Normal faults of probably Early Cretaceous age transect the entire sequence. A gradual change from a NE-SW to a N-S stress field produces oblique strike-slip faults. This deformation is also superimposed on the thrusted and folded (D 1 to D 3) sequence to the east of the Grampians half-graben, producing further thrusts. It has been subjected to a Middle Devonian compressional deformation event, D 4, with the development of thrust and fold structures. The Grampians extensional basin, overlying the Late Proterozoic to Ordovician sequence, records a significant change in the tectonic regime operating during the Late Silurian-Early Devonian. Overprinting the early thrust system are D 4-D 6 deformation events that include reverse, strike-slip and normal faults. The steep (≈ 60°) predominantly W-dipping thrusts represent high-strain zones localised in relatively weak Cambro-Ordovician quartz-rich turbidites, that are sandwiched along the boundaries of the Late Proterozoic metavolcanics. The thrust system follows a NE-SE-trending strike, with an E-directed translation of the tectonic units. Early deformation events, D 1-D 3, in the Stawell Zone pre-date granite emplacement and were synchronous with regional fold-forming events that accompany thrust movements along discrete detachment surfaces. The Cambro-Ordovician turbidite sequence of the Stawell and Glenelg zones rests on a pile of Late Proterozoic metavolcanic rocks, rather than Cambrian metavolcanic units that are characteristic of the Lachlan Fold Belt. The Stawell Zone is interpreted to be part of the eastern extension of the Adelaide Fold Belt into Victoria.
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