Structural relations in the subduction complex of the Paleozoic New England fold belt, eastern Australia.

The New England Fold Belt of SE Australia is divided by the Peel Fault System into a W magmatic arc-frontal arc succession and an E subduction complex assemblage. The W part of the subduction complex consists of repeated slices of a sequence which, where most complete, comprises dolerite overlain by basalt (sometimes pillowed), radiolarian chert, siltstone and, in the younger thicker slices, sandstone. The basal contact of this sequence is always faulted. A planar veined surface separates overlying basic igneous rocks from a sheared mass composed mostly of sedimentary material in which are imbedded tectonically derived blocks of basic igneous rock. This sheared zone passes gradationally down into less deformed sedimentary rocks of the underlying sequence. Slices, each of which is usually a few hundred meters thick, young constantly W (toward the magmatic arc) forming a stacked steeply-dipping sequence tens of kilometers thick. The distribution and inter-relationship of lithologies within the subduction complex is consistent with a model involving the progressive off-scraping and accretion of the upper segments of oceanic lithosphere by imbricate thrust faulting, rather than the subduction of this material beneath the arc. -from Author