Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12073085
A. Bailey, D. Giles
Summary Current declining mineral discovery rates mean fewer future mines. The Mineral Exploration Cooperative Research Centre (MinEx CRC) is a consortium of 36 Participants creating new opportunities for mineral discovery by delivering; 1) more productive, safer and environmentally friendly drilling methods; 2) new technologies for collecting data while drilling and; 3) exploration data on never before sampled rocks in Australia that are hidden but prospective for minerals. The innovative exploration outcomes through industry and researcher cooperation will also grow the high value Mining Equipment, Technology and Services (METS) sector.
{"title":"MinEx CRC - Exploration innovation through industry and researcher cooperation","authors":"A. Bailey, D. Giles","doi":"10.1080/22020586.2019.12073085","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073085","url":null,"abstract":"Summary Current declining mineral discovery rates mean fewer future mines. The Mineral Exploration Cooperative Research Centre (MinEx CRC) is a consortium of 36 Participants creating new opportunities for mineral discovery by delivering; 1) more productive, safer and environmentally friendly drilling methods; 2) new technologies for collecting data while drilling and; 3) exploration data on never before sampled rocks in Australia that are hidden but prospective for minerals. The innovative exploration outcomes through industry and researcher cooperation will also grow the high value Mining Equipment, Technology and Services (METS) sector.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"10 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":"90866913","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: 10.1080/22020586.2019.12073042
M. J. Khoshnavaz, A. Bόna, K. Chambers, H. Siahkoohi, Alireza Khoshnavaz
Summary Monitoring of passive seismic sources generated by mining activities and hydraulic fracturing has an important role in hazard analysis and in development of unconventional reservoirs. Surface arrays are vastly used in such monitoring scenarios with the advantage of wider spatial monitoring aperture, thus monitoring larger volumes over downhole arrays. However, signal-to-noise ratio of surface array records is naturally low. That makes application of coherency-based techniques an appropriate option for surface monitoring. Polarity variations corresponding to the source mechanism across the moveout curves/surfaces is a complicating task in the use of coherency-based monitoring methods to locate passive seismic events. To overcome this issue, we suggest a straight-forward approach that applies semblance, as a coherency analysis tool, on separate clusters of stations followed by averaging the results from all the clusters. To evaluate the performance of the suggested approach, we applied it on a semi-synthetic passive seismic data example generated from a reverse-oblique source and compared the result with the outcome from application of the classic coherency-based technique. It shows the ability of the suggested method to overcome polarity variations task, without conducting any polarity correction step.
{"title":"Surface passive seismic monitoring by the local use of semblance","authors":"M. J. Khoshnavaz, A. Bόna, K. Chambers, H. Siahkoohi, Alireza Khoshnavaz","doi":"10.1080/22020586.2019.12073042","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073042","url":null,"abstract":"Summary Monitoring of passive seismic sources generated by mining activities and hydraulic fracturing has an important role in hazard analysis and in development of unconventional reservoirs. Surface arrays are vastly used in such monitoring scenarios with the advantage of wider spatial monitoring aperture, thus monitoring larger volumes over downhole arrays. However, signal-to-noise ratio of surface array records is naturally low. That makes application of coherency-based techniques an appropriate option for surface monitoring. Polarity variations corresponding to the source mechanism across the moveout curves/surfaces is a complicating task in the use of coherency-based monitoring methods to locate passive seismic events. To overcome this issue, we suggest a straight-forward approach that applies semblance, as a coherency analysis tool, on separate clusters of stations followed by averaging the results from all the clusters. To evaluate the performance of the suggested approach, we applied it on a semi-synthetic passive seismic data example generated from a reverse-oblique source and compared the result with the outcome from application of the classic coherency-based technique. It shows the ability of the suggested method to overcome polarity variations task, without conducting any polarity correction step.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"62 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":"91033774","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: 10.1080/22020586.2019.12073142
N. Cantwell, Matthew Owers, J. Meyers, Sharna Riley
