Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE

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dc.contributor.advisorDe Wit, Maartenen_ZA
dc.contributor.advisorCodilean, Alexandru Ten_ZA
dc.contributor.authorScharf, Taryn Een_ZA
dc.date.accessioned2014-07-30T17:28:03Z
dc.date.available2014-07-30T17:28:03Z
dc.date.issued2012en_ZA
dc.descriptionIncludes abstract.
dc.descriptionIncludes bibliographical references.
dc.description.abstractSouthern Africa is host to a unique mountain system, the Cape Mountains, which includes the coastal Cape Fold Belt (CFB) and an inland Escarpment. Apatite fission track analysis has shown that this mountain system is an erosion feature, exhumed from beneath 2-7 km of overburden by large-scale denudation processes affecting the subcontinent during Gondwana break-up (ca. 140 – 65 Ma). Despite its antiquity and location on a passive continental margin, the ruggedness of the present-day topography of the Cape Mountains compares to that of the world’s active orogens. The coastal Cape Mountains are traversed by deeply-incised, meandering rivers that cut canyons through the most resistant quartzite ridges of these mountains, perpendicular to their structural grain inherited from the CFB. The evolution of this landscape is poorly understood, because little quantitative data exists on the denudation history of the Cape Mountains. This study presents the first in situ-produced cosmogenic 10Be inventories determined for quartz from catchment sediments and bedrock surfaces within the coastal Cape Mountains, with which to quantify denudation rates, exposure ages and the recent geomorphic evolution of these Cape Mountains. River sediments sampled from catchments within the Langeberg and Swartberg Ranges of the Western Cape, as well as bedrock from the Tradouw River traversing the Langeberg Range, were analysed. In addition, charcoal from alluvial material was collected for radiocarbon dating. Catchment-averaged denudation rates reported from these mountains range between 2.1 ± 0.3 and 6.9 ± 1.9 m·Myr-1. These are amongst the lowest reported rates globally, despite the rugged terrain of the mountain system. The spatial consistency between the low denudation rates suggests a landscape approaching geomorphic steady-state. This finding is best attributed to lithological control on denudation rates in a tectonically quiescent environment, and a relatively dry climate.en_ZA
dc.identifier.apacitationScharf, T. E. (2012). <i>Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE</i>. (Thesis). University of Cape Town ,Faculty of Science ,Department of Geological Sciences. Retrieved from http://hdl.handle.net/11427/4220en_ZA
dc.identifier.chicagocitationScharf, Taryn E. <i>"Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE."</i> Thesis., University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2012. http://hdl.handle.net/11427/4220en_ZA
dc.identifier.citationScharf, T. 2012. Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE. University of Cape Town.en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Scharf, Taryn E AB - Southern Africa is host to a unique mountain system, the Cape Mountains, which includes the coastal Cape Fold Belt (CFB) and an inland Escarpment. Apatite fission track analysis has shown that this mountain system is an erosion feature, exhumed from beneath 2-7 km of overburden by large-scale denudation processes affecting the subcontinent during Gondwana break-up (ca. 140 – 65 Ma). Despite its antiquity and location on a passive continental margin, the ruggedness of the present-day topography of the Cape Mountains compares to that of the world’s active orogens. The coastal Cape Mountains are traversed by deeply-incised, meandering rivers that cut canyons through the most resistant quartzite ridges of these mountains, perpendicular to their structural grain inherited from the CFB. The evolution of this landscape is poorly understood, because little quantitative data exists on the denudation history of the Cape Mountains. This study presents the first in situ-produced cosmogenic 10Be inventories determined for quartz from catchment sediments and bedrock surfaces within the coastal Cape Mountains, with which to quantify denudation rates, exposure ages and the recent geomorphic evolution of these Cape Mountains. River sediments sampled from catchments within the Langeberg and Swartberg Ranges of the Western Cape, as well as bedrock from the Tradouw River traversing the Langeberg Range, were analysed. In addition, charcoal from alluvial material was collected for radiocarbon dating. Catchment-averaged denudation rates reported from these mountains range between 2.1 ± 0.3 and 6.9 ± 1.9 m·Myr-1. These are amongst the lowest reported rates globally, despite the rugged terrain of the mountain system. The spatial consistency between the low denudation rates suggests a landscape approaching geomorphic steady-state. This finding is best attributed to lithological control on denudation rates in a tectonically quiescent environment, and a relatively dry climate. DA - 2012 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2012 T1 - Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE TI - Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE UR - http://hdl.handle.net/11427/4220 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/4220
dc.identifier.vancouvercitationScharf TE. Denudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BE. [Thesis]. University of Cape Town ,Faculty of Science ,Department of Geological Sciences, 2012 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/4220en_ZA
dc.language.isoengen_ZA
dc.publisher.departmentDepartment of Geological Sciencesen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.subject.otherGeologyen_ZA
dc.titleDenudation rates and geomorphic evolution of the Cape Mountains, determined by the analysis of the in situ-produced cosmogenic 10BEen_ZA
dc.typeMaster Thesis
dc.type.qualificationlevelMasters
dc.type.qualificationnameMScen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceThesisen_ZA
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