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Earth Explorer is an online source of news, expertise and applied knowledge for resource explorers and earth scientists. Sponsored by Geosoft.


News & Views

News Archive

December 7, 2016

Geosoft introduces IP and resistivity inversion in VOXI Earth Modelling

Geosoft has added induced polarization and resistivity data inversion to its VOXI Earth Modelling 3D inversion software service. Geoscientists are now able to create detailed 3D models of conductivity and chargeability from IP and resistivity survey data with VOXI. The resulting models can assist in interpreting and targeting regions for mineral and environmental applications...

December 5, 2016

Mexico's Deepwater Round Exceeds Expectations

Some of the world's biggest oil companies showed up Dec. 5 and agreed to invest on the Mexican side of the Gulf of Mexico, proving that deepwater exploration still has a pulse despite challenging market conditions...

November 30, 2016

Magnetic inversion results for Ngamiland available for download

A regional-scale geophysical inversion of magnetic field data in the Ngamiland region of northwestern Botswana is now available for download from the Botswana Geoscience Portal, a partnership initiative of the Botswana Geoscience Institute, industry sponsors and Geosoft...

November 30, 2016

LIGO Resumes Search for Gravitational Waves

After a series of upgrades, the twin detectors of LIGO, the Laser Interferometer Gravitational-wave Observatory, have turned back on and resumed their search for ripples in the fabric of space and time known as gravitational waves. LIGO transitioned from their engineering test runs to full science observations at 8 a.m. Pacific Standard Time on November 30...

November 9, 2016

International Volcano Scientists Unite

For the first time, the United States will host the international Volcano Observatory Best Practices workshop, previously held only in Italy. The workshop will take place this month in Vancouver, Washington. It is designed specifically for volcano observatories around the world and their staff to exchange ideas and best practices with each other...

October 4, 2016

USGS Assesses Mineral Potential for Sagebrush Habitats in Six Western States

USGS has completed a comprehensive assessment and inventory of potential mineral resources covering approximately 10 million acres of Federal and adjacent lands in Idaho, Montana, Nevada, Oregon, Utah and Wyoming...

October 3, 2016

Uganda Targets Up to U.S.$100 Million for Mineral Exploration

Uganda is well endowed with mineral resources and, like many naturally-gifted African countries, is becoming keen on ensuring that these resources play a transformative role in its long-term structural transformation dream - the Vision 2040...

September 9, 2016

Small-Scale Fishers Get A Big Boost With First-Of-Its Kind Impact Investment Fund

Conservation organization Rare announces the Meloy Fund for Small-Scale Fisheries at Our Ocean Conference. The Global Environment Facility, one of the largest funders of conservation worldwide, will be investing $6 million into the fund...

September 1, 2016

Scientists take to the skies to track West African pollution

Scientists operating research aircraft over West Africa have detected organic materials in the atmosphere over a number of urban areas, contributing to concerns of the rise in pollution across the region...

August 17, 2016

New IGS Xplore prospectivity maps for Botswana

International Geoscience Services have released a series of base metal prospectivity maps for the Ngamiland District of northwestern Botswana using free geodata available on the recently-launched Botswana Geoscience Portal, hosted by Geosoft. The maps identify favorable areas for copper, zinc and lead mineralization using geological, geochemical and geophysical datasets downloaded directly from the portal.

August 11, 2016

NexGen Makes New High Grade Discovery

NexGen Energy reported the discovery of a new high grade zone of mineralization 4.7 km northeast of the Arrow Deposit as part of an on-going summer drilling program on its 100% owned, Rook I property, Athabasca Basin, Saskatchewan...

August 10, 2016

Rampion UXO Disposal to Take Place This Week

E.ON has confirmed that the two unexploded devices, detected along the Rampion offshore cable route will be safely disposed this week following the consultation with the Marine Management Organisation...

August 9, 2016

Diamonds In The Rough: E&Ps Find New Reserves In Mature Basins

The oil industry’s history demonstrates clearly that new plays and prospects have long been found in mature basins that were thought to be well on the way to being squeezed dry. Through the acquisition of new data, developing new concepts and coming up with fresh interpretations, long-producing basins around the world from the North Sea to Malaysia have continued to reveal new riches...

