Slide 1
Hydrothermal systems are areas with a high geothermal gradient and the presence of water which becomes heated.
Slide 2
Geysers such as Old Faithful at Yellowstone National Park are a surface expression of a Hydrothermal System. At Yellowstone an igneous magma chamber occurs very close to the surface resulting in an anomalously high geothermal gradient. Water percolating through the rocks is heated resulting in geysers, hot springs, fumaroles and hydrothermally altered rocks. As water and steam accumulate in the conduit of a geyser the pressure builds up. Eruption of the geyser represents the sudden release of pressure.
Slide 3
Hot springs occur where the conduit system is more open so there is not a build up of pressure. Fumaroles occur in dry areas where steam and gasses are given off.
Slide 4
Hydrothermal waters are chemically very active and can dissolve minerals as they move through the rocks. When they reach the surface they cool and degas resulting in the precipitation of minerals. Mammoth Hot Springs at Yellowstone is an accumulation of travertine precipitated by hydrothermal waters. Silicate minerals such as feldspar may be altered to clay minerals by hydrothermal fluids forming a mud pot.
Slide 5
The Pinnacles at Crater Lake Oregon formed where hydrothermal fluids moved up conduits, altering the volcanic ash and cementing it together.
  • Geothermal 4
  • Back to Lecture Topics