Summary This study presents the results from several case studies on the application of passive seismic Horizontal to Vertical Spectral Ratio (HVSR) surveying methods for Heavy Mineral Sand (HMS) deposit subsurface layer detection for exploration and mining. The results from these case studies demonstrate the usefulness of this rapid and low cost survey method to complement HMS deposit mapping and its ability to provide additional stratigraphic information in gaps between drillholes. HMS deposits typically occur in geological settings that are ideal for the application of the passive seismic HVSR method, because HMS deposits are typically shallow and may demonstrate acoustic impedance contrasts relative to surrounding sedimentary deposits or underlying acoustic bedrock. Trial HVSR survey results vary between different styles of heavy mineral sand deposits, from providing a direct estimate of the depth to the top of known HMS mineralisation based on a positive HVSR response from more dense and higher velocity HMS lenses, to detecting parallel silt and clay horizons, sometimes producing an inverted HVSR response, to be used as a bounding marker horizons for HMS deposits, and in many cases detecting the acoustic hard rock basement forming the base to the unconsolidated, young sedimentary deposits and basin fill containing HMS layers. In each case study, the use of a lightweight, self-contained and simple to use seismometer has allowed HMS explorers to carry out surveys quickly and cost effectively, in some remote areas with difficult access, mostly using company field staff following a short training session. The techniques and approaches to process and model HVSR data for shallow stratigraphic mapping during these trial surveys have contributed to advancing the passive seismic HVSR surveying method to become more commonly used for large production surveys.
{"title":"Case studies on the application of passive seismic horizontal to vertical spectral ratio (HVSR) surveying for heavy mineral sand exploration","authors":"N. Cantwell, Matthew Owers, J. Meyers, Sharna Riley","doi":"10.1080/22020586.2019.12073142","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073142","url":null,"abstract":"Summary This study presents the results from several case studies on the application of passive seismic Horizontal to Vertical Spectral Ratio (HVSR) surveying methods for Heavy Mineral Sand (HMS) deposit subsurface layer detection for exploration and mining. The results from these case studies demonstrate the usefulness of this rapid and low cost survey method to complement HMS deposit mapping and its ability to provide additional stratigraphic information in gaps between drillholes. HMS deposits typically occur in geological settings that are ideal for the application of the passive seismic HVSR method, because HMS deposits are typically shallow and may demonstrate acoustic impedance contrasts relative to surrounding sedimentary deposits or underlying acoustic bedrock. Trial HVSR survey results vary between different styles of heavy mineral sand deposits, from providing a direct estimate of the depth to the top of known HMS mineralisation based on a positive HVSR response from more dense and higher velocity HMS lenses, to detecting parallel silt and clay horizons, sometimes producing an inverted HVSR response, to be used as a bounding marker horizons for HMS deposits, and in many cases detecting the acoustic hard rock basement forming the base to the unconsolidated, young sedimentary deposits and basin fill containing HMS layers. In each case study, the use of a lightweight, self-contained and simple to use seismometer has allowed HMS explorers to carry out surveys quickly and cost effectively, in some remote areas with difficult access, mostly using company field staff following a short training session. The techniques and approaches to process and model HVSR data for shallow stratigraphic mapping during these trial surveys have contributed to advancing the passive seismic HVSR surveying method to become more commonly used for large production surveys.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"6 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":"81909417","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: 10.1080/22020586.2019.12073106
Peter J. van Ruth, M. Agarwal, Scott Gagen
Summary Managing seismic depth uncertainty is a key consideration in placing horizontal development wells into thin reservoir targets. Seismic depth uncertainty has the potential to erode project value through missed reservoir (late landing or reservoir exits) and/or the cost of corrective actions (e.g. sidetracks). The placement of Laverda Canyon development wells in 2018 utilised a 30 Hz full waveform inversion velocity model and deep directional resistivity data in combination with a near real-time depth update process to optimise well placement. Utilising these methods resulted in a significant reduction in seismic depth uncertainty which culminated in the final Laverda Canyon development well (LAV04WI) being successfully geosteered for ~ 2,200 m within a 10-15 m thick reservoir with only one reservoir exit.
