THE RELATION BETWEEN TECTONIC ACTIVITY AND SEDIMENTARY FRAMEWORK:EVIDENCE FROM THE LAKE ALBERT, EAST AFRICAN RIFT SYSTEM

The Lake Albert is a rift basin with large hydrocarbon potential as a part of the East African Rift System. The study of lake geology is limited for lacking of data. The sedimentation under the tectonic background remains unclear up to date.This paper is devoted to the basin tectonics and lake sedimentation based on logging, drilling, seismic data and the data from Google Earth. The Lake Albert is an unsymmetrical graben formed under active tectonics. A steep normal fault occurs in the west and a gentle slope in the east.Three major facies occur as infillings in the lake, i.e. the deep lacustrine, the shallow lacustrine and delta deposits consisting of deltaic plain and deltaic front. Structures have obvious control over the sedimentation pattern. Sediments came from the north side where fluvial and deltaic deposits prevailed.The first phase of rifting was characterized by strong tectonic activity on the northwest side of the lake, and in the second phase fan-delta and braid river delta facies developed astectonic activities weakened. Sediments were supplied from the southeast and northeast sides of the lake and dominated by fluvial fan delta and braid river delta deposits.There are two major transverse fault zones in the Lake Albert, a synthetic overlapping zone and a convergent collateral zone.The structural pattern of the fault assemblage formed in a relatively low position, which is the dominant path of transportation.Above all, the transverse fault zones have obvious control over the distribution pattern of depositional system.