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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...

Automated image analysis targets ground selection

by Dan Zlotnikov on June 5, 2012 applied

Application of aeromagnetic structural analysis techniques for greenfields gold exploration.

Ground selection is a crucial stage in every greenfields exploration program. This process frequently relies on data acquired from State or Federal Government organizations seeking to encourage exploration activity; many jurisdictions offer their databases to the public at zero or very low cost.

The data thus acquired can come in a variety of forms, but one type commonly available is the result of aeromagnetic surveys. Conducted from the air and able to “see” through vegetation and snow cover, these surveys can reach remote areas at a relatively low cost. Aeromagnetic surveys are particularly beneficial for gold exploration because geology that favours the formation of gold deposits is frequently also associated with changes in rock magnetism. This makes aeromagnetic data particularly useful to gold explorers, but analysis of considerate volume of magnetic data requires significant time and effort in looking for areas of interest.

The analysis of the data is usually performed manually, with a geologist reviewing the maps and seeking to identify potentially gold-bearing areas. When the data cover millions of square kilometres of surveyed land, the process is not only complex but also extremely tedious. Fortunately, tedious, quantitative analysis of large volumes of data is a prime candidate for automation.

Automating the process is exactly what Eun-Jung Holden, a co-leader of geophysics and image analysis and Associate Professor at the Centre for Exploration Targeting (CET) within the University of Western Australia and her colleagues aimed to do. Their paper Identifying structural complexity in aeromagnetic data: An image analysis approach to greenfields gold exploration, published in Ore Geology Reviews in 2012, details the process and the results of two field applications of the CET Grid Analysis techniques.

The study targeted Archean orogenic-gold deposits formed during the Archean eon, some 3.8 to 2.5 billion years ago. These deposits are located in areas where tectonic plate activity during that period produced mountains. A side-effect of the tectonic upheaval was to break up the solid rock and form channels and cavities into which gold-bearing fluid could rise. Although the fluids are long gone, the gold remains. Today, Archean orogenic deposits represent one of the most important types of gold mineralization, accounting for roughly 20% of global gold production.

Besides being a major source for gold, Archean orogenic-type deposits are also excellent targets for magnetic surveying. The same fluid that brought up gold also served to remove magnetite ores in the vicinity, and on aeromagnetic data, the fluid channels show up as distinct lines or lineaments of diminished magnetism.

Algorithms intended to automate the search for such linear features have been proposed before; the innovation this study advances lies in the combination of an automated search for lineaments and for what is known as “structural complexity.” Simply put, the more lineament contacts  there are in vicinity and less parallel  they are to each other, the more structurally complex an area is considered to be. Such areas have been known to correlate with the location of gold deposits, making areas of higher complexity that much more attractive for further investigation.

The CET team applied their technique to two areas known for Archean orogenic gold discoveries in the Eastern Goldfields Superterrane of Western Australia and in the Abitibi greenstone belt in Ontario, Canada. Both are mature, gold-producing areas with many known deposits, which allowed the researchers to compare the results of the automated analysis with existing maps of deposits.

The automated approach has shown itself well in the testing. “Our experimental results demonstrate there is a high correlation between known mineralisation and the regions of structural complexity that are generated by the proposed method,” Holden and her co-authors conclude. They also point out that the same analysis technique can be applied to other inputs, such as traces from a digital geologic map and for other types of deposits.

Holden acknowledges a number of limitations of the technique. The approach cannot identify the time of formation of a particular lineament, ranking ones that formed at the same time as gold mineralization and ones that appeared after (and are not helpful to mineral explorers). The paper also points out, “Mineral exploration decisions are always based on a combined analysis of multiple datasets, typically geology, geophysics, geochemistry and satellite remote sensing. Our structural complexity maps should  complement the other datasets used in the exploration decision-making process.”

Source: Holden, E.-J., et al., Identifying structural complexity in aeromagnetic data: An image analysis approach to greenfields gold exploration, Ore Geol. Rev. (2012), doi:10.1016/j.oregeorev.2011.11.002.