Manilla Explanatory Notes (2010)

Abstract

The Manilla 1:100 000 map sheet area (Manilla) includes rocks of the Tamworth Belt and Central Block of the New England Orogen, which are separated by the Peel Fault. Each block is characterised by its own unique assemblage of rock types, structures, tectonostratigraphic terranes and mineralisation. The Tamworth Belt contains Early Devonian to Late Carboniferous regressive marine to non-marine sequence of sedimentary and minor volcanic rocks. Most of these rocks make up the Gamilaroi terrane. The strata reflect a change from basal slope marine sedimentation through shelfal deposition, near-shore and shoreline marine, and ultimately continental fluvial and glacigene sedimentary and volcanic deposition. Olistostromal sedimentary and volcanic rocks are common throughout the marine strata, representing environments that were proximal to steep slopes, deeply incised submarine canyons, and island-arc flanks. The rocks show an evolution from andesitic and some basaltic volcanism in the Devonian and Early Carboniferous to rhyolitic and rhyodacitic volcanism in the Late Carboniferous. In Manilla, the Tamworth Belt is subdivisible into a number of structural domains characterised by distinctive structural suites. These domains increase in complexity eastward towards the Peel Fault. Low bedding dips, open first-generation folds with open second-generation cross folds and low-angle, bedding-parallel thrusts characterise the west of the area. Vertical and overturned bedding, accompanied by first-generation tight folds, second-generation isoclinal folds with well-developed slaty cleavage and folded, steeply dipping thrusts characterise the rocks adjacent to the Peel Fault.

Reference

Vickery N.M., Brown R.E. & Percival, I.G. (compilers) 2010. Manilla 1:100 000 Geological Sheet 9036, Explanatory Notes. Geological Survey of New South Wales, Maitland.