Tectono‐stratigraphy of a Palaeozoic subduction complex in the central Coffs Harbour Block of north‐eastern New South Wales

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Abstract
The Coffs Harbour Block is a major part of the Tablelands Complex in the SE New England Fold Belt. Complexly deformed rocks of the central Coffs Harbour Block are subdivided into three tectono‐stratigraphic units. The youngest unit is the ?Late Carboniferous Coffs Harbour sequence which consists mainly of turbidites. Greywackes of this unit were derived from the erosion of a silicic volcanic terrain. To the NE of the Coffs Harbour sequence is the Gundahl Complex, a tectonic melange of regional extent. This unit consists of slabs of chert, greenstone, massive greywacke and bedded turbidite sequences embedded in sheared argillite matrix. Greywackes of the Gundahl Complex are oolith‐bearing and rich in intermediate to silicic volcanic rock fragments, characteristics which imply an Early Carboniferous age for greywacke‐bearing blocks. To the NE of the Gundahl Complex are the Willowie Creek beds. These consist mainly of tuffaceous mudstone and fine‐grained intermediate to mafic igneous rocks with minor greywacke, argillite, conglomerate, limestone breccia, chert and jasper. The Siluro‐Devonian Willowie Creek beds are part of a suspect terrain that was accreted to the ancient eastern Australian margin in the ?Middle Devonian. During the Carboniferous all three tectono‐stratigraphic units constituted a subduction complex paralleling the Tamworth‐Yarrol shelves (forearc basin) and the Connors‐Auburn arches (magmatic arc).