Tracing the exhumation history of the Rwenzori Mountains, Albertine Rift, Uganda, using low-temperature thermochronology

• Verfasst von: Bauer, Friederike Ursula [VerfasserIn]
• Verfasst von: Glasmacher, Ulrich A. [VerfasserIn]
• Verfasst von: Ring, Uwe [VerfasserIn]
• Verfasst von: Karl, Markus [VerfasserIn]
• Verfasst von: Schumann, Andreas H. [VerfasserIn]
• Verfasst von: Nagudi, Betty [VerfasserIn]
• Titel: Tracing the exhumation history of the Rwenzori Mountains, Albertine Rift, Uganda, using low-temperature thermochronology
• Verf.angabe: Friederike U. Bauer, Ulrich A. Glasmacher, Uwe Ring, Markus Karl, Andreas Schumann, Betty Nagudi
• E-Jahr: 2013
• Jahr: 6 April 2013
• Umfang: 21 S.
• Fussnoten: Gesehen am 30.11.2020
• Titel Quelle: Enthalten in: Tectonophysics
• Ort Quelle: Amsterdam [u.a.] : Elsevier, 1964
• Jahr Quelle: 2013
• Band/Heft Quelle: 599(2013), Seite 8-28
• ISSN Quelle: 1879-3266
• DOI: doi:10.1016/j.tecto.2013.03.032
• Datenträger: Online-Ressource
• Sprache: eng
• Bibliogr. Hinweis: Erscheint auch als : Druck-Ausgabe: Tracing the exhumation history of the Rwenzori Mountains, Albertine Rift, Uganda, using low-temperature thermochronology. - 2013
• Sach-SW: Albertine Rift
• Sach-SW: East African Rift System
• Sach-SW: Fission-track dating
• Sach-SW: Rock and surface uplift
• Sach-SW: Thermal history modelling
• Sach-SW: Thermochronology
• K10plus-PPN: 1741493137

Abstract

The Rwenzori Mtns form a striking feature within the Albertine Rift of the East African Rift System. They are made up of a dissected Precambrian metamorphic basement block reaching heights of more than 5km. Applying low-temperature thermochronology a complex exhumation history becomes evident, where rock and surface uplift can be traced from Palaeozoic to Neogene times. Fission-track and (U-Th-Sm)/He cooling ages and derived cooling histories allow distinguishing different blocks in the Rwenzori Mtns. In the central part a northern and a southern block are separated by a putative NW-SE trending fault; with the northern block showing distinctly younger apatite fission-track ages (~130Ma) than the southern block (~300Ma). Cooling ages in both blocks do not vary significantly with elevation, despite considerable differences in elevation. Thermal history modelling reflects protracted cooling histories. Modelled t-T paths show decoupled blocks that were relocated separately along distinct fault planes, which reactivated pre-existing structures, inherited from Palaeozoic folding and thrusting. Initial cooling affected the Rwenzori area in Silurian to Devonian times, followed by Mesozoic and Cainozoic cooling events. Pre-Neogene evolution seems to be triggered by tectonic processes like the opening of the Indian Ocean and the south Atlantic. From thermochronological data the formation of a Mesozoic “Albertine high” is conceivable. In Cainozoic times the area was affected by rifting, resulting in differentiated surface uplift. Along the western flank of the Rwenzori Mtns, surface uplift was more pronounced. This is also reflected in their recent topography, formed by accelerated rock uplift in the near past (Pliocene to Pleistocene). Erosion could not compensate for this most recent uplift, resulting in apatite He ages of Oligocene to Miocene age or even older.