The Byrd Glacier discontinuity us a major boundary crossing the Ross Orogen, with crystalline rocks to the north and primarily sedimentary rocks to the south. Most models for the tectonic development of the Ross Orogen in the central Transantarctic Mountains consits of two-dimensional transects across the belt, but do not adress the major longitudinal contrast at Byrd Glacier. This paper presents a tectonic model centering on the Byrd Glacier discontinuity. Rifting in the Neoproterozoic producede a crustal promontory in the craton margin to the north of Byrd Glacier. Oblique convergence of the terrane (Beardmore microcontinent) during the latest Neroproterozoic and Early Cambrian was accompanied by subduction along the craton margin of East Antarctica. New data presented herein in the support of this hypothesis are U-Pb dates of 545.7 ± 6.8 Ma and 531.0 ± 7.5 Ma on plutonic rocks from the Britannia Range, subduction stepped out, and Byrd Glacier. After docking of the terrane, subduction stepped out, and Byrd Group was deposited during the Atdabanian-Botomian across the inner margin of the terrane. Beginning in the upper Botomian, reactivation of the sutured boundaries of the terrane resulted in an outpouring of clastic sediment and folding and faulting of the Byrd Group.

All errors are reported at the 1-sigma level and incorporate only uncertainties from measurement of isotopic ratios. U concentration and U/Th have uncertainty of ~25 %. Decay constants: 235U=9.8485 x 10-10, 238U=1.55125 x 10-10, 238U/235U=137.88. Isotope ratios are corrected for Pb/U fractionation by comparison with standard zircon with an age of 564±4 Ma. Initial Pb composition interpreted from Stacey and Kramers (1975), with uncertainties of 1.0 for 206Pb/204Pb and 0.3 for 207Pb/204Pb.

Supplement to: Stump, Edmund; Gootee, Brian; Talarico, Franco M (2006): Tectonic model for development of the Byrd Glacier discontinuity and surrounding regions of the Transantarctic Mountains during Neoproterozoic-Early Paleozoic. In: Fütterer, D K, Damaske, D, Kleinschmidt, G, Miller, H & Tessensohn, F (eds.), Antarctica: contributions to global earth sciences, Springer, Berlin, Heidelberg, New York, 181-190