Lorne Basin
Last updated:7 June 2023
Basin Details and Geological Overview
The Lorne Basin is a small, intramontane, Triassic basin, surrounded by the New England Fold Belt. Located between Taree and Port Macquarie, the basin is composed of northern and southern segments separated by an outcrop of basement forming a faulted ridge. The overall dimensions of the basin are approximately 20km in an east-west direction and 35km in a north-south direction. It probably extends offshore under the continental shelf, but this is speculative. Although situated between two major sedimentary basins (the Sydney Basin and Clarence-Moreton Basins), the Lorne Basin has no direct connection with either of them.
The basin is filled with Early Triassic continental sediments of the Camden Haven Group. Terrestrial sedimentation into this basin was probably initiated by tectonic activity along surrounding major faults and serpentinite belts. The sediments include alluvial fan deposits of the Laurieton Conglomerate, associated desert plain or playa deposits of the Camden Head Siltstone and overlying fluvial sediments of the Grants Head Formation. Lorne Basin rocks are overlain by minor Cainozoic volcanics and intruded by Cainozoic microgranites.
The thin sedimentary section of terrestrial lithologies has no potential source rocks and is intruded by Cainozoic microgranites. Fluvial channel sandstones within the Grants Head Formation could be considered as potential reservoir rocks, but the sealing quality of associated intraformational siltstone is dubious. The onshore basin has no petroleum prospectivity. The thickness of any possible offshore extension is unknown, but on the available onshore evidence its prospectivity is probably very low.
Basin Summary Table
| State(s) | New South Wales | |
| Area (km2) | Offshore | ? (unknown if the basin extends offshore) |
| Onshore | 500 | |
| Maximum thickness (m) | 300 | |
| Age Range | Triassic | |
| Basin | Overlies | Palaeozoic basement of the New England Fold Belt. |
| Underlies | Neogene coastal fluvio-lacustrine facies. | |
| Subdivisions | There are no formal subdivisions, but northern and southern lobes of the basin are recognised. | |
| Other | - | |
| Indicators | Knowledge | Moderate geophysical and outcrop data onshore; no data at all if the basin extends offshore. |
| Basin type | Intramontane. | |
| System(s) | Nil | |
| Water Depth (m) | 0 - (?) < 200 | |
| Exploration | Status | Frontier |
| Wells | 0 | |
| Seismic line-km | 0 | |
| Discoveries | Nil | |
| Shows | Nil | |
| HC evidence | Nil | |
| Geology | Source(s) | No source identified |
| Reservoirs | Triassic sandstone and conglomerate facies. | |
| Seals | No seal identified. | |
| Trap types | Complex faulting and facies variations could in theory form traps. | |
| Palaeogeographic summary | Initially alluvial fan and desert plain/playa complex; later wetter with meandering fluvial streams. | |
| Timing | Oil generation | No evidence of generation |
| Gas generation | No evidence of generation. | |
| Trap formation | Triassic | |
| Other key times | - | |
| Other important information | Any offshore extension of the basin will lie under whale migration paths for several months of the year. | |
| Geoscience Australia products available | - | |
Key References
| Author(s) | Year | Title |
|---|---|---|
| Bembrick, C.S. | 1976 | Lorne Basin. In R.B. Leslie, H.J. Evans and C.L. Knight, (Editors), Economic geology of Australia and Papua New Guinea. Volume 3. Petroleum. Australasian Institute of Mining and Metallurgy, Monograph Series, 7, 457-458 |
| Herbert, C. and Burg, R.A. | 1972 | Reconnaissance survey of the ceramic potential of the Lorne Basin. Geological Survey of New South Wales Department of Mines, Report 1972/294 |
| Herbert, C. | 1975 | Lorne Basin. In The mineral deposits of New South Wales, Markham, N.L. & Basden, H., (Editors). Geological Survey of New South Wales Department of Mines, 505-509 |
| Packman, G.H. | 1969 | The New England region; Triassic system. In the geology of New South Wales. Journal of the Geological Society of Australia, 16, Part 1, 270-271 |
| Pratt, G.W. and Herbert, C. | 1973 | A reappraisal of the Lorne Basin. NSW Geological Survey Record, 15, 205-212 |