UNCLASSIFIED UNCLASSIFIED THE STAVELY PROJECT UNCOVERing mineral potential in western Victoria Speaker's notes
THE STAVELY PROJECT - Geoscience Australiaaustraliaminerals.gov.au/__data/assets/pdf_file/0008/...\爀屲The Stavely Project is a collaborative p\ oject between the GSV and GA, commencing
THE STAVELY PROJECT UNCOVERing mineral potential in western Victoria
Speaker's notes
Presenter
Presentation Notes
Good afternoon. It’s great to have an opportunity to present an update on the Stavely Project on behalf of my colleagues and co-workers. It will be brief but I would direct you to the presentations and abstracts presented earlier this week on geochemistry, geochronology and tomorrow on structure for more detail in those areas of study. The Stavely Project is a collaborative project between the GSV and GA, commencing in 2013 and is now nearing completion. The aim of the project has been to provide the geological framework to investigate mineral system potential in an effort to improve mineral exploration targeting and reduce risk under cover in western Victoria. The delivery of pre-competitive data and evaluation of modern scientific techniques for explorers were also key objectives. Five of the nine planned data releases are currently out with the remaining expected in the next few months. The overarching Regional Synthesis is expected in the second half of this year and the Explorers Guide late 2016 early 2017. All of these products can be downloaded from the Stavely Project page on the Geoscience Australia website.
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CONTRIBUTORS AND COLLABORATION
Geological Survey of Victoria Ross Cayley, David Taylor, Phil Skladzien, Rob Duncan, Cameron Cairns, Mark McLean, Suzanne Haydon, Melanie Middleton, David Higgins, Cassady O’Neill, Mark Hocking, Marvena Van Kann, Gavin Stilgoe, Lydia Heap, Chris Osborne, Joanna Kowalczyk, Paul McDonald
Geoscience Australia Anthony Schofield, Sarlae McAlpine, Chris Lewis, David Huston, Evgeniy Bastrakov, James Goodwin, Matilda Thomas, Karol Czarnota, Tony Meixner, Tim Barton, Narelle Neumann, Richard Blewett
Speaker's notes
Presenter
Presentation Notes
As the list of contributors and abstract authors suggests, it has been quite the team effort in the design, execution and delivery of the Stavely Project. The project has benefited from engaging researchers with specific skill sets and knowledge and working with existing licence holders to collect additional samples to broaden the dataset and understanding of the region.
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LOCATION AND GEOLOGY Speaker's notes
Presenter
Presentation Notes
The project area is located in the Grampians-Stavely Zone of western Victoria. It includes the regional centres of Hamilton and Horsham, primary land use is agriculture (wheat and sheep) The project area is ~20,000km2 (19,924km2), however just 3.5% (689km2) comprises exposed prospective Cambrian bedrock, which represents portions of the Stavely Arc. For that very small area a number of base metal and precious metal prospects are known within and around the Cambrian bedrock, most of which have a porphyry or VHMS affinity. The prospective Cambrian rocks do appear to extend north of the project area under cover at estimated depths >300m (up to 800m?) The black dots on the geology map to the left represent the stratigraphic drill hole collars completed as part of the Stavely Project. The resulting data and knowledge gained from these drill holes has been key in the development of an updated regional interpretation and a detailed pre-competitive data package for current and future explorers. 14 drill holes were completed for 2,708m, ranging from 70m-360m in total (vertical) depth. The drill holes targeted areas of poor stratigraphic control. Sonic coring (1152m) was employed for the younger basin material with pre-collars ranging from 30m to 212m followed by HQ3 diamond tails (1643m). The detailed geology in the image on the right is that from Victorian seamless geology and some of the more well known mineral prospects exposed at surface are shown for reference. If we simplify and focus on the Grampians-Stavely Zone I will point out the fault slices of Cambrian volcanic rocks, which are distinguished as belts, shown here from west to east; orange (Boonawah/Black Range), green (Bunnugal/Dimboola) and purple (Mt Stavely/Mt Dryden). The cover that obscures thee belts range from Late Silurian Grampians Group, Rocklands Rhyolite, the Otway Basin to the south of the Grampians Ranges, the Murray Basin to the north and the Newer Volcanics. Minor Permian stratigraphy has been identified in onshore petroleum bores to the north of the project area. Taking away all the cover the