1 Evidence for Extending Anomalous Miocene Volcanism at the Edge of the 2 East Antarctic Craton 3 4 K. J. Licht1, T. Groth1, J. P. Townsend2, A. J. Hennessy1, S. R. Hemming3, T. P. Flood4, and M. 5 Studinger5 6 1Department of Earth Sciences, Indiana University-Purdue University Indianapolis, Indianapolis, IN, 7 USA, 2HEDP Theory Department, Sandia National Laboratories, Albuquerque, NM, USA, 3Department of 8 Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, Palisades, 9 NY, USA, 4Geology Department, St. Norbert College, DePere, WI, USA, 5NASA Goddard Space Flight 10 Center, Greenbelt, MD, USA 11 12 Corresponding author: Kathy Licht (
[email protected]) 13 14 Key Points: 15 x Olivine basalt, hyaloclastite erratics and detrital zircon at Earth’s southernmost moraine 16 (Mt. Howe) indicate magmatic activity 17- 25 Ma. 17 x The source, indicated by a magnetic anomaly (-740 nT) ~400 km inland from the West 18 Antarctic Rift margin, expands extent of Miocene lavas. 19 x Data corroborate lithospheric foundering beneath southern Transantarctic Mountains based 20 on location of volcanism (duration < 5 my). 21 22 Abstract 23 Using field observations followed by petrological, geochemical, geochronological, and 24 geophysical data we infer the presence of a previously unknown Miocene subglacial volcanic 25 center ~230 km from the South Pole. Evidence of volcanism is from boulders of olivine-bearing 26 amygdaloidal/vesicular basalt and hyaloclastite deposited in a moraine in the southern 27 Transantarctic Mountains. 40Ar/39Ar ages from five specimens plus U-Pb ages of detrital zircon 28 from glacial till indicate igneous activity 25-17 Ma.