Geology of the Moorarie 1:100 000 sheet

The MOORARIE 1:100 000 map sheet covers the boundary between the northern edge of the Archaean Yilgarn Craton and the southern part of the Palaeoproterozoic Capricorn Orogen.
In this area, the Yilgarn Craton comprises parts of the Narryer granite–gneiss and Murchison granite– greenstone terranes, which were juxtaposed during the late Archaean. On MOORARIE these terranes are separated by a northerly trending fault. The Narryer Terrane is mainly composed of granitic gneiss, with both early and late Archaean protolith ages. Layers of supracrustal rocks are tectonically interleaved with this granitic gneiss, and both were deformed together before the intrusion of late Archaean granite. The Murchison Terrane comprises middle to late Archaean granite, greenstones, and granitic gneiss.
The northeastern part of the Narryer Terrane, north of the Seabrook Fault, was deformed in a ductile regime, metamorphosed at high grade, and intruded by voluminous granitic magmas at c. 1800 Ma during the Capricorn Orogeny. This reworked portion of the Narryer Terrane is termed the Yarlarweelor gneiss complex. The southern part of the Yarlarweelor gneiss complex is in faulted contact with the Bryah and Padbury Groups, and the southern part of the Narryer Terrane, in which Palaeoproterozoic deformation is minor and commonly restricted to faults and shear zones. The Bryah and Padbury Groups mainly comprise mafic and ultramafic igneous rocks and sedimentary rocks respectively, all metamorphosed to greenschist facies. On MOORARIE all the exposed contacts between these groups are faults.
The currently mined talc deposit at Mount Seabrook formed during low-grade metasomatism in structures parallel to the regional Palaeoproterozoic faults.