Jormua Ophiolite: Difference between revisions
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The crustal rocks of the ophiolite include [[pillow lava]], [[hyaloclastite]], [[sheeted dyke complex|sheeted dyke]]s, [[gabbro]], [[plagiogranite]] and [[ultramafic]] [[cumulate rock]].<ref name=PeltonenKontinen2004>{{cite book |last=Peltonen |first=P.|last2=Kontinen |first2=A. |date=2004|chapter=The Jormua Ophiolite: A Mafic-Ultramafic Complex from an Ancient Ocean-Continent Transition Zone |title=Precambrian Ophiolites and Related Rocks|editor-last=Kusky |editor-first=Timothy M.|series=Developments in Precambrian Geology|volume=13 |url= |location= |publisher=Elsevier B.V.|page= |isbn= |author-link= }}</ref> [[mantle (geology)|Mantle]] rocks exposed in the ophiolite are the [[peridotite]] varieties of [[lherzolite]], [[harzburgite]] and [[dunite]].<ref name=PeltonenKontinen2004/> |
The crustal rocks of the ophiolite include [[pillow lava]], [[hyaloclastite]], [[sheeted dyke complex|sheeted dyke]]s, [[gabbro]], [[plagiogranite]] and [[ultramafic]] [[cumulate rock]].<ref name=PeltonenKontinen2004>{{cite book |last=Peltonen |first=P.|last2=Kontinen |first2=A. |date=2004|chapter=The Jormua Ophiolite: A Mafic-Ultramafic Complex from an Ancient Ocean-Continent Transition Zone |title=Precambrian Ophiolites and Related Rocks|editor-last=Kusky |editor-first=Timothy M.|series=Developments in Precambrian Geology|volume=13 |url= |location= |publisher=Elsevier B.V.|page= |isbn= |author-link= }}</ref> [[mantle (geology)|Mantle]] rocks exposed in the ophiolite are the [[peridotite]] varieties of [[lherzolite]], [[harzburgite]] and [[dunite]].<ref name=PeltonenKontinen2004/> |
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==References== |
==References== |
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Revision as of 14:04, 17 August 2018
The Jormua Ophiolite is a remnant of ancient oceanic crust near the village of Jormua close to the geographical centre of Finland. The rocks of the Jormua Ophiolite formed about 1,950 million years ago in the Paleoproteozoic Era. The conditions under which the ocean crust rocks of Jormua formed was likely similar to present-day Red Sea. Thus, a linear sea of this type is thought to have existed between two continental landmasses in Finland. At some point this sea closed and the ophiolite was obducted.[1]
The Jormua ophiolite is part of a larger chain of ophiolites that occur within the Kainuu Schist Belt. It is also the best preserved of these ophiolites.[1]
The crustal rocks of the ophiolite include pillow lava, hyaloclastite, sheeted dykes, gabbro, plagiogranite and ultramafic cumulate rock.[2] Mantle rocks exposed in the ophiolite are the peridotite varieties of lherzolite, harzburgite and dunite.[2]
References
- ^ a b Peltonen, Petri; Kotinen, Asko; Huhma, Hannu (1996). "Petrology and Geochemistry of Metabasalts from the 1.95 Ga Jormua Ophiolite, Northeastern Finland". Journal of Petrology. 37 (6): 1359–1383.
- ^ a b Peltonen, P.; Kontinen, A. (2004). "The Jormua Ophiolite: A Mafic-Ultramafic Complex from an Ancient Ocean-Continent Transition Zone". In Kusky, Timothy M. (ed.). Precambrian Ophiolites and Related Rocks. Developments in Precambrian Geology. Vol. 13. Elsevier B.V.