b'AEGC 2021Short abstractsand that precipitation may occur sometime after the date ofInversion of Magnetotelluric (MT) data for electromagnetic intrusion, often in structurally controlled sites that are unrelatedresistivity yields insights into earth processes related to mineral to the granite intrusion process. formation and geodynamics, can be used to map thickness Etheridge and Wall (1994) argued that compositional andof sediments for energy resource exploration, locate areas for higher thermal structures of the Proterozoic led to less markedgeothermal development, as well as map deep earth structure. partitioning of deformation, with extensional and compressionalHowever, the presence of data noise, non-linear physics and sparse deformation occurring much further into the continental interiorreceiver coverage lead to uncertainties in the inverted resistivity. than at present. The wide spatial extent of Proterozoic GranitesBayesian inversion can produce crucial uncertainty information on supports this and opens up exploration parameter space tothe inferred subsurface resistivity, but has largely been restricted much wider areas than are currently being considered. to 1D earth models. This is due to their large computational cost as well as dimensionality of the resistivity model space. We render this problem tractable from the dimensionality standpoint by using 167: Northern Lawn Hill Platformmodelling thea stochastic interpolation algorithm known as a Gaussian process great-grandparent emerging region (GP). This allows for a parsimonious model parameterisation within a standard, trans-dimensional Bayesian framework. The Gaussian Ms Tehani Palu 1, Dr Amber Jarrett1, Dr Susannah MacFarlane1,process links a trans-dimensional, parallel tempered Markov chain Dr Christopher Boreham1 and Dr Barry Bradshaw1 Monte Carlo (McMC) sampler to MARE2DEM, a parallel adaptive finite element forward solver. MARE2DEM computes the model 1 Geoscience Australia response using a dense parameter mesh with resistivity assigned The northern Lawn Hill Platform (nLHP) is considered anvia the Gaussian process model.emerging region with less than 15 wells drilled to date. WithWe demonstrate the trans-dimensional Gaussian process renewed interest in unconventional gas, new exploration(TDGP) sampler by inverting both synthetic and field opportunities exist in this early Proterozoic region.magnetotelluric data for 2D models of electrical resistivity on Petroleum systems analysis is presented here to improve thea HPC cluster. For the Gemini field Gulf of Mexico real data understanding of burial history, source rock richness andinversion, our algorithm achieves a parameter reduction of over maturity of the nLHP of the Isa Superbasin, far NW Queensland. 32x. Resistivity probability distributions computed from the A pseudo-3D geological model was built and calibrated, inensemble of models produced by the inversion yield credible combination with 1-D burial and thermal history modellingintervals and interquartile plots that quantitatively show the of Desert Creek 1 and Egilabria 1. These were combined with2D uncertainty. This uncertainty can also be propagated to source rock characteristics (e.g., Rock Eval and kerogen kinetics)other physical properties that impact resistivity such as bulk which helped assess the hydrocarbon generation potentialcomposition, porosity and pore-fluid content.by source rock, allowing a broader assessment of petroleum prospectivity of the nLHP. 174: Ground Penetrating Radar investigation as part of The study focussed on two potential source rocks; the Lawn 4a multidisciplinary archaeological project, The Plain of Sequence and the River Supersequence. Maturity modellingJars, Lao PDRof the Lawn 4 Sequence at Desert Creek 1 and Egilabria 1 predicted equivalent vitrinite reflectance (EqVR) of over 1.2%Mr Jamie Speer 1, Dr Dougald OReilly2 and Dr Louise Shewan3and 2%, respectively. The River Supersequence was modelled1 GBG Australiaas overmature at both wells. Combining these results with the2 Australian National University Canberrapseudo-3D model and source rock characteristics demonstrates3 University of Melbournethat the highest maturities are encountered in the deepest depocentres to the east and gradually decrease in maturity toThe Ground Penetrating Radar (GPR) investigation was the west, indicating some potential for wet gas. undertaken within the multidisciplinary team undertaking the Modelling results show generation of varying amounts ofPlain of Jars Archaeological Research Project, a joint Lao-gas and oil from each potential source rock. Overall, due toAustralian project funded by the Australian Research Council. the age of the sediments, maximum depth of burial and highThe international project team comprising university and palaeotemperatures, the most likely hydrocarbon phase is gasindustry based archaeologists, a geologist, a geophysicist and from primary generation and supplemented by secondary gasgeospatial experts.from oil cracking. In spite of high maturities, encouraging gasThe Plain of Jars in Central Laos comprises numerous megalithic shows from the Egilabria prospect support continued explorationsites with some sites containing over 400 stone Jars. The region interest in this region for unconventional hydrocarbons. was unknown to European Archaeology prior to the work of Madeline Colani and her sister Eleonore in the 1930s.168: Nonlinear, 2D uncertainty estimation inThe first stage of the GPR project work took place in February Magnetotelluric inversion using trans-dimensional2016 at Site 1, with data collection undertaken on other sites Gaussian processes (Sites 2, 3 and 52) in 2017.Dr Daniel Blatter1, Dr Anandaroop Ray 2 and Dr Kerry Key3 Processing of the data produced 3D data blocks for imaging and evaluation of potential excavation sites. During the initial 1 Scripps Institution of Oceanography, University of Californiasite visit, one location was selected as a dig site with the most San Diego potential, this became the excavation Unit 2. The resulting 2 Geoscience Australia finds included marker stones and a burial site containing two 3 Lamont-Doherty Earth Observatory, Columbia University partial skeletons. Investigation of anomalous GPR signals in the 91 PREVIEW AUGUST 2021'