地幔楔
地幔楔（mantle wedge)，是大洋板塊在海溝（板塊匯聚邊界）處向地幔俯衝時與上盤的大陸板塊（非潛沒板塊）之間夾雜的三角楔形的地幔舌部。可用地震波速成像來辨識。[1]
俯衝的洋殼攜帶了大量揮發性水分（水合礦物的分解與滲透的海水），水分的上升將降低其上的地幔楔的熔化溫度。[2][3][4] 地幔楔的流動導致的減壓也有助於其熔化。熔融的地幔楔上升形成了火山活動。[5]
弧前地幔擴展至俯衝帶與地幔楔較冷的鼻部相遇之處，深度約為10–40 km.[1]俯衝帶之處的地震波衰減低，波速快。[6]地幔楔區域的地震波斷層成像顯示為低速高衰減區域，Vp= 7.4 km·s−1 ，Vs= 4 km·s−1.[1] 沒有火山弧的地幔楔就沒有這種低速。這反映了地幔楔是否熔融。
參考文獻
- ^ 1.0 1.1 1.2 Weins, A. D.; Conder, A. J.; Faul H. U. The seismic structure and dynamics of the mantle wedge. Annual Review of Earth and Planetary Sciences. 2008,. 10.1146.
- ^ Kelley, K.; Plank, T.; Newman, S.; Stolper, E.; Grove, T.; Parman, S.; Hauri, E. Mantle melting as a function of water content beneath the Mariana arc. Journal of Petrology. 2010, 51 (8): 1711–1738. doi:10.1093/petrology/egq036.
- ^ Van Keken, Peter E. The structure and dynamics of the mantle wedge (PDF). Earth and Planetary Science Letters. 2003, 215 (3–4): 323–338 [2016-08-20]. Bibcode:2003E&PSL.215..323V. doi:10.1016/S0012-821X(03)00460-6. （原始內容 (PDF)存檔於2011-07-21）.
- ^ Kimura, J.; Yoshida, T. Contributions of slab fluid, mantle wedge and crust to the origin of quaternary lavas in the NE Japan arc. Journal of petrology. 2006, 47 (11): 2185–2232. doi:10.1093/petrology/egl041.
- ^ Hirshmann, M. M. Ironing out the oxidation of earth's mantle. Science Magazine. 2012,. 10.1126.
- ^ Stachnik, J. C.; Abers, A. G. Seismic attenuation and mantle wedge temperatures in the Alaska subduction zone. Journal of geophysical research. 2004, 10 (B10304).