August 2008 Geology and GSA Today media ...(million years ago. Burgess et al. use th...)

Date:7/23/2008

million years ago. Burgess et al. use these past climate indicators to shows that the water around this coast, then located at approximately 55 degrees S, reached temperatures of 23 to 25 degrees Celsius, more than 10 degrees Celsius warmer than similar latitudes today. The fossils also record a cyclic variation in temperature, with warming and cooling by approximately 1.5 degrees Celsius about every 18,000 years, which is thought to be caused by variations in Earth's orbit around the sun. These climate swings are similar to those that caused the more recent ice ages, but Burgess et al. show that, at that time, there was little or no ice present on Earth.

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Three-dimensional morphology of magmatic sulfides sheds light on ore formation and sulfide melt migration

Stephen Barnes et al., CSIRO Exploration and Mining, P.O. Box 1130, Bentley 6102, Western Australia, Australia. Pages 655-658.

Due to high demand for nickel from China and a prolonged period of high prices, the nickel mining industry is currently experiencing a major boom. Previously sub-economic, low-grade nickel deposits, such as those found at Mount Keith and Black Swan in Western Australia, are now being mined profitably. The nickel ores take the form of dispersed aggregates of nickel-iron sulfide minerals, which originally formed as immiscible liquid droplets within spectacularly hot, fluid magmas called komatiites. Barnes et al. have applied the technique of X-ray computed tomography (CAT or CT scanning), common in medical applications, to investigate the size and shape of these sulphide liquid droplets, and they have come to unexpected conclusions about the origins of the ore deposits. The application of a new generation of high-resolution CT instruments to rock textures is a promising development in the earth sciences.

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Anomalous cold in the Pangaean tropics

Gerilyn Soreghan et al., University of Oklahoma, Geology and G
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Contact: Christa Stratton cstratton@geosociety.org 303-357-1093 Geological Society of America Source:Eurekalert

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