Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073104
Xue-jun Yang, G. Smith
Summary The Gippsland basin geological history is modelled using the Badlands software constrained by a realistic 3D structural and stratigraphic model built in Petrel. The aim is to assess and calibrate the theoretical tectonic and sedimentary models using empirical data for a rift basin. The theoretical models are used to assess and measure the relative effect of significant variables for sedimentary basins, including climate, extension, subsidence, uplift, erosion and sedimentation. The modelling results indicate several insights for the Gippsland Basin. The initial paleo-topography at ~145 Ma was an extensive highland area. The Early Cretaceous paleo-environment was intracratonic, with sediment transport from east to west, and at some stage included an inland sea. The Mid Cretaceous uplift caused emergence of the entire basin, substantial regional erosion and changed the basin architecture. Subsidence associated with Tasman Sea rifting formed the Central Deep and flipped the fluvial paleo-drainage system towards the east. Latrobe Group sediments filled the basin being progressively transgressed by rising sea level to flood most areas by the Oligocene. The models simulate the progradation of the carbonate shelf sediments, sub-marine channels and anticlines over the basin since then.
{"title":"Gippsland Basin 3D forward modelling in Badlands","authors":"Xue-jun Yang, G. Smith","doi":"10.1080/22020586.2019.12073104","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073104","url":null,"abstract":"Summary The Gippsland basin geological history is modelled using the Badlands software constrained by a realistic 3D structural and stratigraphic model built in Petrel. The aim is to assess and calibrate the theoretical tectonic and sedimentary models using empirical data for a rift basin. The theoretical models are used to assess and measure the relative effect of significant variables for sedimentary basins, including climate, extension, subsidence, uplift, erosion and sedimentation. The modelling results indicate several insights for the Gippsland Basin. The initial paleo-topography at ~145 Ma was an extensive highland area. The Early Cretaceous paleo-environment was intracratonic, with sediment transport from east to west, and at some stage included an inland sea. The Mid Cretaceous uplift caused emergence of the entire basin, substantial regional erosion and changed the basin architecture. Subsidence associated with Tasman Sea rifting formed the Central Deep and flipped the fluvial paleo-drainage system towards the east. Latrobe Group sediments filled the basin being progressively transgressed by rising sea level to flood most areas by the Oligocene. The models simulate the progradation of the carbonate shelf sediments, sub-marine channels and anticlines over the basin since then.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"27 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":"89841735","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: 10.1080/22020586.2019.12073075
G. Visser
Summary The last decade has seen extensive development of Bayesian geophysical inversion methods which produce ensembles of models as outputs. Many of these are limited to producing 1D or very simple and narrow models. It is well established that tying such narrow inversions together using lateral priors can significantly improve inversion results. Such laterally constrained inversion can, however, be complicated to code and add computational overhead. For this reason, available Bayesian geophysical inversion codes often do not include lateral priors as an option. I introduce a simple and easy to use method that allows lateral priors to be added to Bayesian ensemble inversion results as a post-processing step. This method has the potential to extend the use of many existing inversion codes and results. It can significantly reduce computational costs when practitioners want to experiment with different lateral priors. The method is demonstrated using synthetic magnetotelluric data and VTEM data from Cloncurry in Queensland.
