ORCID Profile
0000-0001-7106-0789
Current Organisation
University of Adelaide
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Publisher: Springer Science and Business Media LLC
Date: 14-05-2020
Publisher: Springer Science and Business Media LLC
Date: 29-01-2018
Publisher: Springer Science and Business Media LLC
Date: 29-08-2019
Publisher: Informa UK Limited
Date: 10-2013
Publisher: Elsevier BV
Date: 05-2022
Publisher: Informa UK Limited
Date: 03-2003
DOI: 10.1071/EG03057
Publisher: Informa UK Limited
Date: 03-2000
DOI: 10.1071/EG00187
Publisher: American Geophysical Union (AGU)
Date: 03-2016
DOI: 10.1002/2015JB012541
Publisher: Springer Science and Business Media LLC
Date: 24-04-2018
Publisher: Oxford University Press (OUP)
Date: 03-1998
Publisher: Informa UK Limited
Date: 12-2015
DOI: 10.1071/EG14066
Publisher: Springer Science and Business Media LLC
Date: 19-07-2011
Publisher: Informa UK Limited
Date: 03-07-2016
Publisher: Informa UK Limited
Date: 06-2002
DOI: 10.1071/EG02115
Publisher: Oxford University Press (OUP)
Date: 17-04-2015
DOI: 10.1093/GJI/GGV116
Publisher: Informa UK Limited
Date: 06-2005
DOI: 10.1071/EG05189
Publisher: Elsevier BV
Date: 08-2021
Publisher: Wiley
Date: 02-03-2020
DOI: 10.1002/HYP.13732
Publisher: Informa UK Limited
Date: 03-2000
DOI: 10.1071/EG00052
Publisher: Society of Geomagnetism and Earth, Planetary and Space Sciences
Date: 1994
DOI: 10.5636/JGG.46.1067
Publisher: Wiley
Date: 02-2011
Publisher: Springer Science and Business Media LLC
Date: 03-2003
Publisher: Springer Science and Business Media LLC
Date: 1999
Publisher: Elsevier BV
Date: 09-2013
Publisher: Society of Exploration Geophysicists
Date: 05-2013
Abstract: Realization of enhanced geothermal systems (EGSs) prescribes the need for novel methods to monitor subsurface fracture connectivity and fluid distribution. Magnetotellurics (MT) is a passive electromagnetic (EM) method sensitive to electrical conductivity contrasts as a function of depth, specifically hot saline fluids in a resistive porous media. In July 2011, an EGS fluid injection at 3.6-km depth near Paralana, South Australia, was monitored by comparing repeated MT surveys before and after hydraulic stimulation. An observable coherent change above measurement error in the MT response was present and causal, in that variations in phase predict variations in apparent resistivity. Phase tensor residuals proved the most useful representation for characterizing alterations in subsurface resistivity structure, whereas resistivity tensor residuals aided in determining the sign and litude of resistivity variations. These two tensor representations of the residual MT response suggested fluids migrated toward the northeast of the injection well along an existing fault system trending north-northeast. Forward modeling and concurrent microseismic data support these results, although microseismic data suggest fractures opened along two existing fracture networks trending north-northeast and northeast. This exemplifies the need to use EM methods for monitoring fluid injections due to their sensitivity to conductivity contrasts.
Publisher: Informa UK Limited
Date: 03-1999
DOI: 10.1071/EG999001
Publisher: American Geophysical Union (AGU)
Date: 28-01-2015
DOI: 10.1002/2014GL060088
Publisher: Elsevier BV
Date: 11-2014
Publisher: Society of Exploration Geophysicists
Date: 07-2010
DOI: 10.1190/1.3475706
Abstract: Increased interest in the character of sediments at the base of waterways, for the purpose of managing river salinization, has led to the application of several geophysical techniques for collecting information from this zone. These instream methods are based on established ground and airborne electrical and electromagnetic technologies, including towed transient electromagnetic systems, towed direct current resistivity array systems, and frequency-domain helicopter electromagnetic systems. Although these systems are in idually successful, a systematic examination of their relative effectiveness for identifying variations in substrate conductivity for a common stretch of a river remains lacking. We have compared results obtained from data collected using three instream geophysical techniques for a common stretch of the Murray River in southeastern Australia. The Murray River is an important water resource for drinking and agricultural purposes. Data from these surveys were acquired tolocate areas of significant saltwater accession to the Murray from a saline regional groundwater system that discharges into it. The three methods indirectly inform on those reaches that most likely contribute to higher salt loads in the river, and they do this through the identification of a conductive substrate (a gaining reach). For a [Formula: see text] stretch of the river, the methods identified similar variations in the conductivity structure of sediment substrate, although differences were observed in the modeled response relating to intrinsic differences between each system, including the s ling interval and resolution. The helicopter electromagnetic (EM) system is capable of acquiring hundreds of kil-ometers of data in a day, under any river flow condition, from near the river surface to depths in excess of [Formula: see text]. The other two techniques require safe river flow conditions for acquisition, with as much as 50 river km of data per day possible. The ground-based methods had enhanced lateral and vertical resolving capabilities relative to the helicopter EM system, but their depth of investigation was less (usually only [Formula: see text]).
