August 2009 Geology and GSA Today media ...(spectra. The authors conclude that a sal...)

Date:7/31/2009

spectra. The authors conclude that a salt and ice-rich regolith at Hebes dissolved and melted when the region was heated early in the planet's history. They suggest that a similar geologic history may apply to other parts of Valles Marineris. The study supports the conclusions of previous studies that brines derived from hydrous salts and ice moved through a pressurized aquifer and erupted in the giant outflow channels. The emerging picture is that the Martian regolith still may be rich in water.

---

A lacustrine carbonate record of Holocene seasonality and climate
Chad A. Wittkop et al., Dept. of Chemistry and Geology, Minnesota State University, Mankato, Minnesota 56001, USA. Pages 695-698.

Sediments from a small lake in Michigan contain millimeter-sized layers of organic matter and the mineral calcite, deposited in pairs each year for the past 9000 years. The amount of the mineral calcite in these layers varies through time, and Wittkop et al. show how these variations are linked to long-term changes in the Northern Hemisphere growing season as controlled by dynamics of Earth's orbit around the sun. Short-term variations in calcite abundance also occur on a scale of decades. While the cause of the short-term variations is more difficult to determine, comparison with other climate records from the same region and time period suggest changes in precipitation and temperature may be the cause. These short-term cycles share similarities with other records documenting the pattern of El Nio events over the past 5000 years, which suggest that such events have become more frequent and intense in this time.

---

Middle Miocene oxygen minimum zone expansion offshore West Africa: Evidence for global cooling precursor events
S. Kender et al., British Geological Survey, Keyworth, Nottingham NG12 5GG, UK. Pages 699-702.

The Middle Miocene Climatic Optimum (16 to 14 million years ago), considered genera
'/>"/>

Contact: Christa Stratton cstratton@geosociety.org 303-357-1093 Geological Society of America Source:Eurekalert

1 GOOD

Page: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Related biology news :

1. USGS news: August science picks
2. August LabBits: A media tip sheet from the MBL in Woods Hole
3. AGU journal highlights -- August 6, 2008
4. Story tips from the US Department of Energys Oak Ridge National Laboratory, August 2008
5. Highlights from the August 2008 Journal of the American Dietetic Association
6. August 2008 Geology and GSA Today media highlights
7. BioScience tip sheet July/August 2008
8. Geoscientists meet to discuss Rocky Mountain geology
9. April 2009 Geology and GSA Today media highlights
10. February 2009 Geology and GSA Today media highlights
11. January GEOLOGY media highlights