双模火山活动

双模火山活动（英语：Bimodal volcanism）是指一种火山活动能从单一火山中心喷发出镁铁质和长英质熔岩，很少或没有中间成分的熔岩。这种类型的火山活动通常与伸展构造区域有关，特别是裂谷。

产状

大多数双模火山活动与地壳变薄有关，而在变质岩石中，若有此类岩石也被用来证明过去裂谷存在的证据^[1] 。在活跃的大陆裂谷地区有很多例子，如美国西部的盆地和山脉区。双模式火山活动也被解释为过渡区域产物^[2]，例如早期形成阶段的弧后盆地^[3]以及大陆和海洋壳的热点，例如黄石公园、阿纳欣（Anahim）和加那利（Canary）群岛的产物^[4]^[5]^[6]。

成因

双模火山活动通常被解释是因为地壳部分熔融。当大量热的玄武质岩浆从地幔源中上升时，能造成地壳部分熔融而产生花岗质岩浆。这两种岩浆分别在独立的岩浆室，导致周期性喷发这两种类型的熔岩^[7]^[8]。

参考文献

[1]
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.
[2]
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
[3]
Fujioka, K., Nishimura, A., Koyama, M., and Kotake, N., 1990. Bimodal arc volcanism and backarc rifting along Izu-Bonin Arc. Eos, 71, 956.
[4]
Christiansen, R.L.; Foulger G.R.; Evans J.R. (2002). "Upper-mantle origin of the Yellowstone hotspot" (PDF). Bulletin of the Geological Society of America. 114 (10): 1245–1256. Bibcode:2002GSAB..114.1245C. doi:10.1130/0016-7606(2002)114<1245:umooty>2.0.co;2. Retrieved 3 December 2012.
[5]
Kuehn, Christian; Guest, Bernard; K. Russell, James; A. Benowitz, Jeff (2015). "The Satah Mountain and Baldface Mountain volcanic fields: Pleistocene hot spot volcanism in the Anahim Volcanic Belt, west-central British Columbia, Canada". Bulletin of Volcanology. Springer: 25
[6]
Freundt-Malecha, B.; Schminke H.-U.; Freundt A. (2001). "Plutonic rocks of intermediate composition on Gran Canaria: the missing link of the bimodal volcanic rock suite". Contributions to Mineralogy and Petrology. 141 (4): 430–445. Bibcode:2001CoMP..141..430F. doi:10.1007/s004100100250
[7]
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.
[8]
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.

[”Brewer”-1] [1]
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”-2] [2]
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”-3] [3]
Fujioka, K., Nishimura, A., Koyama, M., and Kotake, N., 1990. Bimodal arc volcanism and backarc rifting along Izu-Bonin Arc. Eos, 71, 956.

[”Christiansen”-4] [4]
Christiansen, R.L.; Foulger G.R.; Evans J.R. (2002). "Upper-mantle origin of the Yellowstone hotspot" (PDF). Bulletin of the Geological Society of America. 114 (10): 1245–1256. Bibcode:2002GSAB..114.1245C. doi:10.1130/0016-7606(2002)114<1245:umooty>2.0.co;2. Retrieved 3 December 2012.

[”Kuehn”-5] [5]
Kuehn, Christian; Guest, Bernard; K. Russell, James; A. Benowitz, Jeff (2015). "The Satah Mountain and Baldface Mountain volcanic fields: Pleistocene hot spot volcanism in the Anahim Volcanic Belt, west-central British Columbia, Canada". Bulletin of Volcanology. Springer: 25

[”Freundt”-6] [6]
Freundt-Malecha, B.; Schminke H.-U.; Freundt A. (2001). "Plutonic rocks of intermediate composition on Gran Canaria: the missing link of the bimodal volcanic rock suite". Contributions to Mineralogy and Petrology. 141 (4): 430–445. Bibcode:2001CoMP..141..430F. doi:10.1007/s004100100250

[”Maria,”-7] [7]
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,”-8] [8]
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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