Fig. 4. Typical meso- and microscale features of the main rock types in the Waroonga greenstone belt.
a Polished hand specimen (sample 209029) from the core of a garnet amphibolite body. Subhedral to euhedral, cm-sized garnet and pale-green clinopyroxene porphyroblasts (M1 assemblage) show variable degrees of retrogression, as marked by hornblende-rich black rims. b Plane polarized light view of hand sample shown in a, highlighting the texturally preserved peak (M1) assemblage of clinopyroxene, garnet, quartz and rutile. Peak pyroxene (Cpx1), whose outline is marked by dashed yellow lines, is replaced by clinopyroxene (Cpx2)–plagioclase1 symplectites (M2 assemblage) and by hornblende–plagioclase2 symplectites. The latter developed at the expenses of both Cpx1 and garnet. c Garnet porphyroblast (sample 209029) preserving evidence of two internal foliations (Sx crenulating Sx-1 foliation) that, since they predate garnet growth, find no equivalence in mesoscale fabrics observable in the field. d Transposed bedding in strongly deformed Banded Iron Formation (BIF), showing rootless, isoclinal folds. e Transposed bedding in strongly deformed quartzite, in primary contact with BIF. f Micrograph from quartzite shown in e, with granulite-facies assemblage comprising skeletal garnet (with sillimanite inclusions) wrapped by plagioclase ribbons, and small clinopyroxene porphyroblasts scattered in quartz ribbons. Plane polarized light.