August 2008 Geology and GSA Today media ...(p to 464 degrees Celsius. For several ye...)

Date:7/23/2008

p to 464 degrees Celsius. For several years now, the phase of high-temperature activity has seemed to remain stable. These are the first hydrothermal fluids that could be sampled at temperature and pressure conditions at which seawater is a so-called supercritical fluid. The specific properties of a supercritical fluidin terms of solution and transport of metalsmake this hydrothermal field an exciting natural laboratory to investigate mineral deposit formation at conditions that previously could only be simulated in the laboratory.

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Temperature of the plume layer beneath the Yellowstone hotspot

Derek Schutt and Ken Deuker, Dept. of Geosciences, Warner College of Natural Resources, Colorado State University, Colorado 80523-1482, USA. Pages 623-626.

The basalt-covered Snake River Plain and the geysers of Yellowstone National Park (Wyoming) are caused by the Yellowstone hotspota hot region deep below Yellowstone National Park. But how hot is this hotspot and what is causing it? Recently, Schutt and Deuker measured the temperature of the hotspot. They built on past work that found that earthquake energy travels much more slowly in the rocks 100 kilometers and more below southern Idaho and northwestern Wyoming than nearly anywhere else in Earth at this depth. They modeled the effects of temperature and other processes that affect the speed at which seismic energy travels, and found the Yellowstone hotspot to be 50-200 degrees Celsius hotter than its surroundings, perhaps as hot as 1450-1500 degrees Celsius at 100 kilometer depth. Combined with other work on the shape of the low-velocity region, Schutt and Deuker's study implies that the hotspot is an upwelling from deep within Earth, possibly coming from as deep as the boundary between Earth's core and mantle (located 2900 kilometers deep).

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Tectonic controls on the nature of large silicic calderas in volcanic arcs

Gwyneth Hughes and Gail M
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Contact: Christa Stratton cstratton@geosociety.org 303-357-1093 Geological Society of America Source:Eurekalert

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