This paper analyzes throw-depth (T-z) profiles from a high resolution 2D reflection seismic grid in the central basin of Lake Malawi to investigate whether evidence exists: 1) for migration of faulting away from the border fault of the half-graben; and 2) that faults in the hangingwall lengthened over the last 1.3 million years. We use the high-precision age model from a 2005 scientific drilling project in our study area to constrain the ages of our seismic horizons and examine a fault array and two individual faults within the hangingwall of the central basin border fault. We account for climatic and sedimentological controls on stratal growth with a lake-level curve that accompanies the age model. A comparison of our hangingwall T-z profiles with published throw-distance (T-x) profiles for the border fault shows synchronous faulting over the last 1.3 m.y. rather than basinward migration of faulting. Furthermore, we find no evidence for significant propagation of the tips of the hangingwall faults in the last 1.3 m.y. and conclude that the lack of basinward migration of faulting is a consequence of strain localization on faults established at an early stage in basin development.
Bibliographical noteFunding Information:
We thank reviewers Atle Rotevatn and Oliver Duffy and Editor William M. Dunne for their constructive reviews of this manuscript. We thank Jeff Karson, Dan Curewitz, Donna Shillington and Rob Moucha for their discussions and feedback on earlier drafts of the manuscript. ProMax processing software and Decision Space interpretation software made available to Syracuse University through a software grant from Landmark Solutions. Financial support for the project was provided from the U.S. National Science Foundation grant EAR1110882 to CAS, and from sponsors of the Syracuse University Lacustrine Rift Basin Industrial Associates .
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- Border fault migration
- East African Rift System
- Malawi (Nyasa) Rift
- Syndepositional faulting
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