Publisher: Elsevier BV
Date: 10-2016
Publisher: Oxford University Press (OUP)
Date: 09-1993
Publisher: Geological Society of America
Date: 09-2009
DOI: 10.1130/G30175A.1
Publisher: Springer Science and Business Media LLC
Date: 04-08-2021
DOI: 10.1038/S41598-021-94531-8
Abstract: Orogenic gold deposits provide a significant source of the world’s gold and form along faults over a wide range of crustal depths spanning sub-greenschist to granulite grade faces, but the source depths of the gold remains poorly understood. In this paper we compiled thirty years of long-period magnetotelluric (MT) and geomagnetic depth sounding (GDS) data across western Victoria and south-eastern South Australia that have sensitivity to the electrical resistivity of the crust and mantle, which in turn depend on past thermal and fluid processes. This region contains one of the world’s foremost and largest Phanerozoic (440 Ma) orogenic gold provinces that has produced 2% of historic worldwide gold production. Three-dimensional inversion of the long-period MT and GDS data shows a remarkable correlation between orogenic gold deposits with 1 t production and a 20 Ω m low-resistivity region at crustal depths 20 km. This low-resistivity region is consistent with seismically-imaged tectonically thickened marine sediments in the Lachlan Orogen that contain organic carbon (C), sulphides such as pyrite (FeS 2 ) and colloidal gold (Au). Additional heat sources at 440 Ma due to slab break-off after subduction have been suggested to rapidly increase the temperature of the marine sediments at mid to lower crustal depth, releasing HS − ligands for Au, and CO 2 . We argue that the low electrical resistivity signature of the lower crust we see today is from a combination of flake graphite produced in situ from the hibolite grade metamorphism of organic-carbon in the marine sediments, and precipitated graphite through retrograde hydration reactions of CO 2 released during the rapid heating of the sediments. Thus, these geophysical data image a fossil source and pathway zone for one of the world’s richest orogenic gold provinces.
Publisher: Oxford University Press (OUP)
Date: 12-1998
Publisher: Geological Society of London
Date: 2011
Publisher: Informa UK Limited
Date: 1989
DOI: 10.1071/EG989177
Abstract: The Tasman Project of Seafloor Magnetotelluric Exploration (TPSME) took place between December 1983 and April 1984 (Filloux et al., 1985 Ferguson et al., 1985 Lilley etal., 1989). Seven magnetotelluric and two (additional) magnetometer sites spanned a range of tectonic features across the Tasman Sea. Initial analysis by Ferguson (1988) indicated large-scale three-dimensional induction effects to be present in the data. It was concluded that the most probable causes were the continental margin effect and changes in bathymetry.In the present paper, a method is presented of modelling the salt water of the Tasman Sea and adjoining oceans as a thin sheet of variable lateral conductance, which overlies a series of uniform layers representing the solid Earth. The theory and a suitable computer algorithm were developed in a group led by J. T. Weaver at the University of Victoria, B.C., Canada. Many of the features present in the TPSME data are reproduced by this method, and with a greater understanding of induction processes in the ocean which is thus obtained, it is possible to remove three-dimensional effects from observed data. The TPSME data are then solely a measure of the response of the Earth directly beneath the observing sites, and one-dimensional modelling techniques may be used to determine the conductivity structures.
