@article{a12de75565814695803cbc540f0ae9cc,
title = "Constraints on Rift Basin Structure and Border Fault Growth in the Northern Malawi Rift From 3-D Seismic Refraction Imaging",
abstract = "We present new constraints on rift basin structure in the northern Malawi Rift from a 3-D compressional velocity model to investigate border fault geometry, accommodation zone structure, and the role of preexisting structures underpinning this rift system. The velocity model uses observations from the first wide-angle refraction study conducted using lake-bottom seismometers in one of the East African great lakes. The Malawi Rift is flanked by basin-bounding border faults and crosses several significant remnant structures, making it an ideal location to investigate the development of normal faults and their associated basins. The 3-D velocity model reveals up to ~5 km of synrift sediments, which smoothly transition from eastward thickening against the Livingstone Fault in the North Basin to westward thickening against the Usisya Fault in the Central Basin. Greater than 4 km of sediment are imaged within the accommodation zone pointing to the early development of the border faults. We use new constraints on synrift sediment thickness to construct displacement profiles for both faults. Both faults accommodate large throws (>7 km) consistent with their significant lengths. The dimensions of these faults are close to or larger than the maximum size predicted by models of fault growth. The presence of an intermediate velocity unit with velocities of 3.75–4.5 km/s is interpreted to represent sediment deposits beneath Lake Malawi from prior rifting in the Permo-Triassic (Karoo) and/or Cretaceous-Paleogene. The distribution of preexisting basins implied by these sediments may help account for changes in intrabasinal faulting and border fault development between the two basins.",
author = "Accardo, {N. J.} and Shillington, {D. J.} and Gaherty, {J. B.} and Scholz, {C. A.} and Nyblade, {A. A.} and Chindandali, {P. R.N.} and G. Kamihanda and T. McCartney and D. Wood and {Wambura Ferdinand}, R.",
note = "Funding Information: The authors gratefully acknowledge all of those involved in the successful acquisition of this large and complex experiment. Acquisition of this data set would not have been possible without the support from communities in our study area, national and regional governmental entities in Malawi and Tanzania, and administrative and technical support from institutes, companies, and geological surveys in the United States, Malawi, Tanzania, Denmark, and Canada. We gratefully acknowledge the captains and crews of the Katundu, Ndunduma, and Chilembwe and the entire science party that helped to acquire this data set. Instruments were provided by the Ocean Bottom Seismology Instrumentation Program (OBSIP) from the Scripps Institute of Oceanography (SIO). We particularly acknowledge Jeff Babcock, Ernest Aaron, Mark Gibaud, Martin Ripa, and others at the SIO Institutional Instrument Contributor. We gratefully acknowledge Per Trinhammer from Aarhus University and Jack Schelling for their incredible help with seismic source operations. We also thank Jacob Greenberg for his help with onboard ship operations. We thank Cynthia Ebinger and Jean-Arthur Olive for very useful discussions regarding this work. Seismic data used in this study are available through the Incorporated Research Institutions for Seismology Data Management Center (http://ds.iris.edu/ds/nodes/dmc/), network code YQ. Data were processed using Seismic Unix maintained by John Stockwell (http://www.cwp.mines.edu/cwpcodes/) and picked using OpendTect (https://www.opendtect.org/). This research was supported by National Science Foundation (NSF) grant EAR-1110921, Lamont-Doherty Earth Observatory, and the NSF Graduate Student Research Fellowship Program. We also thank Lindsay Worthington, Jolante van Wijk, Uri Ten Brink, and an anonymous reviewer for insightful reviews that strengthened this manuscript. Funding Information: The authors gratefully acknowledge all of those involved in the successful acquisition of this large and complex experiment. Acquisition of this data set would not have been possible without the support from communities in our study area, national and regional governmental entities in Malawi and Tanzania, and administrative and technical support from institutes, companies, and geological surveys in the United States, Malawi, Tanzania, Denmark, and Canada. We gratefully acknowledge the captains and crews of the Katundu, Ndunduma, and Chilembwe and the entire science party that helped to acquire this data set. Instruments were provided by the Ocean Bottom Seismology Instrumentation Program (OBSIP) from the Scripps Institute of Oceanography (SIO). We particularly acknowledge Jeff Babcock, Ernest Aaron, Mark Gibaud, Martin Ripa, and others at the SIO Institutional Instrument Contributor. We gratefully acknowledge Per Trinhammer from Aarhus University and Jack Schelling for their incredible help with seismic source operations. We also thank Jacob Greenberg for his help with onboard ship operations. We thank Cynthia Ebinger and Jean-Arthur Olive for very useful discussions regarding this work. Seismic data used in this study are available through the Incorporated Research Institutions for Seismology Data Management Center (http://ds.iris.edu/ds/nodes/dmc/), network code YQ. Data were processed using Seismic Unix maintained by John Stockwell (http://www.cwp.mines.edu/ cwpcodes/) and picked using OpendTect (https://www.opendtect. org/). This research was supported by National Science Foundation (NSF) grant EAR-1110921, Lamont-Doherty Earth Observatory, and the NSF Graduate Student Research Fellowship Program. We also thank Lindsay Worthington, Jolante van Wijk, Uri Ten Brink, and an anonymous reviewer for insightful reviews that strengthened this manuscript. Publisher Copyright: {\textcopyright}2018. American Geophysical Union. All Rights Reserved.",
year = "2018",
month = nov,
doi = "10.1029/2018JB016504",
language = "English (US)",
volume = "123",
pages = "10,003--10,025",
journal = "Journal of Geophysical Research: Oceans",
issn = "2169-9275",
publisher = "Wiley-Blackwell",
number = "11",
}