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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...

Deconstructing Plate Tectonics

The Geological Survey of Norway designs a convenient tool that looks back in geological time and re-creates continental drift; helping the oil and gas industry to model offshore basins

By Graham Chandler

A quick glance at the eastern coastline of Brazil and the western coastline of the African continent and their jigsaw puzzle-like fit across the South Atlantic looks perfectly intuitive. But earth scientists know that’s less straight forward than it looks. It took at least 200 million years at the snail’s pace spreading of about two centimetres per year for them to get where they are today and apparently their drifting wasn’t in a straight line.

At least that’s what the Geological Survey of Norway found when they applied a new tool they built to allow researchers to track these continental movements back in time. It’s a boon to the petroleum industry for modelling basins. Deep basins hundreds of kilometres off the coasts of Brazil and Angola, known as sub-salt basins, are yielding multi-billion barrel finds of crude in recent years; and the search goes on for similar deep offshore deposits elsewhere on the planet. Knowledge of pre-drift extensions and how they matched up eons ago is valuable in this pricey exploration territory.

“Putting a location in its paleogeographic context is interesting when trying to establish the sources of far travelled sediment—they may be on another tectonic plate,” explains Mark Smethurst, Senior Geophysicist with the Geological Survey of Norway, who led development of the software tool. One needs to know the tectonic framework for a deforming plate margin and the development of rifts; to establish the total magnitude of extension across plate boundaries, he says.

The concept behind it, at least, seems relatively simple. The earth’s plates have been in constant motion relative to one another for at least two and a half billion years. Mathematically, the translation of a plate from one of these places to another can be described by a rotation around an Euler pole, or pivot point—whose geographic position can be expressed in latitude and longitude together with its rotation in degrees.

So one way to look back in geological time to examine ancient plate locations is to use these Euler relationships to rotate present day positional information back in time. “Rotating magnetic and gravity anomalies for two now widely separated plates back to their original adjacent positions—for example data for South America and Africa or for the Falklands and southern Africa—permits the correlation of anomalies and pre-drift geology between the plates,” says Smethurst.

“The point about an Euler rotation is simply that the translation of an object from one place to another on the surface of the sphere can be described by an Euler pole of rotation where the pole is a rotation axis passing through the centre of the Earth (assuming it is spherical),” continues Smethurst. But, he adds, in some cases several rotations would be in order. “The more complicated the motion of the object through time, the more rotation components you need to describe it.”

Smethurst and his team set out to design a tool to be used within Geosoft. They wrote a rotation algorithm that can be implemented in Oasis montaj; functioning as a GX (Geosoft Executable) routine. The function reads spatial co-ordinates from any Geosoft database and writes rotated co-ordinates back to the same database.

“We have stand alone plate reconstruction packages that produce paleogeographies and analyze plate motions,” says Smethurst. “And we use Oasis montaj and ArcGIS a great deal, so it is often convenient to rotate (reconstruct) features and data sets in the software packages we happen to be working in—rather than port data to a separate software package, reconstruct them, and bring them back. The basic building block used in producing plate reconstructions is the rotation on the sphere algorithm. It was therefore relevant to create a rotation on the sphere GX for montaj and a similar plug-in for ArcGIS.”

Although the tool is simple in concept, a user still needs knowledge about past plate movements for it to be effective, i.e. someone needs to specify accurate Euler pole values or the output may be misleading. If it is the user, how would he or she know what Euler value to input for example if he or she wished to know what a particular geology looked like 150 million years ago?
Smethurst explains. “The most primitive method of deriving original rotation parameters is through fitting continents together manually by simply matching their boundaries,” he says. “Otherwise one can use ocean floor magnetic anomalies and fracture zones to determine relative motions between plates. Paleomagnetic study data also provide a method of positioning continents but this provides control only on paleo-latitude and orientation, not longitude.”

And, he says, there are many researchers working on restoring continents and other features, like large igneous provinces, back to their original positions on Earth. These data can be mined and applied for Euler value inputs. “Euler rotation parameters appear in publications,” he says, but adding a caution: “however, extensive suites of rotations that describe the motions of most plates though long periods of geological time are seldom unfolded for all to see. Some projects, like EarthyByte/GPlates offer rotation parameters for all to use (if referenced properly) but these may not be the most up-to-date rotation histories.” Otherwise, he adds, industry participates in commercial and semi-commercial initiatives involving the supply of plate reconstruction software and plate rotation (motion) models.

Overall, “the need for doing plate reconstructions if of course to study plate tectonic processes,” says Smethurst. And that is particularly attractive to oil and gas explorers. “In my experience the hydrocarbon exploration industry has a very strong interest in establishing the paleogeography of the regions they are interested in,” he says. “We are talking about restoring now far separated plate margins back to their original relative positions, looking at their paleo-latitudes, their likely positions in climate zones, the rate of convergence and divergence of plates and what tectonic scenario this would create along plate margins.”

It’s not just the oil and gas industry. One of the Survey’s main findings is of interest to the academic world as well, and has supported the knowledge base of ancient continental drift for earth scientists. In this application, Smethurst and his team applied the tool to plate motions in the South Atlantic Ocean. “We reconstructed South America and Africa, including potential field data for the two areas,” he says, “to compare the geometries of the continental shelves on each side of the ocean and to look for structures internal to South America that could reasonably have permitted the South Atlantic to open sequentially from the south to the north.” That is, he explains, the southern part of South America had to move away from Africa while the northern part remained firmly attached.

It was an intriguing and useful conclusion. “Fitting South America and Africa back together creates an overlap between the two continent - ocean boundaries,” says Smethurst. “This is natural because both continental margins were extended before the ocean tract developed. Measuring the overlap provides an indication of the total amount of pre-drift extension in the two margins - useful to the petroleum industry in basin modelling.”