location and extent of the Cambrian volcanic belts and intrusions, both Cambrian and Devonian, can be delineated at the regional scale using potential field data and confirmed locally with historical drill hole intersections. Shown for reference are the bounding faults of the Grampians-Stavely Zone. The background image is an overlay of tilt and bandpass filtered regional (State) TMI, blue colours indicate lower magnetic intensity; red colours indicate higher magnetic intensity. No early Paleozoic map would be complete without faults and this area is no exception with both surface mapping and potential field data being used to develop the interpretation. The final image shows the location of the deep seismic reflection survey lines for reference which we will touch briefly on now. Background image is an overlay of Tilt and Band Pass filtered TMI. Background image is a NE sun-shaded, partially-transparent histogram-equalised pseudocolour layer of the tilt-angle total magnetic intensity (TMI) reduced to the pole (RTP), overlain on a 3-30 km band pass filtered, histogram-equalised pseudocolour layer of TMI (RTP). Blue colours indicate lower magnetic intensity and phase angle values; red colours indicate higher magnetic intensity and phase angle values.
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LOCATION AND GEOLOGY Speaker's notes
Presenter
Presentation Notes
The project area is located in the Grampians-Stavely Zone of western Victoria. It includes the regional centres of Hamilton and Horsham, primary land use is agriculture (wheat and sheep) The project area is ~20,000km2 (19,924km2), however just 3.5% (689km2) comprises exposed prospective Cambrian bedrock, which represents portions of the Stavely Arc. For that very small area a number of base metal and precious metal prospects are known within and around the Cambrian bedrock, most of which have a porphyry or VHMS affinity. The prospective Cambrian rocks do appear to extend north of the project area under cover at estimated depths >300m (up to 800m?) The black dots on the geology map to the left represent the stratigraphic drill hole collars completed as part of the Stavely Project. The resulting data and knowledge gained from these drill holes has been key in the development of an updated regional interpretation and a detailed pre-competitive data package for current and future explorers. 14 drill holes were completed for 2,708m, ranging from 70m-360m in total (vertical) depth. The drill holes targeted areas of poor stratigraphic control. Sonic coring (1152m) was employed for the younger basin material with pre-collars ranging from 30m to 212m followed by HQ3 diamond tails (1643m). The detailed geology in the image on the right is that from Victorian seamless geology and some of the more well known mineral prospects exposed at surface are shown for reference. If we simplify and focus on the Grampians-Stavely Zone I will point out the fault slices of Cambrian volcanic rocks, which are distinguished as belts, shown here from west to east; orange (Boonawah/Black Range), green (Bunnugal/Dimboola) and purple (Mt Stavely/Mt Dryden). The cover that obscures thee belts range from Late Silurian Grampians Group, Rocklands Rhyolite, the Otway Basin to the south of the Grampians Ranges, the Murray Basin to the north and the Newer Volcanics. Minor Permian stratigraphy has been identified in onshore petroleum bores to the north of the project area. Taking away all the cover the location and extent of the Cambrian volcanic belts and intrusions, both Cambrian and Devonian, can be delineated at the regional scale using potential field data and confirmed locally with historical drill hole intersections. Shown for reference are the bounding faults of the Grampians-Stavely Zone. The background image is an overlay of tilt and bandpass filtered regional (State) TMI, blue colours indicate lower magnetic intensity; red colours indicate higher magnetic intensity. No early Paleozoic map would be complete without faults and this area is no exception with both surface mapping and potential field data being used to develop the interpretation. The final image shows the location of the deep seismic reflection survey lines for reference which we will touch briefly on now. Background image is an overlay of Tilt and Band Pass filtered TMI. Background image is a NE sun-shaded, partially-transparent histogram-equalised pseudocolour layer of the tilt-angle total magnetic intensity (TMI) reduced to the pole (RTP), overlain on a 3-30 km band pass filtered, histogram-equalised pseudocolour layer of TMI (RTP). Blue colours indicate lower magnetic intensity and phase angle values; red colours indicate higher magnetic intensity and phase angle values.
