Structural analysis of metasedimentary enclaves: Implications for tectonic evolution and granite petrogenesis in the southern Lachlan Fold Belt, Australia

Abstract

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