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Title: The preservation of organic matter in impact craters
Author: Lindgren, Paula
ISNI:       0000 0001 3610 503X
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2007
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The aim of this study is to attain a better understanding of the fate of carbon and the degree of preservation of organic matter in impacts craters. This topic is relevant to prebiotic chemistry, planetary exploration and panspermia. Three natural impact craters were investigated: The Eocene Haughton impact structure on Devon Island in the Canadian High Arctic, where the target is composed of a thick sedimentary sequence with pre-impact hydrocarbons, the Ordovician Lockne impact structure in central Sweden, where organic- and uranium-rich Alum Shale is present in the target, and the Pre-Caledonian Gardnos impact structure in south-central Norway, also with carbon-rich shales in the target. An analogue example of rapid heating of organic matter by igneous intrusion in carbon-rich rock, and an experimental hypervelocity impact in a carbon-rich rock were also studied. In the Haughton impact crater, fossil biological markers are preserved within lithic clasts in the impact melt breccia. Fossil biological markers are also preserved in the experimental impact crater, and in the material excavated during the experimental impact. Instantaneous melting and quenching in the Gardnos suevite (impact melt rock) has caused the incorporation of disordered carbon in the suevite melt. In the Haughton impact melt breccias, around 20% total organic carbon is preserved after impact, and in the Gardnos impact crater, at least 38% of the original carbon is preserved in a disordered form. In the Lockne impact crater, carbon is particularly preserved by polymerisation around radioactive minerals. This study shows that organic matter does not necessarily oxidise or change in to highly crystalline forms during an impact event, but that substantial amounts can be preserved in a disordered form.
Supervisor: Not available Sponsor: Biotechnology and Biological Sciences Research Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available