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LOCATION AND GEOLOGY Speaker's notes
Presenter
Presentation Notes
The project area is located in the Grampians-Stavely Zone of western Victoria. It includes the regional centres of Hamilton and Horsham, primary land use is agriculture (wheat and sheep) The project area is ~20,000km2 (19,924km2), however just 3.5% (689km2) comprises exposed prospective Cambrian bedrock, which represents portions of the Stavely Arc. For that very small area a number of base metal and precious metal prospects are known within and around the Cambrian bedrock, most of which have a porphyry or VHMS affinity. The prospective Cambrian rocks do appear to extend north of the project area under cover at estimated depths >300m (up to 800m?) The black dots on the geology map to the left represent the stratigraphic drill hole collars completed as part of the Stavely Project. The resulting data and knowledge gained from these drill holes has been key in the development of an updated regional interpretation and a detailed pre-competitive data package for current and future explorers. 14 drill holes were completed for 2,708m, ranging from 70m-360m in total (vertical) depth. The drill holes targeted areas of poor stratigraphic control. Sonic coring (1152m) was employed for the younger basin material with pre-collars ranging from 30m to 212m followed by HQ3 diamond tails (1643m). The detailed geology in the image on the right is that from Victorian seamless geology and some of the more well known mineral prospects exposed at surface are shown for reference. If we simplify and focus on the Grampians-Stavely Zone I will point out the fault slices of Cambrian volcanic rocks, which are distinguished as belts, shown here from west to east; orange (Boonawah/Black Range), green (Bunnugal/Dimboola) and purple (Mt Stavely/Mt Dryden). The cover that obscures thee belts range from Late Silurian Grampians Group, Rocklands Rhyolite, the Otway Basin to the south of the Grampians Ranges, the Murray Basin to the north and the Newer Volcanics. Minor Permian stratigraphy has been identified in onshore petroleum bores to the north of the project area. Taking away all the cover the location and extent of the Cambrian volcanic belts and intrusions, both Cambrian and Devonian, can be delineated at the regional scale using potential field data and confirmed locally with historical drill hole intersections. Shown for reference are the bounding faults of the Grampians-Stavely Zone. The background image is an overlay of tilt and bandpass filtered regional (State) TMI, blue colours indicate lower magnetic intensity; red colours indicate higher magnetic intensity. No early Paleozoic map would be complete without faults and this area is no exception with both surface mapping and potential field data being used to develop the interpretation. The final image shows the location of the deep seismic reflection survey lines for reference which we will touch briefly on now. Background image is an overlay of Tilt and Band Pass filtered TMI. Background image is a NE sun-shaded, partially-transparent histogram-equalised pseudocolour layer of the tilt-angle total magnetic intensity (TMI) reduced to the pole (RTP), overlain on a 3-30 km band pass filtered, histogram-equalised pseudocolour layer of TMI (RTP). Blue colours indicate lower magnetic intensity and phase angle values; red colours indicate higher magnetic intensity and phase angle values.
