Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.596565
Title: Fault growth and landscape development in Central Otago, New Zealand, using in situ cosmogenic isotopes
Author: Bennett, E. R.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2005
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Abstract:
Central Otago in New Zealand is a region dominated by late Tertiary NE trending anticlines which form above buried reverse faults. As the folds uplift, soft Tertiary sediments are rapidly eroded, exposing the underlying basement schist. At the base of the sedimentary cover there is patchy occurrence of hard silica cemented quartz-rich boulders which remain exposed on the schist surface after the overlying sediments are removed. 10Be and 26Al accumulate in the quartz within the boulders upon exposure to cosmic radiation. Cosmogenic dating of the boulders provides the means to conduct landscape evolution studies, and monitor the growth of the anticlines over the last 1-2 million years. At South Rough Ridge a consistent and coherent link is demonstrated between the cosmogenic dates and the tectonic geomorphology. This implies that boulders in Central Otago can reach 10Be concentrations equivalent to minimum ages of 660 ka or older without being saturated with respect to erosion. At Rough Ridge, which was expected to be older on geomorphic grounds, the 10Be concentrations of the boulders give even older ages of up to 1.4 Ma, demonstrating the very low maximum erosion rates experienced by these boulders of ~0.4 mm kyr-1.  The best exposed and preserved occurrence of the quartz-rich boulders is on North Rough Ridge, where their suitability for cosmogenic exposure studies can be assessed. The stratigraphic context of the boulders, their sedimentary and diagenetic origin, together with their method of emplacement and preservation on the modern land surface, can be studied in detail. At Little Rough Ridge and Raggedy Range, the combined 10Be data and geomorphic studies suggest differing styles of fault growth for these two ranges.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.596565  DOI: Not available
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