{"title":"Smart stitching: adding lateral priors to ensemble inversions as a post-processing step","authors":"G. Visser","doi":"10.1080/22020586.2019.12073075","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073075","url":null,"abstract":"Summary The last decade has seen extensive development of Bayesian geophysical inversion methods which produce ensembles of models as outputs. Many of these are limited to producing 1D or very simple and narrow models. It is well established that tying such narrow inversions together using lateral priors can significantly improve inversion results. Such laterally constrained inversion can, however, be complicated to code and add computational overhead. For this reason, available Bayesian geophysical inversion codes often do not include lateral priors as an option. I introduce a simple and easy to use method that allows lateral priors to be added to Bayesian ensemble inversion results as a post-processing step. This method has the potential to extend the use of many existing inversion codes and results. It can significantly reduce computational costs when practitioners want to experiment with different lateral priors. The method is demonstrated using synthetic magnetotelluric data and VTEM data from Cloncurry in Queensland.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"47 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":"72667546","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: 10.1080/22020586.2019.12073047
N. Rollet, E. Grosjean, D. Edwards, R. Kempton, D. Nguyen, S. Abbott, C. Orlov, G. Bernardel, C. Nicholson
Summary The greater Phoenix area in the Bedout Sub-basin has experienced recent exploration success on Australia’s North West Shelf (NWS). Oil and gas discoveries in the Triassic reservoirs of the Keraudren Formation and Locker Shale have revived interest in mapping the distribution and lateral facies variation of the Triassic succession from the Bedout Sub-basin into the adjacent underexplored Beagle and Rowley sub-basins. This multi-disciplinary study integrating structural architecture, sequence stratigraphy, paleogeography and geochemistry has mapped the spatial and temporal distributions of Triassic source rocks on the central NWS. The Lower-Middle Triassic paleogeography is dominated by a deltaic system building from the Bedout Sub-basin into the Beagle Sub-basin. The oil sourced and reservoired within the Lower‒Middle Triassic sequences at Phoenix South 1 is unique to the Bedout Sub-basin, compared to other oils along the NWS. Its mixed landplant and algal biomarker signature is most likely sourced locally by fluvial-deltaic mudstones within the TR10‒ TR14 or TR15 sequences and represents a new petroleum system on the NWS. A Middle Triassic marine incursion is recorded in the Bedout Sub-basin with the development of a carbonate platform while in the Rowley Sub-basin, volcanics have been penetrated at the top of the thick Lower‒Middle Triassic sediment package. The Late Triassic paleogeographic map suggests a carbonate environment in the Rowley Sub-basin distinct to the clastic-dominated fluvial-deltaic environment in the Beagle Sub-basin. This information combined with results of well-based geochemical analyses highlights the potential for hydrocarbon generation within the Upper Triassic in these sub-basins.
最近，澳大利亚西北大陆架(NWS) Bedout次盆地的大凤凰地区勘探取得了成功。Keraudren组和Locker页岩三叠系储层的油气发现，重新激起了人们对Bedout次盆地到邻近未勘探的Beagle和Rowley次盆地三叠系序列分布和侧向相变化的兴趣。综合构造学、层序地层学、古地理学和地球化学等多学科的研究，绘制了NWS中部三叠系烃源岩的时空分布图。下-中三叠世古地理以Bedout次盆地到Beagle次盆地的三角洲体系为主导。与NWS沿线的其他油藏相比，Phoenix South 1的下-中三叠统层序中的原油来源和储层是Bedout亚盆地独有的。其陆生植物和藻类混合生物标志物极有可能来源于TR10 - TR14或TR15层序内的河流-三角洲泥岩，代表了NWS一种新的含油气系统。Bedout次盆地为中三叠统海相侵入，碳酸盐岩台地发育;Rowley次盆地为下中三叠统较厚的沉积包体顶部穿透火山活动。晚三叠世古地理图表明罗利次盆地为碳酸盐岩环境，与比格尔次盆地以碎屑岩为主的河流三角洲环境截然不同。这些信息与基于良好基础的地球化学分析结果相结合，突出了这些次盆地的上三叠统生烃潜力。
{"title":"Triassic petroleum systems on the central North West Shelf – Learnings from the greater Phoenix area seismic mapping and geochemical studies","authors":"N. Rollet, E. Grosjean, D. Edwards, R. Kempton, D. Nguyen, S. Abbott, C. Orlov, G. Bernardel, C. Nicholson","doi":"10.1080/22020586.2019.12073047","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073047","url":null,"abstract":"Summary The greater Phoenix area in the Bedout Sub-basin has experienced recent exploration success on Australia’s North West Shelf (NWS). Oil and gas discoveries in the Triassic reservoirs of the Keraudren Formation and Locker Shale have revived interest in mapping the distribution and lateral facies variation of the Triassic succession from the Bedout Sub-basin into the adjacent underexplored Beagle and Rowley sub-basins. This multi-disciplinary study integrating structural architecture, sequence stratigraphy, paleogeography and geochemistry has mapped the spatial and temporal distributions of Triassic source rocks on the central NWS. The Lower-Middle Triassic paleogeography is dominated by a deltaic system building from the Bedout Sub-basin into the Beagle Sub-basin. The oil sourced and reservoired within the Lower‒Middle Triassic sequences at Phoenix South 1 is unique to the Bedout Sub-basin, compared to other oils along the NWS. Its mixed landplant and algal biomarker signature is most likely sourced locally by fluvial-deltaic mudstones within the TR10‒ TR14 or TR15 sequences and represents a new petroleum system on the NWS. A Middle Triassic marine incursion is recorded in the Bedout Sub-basin with the development of a carbonate platform while in the Rowley Sub-basin, volcanics have been penetrated at the top of the thick Lower‒Middle Triassic sediment package. The Late Triassic paleogeographic map suggests a carbonate environment in the Rowley Sub-basin distinct to the clastic-dominated fluvial-deltaic environment in the Beagle Sub-basin. This information combined with results of well-based geochemical analyses highlights the potential for hydrocarbon generation within the Upper Triassic in these sub-basins.