The fire below: heat generation in the lower crust

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dc.contributor.authorWinckle, T. K.
dc.contributor.schoolSchool of Physical Sciencesen
dc.date.issued2023
dc.descriptionThis item is only available electronically. Whole thesis (as available).
dc.description.abstractHeat production within Earthโ€™s lithosphere comes from the decay of heat-producing elements: potassium, uranium and thorium. The distribution of these elements varies by an order of magnitude and with depth. With 30-40% of radioactive decay accounting for heat loss through the continents there are large uncertainties in extrapolated lithospheric temperatures. Consequently, it is critical to improve models of heat production with depth to adequately interpret and model Earth geological processes. In this study I improve estimates of heat-producing elements by focusing on multiple magmatic arcs in geographical regions including: Kohistan-Ladak Arc, Pakistan and India; Talkeetna Arc, Alaska; Sierra Nevada Batholith, California USA; Famatinian Arc, Chile and Argentina; and Fordlandโ€™s New Zealand. These arcs were chosen because of their differential exhumation, exposing a range of maximum pressures that extend from the surface into the lowermost crust when these magmatic arcs were active. Heat production within the crust must be estimated by proxy with previous studies commonly using seismic velocity to estimate heat production at depth. I establish a relationship from surface samples by using heat production coupled with maximum pressure estimates to make a quasi-vertical view of crustal heat production in outcrop. This showed that there is a relationship between heat production and SiO2 wt.%. Heat production also varies geographically. Total alkali content creates anomalously high heat production, like that in the Gangdese Arc which has a mean heat production of ๐‘™๐‘œ๐‘”!"๐ด 0.95 ๐œ‡๐‘Š๐‘š#$. Overall heat production increases with depth but it is very dependent of the composition of the lithologies within the crust.
dc.description.dissertationThesis (B.Sc.(Hons)) -- University of Adelaide, School of Physical Sciences, YEAR
dc.identifier.urihttps://hdl.handle.net/2440/146735
dc.language.isoen
dc.provenanceThis electronic version is made publicly available by the University of Adelaide in accordance with its open access policy for student theses. Copyright in this thesis remains with the author. This thesis may incorporate third party material which has been used by the author pursuant to Fair Dealing exceptions. If you are the author of this thesis and do not wish it to be made publicly available, or you are the owner of any included third party copyright material you wish to be removed from this electronic version, please complete the take down form located at: http://www.adelaide.edu.au/legalsen
dc.subjectHonours
dc.subjectGeology
dc.subjectheat production
dc.subjectcontinental crust
dc.subjectcrustal composition
dc.subjectheat-producing elements
dc.subjectGangdese Arc
dc.subjectSierra Nevada Batholith
dc.subjectFamatinain Arc
dc.subjectFiordlands
dc.subjectKohistan-Ladakh Arc
dc.subjectTalkeetna Arc
dc.titleThe fire below: heat generation in the lower crust
dc.typeThesis

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