Publisher: American Geophysical Union (AGU)
Date: 02-09-2010
DOI: 10.1029/2010GC003101
Publisher: Springer Science and Business Media LLC
Date: 13-08-2004
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR08244
Abstract: Digital soil mapping (DSM) offers apparent benefits over more labour-intensive and costly traditional soil survey. Large cartographic scale (e.g. 1 : 10 000 scale) soil maps are rare in Australia, especially in agricultural areas where they are needed to support detailed land evaluation and targeted land management decisions. We describe a DSM expert system using environmental correlation that applies a priori knowledge from a key area (128 ha) soil–landscape with a regionally repeating toposequence to predict the distribution of saline–sodic subsoil patterns in the surrounding upland farming region (2275 ha) in South Australia. Our predictive framework comprises interrelated and iterative steps, including: (i) consolidating a priori knowledge of the key area soil–landscape (ii) refining existing mentally held and graphic soil–landscape models (iii) selecting suitable environmental covariates compatible with geographic information systems (GIS) by interrogation via 3D visualisation using a GIS (iv) transforming the existing soil–landscape models to a computer model (v) applying the computer model to the environmental variables using the expert system (vi) performing the predictive mapping and (vii) validation. The environmental covariates selected include: digital terrain attributes of slope gradient, topographic wetness index and plan curvature, and airborne gamma-radiometric K%. We apply selected soil profile physiochemical data from a prior soil survey to validate mapping. Results showed that we correctly predicted the saline–sodic subsoils in 10 of 11 reference profiles in the region.
Publisher: Society of Exploration Geophysicists
Date: 11-2016
Abstract: The magnetotelluric (MT) method is introduced as a geophysical tool to monitor hydraulic fracturing of shale gas reservoirs and to help constrain how injected fluids propagate. The MT method measures the electrical resistivity of earth, which is altered by the injection of fracturing fluids. The degree to which these changes are measurable at the surface is determined by several factors, such as the conductivity and quantity of the fluid injected, the depth of the target interval, the existing pore fluid salinity, and a range of formation properties, such as porosity and permeability. From an MT monitoring survey of a shale gas hydraulic fracture in the Cooper Basin, South Australia, we have found temporal and spatial changes in MT responses above measurement error. Smooth inversions are used to compare the resistivity structure before and during hydraulic fracturing, with results showing increases in bulk conductivity of 20%–40% at a depth range coinciding with the horizontal fracture. Comparisons with microseismic data lead to the conclusion that these increases in bulk conductivity are caused by a combination of the injected fluid permeability and an increase in wider scale in situ fluid permeability.
Publisher: Springer Science and Business Media LLC
Date: 11-07-2020
DOI: 10.1186/S40623-020-01223-0
Abstract: The central Australian Musgrave Province at the junction of the South, North and West Australian cratons has undergone and continues to retain evidence of significant whole-of-crust, and most likely ‘whole-of-lithosphere’ tectono-magmatic processes. The area is known for some of the largest geophysical anomalies related to significant Moho offsets of up to 15 km, which resulted from repeated intracratonic reworking since the Neoproterozoic. New magnetotelluric (MT) data have been collected across the Musgrave Province in Western Australia and South Australia as part of the Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP). Station spacing was $$\\sim 50\\,\\hbox {km}$$ ∼ 50 km between 96 sites over an area of 500 × 700 km. Long-period MT impedance and tipper data over a bandwidth of 8 s to 10,000 s period have been inverted using a smooth 3D inverse algorithm. The 3D model shows two predominant resistivity trends. There are deep ( $$ \\,\\hbox {km}$$ 65 km ) north–south mantle conductors that we infer to be related to the Palaeo- to Mesoproterozoic north-trending arc-related rocks that experienced ultra-high temperature metamorphism and widespread magmatism during the Mesoproterozoic Musgravian Orogeny. These conductors are preserved in the crust south of the Musgrave Province. The upper mantle also contains a localised resistive zone that possibly represents generation of mafic- to ultramafic magmas during the c. 1090–1040 Ma Giles Event. The crust ( $$ \\,\\hbox {km}$$ 65 km depth) contains strong east–west crustal conductors interpreted to reflect the east–west structural grain that initiated during the c. 1090–1040 Ma Giles Event and overprinted the older N–S-oriented mantle anomalies. These E–W crustal conductors coincide with magnetic anomalies that represent crustal-scale structures, and high gravity anomalies associated with significant Moho offsets resulting from further reactivation during the c. 630–520 Ma Petermann and c. 450–300 Ma Alice Springs orogenies.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 2015
Publisher: Oxford University Press (OUP)
Date: 03-2009
Publisher: American Geophysical Union (AGU)
Date: 2006
DOI: 10.1029/2005GL025328
Publisher: American Geophysical Union (AGU)
Date: 09-2012
DOI: 10.1029/2012GL053080
Publisher: American Geophysical Union (AGU)
Date: 10-06-2010
DOI: 10.1029/2009JB006698
Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-10-1999
DOI: 10.1126/SCIENCE.286.5440.752
Abstract: The magnetotelluric component of the Mantle Electromagnetic and Tomography (MELT) Experiment measured the electrical resistivity structure of the mantle beneath the fast-spreading southern East Pacific Rise (EPR). The data reveal an asymmetric resistivity structure, with lower resistivity to the west of the ridge. The uppermost 100 kilometers of mantle immediately to the east of the ridge is consistent with a dry olivine resistivity structure indicating a mantle depleted of melt and volatiles. Mantle resistivities to the west of the ridge are consistent with a low-melt fraction (about 1 to 2 percent interconnected melt) distributed over a broad region and extending to depths of about 150 kilometers. The asymmetry in resistivity structure may be the result of asymmetric spreading rates and a westward migration of the ridge axis and suggests distinct styles of melt formation and delivery in the mantle beneath the two plates.
