2.5

COLQUHOUN G.P., HUGHES K.S., DEYSSING L., BALLARD J.C., FOLKES C.B, PHILLIPS G., TROEDSON A.L. & FITZHERBERT J.A. 2023. New South Wales Seamless Geology dataset, version 2.3 [Digital Dataset]. Geological Survey of New South Wales, Department of Regional NSW, Maitland.

This data is part of the New South Wales Seamless Geology database, version 2.3, which is a statewide compilation of the best available digital geological mapping data in an internally consistent GIS format.

Dataset Authors:

Colquhoun, G.P.

Hughes, K.S.

Deyssing, L.

Ballard, J.C.

Phillips G.

Troedson, A.L.

Folkes C.B.

Fitzherbert J.A.

Scheduled updates to this dataset are planned as new data becomes available.

Disclaimer

The information contained in this publication is based on knowledge and understanding at the time of writing (April 2025) and may not be accurate, current or complete. The State of New South Wales (including the DPIRD), the author and the publisher take no responsibility, and will accept no liability, for the accuracy, currency, reliability or correctness of any information included in the document (including material provided by third parties). Readers should make their own inquiries and rely on their own advice when making decisions related to material contained in this publication.

Copyright Statement

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Version 6.2 (Build 9200) ; Esri ArcGIS 10.4.0.5524

The dataset covers the land areas of New South Wales, Australia (including Lord Howe Island). A 10 km buffer into Queensland and Victoria is also included.

The NSW Seamless Geology Project team has compiled the best available geological data for the state into an internally consistent geodatabase. As part of the compilation process, contributing datasets were organised into a series of layers, or time slices, that represent the major lithotectonic subdivisions of the state’s geology. The data was then stitched/smoothed along existing map and dataset boundaries to create a seamless dynamic model of the geology of NSW. Important datasets and projects that contributed to the NSW Statewide Seamless Geology dataset are detailed below.

The Seamless Geology Project commenced in 2013 when merges of the best available datasets began to be assembled in the Statewide Geology Geodatabase (v.2) format. The source datasets for these merges are shown in the feature class “Seamless_V1_Source_Datasets” in this geodatabase. This merged dataset was divided into stratotectonic layers which were then edited by a small team of geologists, resolving edge-match issues and nomenclature problems between the geology of adjacent map sheets, and interpreting various layers under the cover of overlying layers. This produced a series of seamless geology layers which showed, for the first time, the actual distribution of rock units and structures, both in outcrop and under cover. These datasets were released progressively across the state as this work was completed, with three packages having been previously released; a Zone 56 dataset (Colquhoun, Phillips, Hughes, Deyssing, Fitzherbert & Troedson 2015), a Zone 54 dataset (Colquhoun, Phillips, Ballard, Hughes & Deyssing 2016) and a Zone 55 East dataset (Colquhoun, Deyssing, Ballard, Hughes & Troedson 2017). Zone 55 West was completed in mid-2018 but was not released as a separate dataset. Instead, the Zone 55 West data was merged with the previously released Seamless Geology datasets from the various zones and merged and harmonised to produce the first statewide Seamless Geology of NSW (version 1) in October 2018.

Updates to the Seamless Geology dataset have occurred every year since its release in 2018. These changes are detailed in a GS Report which can be accessed via the Download and links section above. Changes to the current version (v. 2.5) are detailed below:

What's new in Version 2.5 (May 2025)?

• Quaternary Lake, Pooncarie area – fixed a mistake in the Cenozoic Sedimentary Province layer around 142.9452990° -33.8148857° (GDA94) where a missing line from the Pooncarie 1:250,000 Geological Sheet had caused a polygon of Q_lps to not appear and was instead filled by Q_lp.

• Mount Frome Syncline and Pine Ridge Syncline – the large syncline southeast of Mudgee has been mistakenly labelled as the Mount Frome Syncline in previous versions of the NSW Seamless Geology. The original name Pine Ridge Syncline has been restored to the structure name attribute in the Seamless Geology as was originally intended by Colquhoun et al. (1997).

• Stephens Creek outcrop – an area of outcrop was added to the dataset approximately 2 km east of Stephens Creek around 141.5438886° -31.8309971° (GDA94).

• Thirlmere Lakes alluvium age – the Thirlmere Lakes alluvium has been moved from the Great Australian Basin layer to the Cenozoic Sedimentary Province layer and mapped as QH_l (Holocene lacustrine deposits).

• Packsaddle Syenite – outcrops of Jurassic syenite and orthosyenite near Packsaddle Trigonometrical Station in the Bancannia area, around 141.974353° -30.577955° (GDA94) were added to the Permian—Mesozoic Igneous Province layer.

• Sub basaltic gravels – to capture sub-basaltic gravels and deep leads correctly, a new layer has been added to the NSW Seamless Geology at version 2.5: Sub-CIP Cenozoic Sedimentary Province. The new layer has been placed below the Cenozoic Igneous Province layer (CIP) and above the Great Australian Basin (GAB) layer in the GIS packages and in MinView.

