One billion years of tectonism at the Paleoproterozoic interface of North and South Australia

Abstract

The Mount Woods Domain, in the northeastern Gawler Craton, occupies a tectonically important location in Proterozoic Australia, yet there is very little published U–Pb geochronology data from this region to underpin tectonic models. New LA-ICP-MS U–Pb monazite and detrital zircon geochronology reveal Archean to Paleoproterozoic basement in the central Mount Woods Domain, comprising metasedimentary rocks and garnet-bearing granite with protolith ages of c. 2550–2400 Ma and metasedimentary rocks deposited after c. 1855 Ma. The southern Mount Woods Domain contains younger metasedimentary sequences deposited after 1750 Ma. Metamorphic monazite and zircon geochronology combined with phase equilibria modelling show the rocks of the central Mount Woods Domain were metamorphosed to granulite facies between 1700 and 1670 Ma, reaching pressure and temperature conditions of 4.8–5.3 kbar and 800–840 ◦C. Monazite geochronology from samples located along major shear zones and in the westernmost Mount Woods Domain record amphibolite facies metamorphism and reworking at 1570–1550 Ma, with a further phase of shear zone activity along the northern margin of the Mount Woods Domain at c. 1480 Ma. Laser ablation inductively coupled plasma triple quadrupole mass spectrometry (LA-ICP-QQQ-MS) Rb–Sr biotite ages from across the Mount Woods Domain range between 1480 and 1390 Ma. The protracted geological history in the Mount Woods Domain from c. 2500–1400 Ma provides a piercing point linking different regions of Proterozoic Australia and western Laurentia during the tenure of the Nuna supercontinent.