Abstracts from the 4th Biennial Conference on Asian Current Research on Fluid Inclusions held in Brisbane, Australia from 10 - 12 August 2012

The Paleoproterozoic Westmoreland region is located 1250 km southeast of Darwin. The Westmoreland region is flanked on the southeast by the Paleoproterozoic Mt Isa Inlier and the Neoproterozoic South Nicholson Basin and in the northwest it is overlapped by Mesoproterozoic sediments of the McArthur Basin. The northern and southern ends of the McArthur basin share many geologic attributes including correlative stratigraphic rock types, which suggests that there is potential for unconformity-related uranium deposits in the southern McArthur basin and adjacent Westmoreland region. In fact, over fifty occurrences of uranium (some with minor gold) and copper mineralisation have been recorded in the Westmoreland region. Fluid inclusion studies have been carried out on selected uranium and copper prospects on the Northern Territory side of the Westmoreland region. Four types of inclusions have been observed, (Type A) Vapour-rich inclusions containing 30 100 vol.% vapour. Varying amounts of CO2 ± N2 ± CH4 have been detected in these inclusions, (Type B) Liquid-rich inclusions with up to 30 vol.% vapour, (Type C) Liquid-only inclusions, and (Type D) Three-phase (vapour + liquid + solid) liquid-rich inclusions containing a small daughter crystal. Type A, vapour-rich inclusions and some Type B, liquid-rich inclusions homogenised over the range 171 to 385 °C and are thought to be related to early metamorphic events. Other Type B and Type D inclusions typically homogenised between 100 and 240 °C with a mode around 120 °C, while the presence of liquid-only inclusions suggests trapping at temperatures below 50 °C. Eutectic melting temperatures indicate the presence of CaCl2 in the fluids but final melting temperatures show the presence of both high and low salinity brines. This suggests mixing between saline basinal fluids and low salinity meteoric fluids that continued down to temperatures below 50 °C.

Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia, in partnership with state and Northern Territory governments. The first phase of the EFTF program (2016-2020) aimed to drive industry investment in resource exploration in frontier regions of northern Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential. One key discovery was the identification of a large sedimentary depocentre concealed beneath the Cambrian Georgina Basin. This depocentre, up to 8 km deep, was termed the ‘Carrara Sub-basin’ by Geoscience Australia. It is interpreted to contain thick sequences of Proterozoic rocks, broadly equivalent to rocks of the greater McArthur Basin (Northern Territory) and northern Lawn Hill Platform and Mount Isa Province (Queensland), known to be highly prospective for sediment-hosted base metals and unconventional hydrocarbons. In order to test geological interpretations in the Carrara Sub-basin, the South Nicholson National Drilling Initiative (NDI) Carrara 1 stratigraphic drill hole was completed in late 2020, as a collaboration between Geoscience Australia, the Northern Territory Geological Survey (NTGS) and the MinEx CRC managing of the drilling operation. NDI Carrara 1 is the first drill hole to intersect Proterozoic rocks of the Carrara Sub-basin. It reached a total depth of 1751 m, intersecting ca. 630 m of Cambrian Georgina Basin overlying ca. 1100 m of Proterozoic carbonates, black shales and minor siliciclastics. Geoscience Australia has undertaken a range of investigations on the lithology, stratigraphy and geotechnical properties of NDI Carrara 1. These analyses include geochronology, isotopic studies, mineralogy, inorganic and organic geochemistry, petrophysics, geomechanics, thermal maturity, and petroleum systems investigations. To increase the understanding of the petroleum potential, molecular hydrogen and helium potential of sedimentary and basement rocks, Geoscience Australia commissioned a fluid inclusion stratigraphy (FIS) study on the downhole samples. Here, volatile components ostensibly trapped with fluid inclusions are released and analysed revealing the level of exposure of the well section to migrating fluids. Integration of thin section (TS) preparations reveal to extent of oil trapping within fluid inclusions while microthemometry (MT) gives an estimation of fluid inclusion trapping temperature. For NDI Carrara 1, FIS analysis was performed on 86 cuttings between 18 m and 282 m base depth and 342 cores between 283.9 m and 1750.45 m base depth, together with 27 samples prepared for TS and 4 samples for MT. To support this study, lithostratigraphic tops were interpreted and compiled by Geoscience Australia. The results of the study are found in the accompanying documents.

Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia (GA), in partnership with state and Northern Territory governments. The EFTF program (2016-2024) aims to drive industry investment in resource exploration in frontier regions of onshore Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential. Under the EFTF program, GA’s National Hydrogen Project and in collaboration with Minerals Resources Tasmania (MRT) undertook a study of hydrogen and helium potential of south-east Tasmania with the sampling of cores from Jericho 1 on Bruny Island. This well was selected based on the availability of core and historic reports of hydrogen-rich natural gases from this well and petroleum exploration wells in the region. Sampling of cores was done at MRT’s Core Repository in Hobart. Geoscience Australia commissioned a fluid inclusion stratigraphy (FIS) study on the downhole samples. Here, volatile components ostensibly trapped with fluid inclusions are released and analysed revealing the level of exposure of the well section to migrating fluids. Integration of thin section (TS) preparations reveal the extent of gas and fluid trapping within fluid inclusions while microthemometry (MT) gives an estimation of fluid inclusion trapping temperature. For Jericho 1, FIS analysis was performed on 179 cores between 87 m and 640.6 m base depth, together with 7 samples prepared for TS and 1 sample for MT. To support this study, lithostratigraphic tops were compiled by MRT. The results of the study are found in the accompanying documents.

<div>The noble gas database table contains publicly available results from Geoscience Australia's organic geochemistry (ORGCHEM) schema and supporting oracle databases for molecular and noble gas isotopic analyses on natural gases sampled from boreholes and fluid inclusion gases from rocks sampled in boreholes and field sites. Data includes the borehole or field site location, sample depths, shows and tests, stratigraphy, analytical methods, other relevant metadata, and the molecular and noble gas isotopic compositions for the natural gas samples. The molecular data are presented in mole percent (mol%) and cubic centimetres (at Standard Pressure and Temperature) per cubic centimetre (ccSTP/cc). The noble gas isotopic values that can be measured are; Helium (He, ³He, ⁴He), Neon (Ne, ²⁰Ne, ²¹Ne, ²²Ne), Argon (Ar, ³⁶Ar, ³⁸Ar, ⁴⁰Ar), Krypton (Kr, ⁷⁸Kr, ⁸⁰Kr, ^82<Kr, ⁸³Kr, ⁸⁴Kr, ⁸⁶Kr) and Xenon (Xe, ¹²⁴Xe, ¹²⁶Xe, ¹²⁸Xe, ¹²⁹Xe, ¹³⁰Xe, ¹³¹Xe, ¹³²Xe, ¹³⁴Xe, ¹³⁶Xe) which are presented in cubic micrometres per cubic centimetre (mcc/cc), cubic nanometres per cubic centimetre (ncc/cc) and cubic picometres per cubic centimetre (pcc/cc). Acquisition of the molecular compounds are by gas chromatography (GC) and the isotopic ratios by mass spectrometry (MS). Compound concentrations that are below the detection limit (BDL) are reported as the value -99999.</div><div><br></div><div>These data provide source information about individual compounds in natural gases and can elucidate fluid migration pathways, irrespective of microbial activity, chemical reactions and changes in oxygen fugacity, which are useful in basin analysis with derived information being used to support Australian exploration for energy resources and helium. These data are collated from Geoscience Australia records and well completion reports. The noble gas data for natural gases and fluid inclusion gases are delivered in the Noble Gas Isotopes web services on the Geoscience Australia Data Discovery Portal at https://portal.ga.gov.au which will be periodically updated.</div><div><br></div><div><br></div>

This report is a synopsis of research compiled and carried out within the Predictive Mineral Discovery CRC F3 project "Micrometallogeny of hydrothermal fluids". The F3 project's original objectives were: (1) Geology-driven terrain and ore fluids investigations to evaluate the chemistry and fluid processes within mineral systems in order to extend the focus of fluid studies beyond direct ore deposit analysis. (2) LAICPMS and PIXE technique and methodology development were techniques utilized throughout the project and methodologies were developed for their combined application. (3) Diamond-cell autoclave experiments component of the project was a scoping-collaboration in year one of F3 with the Museum of South Australia. (4) Database development and fusion with numerical modelling resulted in development of a web-based database for fluid inclusion research has been successful and is currently accessed at http://www.ga.gov.au/minerals/research/methodology/geofluids/flincs_about.jsp

Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia (GA), in partnership with state and Northern Territory governments. The EFTF program (2016-2024) aims to drive industry investment in resource exploration in frontier regions of onshore Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential. Under the EFTF program, the Onshore Energy Project undertook a study of petroleum prospectivity of the onshore Officer Basin in South Australia and Western Australia. Birksgate 1 well in South Australia was selected based on the occurrence of gas and oil shows reported in the well completion report. Sampling of cuttings and cores was done at Geoscience Australia's Petroleum Data Repository in Canberra. Geoscience Australia commissioned a fluid inclusion stratigraphy (FIS) study on the downhole samples. Here, volatile components ostensibly trapped with fluid inclusions are released and analysed revealing the level of exposure of the well section to migrating fluids. Integration of thin section (TS) preparations reveal to extent of gas and fluid trapping within fluid inclusions while microthemometry (MT) gives an estimation of fluid inclusion trapping temperature. For Birksgate 1, FIS analysis was performed on 414 cuttings and 33 cores between 150 feet and 6161 feet base depth, together with 14 samples prepared for TS and 3 samples for MT. To support this study, lithostratigraphic tops were compiled by Geoscience Australia. The results of the study are found in the accompanying documents.

