Abstract

High-K granites extensively intruded all the Palaeoproterozoic terrains of northern Australia, and have been interpreted as the culmination of widespread intracratonic orogeny. One of these terrains, the Lamboo Complex, developed between the Kimberley and North Australian Cratons. The complex is divided into three terranes, referred to as the Western, Central, and Eastern zones, and was intruded by a variety of I-type granites and gabbros. High-K granites of the 1865–1850 Ma Paperbark supersuite are restricted to the Western zone. Tonalite sheets of the Dougalls suite, and unassigned leucogranite sheets, intruded the Central zone at c. 1850 Ma. The 1835–1805 Ma Sally Downs supersuite is composed of tonalite and high-K granite that mainly intruded the Central zone. However, high-K granites of the Sally Downs supersuite intruded all three zones from c. 1820 Ma onwards, and mark the amalgamation of the terranes. The youngest granites in the complex are high-K granites of the 1805–1790 Ma San Sou suite, which intrude the Eastern and Central zones. The temporal and spatial distribution of the granites is not easily reconciled with previous intracratonic models, but is consistent with tectonic processes similar to those operating at present.

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