b'Education matters to the top of the Ordovician basement orRF19PO1 The impact of magmatism onof stacked sills, which are present in the the Permian tillitewhichever occurs firstpetroleum systems of the Carnarvon Basin.Scarborough, Bonaventure and Charon directly below the site of measurement.PhD candidate Michael Curtis at the3D surveys. We have also observed sills The HVSR data is unable to distinguishUniversity of Adelaide writes of his firstexploiting faults as magma pathways, between the Ordovician or Permian rocks.six months since starting the project: especially in the Indian 2000 3D survey.Faulting is also evident in HVSR data. The HVSR method can be used to accuratelyThe primary aim of this project is toWe have constrained the timing of determine depth to basement in areasimprove knowledge of the timing andigneous activity in several 3D seismic which lack Permian tillite. This techniquedistribution of rift-related igneoussurveys by dating stratigraphy onto could be used to reduce explorationactivity in this important petroliferouswhich magma extrudes, stratigraphy expenditure by allowing the targetingbasin, and to assess the impacts of thisdeformed by injection of magma of basement highs, to optimise drillholeactivity on petroleum exploration andbeneath, and stratigraphy on which placement. development issues. cooling-related vent structures are identified. For example, in the HC93 RF19M03 Using analogue interpretationsThe project has commenced with a3D Survey, we identified a volcano that of geophysics to understand geologydetailed interpretation of the distributionhas erupted lava onto sediments of hiding undercover: A case study fromof intrusive igneous rocks present in thethe Lower Barrow Group (c. 145Ma the Mount Isa Inlier. BSc (honours)Exmouth Sub-basin and the westernEarly Cretaceous); further south, in the student Hannah Williamson of MonashExmouth Plateau using open file 3DCoverack survey, we have mapped University writes: seismic reflection surveys. Their extentintrusions terminating in Aptian age ranges from (and likely continues beyond)sedimentary rocks (c. 120 MaMid The objectives of this project were tothe Coverack 3D seismic reflection surveyCretaceous). This shows younging of interpret the 3D structural architecturein the south of the Exmouth Sub-basinmagmatism to the south, and that the of an outcropping region south of Mtto the Bonaventure 3D survey in themagmatic system was active both during Isa, using potential field geophysicsnorth-western Exmouth Plateau. In theand after breakup on the Cuvier Margin.combined with field data and high- region of the Coverack Survey, where resolution digital data. This interpretationintrusives often terminate less than aTo date we have identified six wells that will then be applied to understand thekm below the seafloor, they can easilypenetrate igneous material. We have continuation of the same geology atbe identified on magnetic data. Thesecompiled their well log data, to gain depth beneath the Georgina Basin. Theigneous rocks are the result of significantan understanding of the identifiable expected outcomes will be a greatermagmatism underlying the location ofpetrophysical properties of ash fall understanding of the tectonic evolutionlater Cretaceous rift axes that were activedeposits, lava flows, volcanoes and of a poorly studied portion of the Mt Isawhile Greater India broke away fromintrusions in the Carnarvon Basin. We Inlier, as well as recommendations forthe Australasian continent during thenote that ashfall deposits penetrated in regions of exploration focus that AngloValanginian, c. 140 Ma. Enfield-3, Enfield-4 and Stybarrow-2 are American should more closely target inof similar age to the volcano interpreted their Exploration Lease. Our mapping reveals intrusions in thein the HC93 3D survey and suggest they Northern Carnarvon Basin have variousmay be related.The project is coming along well and Imorphologies that we have categorised have undertaken three weeks of fieldin a scheme developed by Plankeet etThe next stage of the project will work where there is ground truth in theal. (2005): Saucer sills are disc shaped,evaluate this data with respect to the study area to constrain critical structuraland climb gently upwards from theirCarnarvon Basin petroleum systems, geology relationships, particularly alongcentres. These intrusions tend to bewith particular focus on regional the Wonomo Fault and surrounds, whichisolated, situated several hundred metresheating effects of intrusions on source is interpreted as a potential along strikebelow the palaeo-seabed, and generallyrocks, reservoir compartmentalisation, equivalent of the mineralised Mt Isa Fault23 km in diameter. Layer parallel sillsand potential trap formation in fold System. are sub-horizontal, tens of km in length,structures generated by intrusion. are generally confined to depths of aFieldwork is planned on the Isle of Skye During this field season magneticfew km, and act as conduits for magmain Scotland for mid-September 2019, susceptibility data was collected for allacross large distances. Layer parallel sillsin order to conduct 3D drone scanning major rock packages exposed. These dataare particularly apparent at depth inof world class exposures of intrusions have been used to construct an integratedthe Scarborough and Bonaventure 3Dhosted in a variety of clastic lithologies, structural and lithological geological mapsurveys. analogous to intruded host rocks in based on geology and aeromagneticthe Carnarvon Basin. Data related to expression of the area. This map hasMagma ascends from deep in theintrusion thicknesses in clastic host illustrated areas where the geologybasin by way of transgressive sills androcks will be collected. Gaining a better has not been correctly mapped. Rockclimbing saucersills. Transgressiveunderstanding of the relative number of property data is also used to constrainsills are planar in nature, and progresssmall, seismically undetectable (thinner two long forward models of the geology.steeply through stratigraphy as high- than 40 m) intrusions compared to larger These forward models are constructedangle sheets. Climbing saucer sills fanintrusions will assist in estimating their and illustrate the geology of the regionoutwards and upwards in the directionoverall impact on petroleum systems in and the 3D architecture. They will beof magma transport and are commonlythe Carnarvon Basin. This fieldwork will used to simulate buried geology to theobserved in the Coverack 3D survey.be followed up with a four-week study south of the Mount Isa inlier and informThe diameter of these sill types variesplacement at the University of Aberdeen, the geophysical expressions of majorfrom 2 km to >10 km. In addition toalongside project co-supervisor Dr Nick exploration targets to the south, whichthe isolated sills we have also identifiedSchofield, a world expert on the impact will be the final phase of the project. many large, interconnected complexesof magmatism on petroleum systems.37 PREVIEW OCTOBER 2019'