This data package was preduced in response to a request by Rodney King from Teck Australia for a compilation of GA borehole datasets from the Isa Superbasin, in particular for gamma-ray data. The data set includes drill hole/section location information, and lithological, geochemical and gamma ray data. All data were extracted from GA databases.

The ca. 1.4 Ga Roper Group of northern Australia comprises the sedimentary fill of one of the most extensive Precambrian hydrocarbon-bearing basins preserved in the geological record. It is interpreted to have been deposited in a large epeiric sea known as the Roper Seaway. This study presents hydrocarbon biomarkers, high-resolution trace element redox geochemistry and neodymium isotopes of immature to mature black shales to understand the microbial diversity and palaeo-environment of the Roper Seaway.

Abstract: The onshore Georgina Basin in northern Australia is potentially prospective for unconventional hydrocarbons, however, like many frontier basins it is under-explored. A well-connected hydraulic fracture network has been shown to be essential for the extraction of resources from the tight reservoirs that categorise unconventional plays, as they allow for economic flows of fluid from the reservoir to the well. One of the fundamental scientific questions regarding hydraulic stimulation within the sub-surface of sedimentary basins is the degree to which local and regional tectonic stresses act as a primary control on fracture propagation. As such, an understanding of present-day stresses has become increasingly important to modern petroleum exploration and production, particularly when considering unconventional hydrocarbon reservoirs. This study characterises the regional stress regime in the Georgina Basin using existing well data. Wellbore geophysical logs, including electrical resistivity image logs, and well tests from 31 petroleum and stratigraphic wells have been used to derive stress magnitudes and constrain horizontal stress orientations. Borehole failure features interpreted from wellbore image and caliper logs yield a maximum horizontal stress orientation of 044°N. Integration of density log data results in a vertical stress gradient of 24.6 MPa km-1. Leak-off and mini-fracture tests suggest that this is the minimum principle stress, as leak-off values are generally shown to be at or above the magnitude of vertical stress. The maximum horizontal stress gradient is calculated to be in the range of 34.0-53.9 MPa km-1. As such, a compressional stress regime favouring reverse/reverse'strike-slip faulting is interpreted for the Georgina Basin.

Baseline information on biodiversity and habitats is required to manage Australia's northern tropical marine estate. This study aims to develop an improved understanding of seafloor environments of the Timor Sea. Clustering methods were applied to a large dataset comprising physical and geochemical variables which describe organic matter (OM) reactivity/quantity/source and geochemical processes. Infauna data were used to assess different groupings. Clusters based on physical/geochemical data discriminated infauna better than geomorphic features. Major variations amongst clusters included grainsize and a cross-shelf transition in from authigenic-Mn /As enrichments (inner shelf) to authigenic-P enrichment (outer shelf). Groups comprising raised features had the highest reactive OM concentrations (e.g. low chlorin indices and C:N-ratios, and high k) and benthic algal '13C signatures. Surface area normalised OM concentrations higher than continental shelf norms were observed in association with: (i) low -15N, inferring Trichodesmium input; and (ii) pockmarks, which impart bottom-up controls on seabed chemistry and cause inconsistencies between bulk and pigment OM pools. Low Shannon-Wiener diversity occurred in association with low redox and porewater pH and evidence for high energy. Highest beta-diversity was observed at euphotic depths. Geochemical data and clustering methods used here provide insight into ecosystem processes influencing biodiversity patterns in the region.

Nolans Bore is a REE-U-P deposit (47 Mt grading 2.6% REO, 186 ppm U3O8 and 11% P2O5) hosted by apatite veins and breccias within the ~1805 Ma Boothby Orthogneiss of the Aileron Province, Northern Territory. Allanite SHRIMP U-Pb analyses indicate a vein crystallisation age of 1525±40 Ma, but mineral system processes necessary to the development of the deposit commenced before 1800 Ma and continue today. Processes leading to the formation of Nolans Bore began with north-dipping subduction along the south margin of the Aileron Province at 1820-1750 Ma, producing a metasomatised, volatile-rich lithospheric mantle wedge. About 200 Ma later, towards the end of the Chewings Orogeny, this reservoir became a source of alkaline low-degree partial melts which passed into the mid- and upper-crust. Among these alkaline products was a phosphate-rich magmatic-hydrothermal fluid which deposited the Nolans Bore apatite veins by local fluid-rock interaction and/or fluid mixing at ~400 degrees C. The deposit then became a radiogenic heat source, owing to its size and high concentration of Th, raising the local ambient temperature to ~300 degrees C, above the closure temperature of some mineral isotopic systems. For example, vein apatite U-Pb ages are in the range ~1240 to ~960 Ma, significantly younger than initial emplacement. The system finally cooled below 300 degrees C (the 40Ar-39Ar closure temperature of biotite) at ~370 Ma, possibly in response to unroofing during the Alice Springs Orogeny. Subsequent to surface exposure, weathering of fluorapatite produced acidic fluids and intense, near-surface kaolinitised zones that form high-grade, supergene-enriched cheralite-rich ores. This groundwater-mediated process continues today. The local heat production of Th- and/or U-rich deposits is an important feature that may be partly responsible for the arrays of post-emplacement isotopic ages which characterise such mineral systems. Other physical and chemical processes continue to be generated by the high abundances of reactive and heat-producing elements at Nolans Bore, with significant effects on the economic, isotopic and geochemical characteristics of the deposit and its host, an observation that may apply to other such deposits.