Encyclopedia of Astrobiology

Living Edition
| Editors: Muriel Gargaud, William M. Irvine, Ricardo Amils, Henderson James Cleaves, Daniele Pinti, José Cernicharo Quintanilla, Michel Viso

Ophiolite

  • Nicholas Arndt
Living reference work entry
DOI: https://doi.org/10.1007/978-3-642-27833-4_1116-3

Definition

An ophiolite is a slice of oceanic crust and underlying mantle that is thrust onto a continent by obduction. The stratigraphic sequence observed in an ophiolite corresponds to the layering observed of oceanic crust (from top to bottom): an upper layer of oceanic sediment (siliceous or carbonate ooze); a layer of pillow basalt followed a layer of sheeted near-vertical dykes; layers of gabbro and plagioclase or mafic cumulates; and a basal layer of “tectonite,” the deformed harzburgite (a type of peridotite) of the uppermost mantle. Many ophiolites contain only some of these lithologies.

Debate surrounds the question of whether any ophiolite represents normal oceanic crust formed at a mid-oceanic spreading centre. The geochemical compositions of basalt rocks indicate that many ophiolites are segments of crust that formed in back-arc basins. Reactions between water and ophiolite at high temperatures (300 °C) can produce low-molecular hydrocarbonsby abiotic...

Keywords

Oceanic Crust Greenstone Belt Basalt Rock Spreading Centre Pillow Lava 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  1. 1.Maison des GéosciencesLGCA, Université J. FourierSt-Martin d’HèresFrance