Publisher: Society of Geomagnetism and Earth, Planetary and Space Sciences
Date: 1997
DOI: 10.5636/JGG.49.1327
Publisher: Springer Science and Business Media LLC
Date: 11-01-2018
Publisher: Georg Thieme Verlag KG
Date: 25-09-2008
Publisher: Informa UK Limited
Date: 03-2004
DOI: 10.1071/EG04033
Publisher: American Geophysical Union (AGU)
Date: 18-06-2013
DOI: 10.1002/GRL.50486
Publisher: Informa UK Limited
Date: 03-2007
Publisher: Elsevier BV
Date: 09-2004
Publisher: American Geophysical Union (AGU)
Date: 2000
DOI: 10.1029/00EO00258
Publisher: Society of Exploration Geophysicists
Date: 2010
DOI: 10.1190/1.3513650
Publisher: American Geophysical Union (AGU)
Date: 04-2017
DOI: 10.1002/2016JB013854
Publisher: Springer Science and Business Media LLC
Date: 06-1993
DOI: 10.1007/BF01204130
Publisher: Informa UK Limited
Date: 12-2005
Publisher: Society of Exploration Geophysicists
Date: 2016
Abstract: Extraction of unconventional energy has become a major global industry in the last decade and is driven by changes in technology and increasing demand. One of the key factors for the success of gas extraction is establishing sufficient permeability in otherwise low-porosity and low-permeability formations. Permeability can be established through hydraulic stimulation of deep formations, either through existing fracture networks or by creating new pathways for fluids to flow, and through depressurization of coalbeds by extracting existing subsurface fluids. Geophysical monitoring of hydraulic stimulation and depressurization can be used to determine lateral and vertical constraints on fluid movements in the target lithologies. Such constraints help to optimize production and well placement. In addition, independent verification is critical for social and environmental regulation, to ensure that hydraulic stimulations and depressurization do not interact with overlying aquifers. To date, the primary and most successful geophysical technique has been microseismic, which measures small seismic events associated with rock fractures from arrays of surface and downhole geophones. The microseismic approach has been used widely for many types of unconventional energy-resource development. The magnetotelluric (MT) method is an alternative approach to monitoring hydraulic stimulations and depressurization. In contrast to microseismic, which delineates the locations of rock fractures, MT is sensitive directly to the presence of fluid as measured by the earth's bulk electrical resistivity, which is dependent on permeability. MT is sensitive to the direction of fluid connection, so it might yield important information on how fluids migrate with time. Because subsurface fluids conduct electrical current dependent on the porosity, connectivity, and ionic saturation of the fluid, it follows that the introduction or removal of fluids will change the electrical resistivity of the formation. The physics of the approach is outlined, and the feasibility of the MT method for monitoring unconventional energy-resource development is demonstrated. Two case studies are conducted, one for a shallow (CSG) depressurization and the second for a deep hydraulic stimulation of a shale-gas reservoir.
