积相。这些相包括邻近边界断层的扇三角洲和斜坡裙、深水湖底扇和河道系统、低位三角洲以及一系列碎屑和碳酸盐滨海沉积物。每一个都位于半地堑内的特定区域，并在湖面变化周期内的特定时间发育。热带地区的裂谷湖对水位波动高度敏感。高幅度和高频的湖面变化可能导致沉积层序和相结构比被动边缘更加复杂。对层序发育的控制，例如沉积物供应和湖水位变化，可能比被动边缘更紧密地结合在一起。进积斜形沉积组合在这些盆地中并不常见，可能是因为相对于湖泊表面积而言，流域面积较小，而且盆地边缘的坡度梯度较高。在这些地震数据中，侵蚀截断面比下重叠面更容易观察到。
Seismic-reflection data from Lakes Malawi and Tanganyika in the western branch of the east African rift system reveal a variety of coarse-grained depositional facies. These facies include fan deltas and slope aprons adjacent to border faults, deep-water sublacustrine fans and channel systems, lowstand deltas, and an array of clastic and carbonate littoral deposits. Each is located in specific areas within half-grabens and develops at specific times within the cycle of lake-level variations. Rift lakes in tropical settings are highly sensitive to level fluctuations. High-amplitude and high-frequency lake-level variations may cause the resulting depositional sequence and facies architecture to be more complex than on passive margins. Controls on sequence development, such a sediment supply and lake-level variation, may be more closely coupled than on passive margins. Progradational clinoform depositional packages are uncommon in these basins probably because of the small size of catchments relative to lake surface areas and because of high slope gradients on the basin margins. Erosional truncation surfaces are more readily observed in these seismic data than are downlap surfaces.