Blueschist and eclogite in tectonic melange, Port Macquarie, New South Wales, Australia
- Mineralogical Society
- Publication Type:
- Journal Article
- Mineralogical Magazine, 2003, 67 (4), pp. 609 - 624
- Issue Date:
The Rocky Beach Metamorphic Melange contains metre-scale phacoids of high-P low-T metamorphic rocks embedded in chlorite-actinolite schist. The phacoids include eclogite, glaucophane schist and omphacitite and provide evidence for four episodes of metamorphism with mineral assemblages: M1 = actinolite-glaucophane-titanite-apatite, M2 = almandine-omphacite-lawsonite ± quartz, M3 = phengiteglaucophane-K-feldspar-quartz, and M4 = chlorite-actinolite-calcite-quartz-titanite-white mica ± albite ± talc. M1-M3 occurred at a Neoproterozoic-Early Palaeozoic convergent plate boundary close to the eastern margin of Gondwana. Peak metamorphic conditions were attained during the static phase M2, with temperatures of ~560ºC and pressures in excess of 1.8 GPa, equivalent to a depth of burial of at least 54 km.
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