Zircon, monazite and feldspar datasets from Indo- and Australo-Antarctica

Simplified core logs. Figure DR2. Images of pebbles from NPB0101 Grab-19.

Figure DR3. Provenance signals with depth in the sediment cores and feldspar type. Figure DR4.

Glacial and oceanographic context for samples from the Mirny region, Davis Sea. Table DR1. Sample details.

Table DR2. Feldspar Pb-isotope data. Table DR3.

Zircon and monazite U-Pb data. Details of analytical methods from Mulder et al. (2019): SAMPLING AND METHODS The Pb-isotopic signature of feldspar reflects the petrogenesis of crystalline rocks and has been successfully used to map tectonothermal provinces, including in Antarctica (e.g., Flowerdew et al., 2013a). We characterized the feldspar Pb-isotopic composition of Indo-Antarctica and Australo-Antarctica using data from igneous and metamorphic rocks exposed between 50°E and 120°E (Fig. 1B; Tables DR1 and DR2 in the GSA Data Repository).

Feldspar Pb-isotope data from Indo-Antarctica include the Archean–Cambrian basement rocks analyzed by Flowerdew et al. (2013a), complemented by new analyses from five Proterozoic charnockites in the Rayner Complex (Fig. 1B; Table DR1; for sample descriptions, see Halpin et al. [2012]). New data from Australo-Antarctica include 31 Archean–Cambrian samples from the Wilkes, Bunger, and Charcot Provinces (Fig. 1B; Table DR1; for sample descriptions, see Sheraton et al., 1992, 1995; Morrissey et al., 2017).

To test if offshore detrital feldspar is a reliable proxy for onshore basement, we analyzed detrital feldspar grains from Pleistocene sediment in Ocean Drilling Program (ODP) core 188-1167A from Prydz Bay, Antarctica (Shipboard Scientific Party, 2001; Fig. 1B; Fig. DR1), which was sourced from basement terranes surrounding the Lambert Rift (Fig. 1B; Appendix DR2; O’Brien et al., 2007; Veevers et al., 2008). The subglacial geology surrounding the inferred paleo–plate boundary near Mirny Station was then investigated by analyzing detrital feldspar, monazite, and zircon grains from coarse (greater than 50 mm) Holocene sediments collected ~50–70 km offshore from Mirny Station during R/V Nathaniel B. Palmer cruise NB0101 (marine-geo.org/link/entry.php?id=NBP010; Fig. 1B, inset; Figs.

DR1 and DR2). Ice-drainage models demonstrate that these sediments were sourced from small glaciers along the coastline near Mirny Station (Fig. 1B, inset; Appendix DR2; Figs. DR3 and DR 4; Rignot et al., 2011).