Dike Emplacement at Craters of the Moon National Monument

The Craters of the Moon lava field spreads across 618 square miles and is the largest young basaltic lava field in the lower 48 states. The area contains more than 25 volcanic cones including outstanding examples of spatter cones. Sixty distinct lava flows form the Craters of the Moon lava field ranging in age from 15,000 to just 2,000 years old.

The Great Rift, the pathway that allowed molten rock to come to the surface runs from north of the visitor center, through this area, and to the SE, a distance of about 60 miles.   A portions of the rift were forced open by rising magma, huge amounts of molten rock were spewed out onto the surface of Craters of the Moon.

Stages of Eruptions: Great Rift

• Magma comes from great depths rather than having intruded almost exclusively by lateral motion from a high, crustal-level magma reservoir.   The magma is tapped directly from a partially melted lithospheric mantle.
• In the ESRP, dikes rise along a pathway aligned with Basin and Range faulting (northwest trend)
• Dikes are blade-like in shape
  • Tens of km long
• Few km high
• Dikes have a critical depth of ~ 750-1000 m in the ESRP
• As a dike rises to the surface, 2 maxima oriented on each side of dike equally spaced by a distance roughly equal to twice the depth to the crack-rift center
  • Tension cracks
  • Faults in alignment- do not exist in ESRP

Full Downloads:

Quicktime (.mov)
80 kb

Flash Player (.swf)
328 kb

Download Instructions:

PC
(right click to Save Download As...)

MAC
(hold control and click then drag to Download Linked File)