Fanning, Christopher MarkElliot, D.HLarsen, DFleming, T.HVervoort, J.D.2021-09-300016-7568http://hdl.handle.net/1885/249014The Hanson Formation, Antarctica, consists of interbedded sandstones and tuffaceous rocks of Early Jurassic age. The sandstones, pebbly to medium-grained, range between quartzo-feldspathic and volcaniclastic, with some of the former being coarse-grained arkoses that imply proximal sources. Geochronology of detrital zircons provides evidence for source rock ages, whereas sandstone petrology demonstrates a mixed provenance. Tuffaceous strata are reworked fine to very fine-grained tuffs resulting from distal Plinian eruptions. Dated tuffs provide time constraints on the duration of volcanism. The sandstones and tuffs accumulated in a rift environment. Geochemically the tuffs are rhyolitic in composition, and the Sr and Nd isotope data together with the patterns on multi-element diagrams suggest they were derived from a volcanic arc, which is interpreted to have been located along the West Antarctic Gondwana margin. The silicic volcanism extends the distribution and timing of magmatism in the Early Jurassic along that margin. The Early Jurassic extensional regime was delimited by the plate margin region and the East Antarctic craton. The rift valley system along the East Antarctic craton margin, in which the Hanson strata accumulated, was the focus for subsequent emplacement of the intrusive and extrusive rocks of the Lower Jurassic Ferrar Large Igneous Province. The Early Jurassic extensional rifts may have been reactivated during Cretaceous–Cenozoic development of the West Antarctic Rift System.Preparation of this manuscript, and some of the fieldwork on which this paper is based, has been supported by NSF Grant ANT-0944662. The first author wishes to acknowledge significant research support over many years from the Office of Polar Programs, National Science Foundation. The first author also acknowledges support from the Italian Antarctic Program that enabled examination of the Deep Freeze Range rocks. The most recent fieldwork was made possible by the helicopter support provided by Petroleum Helicopters Inc. and by Raytheon Polar Servicesapplication/pdfen-AU© Cambridge University Press 2016JurassicstratigraphygeochemistrytectonicsAntarctica201710.1017/S00167568160003882020-11-23