Mid-Pleistocene to recent crustal extension in the inner graben of the Northern Kenya Rift
- Magmatic continental rifts often constitute nascent plate boundaries, yet long-term extension rates and transient rate changes associated with these early stages of continental breakup remain difficult to determine. Here, we derive a time-averaged minimum extension rate for the inner graben of the Northern Kenya Rift (NKR) of the East African Rift System for the last 0.5 m.y. We use the TanDEM-X science digital elevation model to evaluate fault-scarp geometries and determine fault throws across the volcano-tectonic axis of the inner graben of the NKR. Along rift-perpendicular profiles, amounts of cumulative extension are determined, and by integrating four new Ar-40/Ar-39 radiometric dates for the Silali volcano into the existing geochronology of the faulted volcanic units, time-averaged extension rates are calculated. This study reveals that in the inner graben of the NKR, the long-term extension rate based on mid-Pleistocene to recent brittle deformation has minimum values of 1.0-1.6 mm yr(-1), locally with values up to 2.0 mmMagmatic continental rifts often constitute nascent plate boundaries, yet long-term extension rates and transient rate changes associated with these early stages of continental breakup remain difficult to determine. Here, we derive a time-averaged minimum extension rate for the inner graben of the Northern Kenya Rift (NKR) of the East African Rift System for the last 0.5 m.y. We use the TanDEM-X science digital elevation model to evaluate fault-scarp geometries and determine fault throws across the volcano-tectonic axis of the inner graben of the NKR. Along rift-perpendicular profiles, amounts of cumulative extension are determined, and by integrating four new Ar-40/Ar-39 radiometric dates for the Silali volcano into the existing geochronology of the faulted volcanic units, time-averaged extension rates are calculated. This study reveals that in the inner graben of the NKR, the long-term extension rate based on mid-Pleistocene to recent brittle deformation has minimum values of 1.0-1.6 mm yr(-1), locally with values up to 2.0 mm yr(-1). A comparison with the decadal, geodetically determined extension rate reveals that at least 65% of the extension must be accommodated within a narrow, 20-km-wide zone of the inner rift. In light of virtually inactive border faults of the NKR, we show that extension is focused in the region of the active volcano-tectonic axis in the inner graben, thus highlighting the maturing of continental rifting in the NKR.…
Verfasserangaben: | Simon RiedlORCiDGND, Daniel MelnickORCiDGND, Lucy NjueORCiD, Masafumi SudoORCiDGND, Manfred StreckerORCiDGND |
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DOI: | https://doi.org/10.1029/2021GC010123 |
ISSN: | 1525-2027 |
Titel des übergeordneten Werks (Englisch): | Geochemistry, geophysics, geosystems |
Verlag: | American Geophysical Union |
Verlagsort: | Washington |
Publikationstyp: | Wissenschaftlicher Artikel |
Sprache: | Englisch |
Datum der Erstveröffentlichung: | 04.03.2022 |
Erscheinungsjahr: | 2022 |
Datum der Freischaltung: | 03.01.2024 |
Freies Schlagwort / Tag: | DEM analysis; Kenya Rift; TanDEM-X DEM; extensional tectonics; geochronology; normal faults |
Band: | 23 |
Ausgabe: | 3 |
Aufsatznummer: | e2021GC010123 |
Seitenanzahl: | 25 |
Fördernde Institution: | GEOTHERM program [BGR 05-2343, BMZ PN 2009.2222.9]; graduate program; "Shaping Earth's Surface in a Variable Environment" of the German; Science Foundation (Deutsche Forschungsgemeinschaft, DFG) [GK 1364, STR; 373/19-1]; Projekt DEAL |
Organisationseinheiten: | Mathematisch-Naturwissenschaftliche Fakultät / Institut für Geowissenschaften |
DDC-Klassifikation: | 5 Naturwissenschaften und Mathematik / 55 Geowissenschaften, Geologie / 550 Geowissenschaften |
Peer Review: | Referiert |
Publikationsweg: | Open Access / Gold Open-Access |
DOAJ gelistet | |
Lizenz (Deutsch): | CC-BY-NC-ND - Namensnennung, nicht kommerziell, keine Bearbeitungen 4.0 International |