Palynological studies of Triassic-Jurassic well sections in the Offshore North Perth Basin have helped to reveal a more complicated geological history than previously recognised. This work is part of a major Geoscience Australia project studying the geological history and petroleum prospectivity of the basin. Seismic and well log interpretations have been combined with the sedimentological data to develop a high resolution sequence stratigraphic framework. This work is heavily reliant on the palynological data to provide the necessary age control, palaeoenvironmental interpretations and well correlations. Abstract continues (no space in field).

Abstract tittled "New frontier exploration opportunities on Australia's southwest margin" to accompany presentation at the SEAPEX conference 2011.

Paleoproterozoic sedimentary rocks of northern Australia host one of the world's most important zinc repositories. Despite more than fifty years of geological investigation, including the production of 1:250,000 and 1:100,000 geological maps and the drilling of countless mineral exploration holes public domain datasets contain comparatively little measured section and basic sedimentological information. Because these datasets are essential for understanding sediment architecture and basin shape they from a necessary stepping stone to formulating models aimed at constraining the flow of mineralising fluids in these basins. This data record provides the mineral exploration industry, university and government geoscientists with 37 single sections which are subsequently combined to form twenty six composite outcrop and drill core stratigraphic sections through the Surprise Creek Formation, Warrina Park and Torpedo Creek Quartzites, lower Gunpowder Creek Formation and Moondarra Siltstone. Close to twenty three thousand meters of stratigraphic/sedimentological description and interpretation are provided. Most sections contain grain size, lithology, bed thickness, sedimentary structure and gamma ray data from which facies and sequence stratigraphic surfaces are interpreted. Gamma ray data is not available for drill holes Templeton 1 and UD784. The section at Fiery Creek is generalised from the earlier work of researchers at Monash University and does not contain the detailed sedimentological information found in the rest of the logs. Eight sections contain revised interpretations from the earlier NABRE work. Despite the absence of invertebrate fossils the sequence interpretations, in combination with SHRIMP zircon ages and Apparent Polar Wander Path data, permit the erection of a well-constrained chronostratigraphic framework for these Paleoproterozoic rocks. Previous lithostratigraphic subdivisions were diachronous and emphasised local stratigraphic successions rather than basin-wide correlations. The data contained in this Geoscience Australia record and the earlier companion data releases of AGSO Records 1999/10, 1999/15 1999/19 and 2000/03 contain chronostratigraphic sequence subdivisions from which original basin shape and sediment architecture can be derived. Lithostratigraphic miscorrelations associated with quartzite sandbodies of the Warrina Park and Torpedo Creek Quartzites, unit Prc of the Surprise Creek Formation and the lower parts of the Gunpowder Creek Formation and Moondarra Siltstone are resolved. Detailed descriptions and discussions of facies, SHRIMP Zircon ages, lithostratigraphic miscorrelations and rationale for sequence stratigraphic interpretations are provided in Jackson et al., (in prep).

Measured sections and sequence stratigraphic interpretations of the Upper McNamara and Fickling Groups, Queensland.

Techtonostratigraphic synthesis - Compilation and analysis of Geoscience Australia's studies of basins along Australia's southern margin over the last 10 years.