Publisher: Society of Exploration Geophysicists
Date: 09-2005
DOI: 10.1190/1.2057981
Abstract: The self-potential (SP) method for mineral exploration is seldom used on land, primarily because of electrode noise problems and nonunique interpretations. Marine measurements of the horizontal gradient of the SP field, on the other hand, are relatively simple to make with an array of electrodes towed behind a ship. With low ship speeds of 5 to 10 km/hour, dense spatial s ling (∼1 m) can be obtained with resolution of better than 1 μV/m. In this paper we report on gradient SP data recorded on the continental shelf of South Australia by a horizontal array of towed electrodes approximately 20 m above the seafloor. Ocean waves and swells with periods of 5 to 15 s yielded large litude signals ±20 μV/m, but subseafloor mineralization produced SP gradient anomalies of ±50 μV/m and widths of 2 km or more in a number of parallel traverses. Integrating the observed SP gradients along each line delineated SP anomalies of litude up to −100 mV. Self-potential and magnetic anomaly data show limited spatial correlation and have different wavelengths, suggesting that SP sources are probably nonferrous minerals, such as graphite, and are deeper than the magnetic sources. The source of the SP signal is probably reduction-oxidation (redox) potential ([Formula: see text]) variations across a conducting body below the seafloor. We approximate the source as being two dimensional and find the most probable locations of line sources by an image reconstruction method. Numerical finite-element modeling of more realistic source regions suggests shallow, easterly dipping (∼15°) conductors of 1 Ω.m in the uppermost 2 km.
Publisher: American Geophysical Union (AGU)
Date: 15-08-1996
DOI: 10.1029/96GL01673
Publisher: Oxford University Press (OUP)
Date: 09-2001
Publisher: Informa UK Limited
Date: 03-2000
DOI: 10.1071/EG00255
Publisher: American Geophysical Union (AGU)
Date: 08-2000
DOI: 10.1029/2000GL011473
Publisher: Elsevier BV
Date: 08-2005
Publisher: Informa UK Limited
Date: 09-2006
DOI: 10.1071/EG06231
Publisher: Elsevier BV
Date: 09-2015
Publisher: Society of Exploration Geophysicists
Date: 04-2011
DOI: 10.1190/1.3575286
Abstract: Finding and utilizing reliable water supplies for desert communities is important but difficult and expensive. This is especially the case in the remote north and northwest of South Australia, where there are a number of small Aboriginal communities with populations of less than a hundred people. Rainfall is sparse and intermittent (less than 200 mm/yr), and residents rely on groundwater for nonpotable supplies. Previous drilling in shallow sediments aiming for porous aquifers has led to problems with long-term well production. More recent wells targeting deeper fractured rock aquifers are showing more promise unfortunately, such boreholes are more expensive and difficult to install. The aim of our work is to use natural-source magnetotelluric (MT) imaging to try and identify better sites for bores, and therefore reduce the risk of drilling a dry well. We hope to do this by imaging the 3D conductivity structure, allowing the identification of possible aquifers, and also by measuring the anisotropy due to water-bearing fractures, through the sensitivity of natural-source MT responses to electrically anisotropic layers in the subsurface. The first phase of our work, described here, is to test the method at a site where the hydrogeology is relatively well understood. The second phase will apply it to a community in need.
Publisher: Informa UK Limited
Date: 03-2001
DOI: 10.1071/EG01070
Publisher: Informa UK Limited
Date: 13-03-2017
Publisher: American Geophysical Union (AGU)
Date: 08-2011
DOI: 10.1029/2010RS004523
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR07191
Abstract: We describe a soil–landscape investigation conducted in a South Australian upland hillslope (128 ha) to understand the distribution and causes of saline–sodic soil patterns using convenient, ground-based geophysical surveys of the hillslope. These surveys included: (i) EM31 for deep (~6 m) apparent electrical conductivity (ECa) patterns, (ii) EM38 for shallow ( .5 m) ECa patterns, and (iii) Bartington MS2-D loop sensor for surface volume magnetic susceptibility (κ) patterns. From these surveys we inferred hillslope distributions of: (i) deep (~6 m) concentrations of salinity associated with deep groundwater systems and deposits of magnetic gravels (dominated by maghemite and hematite) (EM31 sensor) (ii) shallow ( .5 m) soil salinity (EM38 sensor) and (iii) preservation of pedogenic magnetic materials (e.g. maghemite and hematite) (MS2-D loop sensor). We also describe terrain analysis to locate near-surface hydropedological patterns using topographic wetness index. When combined in 3D geographic information system, strong visual matches were identified between patterns in: (i) geophysical surveys, (ii) terrain, and (iii) soil survey data, thus allowing integrated interpretations of soil–landscape pedogenic processes to be made on a whole-of-landscape basis. Such mechanistic interpretations of soil–landscape processes reveal and map intricate saline and sodic soil–regolith patterns and groundwater and fresh surface water flow paths that were not revealed during a previous traditional soil survey.
