Abstract
The East African Rift Systems (EARS) exerted a major influence on river drainage basins and regional climate of east Africa during the Cenozoic. Recent studies have highlighted an offshore branch of the EARS in the western Indian Ocean, where the Kerimbas Graben and the Davie Ridge represent its sea floor expression. To date, a clear picture of the impact and timing of this EARS offshore branch on the continental margin of the western Indian Ocean, and associated sediment dispersal pathways, is still missing. This study presents new evidence for four giant canyons along the northern portion of the Davie Ridge offshore Tanzania. Seismic and multibeam bathymetric data highlight that the southernmost three canyons are now inactive, supra‐elevated relative to the adjacent sea floor of the Kerimbas Graben and disconnected from the modern slope systems offshore the Rovuma and Rufiji River deltas. Regional correlation of dated seismic horizons, integrated with well data and sediment samples, proves that the tectonic activity driving the uplift of the Davie Ridge in this area has started during the middle‐upper Miocene and is still ongoing, as suggested by the presence of fault escarpments at the sea floor and by the location and magnitude of recent earthquakes. Our findings contribute to placing the Kerimbas Graben and the Davie Ridge offshore Tanzania in the regional geodynamic context of the western Indian Ocean and show how the tectonics of the offshore branch of the EARS modified the physiography of the margin, re‐routing the deep‐water drainage network since the middle Miocene. Future studies are needed to understand the influence of changing sea floor topography on the western Indian Ocean circulation and to evaluate the potential of the EARS offshore tectonics in generating tsunamigenic events.
This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.
| Original language | English |
|---|---|
| Pages (from-to) | 789-803 |
| Number of pages | 15 |
| Journal | Basin Research |
| Volume | 32 |
| Issue number | 5 |
| Early online date | 8 Aug 2019 |
| DOIs | |
| Publication status | Published - Oct 2020 |
Bibliographical note
The Paleogene GLObal Warming events (GLOW) cruise, onboard of RV Pelagia, was funded by the ESF EUROCORES program. PNP was supported by NERC UK‐IODP grant NE/F523293/1. BSW was supported by the Joint Oceanographic Institutions/US Science Support Program. We thank the Royal Netherlands Institute for Sea Research (NIOZ) for technical and logistic sup-port during and after the cruise. We thank the scientific party for all their support on board the vessel, in particu-lar Niamh O'Sullivan and Chris Nicholas. We are grate-ful to the Tanzania Petroleum Development Corporation (TPDC), WesternGeco Schlumberger, Royal Dutch Shell and Shell Tanzania for giving access to the seismic and well data and allowing the publication of this work. We also thank Schlumberger for providing academic licenses of the seismic interpretation software Petrel. The Editor Cynthia Ebinger, an anonymous reviewer, and Marco Ligi are thanked for their constructive and detailed comments which improved the manuscript significantly. The authors have no conflict of interest to declare.Data Availability Statement
For more information about the data acquired during the GLOW cruise contact Dick Kroon and Henk de Haas. The bathym-etric data are available at doi.org/10.1002/2017GC007274. The other data that support the findings of this study are not publicly available due to privacy restrictions.Keywords
- Davie Ridge
- East African Rift System
- Indian Ocean
- Sediment Routing System
- Submarine Canyons
- Tanzania
Access to Document
- Maselli_et_al-2019-Basin_Research_AAM
This is the peer reviewed version of the following article: [FULL CITE], which has been published in final form at https://doi.org/10.1111/bre.12398. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.