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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...

Mapping the Cenotes with Airborne EM: Protecting Aquifers in the Yucatán

by Dan Zlotnikov on November 5, 2013 applied

EM mapping of the cenotes has benefited from data collected by cave divers over many years of exploration. To date, divers have mapped 262 underwater caves and cave systems, for a total of 1138.4 kilometres of underwater passage.

Mexico’s Yucatán Peninsula has long been a popular tourist attraction and for various reasons. These include welcoming beaches, fascinating Mayan ruins, and of course, the cenotes, which consist of beautiful sinkholes or openings that expose the groundwater and lead to the longest underwater cave systems in the world.

But the cenotes are more than just a tourist attraction for swimming, snorkelling, and diving: The aquifer is the sole source of fresh water in the region. This has posed a serious challenge for ongoing development and prompted a local non-profit group, the Amigos de Sian Ka’an, to commission an airborne EM survey to map the flow of fresh water underground. The survey was flown by the Geological Survey of Austria on helicopters provided by the Mexican military. The collected data were then analysed by Dr. Yusen Ley-Cooper, who is now a research scientist with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO).

As Dr. Ley-Cooper explains, the aquifers face two simultaneous threats.

“One is that sewage is being pumped into them [aquifers are underground layers of material from which ground water is extracted using a well]. The other is that hotels and the local, growing population have a requirement for fresh water and so are extracting from these aquifers. And because the cenotes are near the coast, if you over-extract, you end up drawing in salt water, further contaminating the water supply.” This survey, flown with a frequency domain system at a 200-metre line separation, had an unusual ancillary database against which to cross-reference its results: A detailed set of maps of the network already existed – the result of data collected by cave divers over many years of exploration, which have been archived by the Quintana Roo Speleological Survey (QRSS) .

Dr. Ley-Cooper explains that the diver-collected data was a stroke of serendipity.

“There are several divers’ associations who have, over several decades, mapped the underground water pathways as part of their goal to encourage conservation and awareness of the underwater caves and cenotes of Quintana Roo through collaboration and knowledge."

To date, QRSS divers have mapped 262 underwater caves and cave systems, for a total of 1138.4 kilometres of underwater passage. They’ve also collected water chemistry samples and biological, archeological, and environmental observations of the caves.

“These findings have been incorporated into a number of different fields of research. They constantly push the limits and go further and further, trying to map and expand the network,” adds Dr. Ley-Cooper.

Last year, the divers managed to connect two networks which previously seemed not to connect, making this part of the Yucatán the largest karst environment in the world.

Fig.1 Left panel shows airborne EM conductivity depth map (conductance) at 15m below surface produced using conductivity depth transform EMflow. On the panel of the right the same image has been overlaid by speleological 'Cenote' routes mapped by cave divers (black dendrtic pattern). Brown line to the east of the map delimits the coast line.

Fig. 2 Left panel shows airborne EM conductance now a t a deeper depth of 20m below surface. The map on the right has been overlaid by speleological 'Cenote' routes mapped by cave divers. A salt intrusion can also be clearly delineated  by the higher (red to pink) conductance values pushing its way through on the east side of the coast line.

"We're very grateful to the divers for the years of information they've been recovering,” says Dr. Ley-Cooper. “We overlaid their records on to the airborne data so that an objective assessment of two totally independent datasets could  be made."

He notes that a major advantage of airborne EM is that data are collected at multiple frequencies. Each sounding allows the geophysical team to discern responses at varying depths. “You can actually say, for example, this is at approximately five or ten or fifteen metres to the resolution of the instrument in a particular survey site.”

This type of survey produces a vast amount of data to manage and process. Dr.  Ley-Cooper, who used Geosoft Oasis montaj for the task, says people sometimes don’t appreciate the scale of the challenge. “Each airborne EM survey has thousands -- potentially millions -- of soundings, and each sounding has a position, an altitude reading, and different channel responses from that point. What Oasis montaj does really well is handling the database and gridding the airborne EM data.”

Though the cost of this type of survey varies significantly with the boom-bust commodity cycle, Dr. Ley-Cooper feels there are ample benefits to the technique for groundwater management. Airborne EM can cover large areas in a short timespan, potentially reach depths of hundreds of metres, generate a 3D model of the target region’s water-bearing layers, and be easily integrated with other data for an even more comprehensive understanding of the hydrogeology. This makes the technique an excellent tool for mapping aquifers, monitoring groundwater salinization, or planning new water wells, as well as other hydrogeological applications.

Dr. Ley-Cooper adds that if a partner provides the necessary aircraft –as the Mexican military did in this case– then the expense is reduced considerably, putting this powerful tool within reach of hydrogeologists and planners.


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