{"title":"Managing uncertainty to deliver complex development wells","authors":"Peter J. van Ruth, M. Agarwal, Scott Gagen","doi":"10.1080/22020586.2019.12073106","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073106","url":null,"abstract":"Summary Managing seismic depth uncertainty is a key consideration in placing horizontal development wells into thin reservoir targets. Seismic depth uncertainty has the potential to erode project value through missed reservoir (late landing or reservoir exits) and/or the cost of corrective actions (e.g. sidetracks). The placement of Laverda Canyon development wells in 2018 utilised a 30 Hz full waveform inversion velocity model and deep directional resistivity data in combination with a near real-time depth update process to optimise well placement. Utilising these methods resulted in a significant reduction in seismic depth uncertainty which culminated in the final Laverda Canyon development well (LAV04WI) being successfully geosteered for ~ 2,200 m within a 10-15 m thick reservoir with only one reservoir exit.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"82 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":"84425481","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: 10.1080/22020586.2019.12073126
C. Foss, Blair McKenzie, L. Katona
Summary Magnetic field anomalies measured by the Gawler Craton Aeromagnetic Survey (GCAS) have revealed anomalies of amplitude > 18,000 nT over Paragon Bore. The flying height is 60 metres above ground and depth to basement is 150 metres below ground, so the causative basement sources clearly have magnetizations of extreme intensity. We apply an iterative processing of the GCAS TMI data to a vector-consistent TMI. This also supplies vector component grids which we downward continue to the ground surface and then transform to declination and inclination maps. We invert the measured TMI using a model of multiple ellipsoids to enable inclusion of substantial self-demagnetization effects. Vector components forward computed from the inversion model at ground level are also transformed to declination and inclination maps which closely match those derived from the filter transform. Deviations of declination and inclination about the regional values are -15° to +21° and -14° to +5° respectively. High magnetic susceptibility values reported from borehole intersections (up to 1.6 SI in 2 boreholes) are mostly associated with banded iron formation (BIF) and metasomatic magnetite-rich rocks. These values are about 1/3rd of the equivalent inversion model intersection susceptibilities. We suggest that this apparent discrepancy is due to self-demagnetization effects in the susceptibility measurements and the presence of substantial (possibly viscous) remanent magnetization.
{"title":"Distortion of the Magnetic Field at Paragon Bore, South Australia","authors":"C. Foss, Blair McKenzie, L. Katona","doi":"10.1080/22020586.2019.12073126","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073126","url":null,"abstract":"Summary Magnetic field anomalies measured by the Gawler Craton Aeromagnetic Survey (GCAS) have revealed anomalies of amplitude > 18,000 nT over Paragon Bore. The flying height is 60 metres above ground and depth to basement is 150 metres below ground, so the causative basement sources clearly have magnetizations of extreme intensity. We apply an iterative processing of the GCAS TMI data to a vector-consistent TMI. This also supplies vector component grids which we downward continue to the ground surface and then transform to declination and inclination maps. We invert the measured TMI using a model of multiple ellipsoids to enable inclusion of substantial self-demagnetization effects. Vector components forward computed from the inversion model at ground level are also transformed to declination and inclination maps which closely match those derived from the filter transform. Deviations of declination and inclination about the regional values are -15° to +21° and -14° to +5° respectively. High magnetic susceptibility values reported from borehole intersections (up to 1.6 SI in 2 boreholes) are mostly associated with banded iron formation (BIF) and metasomatic magnetite-rich rocks. These values are about 1/3rd of the equivalent inversion model intersection susceptibilities. We suggest that this apparent discrepancy is due to self-demagnetization effects in the susceptibility measurements and the presence of substantial (possibly viscous) remanent magnetization.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"22 1","pages":"1 - 6"},"PeriodicalIF":0.0,"publicationDate":"2019-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89149664","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: 10.1080/22020586.2019.12072924
Abdelrahman Elkhateeb, R. Rezaee, A. Kadkhodaie