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LOCATION AND GEOLOGY Speaker's notes
Presenter
Presentation Notes
The project area is located in the Grampians-Stavely Zone of western Victoria. It includes the regional centres of Hamilton and Horsham, primary land use is agriculture (wheat and sheep) The project area is ~20,000km2 (19,924km2), however just 3.5% (689km2) comprises exposed prospective Cambrian bedrock, which represents portions of the Stavely Arc. For that very small area a number of base metal and precious metal prospects are known within and around the Cambrian bedrock, most of which have a porphyry or VHMS affinity. The prospective Cambrian rocks do appear to extend north of the project area under cover at estimated depths >300m (up to 800m?) The black dots on the geology map to the left represent the stratigraphic drill hole collars completed as part of the Stavely Project. The resulting data and knowledge gained from these drill holes has been key in the development of an updated regional interpretation and a detailed pre-competitive data package for current and future explorers. 14 drill holes were completed for 2,708m, ranging from 70m-360m in total (vertical) depth. The drill holes targeted areas of poor stratigraphic control. Sonic coring (1152m) was employed for the younger basin material with pre-collars ranging from 30m to 212m followed by HQ3 diamond tails (1643m). The detailed geology in the image on the right is that from Victorian seamless geology and some of the more well known mineral prospects exposed at surface are shown for reference. If we simplify and focus on the Grampians-Stavely Zone I will point out the fault slices of Cambrian volcanic rocks, which are distinguished as belts, shown here from west to east; orange (Boonawah/Black Range), green (Bunnugal/Dimboola) and purple (Mt Stavely/Mt Dryden). The cover that obscures thee belts range from Late Silurian Grampians Group, Rocklands Rhyolite, the Otway Basin to the south of the Grampians Ranges, the Murray Basin to the north and the Newer Volcanics. Minor Permian stratigraphy has been identified in onshore petroleum bores to the north of the project area. Taking away all the cover the location and extent of the Cambrian volcanic belts and intrusions, both Cambrian and Devonian, can be delineated at the regional scale using potential field data and confirmed locally with historical drill hole intersections. Shown for reference are the bounding faults of the Grampians-Stavely Zone. The background image is an overlay of tilt and bandpass filtered regional (State) TMI, blue colours indicate lower magnetic intensity; red colours indicate higher magnetic intensity. No early Paleozoic map would be complete without faults and this area is no exception with both surface mapping and potential field data being used to develop the interpretation. The final image shows the location of the deep seismic reflection survey lines for reference which we will touch briefly on now. Background image is an overlay of Tilt and Band Pass filtered TMI. Background image is a NE sun-shaded, partially-transparent histogram-equalised pseudocolour layer of the tilt-angle total magnetic intensity (TMI) reduced to the pole (RTP), overlain on a 3-30 km band pass filtered, histogram-equalised pseudocolour layer of TMI (RTP). Blue colours indicate lower magnetic intensity and phase angle values; red colours indicate higher magnetic intensity and phase angle values.
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LOCATION AND GEOLOGY Speaker's notes
Presenter
Presentation Notes
The project area is located in the Grampians-Stavely Zone of western Victoria. It includes the regional centres of Hamilton and Horsham, primary land use is agriculture (wheat and sheep) The project area is ~20,000km2 (19,924km2), however just 3.5% (689km2) comprises exposed prospective Cambrian bedrock, which represents portions of the Stavely Arc. For that very small area a number of base metal and precious metal prospects are known within and around the Cambrian bedrock, most of which have a porphyry or VHMS affinity. The prospective Cambrian rocks do appear to extend north of the project area under cover at estimated depths >300m (up to 800m?) The black dots on the geology map to the left represent the stratigraphic drill hole collars completed as part of the Stavely Project. The resulting data and knowledge gained from these drill holes has been key in the development of an updated regional interpretation and a detailed pre-competitive data package for current and future explorers. 14 drill holes were completed for 2,708m, ranging from 70m-360m in total (vertical) depth. The drill holes targeted areas of poor stratigraphic control. Sonic coring (1152m) was employed for the younger basin material with pre-collars ranging from 30m to 212m followed by HQ3 diamond tails (1643m). The detailed geology in the image on the right is that from Victorian seamless geology and some of the more well known mineral prospects exposed at surface are shown for reference. If we simplify and focus on the Grampians-Stavely Zone I will point out the fault slices of Cambrian volcanic rocks, which are distinguished as belts, shown here from west to east; orange (Boonawah/Black Range), green (Bunnugal/Dimboola) and purple (Mt Stavely/Mt Dryden). The cover that obscures thee belts range from Late Silurian Grampians Group, Rocklands Rhyolite, the Otway Basin to the south of the Grampians Ranges, the Murray Basin to the north and the Newer Volcanics. Minor Permian stratigraphy has been identified in onshore petroleum bores to the north of the project area. Taking away all the cover the location and extent of the Cambrian volcanic belts and intrusions, both Cambrian and Devonian, can be delineated at the regional scale using potential field data and confirmed locally with historical drill hole intersections. Shown for reference are the bounding faults of the Grampians-Stavely Zone. The background image is an overlay of tilt and bandpass filtered regional (State) TMI, blue colours indicate lower magnetic intensity; red colours indicate higher magnetic intensity. No early Paleozoic map would be complete without faults and this area is no exception with both surface mapping and potential field data being used to develop the interpretation. The final image shows the location of the deep seismic reflection survey lines for reference which we will touch briefly on now. Background image is an overlay of Tilt and Band Pass filtered TMI. Background image is a NE sun-shaded, partially-transparent histogram-equalised pseudocolour layer of the tilt-angle total magnetic intensity (TMI) reduced to the pole (RTP), overlain on a 3-30 km band pass filtered, histogram-equalised pseudocolour layer of TMI (RTP). Blue colours indicate lower magnetic intensity and phase angle values; red colours indicate higher magnetic intensity and phase angle values.
