Propagation history and passive rotation of mesoscale normal faults: implications for synrift stratigraphic development |
| |
| Authors: | I R Sharp R L Gawthorpe B Armstrong & J R Underhill |
| |
| Institution: | Basin and Stratigraphic Studies Group, Department of Earth Sciences, The University, Oxford Road, Manchester M13 9PL, UK;Department of Geology and Geophysics, The University of Edinburgh, Grant Institute, The King's Buildings, West Mains Road, Edinburgh EH9 3JW, UK |
| |
| Abstract: | Field data from onshore exposures of the Oligo-Miocene Gulf of Suez Rift in the Sinai document the passive rotation of early formed mesoscale synthetic and antithetic faults and associated half-graben due to long-lived activity on large displacement (2–5 km) block-bounding faults. Early formed small-displacement (<350 m) mesoscale antithetic faults and half-graben within regional-scale fault blocks underwent progressive steepening due to footwall uplift, rotational faulting and footwall flexing on large-displacement, block-bounding faults. In contrast, mesoscale synthetic faults were progressively rotated to shallower angles. Analysis of palaeohorizontal surfaces within synrift sediments deposited in half-graben adjacent to the mesoscale faults indicate passive rotations of up to 25° about horizontal axes since deposition. Passive burial and in-filling of early formed mesoscale faults and half-graben by synrift sediments is consistent with extension being transferred from numerous mesoscale faults to few block-bounding macroscale faults as extension preceded. Furthermore, this transfer of extension appears to be associated with a marked change in basin configuration, synrift sediment dispersal patterns and facies development. Identification of early formed, passively rotated normal faults and half-graben is important for correctly reconstructing the early stages of basin palaeogeography and sediment dispersal, and for addressing models of rift basin evolution. |
| |
| Keywords: | |
|
|
