Discriminating models of rift mechanics using transient river profiles in extensional footwalls
Abstract
Assessments of rift mechanics and normal fault geometries at depth derived from the patterns of uplift in footwalls and rift flanks are almost exclusively attained through modelling efforts. Here, we explore longitudinal river profile morphologies associated with rift flank uplift patterns of commonly proposed extension mechanisms and compare results to fluvial topography in the Corinth Rift. We first use a detachment-limited stream power incision model to study river profile morphologies derived from uniform and non-uniform uplift, with flexural and linear uplift decay, for single and multiple faults. We then compare our results to the morphology of footwall river profiles along the uplifting southern flank of the rapidly-extending, asymmetric Corinth Rift. River profiles and χ-plots of footwall rivers are consistent with stream power models of transient river incision in response to flexural uplift along a single fault. The elastic flexure that dominates the present mode of extension along the current rift flank is maximal in the rift centre and decays (i) to the west, where transient river profiles exhibit a morphology consistent with relatively lower rates of flexural uplift and there exists evidence for active drainage reorganization, and (ii) to the east, where river profiles are still adjusting but near equilibrium with the modern displacement field. These changes in river morphology along the rift flank and the lateral extent of flexure along strike (~100 km) suggest that the master fault dominating rift growth has either progressively lower rates of footwall flexural uplift or successively later onset of faulting away from the fault center. These observations are at variance with Corinth Rift models of protracted extension and parallel basinward-migrating faults that may or may not be linked to a shallow detachment at depth. We conclude that longitudinal river profiles help evaluate not only the mechanics at play in continental interiors under extension but also lateral and temporal variations in fault growth history.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMEP31C2289F
- Keywords:
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- 1815 Erosion;
- HYDROLOGY;
- 1824 Geomorphology: general;
- HYDROLOGY;
- 8175 Tectonics and landscape evolution;
- TECTONOPHYSICS;
- 8177 Tectonics and climatic interactions;
- TECTONOPHYSICS