Exploring for the Future (EFTF) is an Australian Government program led by Geoscience Australia (GA), in partnership with state and Northern Territory governments. The EFTF program (2016-2024) aims to drive industry investment in resource exploration in frontier regions of onshore Australia by providing new precompetitive data and information about their energy, mineral and groundwater resource potential. Under the EFTF program, the Basin Inventory Project undertook a study of petroleum prospectivity of the onshore Eromanga Basin in Queensland and South Australia. Betoota 1 well in Queensland was selected based on the occurrence of gas and oil shows reported in the well completion report. Sampling of cuttings and cores was done at Geoscience Australia's Petroleum Data Repository in Canberra. Geoscience Australia commissioned a fluid inclusion stratigraphy (FIS) study on the downhole samples. Here, volatile components ostensibly trapped with fluid inclusions are released and analysed revealing the level of exposure of the well section to migrating fluids. Integration of thin section (TS) preparations reveal the extent of gas and fluid trapping within fluid inclusions while microthemometry (MT) gives an estimation of fluid inclusion trapping temperature. For Betoota 1, FIS analysis was performed on 305 cuttings and 48 cores between 54.9 metres and 2993.3 metres base depth, together with 15 samples prepared for TS and 3 samples for MT. To support this study, lithostratigraphic tops were compiled by Geoscience Australia. The results of the study are found in the accompanying documents.

The Palaeoproterozoic Westmoreland region is located 1250 km southeast of Darwin. The Westmoreland region is flanked on the southeast by the Palaeoproterozoic Mt Isa Inlier and the Neoproterozoic South Nicholson Basin and in the northwest it is overlapped by Mesoproterozoic sediments of the McArthur Basin. The northern and southern ends of the McArthur basin share many geologic attributes including correlative stratigraphic rock types, which suggests that there is potential for unconformity-related uranium deposits in the southern McArthur basin and adjacent Westmoreland region. In fact, over fifty occurrences of uranium (some with minor gold) and copper mineralisation have been recorded in the Westmoreland region. Fluid inclusion studies have been carried out on selected uranium and copper prospects on the Northern Territory side of the Westmoreland region. Four types of inclusions have been observed, (Type A) Vapour-rich inclusions containing 30 - 100 vol.% vapour. Varying amounts of CO2 ± N2 ± CH4 have been detected in these inclusions, (Type B) Liquid-rich inclusions with up to 30 vol.% vapour, (Type C) Liquid-only inclusions, and (Type D) Three-phase (vapour + liquid + solid) liquid-rich inclusions containing a small daughter crystal. Type A, vapour-rich inclusions and some Type B, liquid-rich inclusions homogenised over the range 171 to 385 °C and are thought to be related to early metamorphic events. Other Type B and Type D inclusions typically homogenised between 100 and 240 °C with a mode around 120 °C, while the presence of liquid-only inclusions suggests trapping at temperatures below 50 °C. Eutectic melting temperatures indicate the presence of CaCl2 in the fluids but final melting temperatures show the presence of both high and low salinity brines. This suggests mixing between saline basinal fluids and low salinity meteoric fluids that continued down to temperatures below 50 °C.

The Palaeoproterozoic Murphy Inlier is situated at the southern end of the McArthur Basin in northern Australia. The inlier contains over 50 uranium, copper, tin and base metal occurrences. Fluid inclusion studies were carried out on samples of quartz veining from the uranium and copper deposits as well as from the basement rocks to determine the composition of the fluids and to investigate how uranium and copper were transported in these fluids. Four types of fluid inclusions were observed in this study; Type A vapour-rich inclusions with 30 vol.% vapour, Type B two phase aqueous inclusion with - 20 vol.% vapour, Type C multiphase inclusions with one or more solid phases and, Type D liquid-only inclusions. At least three different fluids were identified in the Murphy Inlier. The first is a high temperature fluid denoted by Types A and B inclusions which homogenise over the range from 220 to 380 ºC. In the basement rocks, this fluid is enriched in N2 indicating that it may be related to metamorphic processes. In the uranium deposits this fluid is dominated by CO2 indicating that these fluids are relatively oxidized, while in the copper deposits both CO2 and CH4 are present indicating that these fluids are more reduced than in the regions of uranium mineralisation. The second fluid is a NaCl-rich with salinities ranging from 0.2 to 29.8 mass % NaCl and the third fluid is CaCl2-rich with salinities ranging from 0.1 to 24.7 mass % CaCl2. There is also evidence for fluid mixing between the NaCl-rich and CaCl2-rich end member fluids.