Bimodal volcanism: Difference between revisions
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==Occurrence== |
==Occurrence== |
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Most occurrences of bimodal volcanism are associated with thinning of the crust and the presence of such rocks in metamorphic sequences has been used to provide evidence for past rifting events.<ref>[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-4D9D9JJ-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d28c36995569a758f71c89d2f2757b66 Brewer, T.S., Ahall, K-L., Menuge, J.F., Storey, C.D. & Parrish, R.R. 2004. Mesoproterozoic bimodal volcanism in SW Norway, evidence for recurring pre-Sveconorwegian continental margin tectonism, Precambrian Research, 134, 249-273.]</ref> Most examples come from areas of active continental rifting such as the [[Basin and Range]] province. Bimodal volcanism has also been described from areas of transtension,<ref>[http://alaska.usgs.gov/staff/geology/2007_Till_et_al_Tintina.pdf Till, A.B., Roeske, S.M., Bradley, D.C., Friedman, R. & Layer, P.W. 2007. Early Tertiary transtension-related deformation and magmatism along the Tintina fault system, Alaska, The Geological Society of America Special Paper 434, 233-264]</ref> the early phases of [[back-arc basin]] formation |
Most occurrences of bimodal volcanism are associated with thinning of the crust and the presence of such rocks in metamorphic sequences has been used to provide evidence for past rifting events.<ref>[http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VBP-4D9D9JJ-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=d28c36995569a758f71c89d2f2757b66 Brewer, T.S., Ahall, K-L., Menuge, J.F., Storey, C.D. & Parrish, R.R. 2004. Mesoproterozoic bimodal volcanism in SW Norway, evidence for recurring pre-Sveconorwegian continental margin tectonism, Precambrian Research, 134, 249-273.]</ref> Most examples come from areas of active continental rifting such as the [[Basin and Range]] province. Bimodal volcanism has also been described from areas of transtension,<ref>[http://alaska.usgs.gov/staff/geology/2007_Till_et_al_Tintina.pdf Till, A.B., Roeske, S.M., Bradley, D.C., Friedman, R. & Layer, P.W. 2007. Early Tertiary transtension-related deformation and magmatism along the Tintina fault system, Alaska, The Geological Society of America Special Paper 434, 233-264]</ref> the early phases of [[back-arc basin]] formation<ref>Fujioka, K., Nishimura, A., Koyama, M., and Kotake, N., 1990. Bimodal arc volcanism and backarc rifting along Izu-Bonin Arc. Eos, 71, 956.</ref> and in the products of both continental and oceanic [[Hotspot (geology)|hotspots]] (e.g. [[Yellowstone hotspot|Yellowstone]] and the [[Canary hotspot|Canary Islands]]).<ref name="Christiansen">{{cite journal|last=Christiansen|first=R.L.|coauthors=Foulger G.R. & Evans J.R.|date=2002|title=Upper-mantle origin of the Yellowstone hotspot|journal=Bulletin of the Geological Society of America|publisher=[[Geological Society of America]]|volume=114|issue=10|pages=1245-1256|url=http://www.es.ucsc.edu/~rcoe/eart290C_2006/Christiansen_YSHS_GSAB02.pdf|accessdate=3 December 2012}}</ref><ref name="Freundt-Malecha">{{cite journal|last=Freundt-Malecha|first=B.|coauthors=Schminke H.-U. & Freundt A.|date=2001|title=Plutonic rocks of intermediate composition on Gran Canaria: the missing lnik of the bimodal volcanic suite|journal=Contributions to Mineralogy and Petrology|volume=141|pages=430-445|url=http://download.springer.com/static/pdf/370/art%253A10.1007%252Fs004100100250.pdf?auth66=1354745727_bd02ec4ca7972cef6e2cfdb191c43d8e&ext=.pdf|accessdate=3 December 2012}}</ref> |
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==Mechanism of formation== |
==Mechanism of formation== |
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Revision as of 23:12, 3 December 2012
Bimodal volcanism refers to the eruption of both mafic and felsic lavas from a single volcanic centre with little or no lavas of intermediate composition. This type of volcanism is normally associated with areas of extensional tectonics, particularly rifts.
Occurrence
Most occurrences of bimodal volcanism are associated with thinning of the crust and the presence of such rocks in metamorphic sequences has been used to provide evidence for past rifting events.[1] Most examples come from areas of active continental rifting such as the Basin and Range province. Bimodal volcanism has also been described from areas of transtension,[2] the early phases of back-arc basin formation[3] and in the products of both continental and oceanic hotspots (e.g. Yellowstone and the Canary Islands).[4][5]
Mechanism of formation
Bimodal volcanism is normally explained as a result of partial melting of the crust, creating granitic magmas, during the emplacement of large volumes of relatively hot basaltic magma from a mantle source. The two magma types then form separate magma chambers giving rise to periodic eruption of both types of lava.[6][7]
References
- ^ Brewer, T.S., Ahall, K-L., Menuge, J.F., Storey, C.D. & Parrish, R.R. 2004. Mesoproterozoic bimodal volcanism in SW Norway, evidence for recurring pre-Sveconorwegian continental margin tectonism, Precambrian Research, 134, 249-273.
- ^ Till, A.B., Roeske, S.M., Bradley, D.C., Friedman, R. & Layer, P.W. 2007. Early Tertiary transtension-related deformation and magmatism along the Tintina fault system, Alaska, The Geological Society of America Special Paper 434, 233-264
- ^ Fujioka, K., Nishimura, A., Koyama, M., and Kotake, N., 1990. Bimodal arc volcanism and backarc rifting along Izu-Bonin Arc. Eos, 71, 956.
- ^ Christiansen, R.L. (2002). "Upper-mantle origin of the Yellowstone hotspot" (PDF). Bulletin of the Geological Society of America. 114 (10). Geological Society of America: 1245–1256. Retrieved 3 December 2012.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Freundt-Malecha, B. (2001). "Plutonic rocks of intermediate composition on Gran Canaria: the missing lnik of the bimodal volcanic suite" (PDF). Contributions to Mineralogy and Petrology. 141: 430–445. Retrieved 3 December 2012.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Maria, A. & Hermes, O.D. 2001. Volcanic rocks in the Narragansett Basin, southeastern New England: Petrology and significance to early basin formation American Journal of Science, 301, 286–312.
- ^ Tamura, Y. & Tatsumi, Y. 2002. Remelting of an Andesitic Crust as a Possible Origin for Rhyolitic Magma in Oceanic Arcs: an Example from the Izu–Bonin Arc. Journal of Petrology, 43, 1029-1047.
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