• Coolac Serpentinite Belt and Gilmore Fault Zone – the mapping of the Coolac Serpentinite Belt and the Gilmore Fault Zone (covering significant parts of the Tumut, Cootamundra, and Yarrangobilly 1:100,000 map sheet areas) has been extensively updated in version 2.5 of the Seamless Geology. The new mapping was largely derived from the work of Peter Stuart-Smith for his PhD and the Tumut seismic line geology traverse. The mapping was published extensively in the late 1980s and early 1990s.

• Eden–Merimbula Geology update – the Devonian geology of the Eden to Merimbula area (NSW far South Coast) received an upgrade in version 2.5 of the NSW Seamless Geology. The Merimbula Group and Boyd Volcanic Complex were left largely undifferentiated on the Bega 1:250,000 Geological Sheet (2nd edition) and previous versions of the NSW Seamless Geology. The constituent formation and member level units of these groups were added to the Seamless Geology version 2.5 based on the mapping of Steiner (1966), Hall (1960), Fergusson et al. (1979), Goldfields Exploration (1982), and Fergusson (2023).

• Bunga beds update – the Bunga beds of the Boyd Volcanic Complex in Mimosa Rocks National Park has been formalised as the Bunga Formation and the mapping of the unit has been upgraded based on numerous published geological maps of the unit by Cas et al. (1990), Cas and Bull (1993), Rickard and Love (2000), and Giordano and Cas (2001).

• Lachlan Orogen structure points plotting under cover – using several spatial queries during editing, it was noted that 1,126 structure points in the Lachlan Orogen layer plotted underneath younger layers – mostly the Cenozoic Sedimentary Province or the Cenozoic Igneous Province. In many cases, these errors have arisen when later or more detailed mapping was added to the Lachlan Orogen layer, but not the younger cover sequence layers. These errors were fixed by creating 'Voids' in the Cenozoic Sedimentary Province layer (i.e., outcrops), or moving boundaries slightly with the aid of ADS imagery and 5 m DEM data. In the case of older, inaccurately located points, the point was moved into a nearby outcrop area based on ADS imagery data.

• Andersons Tank Limestone Member and Bilpa Conglomerate – the geology of the Anderson Hill area (142.8064472° -31.5821764°, GDA94) 52 km west of Wilcannia, was updated using Figure 1 of Zhen et al. (2024). The Bilpa Conglomerate and Nuchea Conglomerate (Mutawintji Group) around 142.3799483° -31.8754559 (GDA94) were added to the Seamless Geology dataset based on descriptions by Greenfield et al. (2010).

• Hanaminno Limestone (Suoh) suppression – the Hanaminno Limestone was suppressed based on the recommendation of Percival and Zhen (2017) and the limestones of the area were reassigned to 'Hawkins Volcanics – limestone' (Sdoh_l).

• Gunderbooka mapping upgrade – version 2.5 of the NSW Seamless Geology includes a significant upgrade to the geology of the Gunderbooka 1:100,000 map sheet area in north central NSW. The updated mapping dataset (Deyssing and Trigg 2024) is significantly more detailed than the previous mapping over the Gunderbooka area and has resulted in changes to four layers in the Seamless Geology – the Cenozoic Sedimentary Province, Great Australian Basin, Western Devonian Basins, and Lachlan Orogen. The work also resulted in 14 new units, and 4 with updated codes or description changes.

• Malachis Hill Formation and Cheesemans Creek Formation – based on the recent work of Smith et al. (2024), the Cheesemans Creek Formation has been suppressed in favour of the earlier-named Malachis Hill Formation and all polygons formerly assigned to the Cheesemans Creek Formation have been reassigned to the Malachis Hill Formation.

• Structure Points upload from Field Observations database – 2,974 structure points were added to the NSW Seamless Geology dataset, mostly to the Lachlan Orogen, New England Orogen, and the Western Devonian Basins and Great Australian Basin layers.

• Fault attribution – Lachlan Orogen – the fault-related attributes for the Lachlan Orogen were completed during version 2.5. In version 2.4 (and previous versions) of the Seamless Geology, several hundred faults were without fault-related attributes, largely from recently added data.

• Port Macquarie–Laurieton area – the geology of the Port Macquarie-Laurieton area received a substantial upgrade during version 2.5, particularly the rock units of the New England Orogen (east of the Innes Estate Fault). This was based on an update (Och 2023) to earlier PhD thesis mapping of the area (Och 2007) using Nearmap coastal images.

• Thule Granite outcrop changes – 35 small voids (usually on small hills) were added to the Q_r residuum covering the Thule Granite to allow mapped quartz veins in Lachlan Orogen layer to be visible in the surface geology.

dataset

ISO 19139 Geographic Information - Metadata - Implementation Specification ISO 19139 Geographic Information - Metadata - Implementation Specification

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