Y. Tatsumi et al., A 3RD VOLCANIC CHAIN IN KAMCHATKA - THERMAL ANOMALY AT TRANSFORM CONVERGENCE PLATE BOUNDARY, Geophysical research letters, 21(7), 1994, pp. 537-540
The Kamchatka volcanic arc, which is located at the northern edge of t
he Kurile arc, consists of three volcanic chains, all parallel to the
trench axis. In contrast, most subduction zones have only two subparal
lel volcanic chains. The third chain in Kamchatka, which is farthest f
rom the trench, is characterized by the occurrence of voluminous plate
au lavas; volcanoes in the two chains closer to the trench are stratov
olcanoes typical in arc magmatism. The third chain magmatism is also u
nusual in that lavas show concentrations of incompatible elements inte
rmediate between those in the two trenchward chains. Both the unusual
occurrence of the third volcanic chain and the unusual lava chemistry
could be caused by partial melting of K-amphibole bearing periodotites
in the downdragged hydrous layer at the base of the mantle wedge unde
r anomalously high-temperature conditions associated with the characte
ristic tectonic setting of transform/convergence transition in the reg
ion.