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DEEP SEISMIC REFLECTION Speaker's notes
Presenter
Presentation Notes
The work and background that resulted in the concept and delivery of the Stavely Project was the data and knowledge gained from a deep seismic reflection traverse undertaken in western Victoria by the Geological Survey of Victoria, in conjunction with several project partners such as Geoscience Australia and AuScope, in 2009. This followed the central Victoria survey successfully completed in 2006. Two lines: 140km and 60km, were complimented by close spaced ground gravity (200m stations) and later mT The resulting interpretation, which included the integration of the limited Cambrian bedrock and regional potential field datasets, suggested a volcanic arc edifice - now referred to as the Stavely Arc – that was much larger than previously thought. Rest assured that we are drawing closer to publishing this work. One advantage of completing deep seismic reflection in Victoria is the occurrence of exposed Paleozoic bedrock of the Great Dividing Range thereby allowing field observations to be integrated with the resulting imaging of the earths crust.
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UNDERSTANDING THE MINERAL EXPLORATION HISTORY
1970 1980 1990 2000 2010
WMC take out EL’s
GA-GSV Stavely Project
Penzoil drill first copper targets
Tony Crawford completes PhD
CRAE airborne magnetic survey
GSV Airborne Magnetic survey
CRAE withdraw
GSV Regional Seismic Reflection
Modern EL’s taken out for copper exploration
HMS Exploration commences
GSV Stavely report
Crawford & Keys publish
GSV Grampians Special map
report
Geopeko penetrate MB
(160m) mud rotary
GA Willuara Report
GSV identify
HMS
GSV VIMP drilling
Speaker's notes
Presenter
Presentation Notes
The following type of analysis can be very useful – this is very simplified for today and lacks discoveries at present. It is important to understand where and why there may have been gaps in exploration efforts previously in an effort to identify new search space understanding (e.g. access, technology etc). For example within the Stavely Project area the majority of the drilling was completed pre-1995, which is when the State-wide regional airborne magnetics were acquired. Prior to this it would appear most companies were using a wide spaced CRAE survey from 1982 to target, which was incomplete given what we now know regarding the Stavely Arc. Drilling technology has advanced, many examples of early percussion drilling refusing at relatively shallow depths. The average depth of mineral exploration drilling across the project area is ~30m, overwhelming majority of which is RAB/AIR. Approximately two thirds of drilling is HMS, many of which appear to have intersected basement and can be re-purposed as a collective dataset to characterise cover and map depth to basement. The GSV have been compiling and validating historical exploration data in a modern geological database structure as part of this project in an attempt to save time, effort and costs for explorers and improve targeting. +20% mineral occurrences have been collected from within historical reports have been identified – helps to characterise mineral system potential (e.g. evolution of deposit models) – I like to consider how many of these mineral occurrences may remain untested because an individual or company re-prioritised their exploration efforts?
