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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...

Zeroing in on the high-grade: integration provides new clues at Hope Brook

by Virginia Heffernan on July 16, 2014 applied

[Click to enlarge]

Coastal Gold’s Hope Brook Gold project in southwest Newfoundland is a former gold mine with resources of nearly 1.4 million ounces.

The recent decline in gold prices has reinforced the importance of delineating deposits that can withstand the vagaries of the market. Tonnage may have trumped grade during the past decade, when prices were rising. But grade has become king in a stagnant gold price range of US$1200-1400 per oz.

The importance of attracting investors with richer deposits is not lost on Coastal Gold, owner of the Hope Brook Gold project in southwest Newfoundland, a former gold mine with resources of nearly 1.4 million ounces. Although the average grade of the current resource is about 2 grams per tonne, Coastal Gold is attempting to define a higher grade (2-5+ gpt) zone by integrating geophysical and lithogeochemical data within the geological model to steer exploration.

“We have to make a strong case that at current gold prices this project can work,” says President and CEO Bill Pearson. “The more that we can enhance grade, the greater the opportunity to develop a potentially economic mine.”

Hope Brook is a high sulphidation epithermal deposit blessed with a pyritic zone in the footwall that serves as a consistent marker for a silicified zone of mineralization up to 80 m wide and extending for at least five kilometres along strike. Within this lower grade area of earlier silicification is a later, much narrower (5-25 m thick) siliceous brecciated zone containing the high grade.

[Click to enlarge]

New Structural Model with Major Folds: Drilling and geophysics (IP) identified a major fold structure that closes below surface in the Connector Zone. 240 - Connector Zone Target extends for approximately 1,000m along strike.

The pyrite layer – and by extension the larger mineralized zone - is easy to trace using geophysics (IP and electromagnetics), but zeroing in on the higher grade mineralization is much more challenging. That’s where integrating lithogeochemistry into the geological model comes in.

“Geophysics gets us in the ball park, but lithogeochemistry gets us on base,” says Pearson, whose team is collaborating with researchers from Western and Memorial Universities to determine the mineralization style and alteration characteristics of the system, with a particular focus on controls of higher grade mineralization.

Coastal Gold’s search for new areas of higher grade material began in earnest in 2012. After completing 3D inversions of resistivity & electromagnetic data from a Titan 24 airborne survey and importing them into Geosoft Oasis montaj, the company was able to clearly delineate the silicified mineralized zone (resistive) and the pyrite zone (conductive) in the footwall.

Coastal Gold followed up the geophysical survey with a 21-hole reconnaissance drilling program, which hit the mineralized zone in every completed hole. By integrating the geological and geochemical data into Geosoft Target for ArcGIS, Coastal Gold confirmed that the mineralized structure extended over a strike length of 3.4 km.  Within this structure, a major new near surface target was identified over a one kilometre strike length about 900 m southwest of the former mine.

[Click to enlarge]

Hope Brook Gold Resource Model showing the general distribution of resource blocks above the cutoff grade  of 0.5 g Au/t in the Mine Zone and 240 Zone.

More specifically, the exploration team was able to get a much better sense of where the high grade lies within the larger zone by plotting and analyzing the alteration characteristics of the drill core. The higher grade zone is characterized by little to no sodium, higher silica, and copper (as chalcopyrite and lesser bornite) values.

“If we know the mineralization is there, we’ll use the lithogeochemistry to maximize our odds of hitting the high grade,” says Pearson. “If we see the same intense alteration that we see in our higher grade areas, we know the odds favour us to get better results, while weaker alteration suggests we are on the edge and there is no point wasting more money there.”

The lithogeochemical work also helped confirm what the geophysics was saying: that the pyrite zone is a reliable proxy for mineralization; and establish that gold mineralization over the entire property is likely derived from one fluid source, a single event driven by a major magmatic-hydrothermal system at depth.

Further analysis of immobile trace elements confirmed that the geochemistry at Hope Brook has similarities to world-class high sulphidation and porphyry Au-Cu deposits (e.g. Yanacocha, Peru and Lepanto, Phillippines).

BP-Selco discovered the Hope Brook deposit in 1983 and is thought to have outlined a (non NI 43-101 compliant) resource 11.2 million tonnes grading 4.54 gpt gold at a 2.5 gpt cut-off. The deposit was mined from 1987-1997 with total reported production of about 752,000 ounces of gold from underground workings and a small  open pit, plus a copper concentrate in the latter years.

3D inversions of resistivity and electromagnetic data from a Titan 24 survey imported into Geosoft Oasis montaj that clearly delineate the silicified mineralized zone (resistive) and the pyrite zone (conductive) in the footwall.

After completing definition drilling in 2013, Coastal Gold announced a resource update for the remaining deposit including indicated resources of 1,249,000 oz. and inferred resources of 138,000 oz. Work to date on a preliminary economic assessment (PEA) has focused on the potential production from tailings, open pit and underground at a rate of 5,000 tonnes per day.

Difficult financing conditions for miners have prevented Coastal Gold from chasing down the high grade within the new target. But with renewed investor interest the company will continue exploring the area while completing the PEA for the main deposit.

When that day arrives, the exploration team members’ ongoing efforts to integrate all the geophysical, geochemical and geological from the project on a single platform will serve them well as they strive to maximize hit rates and present information to potential investors in a way that is easy to visualize and understand.

Editor’s Note: On July 7, 2015, First Mining Finance Corp. closed the acquisition of Coastal Gold Corp. which wholly owned the Hope Brook Gold Project.

 

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