Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073155
Sharna Riley, J. Meyers, J. Sinnott
Summary Passive seismic HVSR surveying is increasingly being used for investigating the thickness of soft sedimentary cover deposits sitting over hard and fresh bedrock, and for direct drill targeting of paleochannels for groundwater and brine resources. A detailed passive seismic HVSR survey was carried out at the Chilalo Graphite Project in SE Tanzania to assist with defining the thickness of alluvial deposits on the margins of the Mbewmburu River system. These alluvial sediments have the potential to host significant groundwater supply in paleochannels filled with porous coarse clastic material which can to be used for supporting a graphite ore processing. The HVSR data were acquired by local field operators, and then processed and depth converted using a Vs of 370m/s, with the modelled bedrock surface ranging in depth from <4m to 28m. The gridded bedrock depth highlighted two paleochannel features of variable depth within the river valley. One bore was drilled along the margin of a paleochannel and had encouraging water flow, and several water bores have planned to test the thick paleochannel deposits for groundwater potential. Drilling is ongoing at the time of writing and results are pending. The objective of this presentation is to demonstrate the successful application of the passive seismic HVSR method in assisting with hydrogeological studies by providing modelled bedrock surfaces which can be used for direct drill targeting, budgeting and volume estimations, and identifying potential aquiclude clay layers which could affect the hydraulic connectivity and recharge of the groundwater resource.
{"title":"Passive seismic HVSR surveying for groundwater exploration at the Chilalo Graphite Project, Tanzania","authors":"Sharna Riley, J. Meyers, J. Sinnott","doi":"10.1080/22020586.2019.12073155","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073155","url":null,"abstract":"Summary Passive seismic HVSR surveying is increasingly being used for investigating the thickness of soft sedimentary cover deposits sitting over hard and fresh bedrock, and for direct drill targeting of paleochannels for groundwater and brine resources. A detailed passive seismic HVSR survey was carried out at the Chilalo Graphite Project in SE Tanzania to assist with defining the thickness of alluvial deposits on the margins of the Mbewmburu River system. These alluvial sediments have the potential to host significant groundwater supply in paleochannels filled with porous coarse clastic material which can to be used for supporting a graphite ore processing. The HVSR data were acquired by local field operators, and then processed and depth converted using a Vs of 370m/s, with the modelled bedrock surface ranging in depth from <4m to 28m. The gridded bedrock depth highlighted two paleochannel features of variable depth within the river valley. One bore was drilled along the margin of a paleochannel and had encouraging water flow, and several water bores have planned to test the thick paleochannel deposits for groundwater potential. Drilling is ongoing at the time of writing and results are pending. The objective of this presentation is to demonstrate the successful application of the passive seismic HVSR method in assisting with hydrogeological studies by providing modelled bedrock surfaces which can be used for direct drill targeting, budgeting and volume estimations, and identifying potential aquiclude clay layers which could affect the hydraulic connectivity and recharge of the groundwater resource.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"42 1","pages":"1 - 5"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79212550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073102
B. Birt, O. Filiptsova, S. Ryan, Tim Hopper
Summary During the drilling process, numerous decisions must be made, often with limited information. In a known area prior knowledge often guides these decisions. In a recent drilling program in the Northern Perth Basin, as part of a research project to monitor the use of aquifers, petrophysical logs were used to help inform some critical decisions. Further analysis of the data collected from the borehole was going to be used to monitor quality, extent and connectivity of the numerous aquifers that make up the Northern Perth Basin. As an aquifer monitoring program, it is critical to ensure that the bore is accessing the aquifer in question. Therefore, accurate knowledge of depth and quality of formation is key. This paper shows how to use a simple set of petrophysical logs including natural gamma, resistivity and borehole magnetic resonance logs can be used to make informed decisions. For example, using a composite log, decisions were able to be made on screen placement prior to running, and also helped decide if extra bores on the same drilling pad were required. Finally, we were able to determine the salinity of ground water from wireline logs. The ability to make these decisions with accurate information not only ensures successful well completion but also maximises resource use.