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MINERALISATION AND HYDROTHERMAL ALTERATION
Corbett, 2012
Speaker's notes
Presenter
Presentation Notes
Some examples of mineralisation from in and around Thursdays Gossan, one of the better known copper prospects within the Stavely Arc. At this stage porphyry and VHMS systems appear to be the most likely copper targets based on the mineral occurrences currently known. The upside to both is that they both tend to occur within camps. Project drill hole STAVELY17 did intersect gold-silver mineralisation coincident with qz-se-py alterated Glenthompson Sandstone from 45m (17m) in the southeast of the project area with several one metre sample intervals returning >1g/t Au. The widest intersection was 7m @ 0.6g/t Au and 0.81ppm Ag. While drilled for stratigraphy STAVELY17 was within kilometres of the Fairveiw gold prospect (5km) and Wickcliffe VHMS prospect (3km) with trace element geochemistry undertaken at CODES suggesting proximity to a porphyry-epithermal system.
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COVER AND PRESERVATION Speaker's notes
Presenter
Presentation Notes
Cover can be exciting…! It’s not just something that needs to be pre-collared. It needs to be intimately understood. Here we have someone admiring contact metamorphosed sediments of the Grampians Group at Mount Arapiles on the northwest margin of the project area while looking east across the very flat Wimmera Plains, which effectively represents the current erosional surface of the Murray Basin. It’s not just the actual cover rocks but the age and style of deformation imposed upon them given that this is likely to be reflected in the prospective (Cambrian) bedrock and mineral systems. Ross Cayley’s talk tomorrow will cover this concept in much greater detail. The cover can contain significant mineral endowment itself. In the case of the Murray Basin it is heavy mineral sands. The depth of weathering and resulting thickness of (mottled and pallid) regolith (Dundas Surface) needs to be considered. Here is an example of deeply weathered Cambrian Glenthompson Sandstone, looking at approximately 30m (10’s of metres is not uncommon), which is as you may recall earlier is the approximate average depth of historical mineral exploration drilling – how many of the regional percussion traverses have resulted in a representative sample of the prospective basement? What is the impact on near surface historical surface geochemistry sampling? A ferricrete (± silcrete) duricrust has been identified suggesting leaching and potential remobilisation of pathfinder elements. The significance of preservation – past and present cannot be underestimated – We have spent time as part of this project investigating the uplift and burial history from the rock record and reconciling against apatite fission track data (work in progress) Essentially stable since the Devonian (rock relationships, apatite fission track, mica geobarometry) Presence of supergene chalcocite immediately below the unconformity separating Cambrian and Silurian
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COVER AND PRESERVATION Speaker's notes
Presenter
Presentation Notes
Cover can be exciting…! It’s not just something that needs to be pre-collared. It needs to be intimately understood. Here we have someone admiring contact metamorphosed sediments of the Grampians Group at Mount Arapiles on the northwest margin of the project area while looking east across the very flat Wimmera Plains, which effectively represents the current erosional surface of the Murray Basin. It’s not just the actual cover rocks but the age and style of deformation imposed upon them given that this is likely to be reflected in the prospective (Cambrian) bedrock and mineral systems. Ross Cayley’s talk tomorrow will cover this concept in much greater detail. The cover can contain significant mineral endowment itself. In the case of the Murray Basin it is heavy mineral sands. The depth of weathering and resulting thickness of (mottled and pallid) regolith (Dundas Surface) needs to be considered. Here is an example of deeply weathered Cambrian Glenthompson Sandstone, looking at approximately 30m (10’s of metres is not uncommon), which is as you may recall earlier is the approximate average depth of historical mineral exploration drilling – how many of the regional percussion traverses have resulted in a representative sample of the prospective basement? What is the impact on near surface historical surface geochemistry sampling? A ferricrete (± silcrete) duricrust has been identified suggesting leaching and potential remobilisation of pathfinder elements. The significance of preservation – past and present cannot be underestimated – We have spent time as part of this project investigating the uplift and burial history from the rock record and reconciling against apatite fission track data (work in progress) Essentially stable since the Devonian (rock relationships, apatite fission track, mica geobarometry) Presence of supergene chalcocite immediately below the unconformity separating Cambrian and Silurian
