Rauer Islands

The Rauer Islands are located in the Prydz Bay region of East Antarctica and are dominated by orthogneisses and supracrustal metamorphic rocks with protoliths ranging in age from Archean to Proterozoic that are crosscut by a number of Proterozoic mafic dyke suites. These rocks have experienced a number of tectonometamorphic cycles, resulting in a complex interleaving of units with different ages and tectonic histories. The oldest rocks, mainly comprising Archean felsic and mafic orthogneisses, have protolith ages that range from 3,450 to 2,550 Ma and were affected by a high-grade metamorphic event at 2,550 Ma. These gneisses also contain two layered igneous complexes.

Interleaved with the Archean basement rocks are two sequences of Proterozoic gneisses—the Filla and Mather paragneisses. The Filla paragneiss is dominated by high-Fe and -Al metasedimentary units containing assemblages rich in garnet, sillimanite and quartz with minor calcsilicate and mafic units. The Mather paragneiss is dominated by high-Mg and -Al assemblages containing orthopyroxene, sillimanite, and quartz, along with diopside–forsterite marbles and forms part of a sedimentary basin that developed in the Rauer Group between 600 and 575 Ma.