{"title":"Realtime analysis and well planning using wireline logs in a hydrogeological context","authors":"B. Birt, O. Filiptsova, S. Ryan, Tim Hopper","doi":"10.1080/22020586.2019.12073102","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073102","url":null,"abstract":"Summary During the drilling process, numerous decisions must be made, often with limited information. In a known area prior knowledge often guides these decisions. In a recent drilling program in the Northern Perth Basin, as part of a research project to monitor the use of aquifers, petrophysical logs were used to help inform some critical decisions. Further analysis of the data collected from the borehole was going to be used to monitor quality, extent and connectivity of the numerous aquifers that make up the Northern Perth Basin. As an aquifer monitoring program, it is critical to ensure that the bore is accessing the aquifer in question. Therefore, accurate knowledge of depth and quality of formation is key. This paper shows how to use a simple set of petrophysical logs including natural gamma, resistivity and borehole magnetic resonance logs can be used to make informed decisions. For example, using a composite log, decisions were able to be made on screen placement prior to running, and also helped decide if extra bores on the same drilling pad were required. Finally, we were able to determine the salinity of ground water from wireline logs. The ability to make these decisions with accurate information not only ensures successful well completion but also maximises resource use.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"2019 1","pages":"1 - 5"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78958858","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073122
R. Woods, T. Bothwell, B. Birt, Tim Hopper, S. Higginson
Summary Bringing a new well on-line is an expensive proposition and the need to ensure optimal performance is critical. Saturation and contamination of the drilling fluid with fines and subsequent invasion of the formation has historically resulted in hundreds of hours per well of invisible lost time during the clean-up phase of the well. New technologies, workflows and methods that can reduce costs/turnaround on projects were conducted on a large multi-well project in Perth, Western Australia, to maximise well efficiencies. Data from multiple sources were used to optimise and validate well clean-up operations with the aim to maximising production. This case study uses integration of well testing transient pressure data, Borehole Magnetic Resonance (BMR) derived transmissivity and flow logging to quantify success of clean-up/development of water wells, to reduce cost and optimise productivity. This case study demonstrates the successful implementation of an integrated approach to well clean-up using several scales of permeability data from core to wireline BMR to well test. This case study demonstrates that, in this particular setting, the use of the presented methodology was cost effective, yielded positive confirmation of asset delivery, and has led to a 90% reduction in clean-up associated time.
{"title":"A practical approach used to plan and execute, quantify and qualify an effective well clean-up strategy","authors":"R. Woods, T. Bothwell, B. Birt, Tim Hopper, S. Higginson","doi":"10.1080/22020586.2019.12073122","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073122","url":null,"abstract":"Summary Bringing a new well on-line is an expensive proposition and the need to ensure optimal performance is critical. Saturation and contamination of the drilling fluid with fines and subsequent invasion of the formation has historically resulted in hundreds of hours per well of invisible lost time during the clean-up phase of the well. New technologies, workflows and methods that can reduce costs/turnaround on projects were conducted on a large multi-well project in Perth, Western Australia, to maximise well efficiencies. Data from multiple sources were used to optimise and validate well clean-up operations with the aim to maximising production. This case study uses integration of well testing transient pressure data, Borehole Magnetic Resonance (BMR) derived transmissivity and flow logging to quantify success of clean-up/development of water wells, to reduce cost and optimise productivity. This case study demonstrates the successful implementation of an integrated approach to well clean-up using several scales of permeability data from core to wireline BMR to well test. This case study demonstrates that, in this particular setting, the use of the presented methodology was cost effective, yielded positive confirmation of asset delivery, and has led to a 90% reduction in clean-up associated time.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"7 6","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91441099","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073107
C. Elders, T. Bernecker
Summary The widely used scheme of naming basins and their regional subdivisions on the North West Shelf emerged from relatively sparse data collected during the early stages of exploration. Such data allow the recognition of large-scale structures and depocentres with a broadly distinct tectono-stratigraphic framework. While that scheme has endured, the availability of extensive, high quality seismic data and stratigraphic information from numerous exploration wells means that we can define much more precisely the structural elements that comprise the margin and the stratigraphic signatures of the basin fill. This has highlighted some inconsistencies in the existing nomenclature, the presence of structural elements of different ages and the presence of boundaries between basins that sometimes can appear rather arbitrary. We present a revised map for the North West Shelf that shows the structural elements with distinct tectono-stratigraphic signatures that comprise the margin, and applies a consistent nomenclature to them. The aim is to provide a framework that will allow for the better demarcation of distinct hydrocarbon provinces and improved targeting of exploration programmes. This is a work in progress and we invite you to annotate the map shown on our poster with your own comments or to provide feedback via our blog.
