STRUCTURAL-ANALYSIS OF METASEDIMENTARY ENCLAVES - IMPLICATIONS FOR TECTONIC EVOLUTION AND GRANITE PETROGENESIS IN THE SOUTHERN LACHLAN FOLDBELT, AUSTRALIA

Schistose, upper amphibolite facies, metasedimentary enclaves from gra nites across the southern Lachlan Fold Belt of southeastern Australia have a common structural history, The middle crustal region, from whic h the enclaves and their host granites derived, is assumed therefore t o be structurally uniform across the fold belt, The uniform nature of the crustal component represented by the metasedimentary enclaves cast s doubts on the existence of suspect or Proterozoic microcontinental b locks within the terrane collage. A proposed crustal cross section for the southern Lachlan Fold Belt shows a tectonically thickened Paleozo ic section overlying an oceanic substrate, An Ordovician sedimentary c omponent was involved in the generation of both S- and I-type granites .