Layered mafic intrusions, such as the Dufek Intrusion of Antarctica, represent fossilized mafic magma chambers formed in the shallow crust during large igneous province and/or continental breakup events. The Dufek Intrusion of Antarctica is one of the largest layered intrusions, intruded approximately 182 Myr ago during the breakup of Gondwana. It is rivaled in thickness only by the 2.05 Ma Bushveld Complex of South Africa and shows a similar progression in mineral compositions from primitive at the base to more evolved compositions at the uppermost contact with an overlying granophyre layer. This progression in mineral composition suggests that the Dufek magma chamber crystallized from the bottom to the top. In this talk, I will present new high-precision U-Pb zircon ages throughout the 8+ km thick Dufek Intrusion magma chamber stratigraphy. The results are surprising - zircons from the bottom of the intrusion record systematically younger ages than those from the top. I will argue that zircons from layered mafic intrusions do not provide a record of high temperature crystallization, but rather the ages reflect the solidification of interstitial melt in the magma chamber from the top down.