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"123 1","pages":"1 - 7"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79079792","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: 10.1080/22020586.2019.12073229
Sarah G. R. Devriese, R. Ellis, K. Witherly
Summary In this paper, we present an algorithm based on the sensitivity of the data to the model space to reduce the large amount of data commonly collected during 3D DC/IP surveys to only those most relevant and important to the model space. The sensitivity-based data reduction (SBDR) algorithm is demonstrated using both synthetic and field data examples. The results indicate that the SBDR recovered models are valid solutions to the full inversion problem but require a fraction of the computation time and resources, providing a geologic solution in a much shorter time than required to solve the full inversion problem.
{"title":"Sensitivity-based data reduction of large 3D DC/IP surveys","authors":"Sarah G. R. Devriese, R. Ellis, K. Witherly","doi":"10.1080/22020586.2019.12073229","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073229","url":null,"abstract":"Summary In this paper, we present an algorithm based on the sensitivity of the data to the model space to reduce the large amount of data commonly collected during 3D DC/IP surveys to only those most relevant and important to the model space. The sensitivity-based data reduction (SBDR) algorithm is demonstrated using both synthetic and field data examples. The results indicate that the SBDR recovered models are valid solutions to the full inversion problem but require a fraction of the computation time and resources, providing a geologic solution in a much shorter time than required to solve the full inversion problem.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"77 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":"79289921","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: 10.1080/22020586.2019.12073204
D. Stannard, J. Meyers, E. Turner, A. Scopel
Summary The Abra sedimentary replacement Pb-Ag-Cu-Au deposit is located in the Paleoproterozoic Edmund Basin, 900km NNE of Perth. Mineralisation at Abra has no surface expression and the deposit was discovered in 1981 by drill testing coincident magnetic and gravity anomaly highs. The deposit is hosted within siliciclastic and carbonate deposits of the Edmund Group and consists of a stratabound apron of lower grade Pb-Ag-Ba mineralisation in a laminated iron oxide and barite altered siltstone unit that overlies a funnel shaped feeder zone of chlorite altered, brecciated and veined carbonaceous siltstone containing high-grade Pb-Ag in the core, transitioning to Pb-Cu and Cu-Au at depth. As at December 2018, the Abra deposit remains unmined and has an estimated resource of 37.4Mt at 7.5% Pb and 18g/t Ag. Mutton and McInerney (1987) and McInerney et al. (1994) described the geophysical expression of Abra, and recent geophysical survey results are presented here. Abra is characterised by discrete anomaly responses in magnetic, gravity and TDEM survey data. A +450nT magnetic anomaly is observed in ground and airborne magnetic data, which is caused by magnetite within the lower part of the stratabound zone. Dense galena, barite and iron oxide mineralisation in the stratabound zone, and galena in the feeder zone, is surrounded by low-density sedimentary host rock, resulting in a +1mGal gravity anomaly. TDEM surveys have resolved massive sulphide mineralisation as EM conductors, and petrophysical testing on core samples show this is mostly caused by galena. Inverted AMT-MT data sections resolved the deposit halo as a conductive anomaly. ZTEM data failed to resolve a distinct anomaly response. DDIP surveying failed to resolve a chargeable anomaly coincident to known high-grade mineralisation, despite significant disseminated sulphide mineralisation occurring within the deposit. An IP chargeability anomaly observed on the southern side of the deposit is thought to be associated with an alteration zone and low-grade disseminated sulphide mineralisation in a fault zone. A 2D seismic reflection survey line resolved the deposit envelope as strong seismic reflectors surrounded by a seismically bland zone, and this is related to the significant density contrast between the high-density stratabound mineralisation in contact with low-density sedimentary host rocks, as the mineralisation and host rock have similar seismic velocities. Passive seismic HVSR surveying resolved the top of Abra as a subtle HVSR response below a flat impedance contrast horizon interpreted as weathered siltstone over diagenetic cemented siltstone.
