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Confined to Sub-confined Synrift Lacustrine Axial Delta -Modern Environment Observation in Lake Singkarak, Sumatra
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 79th EAGE Conference and Exhibition 2017, Jun 2017, Volume 2017, p.1 - 5
Abstract
Lake Singkarak is a pull-apart basin in West Sumatra, Indonesia, formed by the great Sumatran strike-slip fault system. Along the lake boundary, it consists series of minor normal faults which are parallel to the NNW-SSE of regional fault trend. Most of these faults are situated in northern part of the lake, formed confined fluvial depositional environment and produce Sumpur Delta as pure fluvial delta and become as the largest axial drainage system. The other major axial stream is known as Sumani Delta, that is located in south-eastern part of the lake. With lower faults frequency, sub-confined depositional environment was formed, resulted more open accommodation space and produce a fluvial-meandering delta.
An intensive field study has been performed by investigating data from various elements. Integration of grain texture, depositional facies, fluvial geomorphology and stratigraphic stacking patterns then resulted complete facies model of Sumpur Delta and Sumani Delta. Facies comparison is also established in order to understand the relationship between confined-subconfined environment to their facies product (variation, heterogeneity, distribution and morphology). Based on this study, axial lacustrine delta in Lake Singkarak are interpreted to be linked with the development of the accommodation space, which is controlled by the basin structural evolution.