The Structural Development of the Kanmantoo Schist Based on FIAs from Samples at Petrel Cove and the Strathalbyn Anticline
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Inclusions within porphyroblasts from Petrel Cove and the Strathalbyn Anticline provide evidence for metamorphic events not previously recognized in the Delamerian orogen because they contain more than five foliations defining at least two foliation intersection/inflection axes (FIAs). At Petrel Cove one FIA is preserved within cordierite. An identical FIA is preserved within staurolite in the Strathalbyn Anticline but another younger FIA is present in andalusite. The latter sequence appears to resolve the problem of apparently synchronous multiple phases of growth of staurolite and andalusite in these rocks (e.g., Adshead-Bell & Bell, 1999). Reactivation has destroyed these foliations or rotated them into parallelism with the bedding, which is why they were not distinguished until measurements of FIAs were made. The FIA succession distinguishes a progression of metamorphic events and further work of this type in the region will provide enough data for the shear senses suggested by this preliminary study to be confirmed.
Helen Daly Bohmer Quest Best Paper