The Bass Basin is a moderately explored Cretaceous to Cainozoic intracratonic rift basin on Australia?s southeastern margin. A basin-wide integration of seismic data, well logs, biostratigraphy and sequence stratigraphy has resulted in the identification of six basin phases and related megasequences/ supersequences. These sequences correlate to three periods of extension, a rift-transition phase, and two subsidence phases. The complex nature of facies relationships across the basin is attributed to the (mostly) terrestrial setting of the basin until the Middle Eocene, multiple phases of extension, strong compartmentalisation of the basin due to underlying basement fabric, and differential subsidence during extension and early subsidence phases. Evidence of the initial rift phase (Otway Megasequence) is only clearly observed in the Durroon Sub-basin and in the southwestern Cape Wickham Sub-basin. The second rift phase (Durroon Megasequence) is pervasive throughout the Bass Basin, although a full succession of this megasequence was only penetrated in the Durroon Sub-basin. The third-rift phase (Bass Megasequence) is also pervasive throughout the basin, but appears to have affected only particular depocentres such as the Pelican, Cormorant and Yolla troughs. Here, expanded syn-tectonic growth sections have been intersected. There is wide variation in facies type, environment and thickness of the Bass Megasequence due to differential rates of subsidence. Three component sequences have been recognised within the Bass Megasequence (Furneaux, Tilana and Narimba sequences), with each component sequence correlated to discrete periods of increased accommodation. The shift from rift-to-post-rift conditions (Aroo Megasequence) was signaled by waning subsidence rates and an increasing brackish influence. A wide variation in facies types, environments and thicknesses is also observed. The frequency and thickness of coals began to increase during the deposition of this megasequence, lasting from Early Eocene until the mid-Middle Eocene. A slowdown in subsidence rates allowed the aggradation of coaly facies (many geochemically characterised as ?hydrogen-rich?), indicating there was a balance between accommodation, sediment supply and peat production. The most important sequences for petroleum generation and trapping are the Bass and Aroo megasequences. Most of the coaly source rocks now typed to liquid hydrocarbon generation were deposited during the period of late Early Eocene to Middle Eocene rift-transition phase. The critical factor in sourcing accumulations from the coaly succession appears to be effective primary and secondary expulsion from the source rock and the volume of charge. Biostratigraphic studies have identified lacustrine cycles during the Late Cretaceous to Middle Eocene, with geological evidence indicating these lakes developed during times of increased accommodation. Lacustrine shales are likely to be more important as seal facies, rather than as potential source rocks. The Middle Eocene (Demons Bluff Sequence) and younger marine successions (Torquay Sequence) show low source potential and do not lie within the oil window. Optimal conditions for seal deposition occurred during lacustrine cycles in the Late Cretaceous to Early Eocene, and the mid-Eocene. Untested plays include reservoir/seal pairs associated with seven maximum flooding events in the western Bass Basin. The petroleum systems elements of the Durroon Sub-basin differ significantly from the Cape Wickham Sub-basin owing to the cessation of tectonically-driven subsidence in the eastern Bass Basin (Durroon Sub-basin) from the mid-Campanian onward.

Contents: 1. Lambert IB and Perkin DJ. Australia's mineral resources and their global status. 2. Davidson GJ and Large RR. Proterozoic copper-gold deposits. 3. Dorling SL, Groves DI and Muhling P. Lennard Shelf Mississippi Valley-type (MVT) Pb-Zn deposits, Western Australia. 4. Dowling SE and Hill RET. Komatiite-hosted nickel sulphide deposits, Australia. 5. Gemmell JB, Large RR and Khin Z. Palaeozoic volcanic-hosted massive sulphide deposits. 6. Hoatson DM. Platinum-group element mineralization in Australian Precambrian layered mafic-ultramafic intrusions. 7. Huston DL. The hydrothermal environment. 8. Jaques AL. Kimberlite and lamproite diamond pipes. 9. Kitto PA. Renison-style carbonate-replacement Sn deposits. 10. Lawrie KC and Hinman MC. Cobar-style polymetallic Au-Cu-Ag-Pb-Zn deposits. 11. McGoldrick P and Large RR. Proterozoic stratiform sediment-hosted Zn-Pb-Ag deposits. 12. Mernagh TP, Wyborn LAI and Jagodzinski EA. 'Unconformity related' U and/or Au and/or platinum-group-element deposits. 13. Morris RC. BIF-hosted iron ore deposits - Hamersley style. 14. Phillips GN and Hughes MJ. Victorian gold deposits. 15. Rowins SM, Groves DI and McNaughton NJ. Neoproterozoic Telfer-style Au (Cu) deposits. 16. Senior BR. Weathered-profile-hosted precious opal deposits. 17. Walters SG. Broken Hill-type deposits. 18. Waring CL, Heinrich CA and Wall VJ. Proterozoic metamorphic copper deposits. 19. Wilcock S. Sediment-hosted magnesite deposits. 20. Yeats CJ and Vanderhor F. Archaean lode-gold deposits. 21. Cooke DR and Large RR. Practical uses of chemical modelling - defining new exploration targets in sedimentary basins. 22. Idnurm M and Wyborn LAI. Palaeomagnetism and mineral exploration related studies in Australia: a brief overview of Proterozoic applications. 23. Krassay AA. Outcrop and drill core gamma-ray logging integrated with sequence stratigraphy: examples from Proterozoic sedimentary successions of northern Australia. 24. Waring CL, Andrew AS and Ewers GR. Use of O, C and S stable isotopes in regional mineral exploration. 25. Oliver NHS, Rubenach MJ and Valenta RK. Precambrian metamorphism, fluid flow, and metallogeny of Australia. 26. Taylor G and Butt CRM. The Australian regolith and mineral exploration. 27. Barley ME. Archaean volcanic-hosted massive sulphides. 28. Blevin P. Palaeozoic tin and/or tungsten deposits in eastern Australia. 29. Brand NW, Butt CRM and Elias M. Nickel laterites: classification and features. 30. Butt CRM. Supergene gold deposits. 31. Cooke DR, Heithersay PS, Wolfe R and Calderon AL. Australian and western Pacific porphyry Cu-Au deposits. <strong>Related information</strong> <a href="https://www.ga.gov.au/products/servlet/controller?event=GEOCAT_DETAILS&amp;catno=63681">Blevin PL, Intrusion related gold deposits</a> *Not incuded in original AJGG text. Model first published here September 2005.

