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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...

3D EM Surveys promise to reduce drilling costs

by Virginia Heffernan on MARCH 8, 2013 technology

Field technician setting up one DC/IP and MT survey station.


"The mining industry has traditionally focused on drilling, but high-density omni-directional 3D surveys can reduce drilling costs by focusing drill targets."

The growing ease with which geophysical data are collected, inverted and visualized in three dimensions stands to change the way mining companies conduct their exploration programs.

By densely sampling the subsurface in all directions, rather than interpolating 3-D images from 2-dimensional information, explorers are able to target their drill-holes  more accurately, cutting down on the cost and time required to investigate areas with limited data.

“The mining industry has traditionally focused on drilling,” says Kevin Killin, vice-president of interpretation for Quantec Geoscience, “but high-density omni-directional 3D surveys can reduce drilling costs by focusing drill targets.”

More accurate mapping of the subsurface has become an even stronger imperative as explorers look for smaller and ever more complex ore bodies to replace larger and shallower deposits that have already been discovered and mined.

While sophisticated 3D survey technology such as Quantec’s Orion 3D can cost 50-70% more than traditional 2D surveys, the greater chance of drilling success justifies the cost, Killin says.

The high-performance computer resources, skills and talent necessary to interpret the resulting data are not insignificant. Quantec has amassed a team of 14 geophysicists with post-graduate credentials to help both junior and large companies fully utilize the data collected on their properties.

In late 2011, for instance, Nevada Sunrise Gold ran an Orion 3D geophysical survey over an eight square kilometres section of its Golden Arrow gold project in Nevada in hopes of finding new pockets of gold mineralization to bolster existing resources.

Golden Arrow lies along the northeastern margin of the Walker Lane structural zone, a past producer with current resources exceeding 30 million ounces of gold and 400 million ounces of silver. Intrusive-hosted gold and silver deposits at Golden Arrow represent both low-sulphidation and high-sulphidation type mineralization.  Historic production on the property came from discrete high-grade ore shoots within quartz-adularia-gold veins, but more recent exploration has focused on defining disseminated gold mineralization in two zones known as Gold Coin and Hidden Hill.

[Click to enlarge]

3D Voxel models of resistivity and chargeability in the Hidden Hill region created in Geosoft Oasis montaj using the Orion 3D dataset. Since data is highly sampled in all directions, the models were created using 3D gridding techniques instead of interpolating between 2D inline sections.

Quantec acquired and inverted the 3D data from the Orion 3D survey at Golden Arrow and combined the results with historical lithology, assay data, and ongoing exploratory data. By delineating zones of high resistivity (the host intrusive) and high chargeability (both mineral and host associated), the survey identified new zones of mineralization and confirmed the previously defined Hidden Hill deposit.

Of the 21 reverse-circulation holes drilled in the new target areas, 18 intersected widespread mineralization assaying above 0.2 gram gold per tonne. The survey also changed the geological understanding of the deposit. The “basement” rock was previously assumed to be andesite, and all the historical holes were stopped in this lithology.   The Orion 3D system proved that the potential host rock is under the perceived basement.

Traditional 2D survey layouts use discrete lines, generally spaced an equal distance apart, to measure geophysical signals originating in the subsurface. In contrast, 3D surveys such as Orion use an array layout that collects uniform and omnidirectional information, resulting in a detailed volumetric representation of the subsurface that can optimize drilling success.

“If the deposit is 50 to 100 metres wide and your survey line spacing is 200 to 300 metres, you may not intercept that body on any line,” says Killin, noting the potential inaccuracy and serendipitous nature of the traditional 2D layout. “And if you extrapolate the information you have, it may not show the accurate location and geometry of the body unless you happen to run right over it. Moreover, if you have a body that is close enough to the line to give a response, it will spuriously appear as if it is lying directly underneath that line while it may in fact be so far offset that you will miss it with your drill.”

[Click to enlarge]

Clockwise from top-left; Aerial view of 3D survey layout (bounded by purple rectangle); Oblique view showing survey stations at the surface (yellow and red) and subsurface samples collected by Orion 3D loggers (green). The grey surface indicates depth of investigation for this particular survey; Cross-sectional view of subsurface sampling density.

On the other hand, a typical layout using Orion 3D would collect a couple of hundred thousand samples, resulting in a high-quality dataset that can then be run through a powerful imaging platform to generate and visualize complex subsurface structure with greater certainty.

Quantec uses Geosoft’s Target and Oasis montaj to manage, visualize and share the Orion 3D dataset, incorporating drill hole geology and assay data to increase confidence in the inversion. Data subdivision, which can be a resource intensive exercise, is rendered unnecessary because the internal memory management solution in Oasis montaj can handle very large volumes of data.

Killin says this level of mass computation allows voxel models to be run directly from the dataset, elucidating structurally complex targets and deposits in a 3D software environment that is intuitive and easy to use.

Although Orion 3D is only two years old, it is already generating a lot of interest from the exploration community because it can be customized for each project. “We can modify the layout of the survey for deeper depths, shallow depths, odd-shaped properties, and fine structures such as gold mineralization, or adapt it to a larger area to look for porphyry-type signatures,” says Killin.


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