Abra沉积置换Pb-Ag-Cu-Au矿床位于珀斯东北偏北900km的古元古代埃德蒙盆地。Abra的矿化没有地表表现，矿床是1981年通过钻测发现的。该矿床赋有于埃德蒙群的硅质碎屑和碳酸盐矿床中，由层控带组成，在层状氧化铁和重晶石蚀变粉砂岩单元中有较低品位的铅银钡矿化，层控带覆盖在绿泥石蚀变、角化和脉状碳质粉砂岩的漏斗状给料带上，其中芯部含有高品位的铅银，向深部过渡为铅铜和铜金。截至2018年12月，Abra矿床仍未开采，估计资源量为3740万吨，铅含量为7.5%，银含量为18g/t。Mutton and McInerney(1987)和McInerney et al.(1994)描述了Abra的地球物理表达式，这里给出了最近的地球物理调查结果。Abra的特点是磁、重力和TDEM测量数据的离散异常响应。在地面和航空磁资料中观测到+450nT磁异常，这是由层控带下部的磁铁矿引起的。层控带中密集的方铅矿、重晶石和氧化铁矿化，以及给矿带中密集的方铅矿被低密度的沉积寄主岩包围，形成+1mGal的重力异常。TDEM调查已经解决了大量硫化物矿化作为电磁导体，岩心样品的岩石物理测试表明，这主要是由方铅矿引起的。倒置的AMT-MT数据剖面将沉积晕确定为导电异常。ZTEM数据未能解决一个明显的异常响应。DDIP测量未能解决与已知高品位矿化相一致的带电异常，尽管在矿床内发生了显著的浸染硫化物矿化。在矿床南侧观测到的激电性异常被认为与断裂带中的蚀变带和低品位浸染硫化物矿化有关。二维地震反射测量线将矿床包络层分解为被地震温和带包围的强地震反射带，这与高密度层控矿化与低密度沉积寄主岩接触之间的显著密度差异有关，因为矿化和寄主岩具有相似的地震速度。被动地震HVSR测量将Abra顶部解析为平坦阻抗对比层下方的微妙HVSR响应，解释为成岩胶结粉砂岩上的风化粉砂岩。
{"title":"Update on the geophysical expression of the Abra sedimentary replacement Pb-Ag-Cu-Au deposit, Western Australia","authors":"D. Stannard, J. Meyers, E. Turner, A. Scopel","doi":"10.1080/22020586.2019.12073204","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073204","url":null,"abstract":"Summary The Abra sedimentary replacement Pb-Ag-Cu-Au deposit is located in the Paleoproterozoic Edmund Basin, 900km NNE of Perth. Mineralisation at Abra has no surface expression and the deposit was discovered in 1981 by drill testing coincident magnetic and gravity anomaly highs. The deposit is hosted within siliciclastic and carbonate deposits of the Edmund Group and consists of a stratabound apron of lower grade Pb-Ag-Ba mineralisation in a laminated iron oxide and barite altered siltstone unit that overlies a funnel shaped feeder zone of chlorite altered, brecciated and veined carbonaceous siltstone containing high-grade Pb-Ag in the core, transitioning to Pb-Cu and Cu-Au at depth. As at December 2018, the Abra deposit remains unmined and has an estimated resource of 37.4Mt at 7.5% Pb and 18g/t Ag. Mutton and McInerney (1987) and McInerney et al. (1994) described the geophysical expression of Abra, and recent geophysical survey results are presented here. Abra is characterised by discrete anomaly responses in magnetic, gravity and TDEM survey data. A +450nT magnetic anomaly is observed in ground and airborne magnetic data, which is caused by magnetite within the lower part of the stratabound zone. Dense galena, barite and iron oxide mineralisation in the stratabound zone, and galena in the feeder zone, is surrounded by low-density sedimentary host rock, resulting in a +1mGal gravity anomaly. TDEM surveys have resolved massive sulphide mineralisation as EM conductors, and petrophysical testing on core samples show this is mostly caused by galena. Inverted AMT-MT data sections resolved the deposit halo as a conductive anomaly. ZTEM data failed to resolve a distinct anomaly response. DDIP surveying failed to resolve a chargeable anomaly coincident to known high-grade mineralisation, despite significant disseminated