Publisher: Elsevier BV
Date: 03-2005
Publisher: Elsevier BV
Date: 12-1993
Publisher: Informa UK Limited
Date: 02-10-2016
Publisher: American Geophysical Union (AGU)
Date: 15-11-2016
DOI: 10.1002/2016GL071351
Publisher: American Geophysical Union (AGU)
Date: 06-2005
DOI: 10.1029/2005GL022934
Publisher: Informa UK Limited
Date: 06-2005
DOI: 10.1071/EG05181
Publisher: Informa UK Limited
Date: 06-1993
DOI: 10.1071/EG993117
Publisher: European Association of Geoscientists & Engineers
Date: 2007
Publisher: Informa UK Limited
Date: 06-1993
DOI: 10.1071/EG993195
Publisher: Elsevier BV
Date: 1997
Publisher: Oxford University Press (OUP)
Date: 07-1992
Publisher: Springer Science and Business Media LLC
Date: 2016
Publisher: Oxford University Press (OUP)
Date: 06-08-2015
DOI: 10.1093/GJI/GGV264
Publisher: Informa UK Limited
Date: 03-1991
DOI: 10.1071/EG991175
Publisher: Oxford University Press (OUP)
Date: 04-2004
Publisher: Springer Science and Business Media LLC
Date: 12-02-2018
Publisher: Springer Science and Business Media LLC
Date: 18-08-2011
Publisher: Society of Exploration Geophysicists
Date: 11-2016
Abstract: The depressurization of coal seam gas formations causes in situ fluids to migrate through pores and fractures in the earth. The removal or discharge of large volumes of water from coal measures reduces in situ fluid pressure allowing natural gas to be released from the coal matrix. This process results in a time-dependent resistivity variation in the subsurface. Increasing the connectivity of in situ fluids may lead to a reduction in resistivity of the targeted lithologies. A correct assessment of such resistivity variations is of significant interest not only for the industry to optimize production and extraction well locations but also for the regulatory bodies, in which a desire for a reliable method for monitoring changes in subsurface fluid distribution allows sound risk assessment of potential environmental hazards. From an industrial field study conducted in Queensland, Australia, we have found that the magnetotelluric (MT) method in the bandwidth of 100 Hz to 100 s could be used to monitor changes in the bulk resistivity of depressurized lithologies. Results from our study indicate the orientation of fluid flow resulting from depressurization, which can be mapped and directly attributed to spatial and temporal variations in permeability. The MT method is introduced as a low-cost, low-impact technology that can be used for short- and long-term environmental monitoring.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Geological Society of America
Date: 2006
DOI: 10.1130/G22222.1
Publisher: IEEE
Date: 12-2011
Publisher: Springer Science and Business Media LLC
Date: 23-12-0005
Publisher: The Royal Society
Date: 15-02-1997
Publisher: Society of Exploration Geophysicists
Date: 2003
DOI: 10.1190/1.1817979
Publisher: Oxford University Press (OUP)
Date: 15-09-2016
DOI: 10.1093/GJI/GGW345
Publisher: Springer Science and Business Media LLC
Date: 13-07-2018
DOI: 10.1038/S41598-018-29016-2
Abstract: World-class magmatic mineral systems are characterised by fluid/melt originating in the deep crust and mantle. However, processes that entrain and focus fluids from a deep-source region to a kilometre-scale deposit through the crust are unclear. A magnetotelluric (MT) and reflection seismic program across the margin of the Gawler Craton, Australia yield a distinct signature for a 1590 Ma event associated with emplacement of iron-oxide copper gold uranium (IOCG-U) deposits. Two- and three-dimensional MT modelling images a 50 km wide lower-crustal region of resistivity Ωm along an accreted Proterozoic belt. The least resistive (~1 Ωm) part terminates at the brittle-ductile transition at ~15 km, directly beneath a rifted sedimentary basin. Above the brittle-ductile transition, three narrow low-resistivity zones (~100 Ωm) branch to the surface. The least resistive zone is remarkably aligned with the world-class IOCG-U Olympic Dam deposit and the other two with significant known IOCG-U mineral occurrences. These zones are spatially correlated with narrow regions of low seismic reflectivity in the upper crust, and the deeper lower-crust conductor is almost seismically transparent. We argue this whole-of-crust imaging encapsulates deep mineral system and maps pathways of metalliferous fluids from crust and mantle sources to emplacement at discrete locations.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Graham Heinson.