Implications of the Precambrian lineaments on the Red Sea tectonics based on Landsat study of northeast Sudan

Abstract

Lineament analysis of a Landsat Imagery mosaic (scale 1:1,000,000) of northeast Sugdan indicate significant curvilinear as well as rectilinear fracture patterns of possible Precambrian age. Rectilinear features trend dominantly in N-S (± 10°), NNW and ENE, and less commonly in NW and EW directions. The Precambrian fractures closely match, and have possibly accommodated the Tertiary structures of the Red Sea rift. Projection of the ENE continental fractures offshore on the basis of a modified trend due to rift movements, and "principle of equidistances," corresponds with apparently more precise locations of possible transverse faults. Projections of the proposed transverse faults generally conform with breaks in bathymetric contours, and azimuth trend of the axial trough. Hot brine pools, shallow focus epicenters and anomalous heat flow measurements, all tend to lie at or close to the intersection of the transverse faults and axis of the deep waters. The transverse faults exhibit a general N35-50°E trend as compared with the N60-70_Etrend of the ancestor continental fractures. Deflection in trend caused by faults coinciding with the presnet shore line, may indicate lateral displacement prior to the initial hase of rifting in Miocene times. It also supports the hypothesis of a "two-phase rifting" of the Red Sea. Spreading movements proposed along transverse faults with trend values exceeding N50°E may not be applicable, at least for the more recent separation movements.