{"title":"Revising the structural elements map of the North West Shelf","authors":"C. Elders, T. Bernecker","doi":"10.1080/22020586.2019.12073107","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073107","url":null,"abstract":"Summary The widely used scheme of naming basins and their regional subdivisions on the North West Shelf emerged from relatively sparse data collected during the early stages of exploration. Such data allow the recognition of large-scale structures and depocentres with a broadly distinct tectono-stratigraphic framework. While that scheme has endured, the availability of extensive, high quality seismic data and stratigraphic information from numerous exploration wells means that we can define much more precisely the structural elements that comprise the margin and the stratigraphic signatures of the basin fill. This has highlighted some inconsistencies in the existing nomenclature, the presence of structural elements of different ages and the presence of boundaries between basins that sometimes can appear rather arbitrary. We present a revised map for the North West Shelf that shows the structural elements with distinct tectono-stratigraphic signatures that comprise the margin, and applies a consistent nomenclature to them. The aim is to provide a framework that will allow for the better demarcation of distinct hydrocarbon provinces and improved targeting of exploration programmes. This is a work in progress and we invite you to annotate the map shown on our poster with your own comments or to provide feedback via our blog.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"1 1","pages":"1 - 2"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89744235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073004
C. Dempsey, R. Benson, G. O’Halloran, O. Schenk, A. Karvelas, S. Tewari
Summary The Exmouth Sub-basin forms one of several Jurassic depocentres in the greater Carnarvon Basin and has been prolific in terms of hydrocarbon production with approximately 1 Bbbls of oil and over 1 Tcf of gas discovered/produced to date. The sub-basin was recently covered for the first time with a contiguous, high quality, deep-record 3D seismic survey that has enabled detailed structural and stratigraphic mapping over its full extent, providing new insights into the tectono-stratigraphic history of the area. These interpretations along with those incorporating the sub-basins thermal history and gross depositional environments were used to constrain an integrated petroleum systems model with the ultimate aim of representing hydrocarbon distribution and future exploration potential.
{"title":"New insights into the Exmouth Sub-basin: tectono-stratigraphic evolution","authors":"C. Dempsey, R. Benson, G. O’Halloran, O. Schenk, A. Karvelas, S. Tewari","doi":"10.1080/22020586.2019.12073004","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073004","url":null,"abstract":"Summary The Exmouth Sub-basin forms one of several Jurassic depocentres in the greater Carnarvon Basin and has been prolific in terms of hydrocarbon production with approximately 1 Bbbls of oil and over 1 Tcf of gas discovered/produced to date. The sub-basin was recently covered for the first time with a contiguous, high quality, deep-record 3D seismic survey that has enabled detailed structural and stratigraphic mapping over its full extent, providing new insights into the tectono-stratigraphic history of the area. These interpretations along with those incorporating the sub-basins thermal history and gross depositional environments were used to constrain an integrated petroleum systems model with the ultimate aim of representing hydrocarbon distribution and future exploration potential.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"1 1","pages":"1 - 9"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89703843","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073146
M. Bergqvist, Eric Landström, Eric Landström, S. Luth
Summary Scanning drill cores using combined data from X-Ray Transmission and X-Ray Fluorescence, automatically measuring the weight, and performing 3D tomography of the core at the same time, gives a high-resolution 3D visualisation of the structures, textures and mineral distribution as well as elemental and density distribution along the drill hole. Data such as planar and linear structures can be annotated in the 3D volume and later exported into regional modelling or other software packages together with elemental concentrations and density. Particle sizes and distribution can be exported to produce stereo nets. An example from the European Union Horizon 2020 funded X-Mine project (2017), where a work flow is illustrated.
