リモートセンシングとGISのジャーナル

概要

Evolution and Architecture of Blue Nile Basin Using Integrated Gravity,Reflection Seismic and Wire Line Logs

Mohamed NE*, Mohamed Ali OM, Zaroug I and Ibrahim AE

Parts of the Blue Nile basin showed good oil indications a decade ago, the puzzling question is why no oil draining. The common geological sense will go towards the lateral lithologic variations and its impacts on the porosity and permeability and thus towards the dynamics of the processes that governs and generate this architecture and the modes of its development. This study aims to reveal the basin architecture and its evolution, and it strongly suggests the application of constrained 2D backstripping technique using process oriented gravity modeling (POGM) technique and use the discrimination between the rift and sediment anomalies. By decompaction stratigraphic seismic sections, isostasy, recover the geometry of the crust at time of rift, calculating and adding the contribution of sediments and water to rift gravity anomaly, compare between the observed free air and the calculated gravity. POGM technique results a good discrimination between sediment and rift gravity contributions, and a value of 45 km thickness of elastic lithosphere, which is used to constrain the backstripping technique. Results from the backstripping shows the basin is a half graben type, the extension factor varies from 1.04 up to 1.1, which is accommodated by listric normal fault and the rotated blocks which compromise the hanging wall and developed to be the basin. The relative movement between these blocks and the foot wall goes different behaviors from acting independently to act as one unit this interplay change the normal faults into reverse faults, made temporal segmentation of the basin, relief, internal drainage patterns and migration of basin depocentre. From a tectonostratigraphic point of view, the Blue Nile basin evolution is given by different paleoenviroments and their positions in terms of time and space are controlled by interplay of sediment supply and basin capacity which are climatic and structural/thermal subsidence dependents respectively.