Coats Land crustal block, East Antarctica: A tectonic tracer for Laurentia?

Abstract

Undeformed rhyolite and granophyre in the Coats Land crustal block of East Antarctica, dated as 1112 ± 4 Ma, are identical in age to both the Umkondo large igneous province (LIP) of the Kalahari craton (southern Africa) and the early Keweenawan LIP of Laurentia (North America). Although marine and satellite data demonstrate that Coats Land was close to Kalahari within the Gondwana supercontinent, the Coats Land rocks yield Pb isotope compositions strikingly distinct from those of the Umkondo province, yet indistinguishable from rocks of the Keweenawan province. The anorogenic Red Bluff granitic suite, along the present-day southern Laurentian margin in the Franklin Mountains (Texas, USA), is of comparable age, general rock type, and Pb isotope composition to rocks of Coats Land and may provide a piercing point for a Coats Land-Laurentia link. Paleomagnetic poles permit the Coats Land block to be close to this part of Laurentia ca. 1100 Ma and allow juxtaposition of Kalahari and southern Laurentia ca. 1000 Ma. The Coats Land crustal block may therefore be a critical tectonic tracer for placing Laurentia within late Mesoproterozoic and Neoproterozoic paleogeographic reconstructions. If this hypothesis is correct, Laurentia collided with the Kalahari craton along Antarctica's Maud orogen, which would represent a continuation of the ca. 1000 Ma Grenville orogen of eastern and southern Laurentia.

Tectonic Evolution of the Adirondack Mountains and Grenville Orogen Inliers within the USA

“…9) largely overlaps that of the Llano-Adirondack trend (Eglinton and Kerr 1989;Dalziel et al 2000;Loewy et al 2003Loewy et al , 2011Roller 2004;Fisher 2010). Paleomagnetic poles derived by Dalziel (1992) and Weil et al (1998) are consistent with this model.…”

Antarctica and supercontinent evolution: historical perspectives, recent advances and unresolved issues

“…Undeformed rhyolite and granophyre exposed in Coats Land, between western Dronning Maud Land and the Shackleton Range, have magmatic ages of ages of c. 1110 Ma with no trace of the c. 0.5 Ga tectonism (Gose et al 1997), suggesting that they too are part of the western foreland to the Pan-African Orogen. However, palaeomagnetic and isotopic data from Coats Land support links with Laurentia at 1110 Ma rather than with the Kalahari Craton, consistent with the original SWEAT hypothesis that the Maud Belt is a 1090-1030 Ma collision zone between the Kalahari Craton and Laurentia-Antarctica (Jacobs et al 2003b;Loewy et al 2011).…”

New geophysical compilations link crustal block motion to Jurassic extension and strike-slip faulting in the Weddell Sea Rift System of West Antarctica

“…Specifically, we assess if the presence of significant underplating, intra-crustal magmatism, thin residual crust and a thick overlying sedimentary basin is consistent with observed potential field signatures. Profile constrained by seismic refraction data (Leitchenkov and Kudryavtzev, 1997) (Loewy et al, 2011 Our first 2D model of the crustal architecture (Fig. 7a), constrained to match both the Bouguer anomaly from our new compilation and crustal structure along the Russian seismic refraction line (Leitchenkov and Kudryavtzev, 1997) images both the NWMP and SWMP and the boundary between these provinces.…”