August 8, 2016

Northern Shield Identifies High Quality VTEM Targets at Séquoi

Northern Shield Resources announced the results of the interpretation and modelling of the VTEM survey from the Séquoi Property in the Labrador Trough of Quebec . Séquoi is owned 100% by Northern Shield and is being explored for Noril'sk style Ni-Cu-PGE massive sulphides. After geophysical modelling and interpretation of the VTEM data from Séquoi, six VTEM anomalies of significant interest have been identified...

August 3, 2016

Rio Tinto tailors big data drive to copper

Rio Tinto will put the weight of an exploration big data push and its newly-formed Growth and Innovation group behind its desire to identify a "tier 1" copper asset. Speaking at the annual Diggers & Dealers conference in Kalgoorlie, Growth and Innovation group executive Stephen McIntosh said Australia was "overdue for a tier 1" mineral discovery of any type...

August 1, 2016

Tetra Tech Awarded $200 Million Navy CLEAN Contract

Tetra Tech announced that it has been awarded a $200 million, single-award contract by Naval Facilities Engineering Command (NAVFAC) Atlantic. Through the Comprehensive Long-term Environmental Action Navy (CLEAN) contract, Tetra Tech will provide environmental engineering support services to installations within the NAVFAC Atlantic Area of Responsibility...

May 3, 2016

NATO Science for Peace and Security (SPS), MODUM Partners announce "Young Scientist Summer School on Sea Dumped Chemical Weapons"

This international project cooperates closely with CHEMSEA (Search and Assessment of Chemical Weapons) Project for and sharing and knowledge transfer...

April 12, 2016

Monday mad rush for gold stocks

Renewed optimism about the outlook for gold saw investors pile back into gold stocks, pushing many stock to 52-week highs in heavy volumes...

April 11, 2016

Medgold Resources: Continues to Expand the Boticas Gold Project, Portugal; Proposes $200,000 Private Placement

Medgold Resources is pleased to announce new assay results from contiguous rock-chip sampling from the Limarinho South zone at its Boticas gold project in Portugal, which include a highlight of 6.0m @ 5.7 g/t Au...

April 8, 2016

De-carbonizing our energy sector

Nuclear energy currently provides around 11 percent of the world's electricity. China, the European Union, the United States, India, Russia, South Korea, and other nations’ have major existing fleets...

April 1, 2016

Follow-Up Drilling Results Indicate Wide Gold Zones at Hendricks Gold Discovery

Gascoyne Resources Limited announced that it has received the final assay results from the 10,000 metre aircore exploration drilling programme...

March 26, 2016

The Oil Market Is Finally Hitting Its Breaking Point

After a significant reduction in investments over the past two years, oil companies can no longer overcome the production declines from legacy wells...

March 15, 2016

N-Sea Expands into the French Offshore Wind Industry

Subsea IMR provider, N-Sea, has signed a letter of intent with CERES Recherches & Expertise Sous-Marine and TechSub Industrie Environement, to provide subsea survey, installation and remediation services to the French offshore wind industry...

March 9, 2016

PDAC 2016 Convention Exceeds 22,000 Attendees

Optimism and opportunity abounded at the PDAC 2016 Convention of The Prospectors & Developers Association of Canada in spite of recent industry challenges...

March 3, 2016

6 Alpha Launches EOD Contracting Division

6 Alpha Associates, a specialist risk consultancy practice, with expertise in the assessment and management of unexploded ordnance, has launched a dedicated explosive ordnance disposal division...

Geophysical inversion modelling delivers new targets in the Yukon

by Virginia Heffernan on December 12, 2013 applied

Drilling at the Justin Property 2012: POW Zone

[Click to enlarge]

Regional Scale Airborne Magnetic Map; POW Zone outlined in red.

Drillhole planning can be a high-risk venture when the available information is limited to airborne geophysical results. But Aben Resources found a way to reduce that risk considerably by using 3D inversion to guide exploration on the Justin project, one of the more intriguing plays to emerge from the recent resurgence in Yukon gold exploration.