sulphide mineralisation occurring within the deposit. An IP chargeability anomaly observed on the southern side of the deposit is thought to be associated with an alteration zone and low-grade disseminated sulphide mineralisation in a fault zone. A 2D seismic reflection survey line resolved the deposit envelope as strong seismic reflectors surrounded by a seismically bland zone, and this is related to the significant density contrast between the high-density stratabound mineralisation in contact with low-density sedimentary host rocks, as the mineralisation and host rock have similar seismic velocities. Passive seismic HVSR surveying resolved the top of Abra as a subtle HVSR response below a flat impedance contrast horizon interpreted as weathered siltstone over diagenetic cemented siltstone.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"13 1","pages":"1 - 7"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75855090","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: 10.1080/22020586.2019.12073224
F. Best, Matthew Readford, K. Walcott
Summary Understanding the mobility of individual elements in the oxidised environment is important for the accurate interpretation of geochemical data from regolith and weathered bedrock samples. In the weathered environment, immobile element geochemistry can reflect primary lithological and in situ mineralisation signatures, whereas mobile elements can help establish the degree and extent of weathering. Three exploration case studies are presented here to demonstrate the application of multielement geochemistry in the weathered environment: An example from the Shorty Creek Project, Alaska (Freegold Ventures), highlights the importance of reviewing and understanding pathfinder elements in soil, weathered bedrock and fresh basement. Here, commodity elements Cu and Zn are highly mobile and relatively depleted in the soils and weathered zone over Cu-Au mineralisation, whereas Au, As, Bi and Sb are less mobile and highly anomalous in the oxidised bedrock and associated soils. The Hermosa Deposit, Arizona (South32), where downhole geochemistry can help map the oxide-fresh rock boundary at the deposit scale. Subtle depletion in mobile elements allows the weathered zone to be identified in altered rhyolites, and Zn:S and Pb:S ratios in the mineralised zone helps distinguish Zn and Pb oxides from Zn and Pb sulphides. A review of residual soils over a Ni-Cu-PGE prospect in Northern Queensland, where immobile elements are reliable discriminants of primary lithologies in highly weathered environments. Zirconium, Y, Th and Nb can be used to distinguish felsic from mafic bedrock, and variations in Cr, V, Al, Fe and Sc in soils confidently identify blind, compositionally distinct mafic-ultramafic bodies. This paper also highlights the importance of collecting high quality, multi-element geochemistry with low detection limits at every stage of exploration.
