Winckle, T. K.2025-08-122025-08-122023https://hdl.handle.net/2440/146735This item is only available electronically. Whole thesis (as available).Heat production within Earth’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 Fordland’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 𝑙𝑜𝑔!"𝐴 0.95 𝜇𝑊𝑚#$. Overall heat production increases with depth but it is very dependent of the composition of the lithologies within the crust.enHonoursGeologyheat productioncontinental crustcrustal compositionheat-producing elementsGangdese ArcSierra Nevada BatholithFamatinain ArcFiordlandsKohistan-Ladakh ArcTalkeetna ArcThesis