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Go Deep! Standards Help Scientists Unearth “Ghost” Mountains and Other Antarctic Mysteries

New York, Nov 21, 2011

Buried beneath Antarctica’s ice is a mountain range the size of the European Alps. First discovered by an expedition of Soviet researchers in 1958, scientists are only now unraveling the mystery behind what could be Earth’s most unusual mountains.

Known as the Gamburtsevs, the sub-glacial mountain range is 750 miles long, 8,900 feet high, and covered by 2,000 feet of ice and snow. The study is being led by the Antarctica's Gamburtsev Province (AGAP) project – a multinational research effort supported by Australia, Canada, China, Germany, Japan, the United Kingdom, and the United States. In addition to informing current climate studies, scientists hope that unearthing the mystery of the Gamburtsevs formation will help to shed light on some of the planet’s past geographic changes, and help to predict future possible scenarios. Standards for geophysical methods can be used to help scientists study geologic mysteries like the Gamburtsevs to make important discoveries about the subsurface world.

The story of the Gamburtsevs began roughly one billion years ago – long before complex life evolved on Earth – when continental drift pushed two plates together to form the giant landmass known as Rodinia. This early range eroded above the surface but left a thick, dense root reaching into the Earth's mantle. Then, 250 to 100 million years ago, rifting events to the east of this root caused the crust to pull apart, warming the root, and allowing it to lift land upwards to re-establish the mountains. Rivers and glaciers carved deep valleys and further sculpted the Gambursevs’ landscape. Around 35 million years ago, the glaciers merged to form the East Antarctic Ice Sheet, entombing the Gamburtsevs and protecting them from erosion in the process.

When it comes to environmental studies, there are a number of methods that scientists can use to “look” beneath Earth’s surface. To help piece together the formation of the Gamburtsevs through geologic time, AGAP flew aircraft cross eastern Antarctica, and with ice-penetrating radar, mapped out the shape of the hidden bedrock.

Surface geophysical methods allow subsurface features to be located, mapped, and characterized. ASTM D6429-99(2011)E1, Standard Guide for Selecting Surface Geophysical Methods, is a standard from American National Standards Institute (ANSI) member and audited designator ASTM International that guides the selection of appropriate surface geophysical methods.

ASTM D6432-11, Standard Guide for Using the Surface Ground Penetrating Radar Method for Subsurface Investigation, covers equipment, field procedures, and interpretation methods for assessing subsurface materials using what is known as the impulse Ground Penetrating Radar (GPR) method. This technique uses high-frequency electromagnetic waves to acquire subsurface information. GPR detects changes in electromagnetic properties which, in a geologic setting, are a function of soil and rock material, water content, and bulk density.

The AGAP scientists also conducted gravity and magnetic surveys to gather information about the structure of the mountains. Gravity measurements can be used to map major geologic features over hundreds of square miles by indicating variations in the earth's gravitational field caused by differences in the density of the subsurface soil. ASTM D6430-99(2010), Standard Guide for Using the Gravity Method for Subsurface Investigation, guides the equipment, field procedures, and interpretation methods used in determining subsurface conditions using the gravity method.

The research scientists also used a network of seismometers to study earthquake signals passing through the rock. By listening to seismic waves, scientists can probe the properties of rock embedded deep in the Earth. ASTM D5777-00(2011)E1, Standard Guide for Using the Seismic Refraction Method for Subsurface Investigation, summarizes the equipment, field procedures, and interpretation methods used to determine the depth, thickness, and the seismic velocity of subsurface soil and rock.

In the near future, scientists may begin drilling into the mountains to retrieve rock samples and look for ancient ice. It is thought that somewhere in the Gamburtsev region there may be ices that are more than one million years old. And by examining bubbles of air trapped in such samples, researchers could potentially gather additional details about past conditions, including temperature and the concentration of gases such as carbon dioxide.

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