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,
Anahim and the
Canary Islands).[4][5][6]
Mechanism of formation
Bimodal volcanism is normally explained as a result of
partial melting of the crust, creating
graniticmagmas, 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.[7][8]
^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-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.
S2CID128768061.