Summary The prediction of facies and permeability in complicated reservoirs represents a major challenge that necessitates the usage of advanced statistical techniques. A new approach is presented in this paper to generate a log based continuous facies log and permeability index in the shaly sand of the Irwin River Coal Measures Formation. An integration between the density log and the NMR free fluid index has been carried out. This was done to establish a comprehensive electrofacies model and accommodate the large permeability variations. A new Reservoir Index, equivalent to the Flow Zone Indicator (FZI), has been calculated to allow a quantitative reservoir characterisation that includes facies and permeability independent of any core measurements. The modelled electrofacies and permeability from this analysis showed very effective results of high resolution. In order to calibrate the calculated permeability, the repeat formation tester mobility was used as a reference for the generated model. To further validate the results, the created models have been correlated with the core thin sections and core permeability. Four hydraulic flow units have been identified from the Reservoir Index, hence four different permeability models. From the log dependent results, an excellent match to the formation mobility has been achieved despite the reservoir heterogeneity. Furthermore, the outputs showed very encouraging results with the core data, upon which the methodology can be used in uncored wells. The workflow described in this paper shows a new methodology for reservoir characterisation through electric logs. The methodology allows an independent technique for rock typing in the absence of any core data. Regardless of the degree of the reservoir heterogeneity, a high-resolution facies and permeability index can be generated for advanced formation evaluation.
{"title":"Log dependent approach to predict reservoir facies and permeability in a complicated shaly sand reservoir","authors":"Abdelrahman Elkhateeb, R. Rezaee, A. Kadkhodaie","doi":"10.1080/22020586.2019.12072924","DOIUrl":"https://doi.org/10.1080/22020586.2019.12072924","url":null,"abstract":"Summary The prediction of facies and permeability in complicated reservoirs represents a major challenge that necessitates the usage of advanced statistical techniques. A new approach is presented in this paper to generate a log based continuous facies log and permeability index in the shaly sand of the Irwin River Coal Measures Formation. An integration between the density log and the NMR free fluid index has been carried out. This was done to establish a comprehensive electrofacies model and accommodate the large permeability variations. A new Reservoir Index, equivalent to the Flow Zone Indicator (FZI), has been calculated to allow a quantitative reservoir characterisation that includes facies and permeability independent of any core measurements. The modelled electrofacies and permeability from this analysis showed very effective results of high resolution. In order to calibrate the calculated permeability, the repeat formation tester mobility was used as a reference for the generated model. To further validate the results, the created models have been correlated with the core thin sections and core permeability. Four hydraulic flow units have been identified from the Reservoir Index, hence four different permeability models. From the log dependent results, an excellent match to the formation mobility has been achieved despite the reservoir heterogeneity. Furthermore, the outputs showed very encouraging results with the core data, upon which the methodology can be used in uncored wells. The workflow described in this paper shows a new methodology for reservoir characterisation through electric logs. The methodology allows an independent technique for rock typing in the absence of any core data. Regardless of the degree of the reservoir heterogeneity, a high-resolution facies and permeability index can be generated for advanced formation evaluation.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"1 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":"89176314","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: 10.1080/22020586.2019.12072929
Yunfeng Chen, E. Saygin
Summary Seismic interferometry, commonly known as empirical Green’s function retrieval in seismology, has been widely applied to extract the impulse response of Earth. The conventional approach based on cross-correlation of long-term ambient seismic wavefield relies on the simultaneous recording of noise signals at seismic receivers. Recent studies have demonstrated observationally that the correlation of coda of (ambient noise) cross-correlation function (C3) enables the reconstruction of inter-station Green’s function regardless of the operating time (i.e., synchronous or asynchronous) of stations. Here we extend the C3 scheme to a more general framework that involves the correlation of cross-correlation function (C2). This new approach exploits the deterministic energy of the wavefield and is more robust than C3 that may suffer from incoherent coda wave energy due to less ideal (e.g., sparse, noisy, short duration) network configurations. We apply this technique to the recently deployed ALFREX seismic network in southwestern Australia. We show that the Green’s function between asynchronous stations can be robustly recovered using the C2 approach whereas this is not feasible from C3. The proposed technique can effectively bridge the temporal gaps between temporary networks and demonstrate great potential for improving the spatial coverage of data and resolution in seismic imaging of crustal structures.