{"title":"Application of multi-element geochemistry in the weathered environment: Controls, considerations and implications for exploration","authors":"F. Best, Matthew Readford, K. Walcott","doi":"10.1080/22020586.2019.12073224","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073224","url":null,"abstract":"Summary Understanding the mobility of individual elements in the oxidised environment is important for the accurate interpretation of geochemical data from regolith and weathered bedrock samples. In the weathered environment, immobile element geochemistry can reflect primary lithological and in situ mineralisation signatures, whereas mobile elements can help establish the degree and extent of weathering. Three exploration case studies are presented here to demonstrate the application of multielement geochemistry in the weathered environment: An example from the Shorty Creek Project, Alaska (Freegold Ventures), highlights the importance of reviewing and understanding pathfinder elements in soil, weathered bedrock and fresh basement. Here, commodity elements Cu and Zn are highly mobile and relatively depleted in the soils and weathered zone over Cu-Au mineralisation, whereas Au, As, Bi and Sb are less mobile and highly anomalous in the oxidised bedrock and associated soils. The Hermosa Deposit, Arizona (South32), where downhole geochemistry can help map the oxide-fresh rock boundary at the deposit scale. Subtle depletion in mobile elements allows the weathered zone to be identified in altered rhyolites, and Zn:S and Pb:S ratios in the mineralised zone helps distinguish Zn and Pb oxides from Zn and Pb sulphides. A review of residual soils over a Ni-Cu-PGE prospect in Northern Queensland, where immobile elements are reliable discriminants of primary lithologies in highly weathered environments. Zirconium, Y, Th and Nb can be used to distinguish felsic from mafic bedrock, and variations in Cr, V, Al, Fe and Sc in soils confidently identify blind, compositionally distinct mafic-ultramafic bodies. This paper also highlights the importance of collecting high quality, multi-element geochemistry with low detection limits at every stage of exploration.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"86 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":"75064847","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: 10.1080/22020586.2019.12073240
Keith Gates
Summary NSW legislative changes in 2016 mean that from 1 June 2021, confidential mineral exploration company reports will become open file 5 years after submission. This will result in a large amount of previously confidential data being released on 1 June 2021. In conjunction with the data release, substantial work is being undertaken to improve the quality, accessibility and usability of the datasets. To provide the most functional regional scale geochemical datasets possible, the usability of the datasets must be assessed by following a standard workflow of data validation > exploratory data analysis (EDA) > normalisation > interpolation. Due to the large size of the datasets, programmatical solutions that expedite the validation and EDA processes are necessary. This presentation will give examples of methods used to condition the NSW geochemical data. An innovative data normalisation process will also be demonstrated, addressing the complexity of dealing with spatially overlapping and varied sample methods. An interpolation process that is suitable for use on large volume, large-scale datasets will also be demonstrated.
{"title":"Supporting data-driven exploration in NSW","authors":"Keith Gates","doi":"10.1080/22020586.2019.12073240","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073240","url":null,"abstract":"Summary NSW legislative changes in 2016 mean that from 1 June 2021, confidential mineral exploration company reports will become open file 5 years after submission. This will result in a large amount of previously confidential data being released on 1 June 2021. In conjunction with the data release, substantial work is being undertaken to improve the quality, accessibility and usability of the datasets. To provide the most functional regional scale geochemical datasets possible, the usability of the datasets must be assessed by following a standard workflow of data validation > exploratory data analysis (EDA) > normalisation > interpolation. Due to the large size of the datasets, programmatical solutions that expedite the validation and EDA processes are necessary. This presentation will give examples of methods used to condition the NSW geochemical data. An innovative data normalisation process will also be demonstrated, addressing the complexity of dealing with spatially overlapping and varied sample methods. An interpolation process that is suitable for use on large volume, large-scale datasets will also be demonstrated.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"30 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":"75072998","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: 10.1080/22020586.2019.12072981
M. Combrinck
Summary Conductivity depth data presentations derived using 1D approximations have become a very popular way to present airborne electromagnetic (AEM) data. While data profiles and a single error limit per station can accompany these presentations there are more information contained in data. This work proposes some ideas for augmenting 1D derived data presentations to highlight two and three-dimensional conductors as well as more detailed error level indication. The 1D conductivity depth algorithm used is an extended version of the S-layer differential transform. The depths calculated with the transform is used also present decay constant values corrected for conductive background responses. Fraser filtered X-component data are used to indicate structural complexity and data fit error levels are used to grey out areas on the depth section presentations where the results are less reliable. To demonstrate these ideas a line of Xcite data over the Abra deposit in Western Australia is analysed. The augmentations add valuable information to the conductivity depth section in the sense of drawing attention the where the 1D assumptions are not valid and should encourage interpreters to pursue 2D or 3D modelling techniques for successfully mapping the ore deposit.