{"title":"Access to geological structures, density, minerals and textures through novel combination of 3D tomography, XRF and sample weight","authors":"M. Bergqvist, Eric Landström, Eric Landström, S. Luth","doi":"10.1080/22020586.2019.12073146","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073146","url":null,"abstract":"Summary Scanning drill cores using combined data from X-Ray Transmission and X-Ray Fluorescence, automatically measuring the weight, and performing 3D tomography of the core at the same time, gives a high-resolution 3D visualisation of the structures, textures and mineral distribution as well as elemental and density distribution along the drill hole. Data such as planar and linear structures can be annotated in the 3D volume and later exported into regional modelling or other software packages together with elemental concentrations and density. Particle sizes and distribution can be exported to produce stereo nets. An example from the European Union Horizon 2020 funded X-Mine project (2017), where a work flow is illustrated.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"14 1","pages":"1 - 3"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82037425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073033
F. Effersø, E. Smart, R. Mortimer
Summary This case study illustrates the use of an exploration method that leverages modern exploration techniques for deep-seated VMS and Ni-Cu deposits in a 978 km2 survey area in the highly prospective Areachap Belt, South Africa. The exploration method comprises the use of a high power helicopter TEM (“HTEM”) system, a large fixed loop TEM (“FLTEM”) ground system and drilling that are employed in a staged process to keep down risks and costs and more importantly to optimize the chances of discovering viable economic mineral resources. Based on the HTEM survey 19 high priority VMS targets were detected for ground follow up with FLTEM. The FLTEM data confirmed all of these targets, and 2D plate modelling refined the parameter for optimal drilling of the targets. The first result of the drilling campaign led to the discovery of a significant Ni-Cu deposit. The prospect of this case study is that the employed method may be useful for certain types of mineral exploration. Provided that the electrical conductivity contrast between the mineralisation and the host rock is sufficient then the use of HTEM and FLTEM is a viable choice. The staged exploration process ensures that potential resources are detected and that risks and costs at each step are kept down.
{"title":"VMS and Ni-Cu exploration using an integrated geophysical and drilling method","authors":"F. Effersø, E. Smart, R. Mortimer","doi":"10.1080/22020586.2019.12073033","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073033","url":null,"abstract":"Summary This case study illustrates the use of an exploration method that leverages modern exploration techniques for deep-seated VMS and Ni-Cu deposits in a 978 km2 survey area in the highly prospective Areachap Belt, South Africa. The exploration method comprises the use of a high power helicopter TEM (“HTEM”) system, a large fixed loop TEM (“FLTEM”) ground system and drilling that are employed in a staged process to keep down risks and costs and more importantly to optimize the chances of discovering viable economic mineral resources. Based on the HTEM survey 19 high priority VMS targets were detected for ground follow up with FLTEM. The FLTEM data confirmed all of these targets, and 2D plate modelling refined the parameter for optimal drilling of the targets. The first result of the drilling campaign led to the discovery of a significant Ni-Cu deposit. The prospect of this case study is that the employed method may be useful for certain types of mineral exploration. Provided that the electrical conductivity contrast between the mineralisation and the host rock is sufficient then the use of HTEM and FLTEM is a viable choice. The staged exploration process ensures that potential resources are detected and that risks and costs at each step are kept down.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"1 1","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90188777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073129
W. Soyer, F. Miorelli, R. Mackie
Summary We have quantified the use of finite electric dipole lengths from the point measurement assumptions typical in 3D MT inversion modeling. Electric fields are measured across dipoles of typically 50 m to 200 m at MT soundings. Modeling algorithms, however, normally use point electric field values at the surface of single cells to calculate MT transfer functions. This is perfectly reasonable for the majority of cases, but there are situations with strong shallow variability of resistivity, where measurements may not be simulated well by point electric fields, and detailed information might not be used optimally. We explore the consequences of this omission by quantifying the difference between point solutions and electric field integrations across dipoles in 3D forward calculations for selected cases. The topic ties closely with galvanic distortion and inversion for related parameters, lateral magnetic field variations, and the benefit of providing shallower constraints for the imaging of deeper targets. As a side product, the analysis led us to focus on the fields output from the 3D modeling, and we illustrate electric current systems through the cases analyzed. We observe that in the presence of strong topography and outcropping inhomogeneities, finite dipole solutions can differ considerably from point solutions, while over a variable regolith case the effect appears more contained