{"title":"Green’s function retrieval from deterministic seismic wavefield using higher-order cross-correlation","authors":"Yunfeng Chen, E. Saygin","doi":"10.1080/22020586.2019.12072929","DOIUrl":"https://doi.org/10.1080/22020586.2019.12072929","url":null,"abstract":"Summary Seismic interferometry, commonly known as empirical Green’s function retrieval in seismology, has been widely applied to extract the impulse response of Earth. The conventional approach based on cross-correlation of long-term ambient seismic wavefield relies on the simultaneous recording of noise signals at seismic receivers. Recent studies have demonstrated observationally that the correlation of coda of (ambient noise) cross-correlation function (C3) enables the reconstruction of inter-station Green’s function regardless of the operating time (i.e., synchronous or asynchronous) of stations. Here we extend the C3 scheme to a more general framework that involves the correlation of cross-correlation function (C2). This new approach exploits the deterministic energy of the wavefield and is more robust than C3 that may suffer from incoherent coda wave energy due to less ideal (e.g., sparse, noisy, short duration) network configurations. We apply this technique to the recently deployed ALFREX seismic network in southwestern Australia. We show that the Green’s function between asynchronous stations can be robustly recovered using the C2 approach whereas this is not feasible from C3. The proposed technique can effectively bridge the temporal gaps between temporary networks and demonstrate great potential for improving the spatial coverage of data and resolution in seismic imaging of crustal structures.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"1 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":"89324199","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: 10.1080/22020586.2019.12073053
L. Katona, A. Fabris
Summary This contribution presents a method for efficiently classifying geophysical anomalies and identifying regions and features that share characteristics of many known iron-oxide-copper-gold (IOCG) deposits of the Gawler Craton, and can therefore be used in drill target prioritization. Residual Bouguer gravity and reduced-to-pole total magnetic intensity grids over the Gawler Craton were transformed, generating polygon datasets representing populations of locally anomalous gravity and magnetic intensity. Taken as simple anomaly polygons, there are a very large number of features across the Gawler Craton (>39,000 TMI and >10,000 gravity). Superimposing mineral deposits over these features shows a clear spatial correlation between IOCG deposits and occurrences, and anomalies (>90% of deposits within 1,000 m of an anomaly), but leaves thousands of anomalies of varying magnitudes that cannot all be related to IOCG mineralization. Eliminating TMI and gravity anomalies with a separation of more than 1,000 m reduced the search space to ~20,000 TMI features and ~8,500 gravity features. Limiting the search to a statistically derived gravity threshold ≥0.4 mGal gravity anomalies, the exploration space is reduced to 798 gravity features with coincident TMI features within the Olympic Copper-Gold Province. The Anselin Local Morans I method was used to delineate geographic regions based upon spatial clustering of high magnitude anomalies. The spatial distribution and clustering characteristics of the gravity anomalies provide additional information and can be related to differing basement geology and deposit style. Terranes where lithologies and Cu-Au occurrences are commonly magnetite-rich show clustered high-magnitude gravity anomalies, and correlated spatially with the Mount Woods and Moonta domains within the eastern Gawler Craton. Importantly, it was found that the central, and currently most endowed, the Olympic Domain, was distinct in that it was dominated by spatial outliers (discrete high-magnitude density features). These results could be used as a starting point in developing IOCG exploration strategies, due to the high number of additional untested, spatially coincident gravity and magnetic anomalies that warrant further investigation.