{"title":"Augmenting 1D conductivity depth sections to include information pertaining to 2D/3D conductors","authors":"M. Combrinck","doi":"10.1080/22020586.2019.12072981","DOIUrl":"https://doi.org/10.1080/22020586.2019.12072981","url":null,"abstract":"Summary Conductivity depth data presentations derived using 1D approximations have become a very popular way to present airborne electromagnetic (AEM) data. While data profiles and a single error limit per station can accompany these presentations there are more information contained in data. This work proposes some ideas for augmenting 1D derived data presentations to highlight two and three-dimensional conductors as well as more detailed error level indication. The 1D conductivity depth algorithm used is an extended version of the S-layer differential transform. The depths calculated with the transform is used also present decay constant values corrected for conductive background responses. Fraser filtered X-component data are used to indicate structural complexity and data fit error levels are used to grey out areas on the depth section presentations where the results are less reliable. To demonstrate these ideas a line of Xcite data over the Abra deposit in Western Australia is analysed. The augmentations add valuable information to the conductivity depth section in the sense of drawing attention the where the 1D assumptions are not valid and should encourage interpreters to pursue 2D or 3D modelling techniques for successfully mapping the ore deposit.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"2 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":"75883459","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: 10.1080/22020586.2019.12072984
S. Boucher
Summary This paper presents a technique derived from the full MIMDAS RES/IP/MT survey called IPEx. It offers a more cost-effective, enhanced reconnaissance IP investigation in areas of post-mineral cover, ensuring that a minimumsized predefined chargeable body would not be missed. The MIMDAS system is ideal for its capability to measure very low signals, due to the enhanced telluric correction, especially in caliche-covered areas. A total of four lines were surveyed with IPEx, and substantial anomalies were found, where some in-fill/detailing has been executed. IPEx takes approximately half to two thirds of the normal MIMDAS survey time, making it a lower-cost superior reconnaissance RES/IP/MT survey tool.
{"title":"IPEx: A lower-cost superior reconnaissance RES/IP/MT survey","authors":"S. Boucher","doi":"10.1080/22020586.2019.12072984","DOIUrl":"https://doi.org/10.1080/22020586.2019.12072984","url":null,"abstract":"Summary This paper presents a technique derived from the full MIMDAS RES/IP/MT survey called IPEx. It offers a more cost-effective, enhanced reconnaissance IP investigation in areas of post-mineral cover, ensuring that a minimumsized predefined chargeable body would not be missed. The MIMDAS system is ideal for its capability to measure very low signals, due to the enhanced telluric correction, especially in caliche-covered areas. A total of four lines were surveyed with IPEx, and substantial anomalies were found, where some in-fill/detailing has been executed. IPEx takes approximately half to two thirds of the normal MIMDAS survey time, making it a lower-cost superior reconnaissance RES/IP/MT survey tool.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"347 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":"74106848","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: 10.1080/22020586.2019.12073226
R. Farrington, K. Hill, J. Cunneen, R. Beucher, L. Moresi
Summary This paper outlines a Finite Element modelling workflow using the software package ‘Underworld’ that is applied to sedimentary basin undergoing multiple rifting events. The evolution of the resulting strain rate, viscosity structure, temperature field, and sedimentary structures can be tracked. Application to the Ceduna Sub-basin is discussed.
{"title":"The Bight Basin, Evolution & Prospectivity III; FE modelling","authors":"R. Farrington, K. Hill, J. Cunneen, R. Beucher, L. Moresi","doi":"10.1080/22020586.2019.12073226","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073226","url":null,"abstract":"Summary This paper outlines a Finite Element modelling workflow using the software package ‘Underworld’ that is applied to sedimentary basin undergoing multiple rifting events. The evolution of the resulting strain rate, viscosity structure, temperature field, and sedimentary structures can be tracked. Application to the Ceduna Sub-basin is discussed.","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":"73804447","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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