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dc.contributor.advisorMartin, Candace
dc.contributor.authorKautz, Christopher Quist
dc.date.available2019-05-28T23:16:37Z
dc.date.copyright2006-05-06
dc.identifier.citationKautz, C. Q. (2006, May 6). Tracing the geochemical signature of New Zealand river sediments : transport, elemental fluxes and oceanic deposition (Thesis, Master of Science). University of Otago. Retrieved from http://hdl.handle.net/10523/9339en
dc.identifier.urihttp://hdl.handle.net/10523/9339
dc.description.abstractChemical and physical erosion processes have been investigated in a wide range of high sediment-yielding rivers from New Zealand using major and trace element data from suspended sediments and fluvial bedload grain size fractions. Analyses of bedload samples from the Haast and Clutha rivers, which drain opposing flanks of the Southern Alps, suggest that weathering is strongly partitioned between the chemical weathering of carbonates and physical weathering of silicates. The similarity of sediments from rivers draining both sides of the drainage divide indicates minimal climatic control on weathering intensity of fluvial sediments. Rather, bedload geochemistry is controlled primarily by mechanical attrition and hydrodynamic fractionation. Combined with suspended and bedload sediment data from rivers throughout New Zealand, these findings suggest that HSI fluvial sedimentary evolution is dominated by physical weathering processes and that several cycles of sedimentary recycling may occur without production of a silicate chemical weathering signature. Average fluvial particulate compositions from New Zealand are similar to estimates of average upper continental crust (UCC) composition. Recalculation of global fluvial elemental fluxes using average New Zealand suspended and bedload sediment compositions as a proxy for sediment derived from all high standing islands (HSis, 33% of total) results in world average compositions that more closely resemble the UCC than previous estimates using major world rivers alone. New Zealand fluvial particulates are among the least chemically weathered in the world, with compositions that are modified from source rock chemistry by physical processes. The Bounty Fan (BF) represents the abyssal marine terminus of the eastern South Island sedimentary system (ESISS), which begins in the actively uplifting Southern Alps and includes fluvial and turbidity current sediment transport. The geochemistry of BF sediments is remarkably similar to parent rocks on the South Island. Although sand-size fluvial bedload sediments from ESISS rivers display different compositions to parent rocks, the incorporation of the silt and finer fraction of ESISS bedload in BF sediments serves to preserve parent rock geochemical signatures. ESISS parent lithologies are dominated by Mesozoic sedimentary rocks and their metamorphosed equivalents. Therefore, it is possible that at least two episodes of sedimentary recycling have occurred without the destruction of 'grandparent' rock geochemical signature.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoenen_NZ
dc.publisherUniversity of Otago
dc.titleTracing the geochemical signature of New Zealand river sediments : transport, elemental fluxes and oceanic depositionen_NZ
dc.typeThesisen_NZ
dc.date.updated2019-05-28T23:16:17Z
thesis.degree.disciplineGeologyen_NZ
thesis.degree.nameMaster of Scienceen_NZ
thesis.degree.grantorUniversity of Otagoen_NZ
thesis.degree.levelMastersen_NZ
otago.openaccessOpenen_NZ
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