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COVER AND PRESERVATION Speaker's notes
Presenter
Presentation Notes
Cover can be exciting…! It’s not just something that needs to be pre-collared. It needs to be intimately understood. Here we have someone admiring contact metamorphosed sediments of the Grampians Group at Mount Arapiles on the northwest margin of the project area while looking east across the very flat Wimmera Plains, which effectively represents the current erosional surface of the Murray Basin. It’s not just the actual cover rocks but the age and style of deformation imposed upon them given that this is likely to be reflected in the prospective (Cambrian) bedrock and mineral systems. Ross Cayley’s talk tomorrow will cover this concept in much greater detail. The cover can contain significant mineral endowment itself. In the case of the Murray Basin it is heavy mineral sands. The depth of weathering and resulting thickness of (mottled and pallid) regolith (Dundas Surface) needs to be considered. Here is an example of deeply weathered Cambrian Glenthompson Sandstone, looking at approximately 30m (10’s of metres is not uncommon), which is as you may recall earlier is the approximate average depth of historical mineral exploration drilling – how many of the regional percussion traverses have resulted in a representative sample of the prospective basement? What is the impact on near surface historical surface geochemistry sampling? A ferricrete (± silcrete) duricrust has been identified suggesting leaching and potential remobilisation of pathfinder elements. The significance of preservation – past and present cannot be underestimated – We have spent time as part of this project investigating the uplift and burial history from the rock record and reconciling against apatite fission track data (work in progress) Essentially stable since the Devonian (rock relationships, apatite fission track, mica geobarometry) Presence of supergene chalcocite immediately below the unconformity separating Cambrian and Silurian
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COVER AND PRESERVATION Speaker's notes
Presenter
Presentation Notes
Cover can be exciting…! It’s not just something that needs to be pre-collared. It needs to be intimately understood. Here we have someone admiring contact metamorphosed sediments of the Grampians Group at Mount Arapiles on the northwest margin of the project area while looking east across the very flat Wimmera Plains, which effectively represents the current erosional surface of the Murray Basin. It’s not just the actual cover rocks but the age and style of deformation imposed upon them given that this is likely to be reflected in the prospective (Cambrian) bedrock and mineral systems. Ross Cayley’s talk tomorrow will cover this concept in much greater detail. The cover can contain significant mineral endowment itself. In the case of the Murray Basin it is heavy mineral sands. The depth of weathering and resulting thickness of (mottled and pallid) regolith (Dundas Surface) needs to be considered. Here is an example of deeply weathered Cambrian Glenthompson Sandstone, looking at approximately 30m (10’s of metres is not uncommon), which is as you may recall earlier is the approximate average depth of historical mineral exploration drilling – how many of the regional percussion traverses have resulted in a representative sample of the prospective basement? What is the impact on near surface historical surface geochemistry sampling? A ferricrete (± silcrete) duricrust has been identified suggesting leaching and potential remobilisation of pathfinder elements. The significance of preservation – past and present cannot be underestimated – We have spent time as part of this project investigating the uplift and burial history from the rock record and reconciling against apatite fission track data (work in progress) Essentially stable since the Devonian (rock relationships, apatite fission track, mica geobarometry) Presence of supergene chalcocite immediately below the unconformity separating Cambrian and Silurian
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KEY FINDINGS FROM NEW DATA Mineralisation • Mineralised porphyries: 501-500Ma (U-Pb zircon), molybdenite mineralisation: 502-503Ma (Re-Os) within error
• Mineralised porphyries are not confined to volcanic belts – search space expanded• Porphyries occupy fertility window of Louks (2014)• Current known mineralised porphyries post date D1 (Delamerian) - upright
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KEY FINDINGS FROM NEW DATA Mineralisation • Mineralised porphyries: 501-500Ma (U-Pb zircon), molybdenite mineralisation: 502-503Ma (Re-Os) within error