The conjugate margins of Wilkes Land, Antarctica, and the Great Australian Bight (GAB) are amongst the least understood continental margins. Break up along the GAB-Wilkes Land part of the Australian-Antarctic margin commenced at approximately 83 Ma. Using recent stratigraphic interpretations developed for the GAB, we have established a sequence stratigraphy for the Wilkes Land margin that will, for the first time, allow for a unified study of the conjugate margins. By reconstructing the two margins to their positions prior to break up we were able to identify comparable packages on the Wilkes Land margin to those recognised on the GAB margin. Excluding the glacial sediments on the Antarctic margin, the sedimentary sequence along the Wilkes Land margin is very thin compared to the GAB margin, which has substantially more syn- and post-rift sediments. Despite the differences in thickness, the syn-rift sedimentary package on the Wilkes Land margin exhibits a similar style of extensional faulting and seismic character to its GAB margin counterpart. In comparison, post-rift sequences on the Wilkes Land margin are markedly different in geometry and seismic character from those found on the GAB margin. Isopach mapping shows substantial differences in the thickness of the post-breakup sediments, suggesting different sediment sources for the two margins. The Late Cretaceous Hammerhead Supersequence provides much of the post-rift thickness for the GAB margin as a result of large sediment influx into the basin. This supersequence is characterised by thick progradational succession and was deposited in fluvio-deltaic and marine environments. The equivalent succession on the Wilkes Land margin has a different seismic character. It is thinner and aggradational, suggesting a distal marine environment of deposition.

A detailed sequence stratigraphic study has been undertaken on the three wells in the Houtman Sub-basin: Gun Island 1, Houtman 1 and Charon 1. The study focussed on the Early-Late Jurassic Cattamarra Coal Measures, Cadda Formation and Yarragadee Formation succession. Wireline log character, cuttings, sidewall core and conventional core lithologies and palynological data were used to identify facies and paleoenvironments. Palynology for all wells has been reviewed, including new data collected by Geoscience Australia for Gun Island 1. Facies stacking patterns were used to define systems tracts and subsequently ten third-order depositional sequences. At the second-order (supersequence) level, the Cattamarra Coal Measures record a transgression culminating in maximum flooding in the Cadda Formation followed by highstand aggradation and regression in the Yarragadee Formation. The third-order sequences characterised in this study overprint this supersequence and control the local distribution of facies. The relative dominance of a facies may be either enhanced or diminished depending upon its position within the larger second-order supersequence. For example, a number of transgressive systems tracts within the dominantly non-marine Yarragadee Formation and Cattamarra Coal Measures record multiple, dinocyst-bearing, minor marine incursions into the Houtman Sub-basin. These marine incursions are not evident in the Yarragadee Formation in Charon 1, indicating a lack of accommodation space or proximal sediment input in the north during the mid-late Jurassic. The combined influence of these third-order and second-order sequences on facies distribution has significant implications for the distribution of potential reservoirs and seals in the Houtman Sub-basin and for regional palaeogeographic reconstructions of the Perth Basin.

Paleoproterozoic-earliest Mesoproterozoic sequences in the Mount Isa region of northern Australia preserve a 200 Myr record (1800-1600 Ma) of intracontinental rifting, culminating in crustal thinning, elevated heat flow and establishment of a North American Basin and Range-style crustal architecture in which basin evolution was linked at depth to bimodal magmatism, high temperature-low pressure metamorphism and the formation of extensional shear zones. This geological evolution and record is amenable to investigation through a combination of mine visits and outcrop geology, and is the principal purpose of this field guide. Rifting initiated in crystalline basement -1840 Ma old and produced three stacked sedimentary basins (1800-1750 Ma Leichhardt, 1730-1670 Ma Calvert and 1670-1575 Ma Isa superbasins) separated by major unconformities and in which depositional conditions progressively changed from fluviatile-lacustrine to fully marine. By 1685 Ma, a deep marine, turbidite-dominated basin existed in the east and basaltic magmas had evolved in composition from continental to oceanic tholeiites as the crust became increasingly thinned and attenuated. Except for an episode of minor deformation and basin inversion at c. 1640 Ma, sedimentation continued across the region until onset of the Isan Orogeny at 1600 Ma.