本文提出了一种有效分类地球物理异常的方法，并识别了高勒克拉通许多已知的氧化铁-铜-金(IOCG)矿床的共同特征区域和特征，因此可以用于优选钻探目标。对高勒克拉通的残差布格重力和降极总磁强度网格进行了变换，生成了代表局部异常重磁强度总体的多边形数据集。作为简单的异常多边形，在高勒克拉通(bbb39,000 TMI和>10,000重力)上有非常多的特征。在这些特征上叠加的矿床显示了IOCG矿床、产状和异常之间清晰的空间相关性(大约90%的矿床在异常1000米范围内)，但留下了数千个不同大小的异常，这些异常并不都与IOCG矿化有关。消除距离超过1,000 m的TMI和重力异常，将搜索空间减少到约20,000个TMI特征和约8,500个重力特征。将搜索限制在统计导出的重力阈值≥0.4 mGal的重力异常范围内，将勘探空间减少到奥林匹克铜金省范围内具有一致TMI特征的798个重力特征。采用Anselin Local Morans I方法，基于高震级异常的空间聚类来划分地理区域。重力异常的空间分布和聚集特征提供了额外的信息，可能与不同的基底地质和矿床类型有关。在岩性和Cu-Au产状普遍富含磁铁矿的地体中，显示出密集的高震级重力异常，在空间上与高勒克拉通东部的Mount Woods和Moonta域具有相关性。重要的是，研究发现，中心的、目前最丰富的奥林匹克域是独特的，因为它是由空间异常值(离散的高星等密度特征)主导的。这些结果可以作为IOCG开发勘探策略的起点，因为大量额外的未经测试的、空间重合的重磁异常值得进一步研究。
{"title":"Which anomaly should I drill? Using spatial statistics to inform exploration in covered IOCG terranes","authors":"L. Katona, A. Fabris","doi":"10.1080/22020586.2019.12073053","DOIUrl":"https://doi.org/10.1080/22020586.2019.12073053","url":null,"abstract":"Summary This contribution presents a method for efficiently classifying geophysical anomalies and identifying regions and features that share characteristics of many known iron-oxide-copper-gold (IOCG) deposits of the Gawler Craton, and can therefore be used in drill target prioritization. Residual Bouguer gravity and reduced-to-pole total magnetic intensity grids over the Gawler Craton were transformed, generating polygon datasets representing populations of locally anomalous gravity and magnetic intensity. Taken as simple anomaly polygons, there are a very large number of features across the Gawler Craton (>39,000 TMI and >10,000 gravity). Superimposing mineral deposits over these features shows a clear spatial correlation between IOCG deposits and occurrences, and anomalies (>90% of deposits within 1,000 m of an anomaly), but leaves thousands of anomalies of varying magnitudes that cannot all be related to IOCG mineralization. Eliminating TMI and gravity anomalies with a separation of more than 1,000 m reduced the search space to ~20,000 TMI features and ~8,500 gravity features. Limiting the search to a statistically derived gravity threshold ≥0.4 mGal gravity anomalies, the exploration space is reduced to 798 gravity features with coincident TMI features within the Olympic Copper-Gold Province. The Anselin Local Morans I method was used to delineate geographic regions based upon spatial clustering of high magnitude anomalies. The spatial distribution and clustering characteristics of the gravity anomalies provide additional information and can be related to differing basement geology and deposit style. Terranes where lithologies and Cu-Au occurrences are commonly magnetite-rich show clustered high-magnitude gravity anomalies, and correlated spatially with the Mount Woods and Moonta domains within the eastern Gawler Craton. Importantly, it was found that the central, and currently most endowed, the Olympic Domain, was distinct in that it was dominated by spatial outliers (discrete high-magnitude density features). These results could be used as a starting point in developing IOCG exploration strategies, due to the high number of additional untested, spatially coincident gravity and magnetic anomalies that warrant further investigation.","PeriodicalId":8502,"journal":{"name":"ASEG Extended Abstracts","volume":"2019 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":"88526399","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: 10.1080/22020586.2019.12073238
Justin Brown