The Justin Project is located in an emerging gold district in the southeast Yukon, historically known for its proximity to the Cantung tungsten mine. The property contains significant intrusion-related gold (IRGS) mineralization similar to the Eagle Gold deposit (resources of 6.3 mn ounces), also in the Yukon, and the Fort Knox deposit in Alaska (reserves of 4.3 mn ounces).

The property’s most prospective regions are alteration zones that formed when a granodiorite stock intruded into calcareous limestone. Mineralisation consists of zones of skarn style replacement overprinted by quartz calcite stockwork veining. Both the skarn style and vein style mineralisation contain anomalous gold values.

In 2011 Aben launched a 10-hole 2,000-metre drill program on a shallow skarn on Justin. The POW zone, as it is now known, returned a 60 m intersection grading 1.19 g/t gold including 21 m of 2.47 g/t gold. A follow-up program in 2012 expanded the IRGS system at POW considerably.

Seeing the invisible

[Click to enlarge]

3D wireframe model built using DDH section maps; mineralisation hosted in intrusive contact halo within the hornfels and skarn units.

Commissioned to find other targets similar to POW on the 18,000-acre property, consultant Terralogic Exploration used Geosoft’s wireframing tools to create a 3D geological model of the zone from drill results. The company then employed the wireframe model to validate magnetic results from a survey flown over the whole property. The resulting combination of geology and geophysics successfully delineated several new high quality targets with a minimum of time and effort.

How did Terralogic delineate drill ready targets with such limited geological information? The consulting firm used VOXI Earth Modelling, Geosoft’s new geophysical inversion modeling program, to compare its geophysics results against the drillhole geology quickly and easily.

“Because we had success targeting the POW zone with the magnetic data, it seemed like a natural fit to work through the VOXI modelling process in other areas that had a magnetic signature but very little outcrop,” says Terralogic geologist Mike McCuaig.

From uncertainty to confidence

[Click to enlarge]

Iterative Reweighting Inversion focused susceptibility model in blue; isosurface value = 0.04 SI. Geophysical model correlates to known geology, with larger susceptibility contrasts (>0.04 SI) contained within the hornfels and skarn units.



[Click to enlarge]

Susceptibility model constrained with DDH data in green; isosurface value = 0.04 SI. Drillhole constrained geophysical model correlates highly with known geology but is also very similar to the IRIF model (without drillhole constraints); blue isosurface = 0.04SI.

Collaborating closely with Geosoft, Terralogic ran an unconstrained magnetic inversion of the airborne survey results. Then the team compared the unconstrained inversion to the wireframe model of POW’s geology created in Oasis montaj.

When the two didn’t match, Geosoft went back to the drawing board to create a more realistic rendering of the geophysical results using VOXI’s Iterative Reweighting Inversion Focusing (IRIF).  The result was a sharper geophysical model that better matched what the company knew from drilling.

“I was really impressed with the VOXI IRIF technique and how well it fit with the geology we actually see,” says McCuaig. “It  gives you way more confidence that your modelling is realistic.”

As a final step, Geosoft built a more complex model using drillhole geology to provide structure to the geophysical inversion. Since both methods matched the geophysical response with the known geology, Terralogic had the confidence to apply the IRIF method to areas of limited outcrop that had a similar magnetic signature to the POW zone.

McCuaig says the process of groundtruthing the geology with the magnetic data at the known zone, and then applying the results to the rest the property took only a few days. “Now we have high confidence in areas outside the known mineralization that Aben can test with drillholes in the future” he says.

The new targets generated for Aben using this approach demonstrate the value of VOXI, which allows geologists and geophysicists to collaborate on a cloud-based software platform designed to encourage iterative interpretation using all the pieces of the exploration puzzle.

The VOXI software service  helped to overcome the complexity and frustration inherent in conventional 3D inversions by speeding up the process and making it accessible to all geoscientists with an understanding of geophysics.

“The beauty of Geosoft VOXI is that as you learn about a property, you can add those measurable rock properties to the model and constrain it even further,” says McCuaig. “It’s a very quick and efficient way to assess large tracts of ground given the right exploration target.”

The next episode

The downturn in the mining industry has hit the junior sector particularly hard and Aben is no exception. Once the market returns to life, Aben plans to raise the funds to continue working on Justin. Drilling the targets delineated by VOXI will be one of the company’s top priorities.




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