TY - JOUR
T1 - Evolution of the Kivu Rift, East Africa
T2 - interplay among tectonics, sedimentation and magmatism
AU - Wood, Douglas A.
AU - Zal, Hubert J.
AU - Scholz, Christopher A.
AU - Ebinger, Cynthia J.
AU - Nizere, Irénée
N1 - Funding Information:
We are grateful to C. Magee, an anonymous reviewer, and editor C. Jackson for insightful and constructive reviews. We thank the Government of Rwanda for permission to conduct this research, and to colleagues from the Ministry of Natural Resources, the University of Rwanda (formerly Kigali Institute of Science and Technology), and Kivuwatt Ltd. for assistance with various aspects of the field program. Financial support for the project was provided by the MacArthur Foundation and Vanoil Energy Ltd. The land-based seismic instruments were provided by the Incorporated Research Institutions for Seismology (IRIS) through the PASSCAL Instrument Center at New Mexico Tech. Data collected during this experiment are available through the IRIS Data Management Center. IRIS facilities are supported by the U.S. National Science Foundation under Cooperative Agreement EAR-0552316 and by the Department of Energy National Nuclear Security Administration. MCS data processing and interpretation at Syracuse University used software provided on a grant from Landmark Graphics Corporation. We gratefully acknowledge field assistance from P. Cattaneo, J. Greenberg, J. Corbett, E. Kabende and V. Rugambage, and the crew of the R/V Kilindi. We extend special thanks to A. Vodacek for his leadership of the MacArthur Foundation project, and to A. Nsabimana, D. Mburu, R. Hecky, M.-C. Gasingirwa, A. Umutoni, U. Rutagarama, N. Hakizamungu for their support and scientific collaborations. Finally we thank the people of Kibuye, Rwanda for offering a warm and welcoming base for field operations.
Publisher Copyright:
© 2015 The Authors. Basin Research © 2015 John Wiley & Sons Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists
PY - 2017/2/1
Y1 - 2017/2/1
N2 - The seismically and volcanically active Kivu Rift, in the western branch of the East African Rift System, is a type locale for studies of high-elevation, humid-climate rift basins, as well as magmatic basin development. Interpretations of offshore multi-channel seismic (MCS) reflection data, terrestrial radar topography, lake bathymetry and seismicity data recorded on a temporary array provide new insights into the structure, stratigraphy and evolution of the Kivu rift. The Kivu rift is an asymmetric graben controlled on its west side by a ca. 110 km-long, N-S striking border fault. The southern basins of the lake and the upper Rusizi river basin are an accommodation zone effectively linking 1470 m-high Lake Kivu to 770 m-high Lake Tanganyika. MCS data in the eastern Kivu lake basin reveal a west-dipping half graben with at least 1.5 km of sedimentary section; most of the ca. 2 km of extension in this sub-basin is accommodated by the east-dipping Iwawa normal fault, which bounds an intrabasinal horst. Lake Kivu experienced at least three periods of near desiccation. The two most recent of these approximately correlate to the African Megadrought and Last Glacial Maximum. There was a rapid lake level transgression of at least 400 m in the early Holocene. The line load of the Virunga volcanic chain enhances the fault-controlled basin subsidence; simple elastic plate models suggest that the line load of the Virunga volcanic chain depresses the basin by more than 1 km, reduces flank uplift locally and broadens the depocentre. Not only do the voluminous magmatism and degassing to the lake pose a hazard to the riparian population, but our studies demonstrate that magmatism has important implications for short-term processes such as lake levels, inflow and outlets, as well as long term modification of classic half-graben basin morphology.
AB - The seismically and volcanically active Kivu Rift, in the western branch of the East African Rift System, is a type locale for studies of high-elevation, humid-climate rift basins, as well as magmatic basin development. Interpretations of offshore multi-channel seismic (MCS) reflection data, terrestrial radar topography, lake bathymetry and seismicity data recorded on a temporary array provide new insights into the structure, stratigraphy and evolution of the Kivu rift. The Kivu rift is an asymmetric graben controlled on its west side by a ca. 110 km-long, N-S striking border fault. The southern basins of the lake and the upper Rusizi river basin are an accommodation zone effectively linking 1470 m-high Lake Kivu to 770 m-high Lake Tanganyika. MCS data in the eastern Kivu lake basin reveal a west-dipping half graben with at least 1.5 km of sedimentary section; most of the ca. 2 km of extension in this sub-basin is accommodated by the east-dipping Iwawa normal fault, which bounds an intrabasinal horst. Lake Kivu experienced at least three periods of near desiccation. The two most recent of these approximately correlate to the African Megadrought and Last Glacial Maximum. There was a rapid lake level transgression of at least 400 m in the early Holocene. The line load of the Virunga volcanic chain enhances the fault-controlled basin subsidence; simple elastic plate models suggest that the line load of the Virunga volcanic chain depresses the basin by more than 1 km, reduces flank uplift locally and broadens the depocentre. Not only do the voluminous magmatism and degassing to the lake pose a hazard to the riparian population, but our studies demonstrate that magmatism has important implications for short-term processes such as lake levels, inflow and outlets, as well as long term modification of classic half-graben basin morphology.
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U2 - 10.1111/bre.12143
DO - 10.1111/bre.12143
M3 - Article
AN - SCOPUS:84933579132
SN - 0950-091X
VL - 29
SP - 175
EP - 188
JO - Basin Research
JF - Basin Research
ER -