• Mineralised porphyries are not confined to volcanic belts – search space expanded• Porphyries occupy fertility window of Louks (2014)• Current known mineralised porphyries post date D1 (Delamerian) - uprightExploration • Passive seismic suitable technique for estimating depth to basement• Suitable drilling techniques and depth of cover – proof of concept• Hyperspectral scanning (Hylogger) suggests distal propylitic hydrothermal alteration and pyrophyllite coincident with min
• More work required to characterise hydrothermal alteration and mineralisation• Favourable chlorite and epidote trace element geochemistry in vicinity of Eclipse prospect• Partial leach surface geochemistry orientation survey• Groundwater geochemistry and water bore re-logging• Scalable structural template: Devonian vs Cambrian deformation characteristics
KEY FINDINGS FROM NEW DATA Mineralisation • Mineralised porphyries: 501-500Ma (U-Pb zircon), molybdenite mineralisation: 502-503Ma (Re-Os) within error
• Mineralised porphyries are not confined to volcanic belts – search space expanded• Porphyries occupy fertility window of Louks (2014)• Current known mineralised porphyries post date D1 (Delamerian) - uprightExploration • Passive seismic suitable technique for estimating depth to basement• Suitable drilling techniques and depth of cover – proof of concept• Hyperspectral scanning (Hylogger) suggests distal propylitic hydrothermal alteration and pyrophyllite coincident with min
• More work required to characterise hydrothermal alteration and mineralisation• Favourable chlorite and epidote trace element geochemistry in vicinity of Eclipse prospect• Partial leach surface geochemistry orientation survey• Groundwater geochemistry and water bore re-logging• Scalable structural template: Devonian vs Cambrian deformation characteristics
• Porphyry event north-south orientation, Devonian northeast-southwestTectonics • Serpentinities have similar Cr# (chromite), including Hummocks Serpentinite to west• No detrital zircon younger than ~540Ma in Glenthompson Sandstone• Earliest known igneous activity of Stavely Arc (to date) 510Ma – stratigraphy suggests older ‘boninitic’ rocks• Current known mineralised porphyries represent (low to med K) calc-alkaline magmatism
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS Speaker's notes
Presenter
Presentation Notes
The following simplified sequence will be covered in much more detail and given the justice it desrves as part of Ross Cayley’s presentation tomorrow. If we take the area with the most Cambrian bedrock control (e.g. outcrop and drilling), including overprinting deformation, the relationship with cover (in particular the Late Silurian Grampians Group) and primary features of the cover such as paleo-current directions and integrate new data and findings from the drilling such as stratigraphy and whole rock geochemistry the region can be unfolded, resulting in the twelve volcanic belts identified to date being reconfigured to three original belts, which are interpreted as the early fault slices of the Stavely Arc edifice. In the very limited area (3.5%) where these belts are exposed they are known to host base metal mineral occurrences, which is encouraging for the remainder which reside under cover.
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
Bunnagal/Dimboola Belts
Boonawah/Black Range Belts
Stavely/Dryden Belts
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS Speaker's notes
Presenter
Presentation Notes
From west to east, within the project area: Boonawah/Black Range Belts: 235km Bunnagal/Dimboola Belts: 382km Stavely/Dryden Belts: 542km
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PROSPECTIVITY - UNPACKING THE VOLCANIC BELTS
Bunnagal/Dimboola Belts: 382km
Boonawah/Black Range Belts: 235km
Stavely/Dryden Belts: 542km
Speaker's notes
Presenter
Presentation Notes
From west to east, within the project area: Boonawah/Black Range Belts: 235km Bunnagal/Dimboola Belts: 382km Stavely/Dryden Belts: 542km
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A CAMBRIAN TECTONIC SNAPSHOT Speaker's notes
Presenter
Presentation Notes
Based on the integration of data gained from this project with existing knowledge and findings of previous workers our preferred model at this stage is a west dipping slab being subducted beneath the Delamerian margin. There are potential alternatives, the pros and cons of which are discussed in the upcoming regional synthesis.
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MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
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MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
MINERAL SYSTEMS OF THE STAVELY ARC THROUGH TIME Speaker's notes
Presenter
Presentation Notes
Resolving the 4D geodynamic and metallogenic evolution of the region
UNCLASSIFIED
UNCLASSIFIED
The Stavely Project – UNCOVERing mineral potential in western Victoria
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