This map is part of a series which comprises 50 maps which covers the whole of Australia at a scale of 1:1 000 000 (1cm on a map represents 10km on the ground). Each standard map covers an area of 6 degrees longitude by 4 degrees latitude or about 590 kilometres east to west and about 440 kilometres from north to south. These maps depict natural and constructed features including transport infrastructure (roads, railway airports), hydrography, contours, hypsometric and bathymetric layers, localities and some administrative boundaries, making this a useful general reference map.

Legacy product - no abstract available

I50/B1-26

I50/B1-40 Vertical scale: 100

10% coverage south east D52/B1-140 Vertical scale: 20

60% coverage east & south margins missing 22-2/K55-3/7-7 Vertical scale: 75

E54/B1-73

Abstract for Institute of Australian Geographers 2016 conference, 29 June-1 July, Adelaide

The southern Thomson Orogen of northernmost NSW is one of the least exposed provinces in Australia, and the nature and location of its boundary with the northern Lachlan Orogen remains poorly understood. One candidate is the poorly characterised Olepoloko Fault: some workers have interpreted this crustal-scale geophysical feature as a suture juxtaposing disparate provinces; others contend that it is intra-orogenic. To test these competing hypotheses, we investigate the character of the lower crust on both sides of the Olepoloko Fault, as imaged by Lu-Hf and O-isotope systematics of magmatic zircons in granites with U-Pb ages in the range 430410 Ma. This temporal range should maximise the resolution of spatial variation in isotopic trends. Two hundred kilometres south of the Olepoloko Fault, granites from the central Lachlan Orogen (Nymagee area) indicate derivation from one or more evolved sources (Hf = -8 to -3, 18O = 7 to 10). A similar distance to the north, granites from the inboard Thomson Orogen (Hungerford area) are similar (Hf = -8 to -1, 18O = 8 to 10). Surprisingly, granites in the Cuttaburra area (proximal to the central section of the Olepoloko Fault) are not easily distinguished from either set of inboard granites (Hf = -9 to -7, 18O ~ 7). This contrasts with Thomson granites at the western end of the Olepoloko Fault (Tibooburra area) and Lachlan granites at the eastern end (Byrock area): both are characterised by juvenile Hf (-2 to 0; 0 to +5 respectively), and 18O (6 to 7; 5 to 8 respectively) values indicating a lesser role for supracrustal input. Data coverage remains sparse in this reconnaissance study; however, we have not yet identified any contrast in Lu-Hf or O-isotopic character between the interiors of the Lachlan and Thomson Orogens. Granites to the north of the north-dipping Olepoloko Fault in the Cuttaburra area may have been sourced from either orogen, as `Lachlan crust appears to underlie `Thomson crust here. In the southwest Thomson Orogen, the Tibooburra granites lie within a NW-trending zone of distinctive magnetic character 60120 km wide, bounded by the Olepoloko Fault and Tongo Fault. The lower crust of the northeastern Lachlan Orogen is more juvenile in composition in the Louth-Eumarra Shear Zone, and future analyses will interrogate regional trends in this area, by (1) analysing granites on the northern (Thomson) side of the easternmost extent of the Olepoloko Fault, and (2) exploring links between granites in the Byrock area and those of the Macquarie Arc further east. The status of Olepoloko Fault as a suture is not yet clear; however, our results demonstrate the presence of relatively juvenile crust of both sides of it (at opposite ends). The isotopic data complements geophysical datasets and will inform future investigations, including the current pre-competitive drilling program being run by GA in partnership with GSNSW and GSQ. The drilling program will also provide samples from under cover to infill the isotopic coverage in the region.

Legacy product - no abstract available