Summary Element 25 Limited is developing the Butcherbird High Purity Manganese Project located approximately 130km south of Newman in the Pilbara region of Western Australia. The project hosts Australia’s largest onshore manganese deposit containing 263 Mt grading 10% manganese. The ore occurs as multiple supergene deposits which are the product of weathering of a regionally extensive basal shallow marine manganiferous shale. The resource was defined with a combination of airborne TEM, mapping and drilling. Significant exploration upside remains to expand the known resources. Element 25 is undertaking a Pre-Feasibility on the development of the Butcherbird Project using a hydrometallurgical flowsheet to produce high purity manganese metal and battery grade manganese sulphate. The production of manganese metal using electrowinning requires significant electricity. The project will likely use a combination of gas generation from the goldfields gas pipeline which crosses the project and renewable energy generation using wind and solar. The project will be an Australian first in terms of downstream processing of manganese metal and sulphate.
Element 25 Limited正在开发位于西澳大利亚皮尔巴拉地区纽曼以南约130公里处的Butcherbird高纯度锰项目。该项目拥有澳大利亚最大的陆上锰矿，含锰2.63亿吨，锰品位为10%。该矿床为多个表生矿床，是区域性广泛的基底浅海含锰页岩风化作用的产物。该资源是通过机载瞬变电磁法、测绘和钻井相结合来确定的。已知资源的扩展仍有很大的勘探空间。Element 25正在对bucherbird项目的开发进行预可行性研究，使用湿法冶金流程生产高纯度金属锰和电池级硫酸锰。电积法生产金属锰需要大量的电力。该项目可能会使用穿越该项目的金矿天然气管道产生的天然气，以及利用风能和太阳能的可再生能源发电。该项目将是澳大利亚首个锰金属和硫酸盐下游加工项目。
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Pub Date : 2019-12-01DOI: 10.1080/22020586.2019.12072939
F. Kohanpour, S. Occhipinti, M. Lindsay, W. Gorczyk
Summary Geodynamic models, geological-geophysical interpretations, and isotope analysis illustrate that there are links between the nickel and gold mineral systems in the Halls Creek Orogen, Western Australia. Whole-rock Nd and Ar-Ar analysis of rocks throughout the region, when compared with the geodynamic models suggest that nickel and gold mineralization in the Halls Creek Orogen can be related to basin development and subsequent basin closure during the convergence of North Australian Craton and Kimberley Craton, respectively. Whole-rock Nd analysis confirmed the input of juvenile melts in the centre of the orogen before the 1835-1805 Ma Halls Creek Orogeny, supporting the upwelling of decompression mantle melts during the basin development. These analyses also revealed the spatial links between nickel and gold mineralization and lithological units with positive εNd values. The results of geodynamic models, geophysical interpretation, and isotopic analysis are used to understand the critical processes in the gold and nickel mineralization, which are presented by predictor maps. The GIS-based knowledge-driven fuzzy method used to integrate the predictor maps and create the prospectivity maps. Herein we show that mafic-ultramafic units prospective for nickel mineralization formed by upwelling of decompression mantle melt during crustal thinning and extension during basin development, and typically consist of the most juvenile magmas in the region. Whereas, gold deposits formed during the compressional regime and basin closure, and are located along a major shear zone separating two terranes. Another critical element that appears to be related to gold prospectivity is the presence of lithologies with a juvenile signature. In contrast to nickel analyses which are closely related to mafic-ultramafic units, the source component seems less influential when attempting to target orogenic gold deposits.
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