{"title":"Using finite dipole lengths in complete earth 3D MT modelling","authors":"W. Soyer, F. Miorelli, R. Mackie","doi":"10.1080/22020586.2019.12073129","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073129","url":null,"abstract":"Summary We have quantified the use of finite electric dipole lengths from the point measurement assumptions typical in 3D MT inversion modeling. Electric fields are measured across dipoles of typically 50 m to 200 m at MT soundings. Modeling algorithms, however, normally use point electric field values at the surface of single cells to calculate MT transfer functions. This is perfectly reasonable for the majority of cases, but there are situations with strong shallow variability of resistivity, where measurements may not be simulated well by point electric fields, and detailed information might not be used optimally. We explore the consequences of this omission by quantifying the difference between point solutions and electric field integrations across dipoles in 3D forward calculations for selected cases. The topic ties closely with galvanic distortion and inversion for related parameters, lateral magnetic field variations, and the benefit of providing shallower constraints for the imaging of deeper targets. As a side product, the analysis led us to focus on the fields output from the 3D modeling, and we illustrate electric current systems through the cases analyzed. We observe that in the presence of strong topography and outcropping inhomogeneities, finite dipole solutions can differ considerably from point solutions, while over a variable regolith case the effect appears more contained","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"5 1","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85841965","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073149
C. Plet, C. Siégel, R. Noble, R. Anand, M. Woltering, R. Thorne, A. Pagès, S. Spinks
Summary The future of mineral resources in Australia relies on the discovery of deposits under sedimentary cover. Traditional surface geochemistry techniques are of limited use in this context, and alternative exploration tools such as the detection of soil gases are gaining increasing interest. Previous studies have highlighted the potential of soil gases, such as sulphur gases and soil gas hydrocarbons, for locating buried mineralisation. Here, we performed laboratory weathering experiments of sulphides under sterile and non-sterile conditions to gain insights into the origin of these gases. The experiments revealed that hydrocarbon gases could not be detected, suggesting they commonly originate from microbial ecosystems in the cover and/or in the soil. In addition, equilibrium thermodynamic predictions indicate a larger range of sulphur gases than detected, which suggests the experimental system did not reach thermal equilibrium. Our results also reveal that CS2 is the most abundant gas produced, and could be of particular interest as a pathfinder for mineral exploration through cover.
{"title":"Soil gases, pathfinders for exploration of buried sulphide deposits: insights from laboratory experiments","authors":"C. Plet, C. Siégel, R. Noble, R. Anand, M. Woltering, R. Thorne, A. Pagès, S. Spinks","doi":"10.1080/22020586.2019.12073149","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073149","url":null,"abstract":"Summary The future of mineral resources in Australia relies on the discovery of deposits under sedimentary cover. Traditional surface geochemistry techniques are of limited use in this context, and alternative exploration tools such as the detection of soil gases are gaining increasing interest. Previous studies have highlighted the potential of soil gases, such as sulphur gases and soil gas hydrocarbons, for locating buried mineralisation. Here, we performed laboratory weathering experiments of sulphides under sterile and non-sterile conditions to gain insights into the origin of these gases. The experiments revealed that hydrocarbon gases could not be detected, suggesting they commonly originate from microbial ecosystems in the cover and/or in the soil. In addition, equilibrium thermodynamic predictions indicate a larger range of sulphur gases than detected, which suggests the experimental system did not reach thermal equilibrium. Our results also reveal that CS2 is the most abundant gas produced, and could be of particular interest as a pathfinder for mineral exploration through cover.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"31 1","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86035234","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12072994
Lisa R Tannock, M. Herwegh, A. Berger, K. Regenauer‐Lieb
Summary Giant quartz reefs can develop as part of a larger scale ‘mineral factory’ within a specific space and time, due to a series of interlinking processes and mechanisms. Ascertaining the criteria for giant quartz reef formation is based on data obtained from multidisciplinary, multi-scale analysis. The results show that a ‘quartz reef window’ is met when the following conditions are optimal (i) accommodation space; (ii) permeability; (iii) significant fluid supply; (iv) considerable Time Integrated Fluid Fluxes; (v) temperature conditions; (vi) SiO2 oversaturation; and (vii) cap rock/seal is present. These elements are key to understanding the evolution of giant quartz reef formations, as well as identifying and targeting these mineral lodes.
{"title":"The mineral factory: how to build a giant quartz reef","authors":"Lisa R Tannock, M. Herwegh, A. Berger, K. Regenauer‐Lieb","doi":"10.1080/22020586.2019.12072994","DOIUrl":"https://doi.org/10.1080/22020586.2019.12072994","url":null,"abstract":"Summary Giant quartz reefs can develop as part of a larger scale ‘mineral factory’ within a specific space and time, due to a series of interlinking processes and mechanisms. Ascertaining the criteria for giant quartz reef formation is based on data obtained from multidisciplinary, multi-scale analysis. The results show that a ‘quartz reef window’ is met when the following conditions are optimal (i) accommodation space; (ii) permeability; (iii) significant fluid supply; (iv) considerable Time Integrated Fluid Fluxes; (v) temperature conditions; (vi) SiO2 oversaturation; and (vii) cap rock/seal is present. These elements are key to understanding the evolution of giant quartz reef formations, as well as identifying and targeting these mineral lodes.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"5 1","pages":"1 - 4"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88090437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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