Proterozoic crustal evolution of central East Antarctica: Age and isotopic evidence from glacial igneous clasts, and links with Australia and Laurentia

Abstract

Rock clasts entrained in glacial deposits sourced from the continental interior of Antarctica provide an innovative means to determine the age and composition of ice-covered crust. Zircon U-Pb ages from a suite of granitoid clasts collected in glacial catchments draining central East Antarctica through the Transantarctic Mountains show that crust in this region was formed by a series of magmatic events at

Crustal heat production and estimate of terrestrial heat flow in central East Antarctica, with implications for thermal input to the East Antarctic ice sheet

“…Zircon U-Pb ages from this suite of glacially transported granitoid clasts show that the crust in central East Antarctica was formed by a series of magmatic events at ∼ 2.01, 1.88-1.85, ∼ 1.79, ∼ 1.57, 1.50-1.41, and 1.20-1.06 Ga (Goodge et al, 2008(Goodge et al, , 2012(Goodge et al, , 2017. The dominant granitoid populations are ca.…”

“…Glacial igneous rock clasts were collected as part of a separate study to obtain lithologic, petrologic, and isotopic information about the Precambrian crust of East Antarctica (Goodge et al, 2017). About a dozen sites were sampled where glacial moraines are exposed, extending > 1500 km along the length of the Transantarctic Mountains from the Convoy Range in southern Victoria Land to Strickland Nunatak near Reedy Glacier (Fig.…”

“…A major effort was then undertaken to screen the crystalline clast samples by reconnaissance in situ UPb geochronology in order to cull samples with Ross orogen (∼ 500 Ma) or younger ages in order to focus solely on the Precambrian crustal history of the shield interior. Analysis of the remaining suite of 22 samples included detailed petrography, mineral analysis, geochemical analysis, mineral separation, precise U-Pb geochronology, O-isotope analysis, and Hf-isotope analysis (see Goodge et al, 2017).…”

“…They are granitic to granodioritic in composition and contain hornblende, biotite and/or muscovite; some samples are two-mica granitoids of peraluminous composition. Detailed sample descriptions are provided by Goodge et al (2017), including petrographic features, geochemical data, cathodoluminescence (CL) images of zircons, and zircon isotopic data (U-Pb, O, and Lu-Hf).…”

“…The major ice drainages in East Antarctica are marked by nearly radial flow away from central ice divides and domes toward the continental margin (Fig. 2), providing natural proxy samples of the continental interior by bedrock erosion during glacial flow (Peucat et al, 2002;Goodge et al, 2008Goodge et al, , 2017. Unique among the major drainages, glacial ice in Byrd Glacier and related smaller drainages moves nonradially from the main ice divides because it is obstructed by the high-standing Transantarctic Mountains (peak elevations > 4000 m).…”