Gold and palladium as indicators of an extraterrestrial component in the Cetaceous/Tertiary boundary layer at Woodside Creek and Chancet Quarry, Marlborough, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Sciences at Massey University

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dc.contributor.authorCook, Andrew William
dc.date.accessioned2018-01-15T21:40:09Z
dc.date.available2018-01-15T21:40:09Z
dc.date.issued1998
dc.description.abstractIt is widely believed that a large meteorite approximately 10 km in diameter impacted Earth at the termination of the Cretaceous Period with cosmic velocity, vaporising itself, along with a greater mass of the terrestrial target rocks into a cloud of hot rock vapour. The vapour cloud condensed into particles of sand to clay size at high altitude before returning to Earth to form a worldwide layer marking the Cretaceous/Tertiary boundary. Chemical evidence from this boundary layer suggests that the impactor was a chondritic meteorite, enriched in the platinum group elements compared to the Earth's crust. An enrichment of these elements above their background crustal abundances to approximately 0.1 of the chondritic abundance has been observed in a number of Cretaceous/Tertiary boundary layers worldwide. Iridium is the platinum group element traditionally used as an indicator of the extraterrestrial component (ETC) in likely impact layers due to its rarity in the Earth's crust and low detection limits possible using neutron activation analysis methods. Neutron activation analysis is however expensive and requires specialist facilities, this thesis proposes that the elements gold and palladium can also be used to indicate the ETC in the Cretaceous/Tertiary boundary layer. Samples from two Cretaceous/Tertiary boundary sites, Woodside Creek and Chancet Quarry, were analysed for gold and palladium using graphite furnace atomic absorption spectrometry. A strong correlation was found between iridium, gold, and palladium abundances at these sites, with all showing enrichment at precisely the Cretaceous/Tertiary boundary in proportion to iridium, indicating a common origin for all three elements. Gold showed almost precisely the expected 0.1 of its chondritic abundance in the clay size fraction at both Woodside Creek and Chancet Quarry (15 ng/g). Palladium showed exactly 0.1 of its chondritic abundance at the Chancet Quarry boundary with 53 ng/g. Gold abundances on the boundary at Woodside Creek (55 ng/g) and Chancet Quarry (44 ng/g) showed excellent agreement with published values as did the palladium result for Woodside Creek (22 ng/g).en_US
dc.identifier.urihttp://hdl.handle.net/10179/12596
dc.language.isoenen_US
dc.publisherMassey Universityen_US
dc.rightsThe Authoren_US
dc.subjectNew Zealand Marlborough Districten_US
dc.subjectCosmochemistryen_US
dc.subjectCretaceous/Tertiary boundaryen_US
dc.titleGold and palladium as indicators of an extraterrestrial component in the Cetaceous/Tertiary boundary layer at Woodside Creek and Chancet Quarry, Marlborough, New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Earth Sciences at Massey Universityen_US
dc.typeThesisen_US
massey.contributor.authorCook, Andrew William
thesis.degree.disciplineEarth Sciencesen_US
thesis.degree.grantorMassey Universityen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Science (M. Sc.)en_US
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