Analogue sandbox modelling of the Western Subbasin, Melut Basin, South Sudan: strike-slip tectonic implications for rifting and fault sequences
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Date
2021
Authors
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Journal ISSN
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Publisher
The University of Dodma
Abstract
Melut basin is a passive rift basin that contains numerous oil-rich rift sub-basins, and it has experienced many strike-slip effects from the Central African shear zone. The multi-directional stresses of strike-slip settings have made western sub basin architecture and fault sequences complex and difficult to understand. The lack of practical structural data might have been one of the reasons for the challenging discoveries of oil and gas in the study area. Therefore, it is essential to deepen the structural data adequacy. The objective of this study is to characterize strike-slip tectonic implications for rifting and fault sequences responsible for the creation of accommodation spaces of Melut rift episodes by using analogue sandbox modelling-assisted approach to promote future exploration in the Melut Basin. Analogue modeling as a method used scales of time and length to model geodynamic evolutions. To enhance structural data adequacy, the experiments were carried out at the laboratory and set with the same basement offset 5.3cm/2.9cm, 158°/151°stepovers in the releasing and restraining bends. The analogue modelling rig was set to be displaced by the computer-controlled motor at a rate of 5mm/2min with 65mm dextral displacement motion. The analysis was done using the top views and vertical sections from the models. The experimental results show delimited uplifts and extensional collapses characterized by oblique faults with normal and thrust components, well deformed pull-apart basins, and redistributed accommodative structures for ExpS1, ExpS2, and ExpS3 respectively. The study found out that the first rift phase reflect large and subsided sedimentary layers filled by 15 mm (1.5 km in nature) and accommodated by the two normal bounding faults while the second rifting revealed less tectonic subsidence filled by 9 mm (0.9 km in the nature) deposits and held by normal bounding and tilted faults, and lastly the third rifting showed the bounding normal fault and the oblique fault with a normal component filled by 6 mm (0.6 km in the nature) sediments thickness. The exhibited trans-tensional pull-apart basin and positive flower structures display economic importance. The findings of this study are useful in the future exploration and production of oil and gas in the study area. Semi-regional seismic and extensional modelling studies are recommended to illuminate structural styles.
Description
Dissertation (MSc Petroleum Geosciences)
Keywords
Melut basin, Oil, Sub-basins, Architecture, Gas, Sandbox, Strike-slip
Citation
Duot, J. B. (2021). Analogue sandbox modelling of the Western Subbasin, Melut Basin, South Sudan: strike-slip tectonic implications for rifting and fault sequences (Master's Dissertation). The University of Dodoma, Dodoma.