Abstract
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The Wandilla terrane consists of, from west to east, the Doonside Formation and the Wandilla Formation. The Doonside Formation is dominated by chert and mudstone. Conodonts from a single locality (Devils Bend) indicate an age in the interval Late Silurian to Middle Devonian. The Wandilla Formation consists of mudstone with greywacke, tuff, chert and greenstone. The greywacke is dominated by volcanic detritus with sparse but persistent ooliths that suggest contemporaneity with Early Carboniferous strata of the Yarrol shelf to the west. The Wandilla terrane is structurally complex with two main deformation events. The first deformation (D1) formed widespread lenticular melange during offscraping at the toe of a subduction complex. The second deformation (D2) formed a moderately to shallowly east-dipping cleavage that typically dips less steeply than the north-northwest-trending D1 structures, and contains a down-dip elongation lineation. D2 structures were produced by the Late Permian to Triassic Hunter-Bowen Orogeny. Lithological attributes and structural styles indicate a subduction complex setting for much of the Wandilla terrane and related units farther south. New ages from chert in the subduction complex of the New England Fold Belt are mainly Early Carboniferous, consistent with a major accretionary episode in the late Early and Late Carboniferous. By analogy with the considerably better dated units of the Japanese accretionary terranes, this major period of growth may have been a result of collision of a major topographic feature with the trench (e.g. a mid-ocean ridge). �� 1993 Taylor & Francis Group, LLC.