Ophiolite facts for kids

Kids Encyclopedia Facts
Chromitic serpentinite Styria Province, Austria
Ophiolitic serpentinite from Austria, originally from the Proterozoic-early Paleozoic upper mantle. This peridotite rock was metamoposed in later mountain ranges
Cross-section of an ophiolite

An ophiolite is a section of the Earth's oceanic crust and the underlying upper mantle that has been uplifted and exposed above sea level. The rocks which make up ophiolites are an altered form of basalt. The rocks are often green.

They are found in the mountain belts such as the Alps or the Himalayas. They show where former ocean basins were consumed by subduction. This was one of the discoveries of plate tectonics. Ophiolites have always played a central role in plate tectonic theory and the interpretation of ancient mountain belts.

Stratigraphy and definition

Ofiolite sequence EN
Idealized stratigraphic sequence of an ophiolite

The stratigraphic sequence seen in ophiolites is caused by lithosphere-forming processes at mid-oceanic ridges:

  • Sediments: muds (black shale) and cherts deposited after the crust formed.
  • Extrusive sequence: basalt "pillow lavas" show magma/seawater contact.
  • Vertical, parallel dikes fed lavas above.
  • Gabbros from minerals settling from a magma chamber.
  • Peridotite: mantle rock minerals, heated and pressured in orogeny (mountain-building).

Notable ophiolites

Images for kids

Ophiolite Facts for Kids. Kiddle Encyclopedia.