Deformations of the coastal Pilbara Terrane, Western Australia -an example of continental growth and evolution evidence at an Archean continental crust-
Access this Article
Search this Article
The middle Archean (3.25-3.20Ga) coastal Pilbara Terrane was formed by an immature oceanic island arc-continent collision [D<sub>1</sub>: 3.15-3.05Ga] and was deformed by regional intraplate strike-slip deformations [D<sub>2</sub>: 3.0-2.95Ga; D<sub>3</sub>: 2.90-2.80Ga] (Kiyokwa and Taira, 1999; Kiyokawa et al., submit). The immatured oceanic island arc unit of the Cleaverville-Roebourne Supercomplex tectonically overthrusts the granitecontinental shelf metasedimentary Karratha Supercomplex (see cross section) (Kiyokawa and Taira, 1998). D<sub>1</sub> thrust deformation evidences, such as klippen structure, imbricated thrust piles and a basal decollement with quartz mylonite, are well preserved in the complexes boundary. On the other hand, the D<sub>2</sub> event identified regional strike-slip deformations (eg. reactivated quartz mylonite, steep axis asymmetric fold) and the D<sub>3</sub> deformation locally preserved at the terrane boundary with mylonite shear zone [Sholl shear zone]. These deformations are identified as formation of a juvenile continent and stabilization of early continent in Middle Archean.
- Jour. Geol. Soc. Japan
Jour. Geol. Soc. Japan 105(1), 1-11, 1999-01
The Geological Society of Japan