Earth science: The slippery base of a tectonic plate
Earth science: The slippery base of a tectonic plate
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地球科学：构造板块的光滑底部
作者：
C. Rychert
太平洋板块底部的高分辨率成像显示，当它下降到新西兰下方时，有一个10厘米厚的通道将板块从下地幔中分离出来。Tim Stern和合著者利用爆炸产生的地震波形成了一张高分辨率的海洋板块底部图像，该板块正在新西兰北岛下方俯冲。他们在100公里深处发现了一个不到1公里厚的地震波速度突变，倾斜角度为15°。一个平行的，10公里深，反射事件的存在表明，压缩波速度的减少被限制在一个通道的底部的板块，作者解释为剪切带的积水部分熔体或挥发物。他们的结论是，这是岩石圈-软流圈边界处低粘度通道的独立证据，该通道将板块从下方的地幔流中分离出来，并允许板块构造发生。
High-resolution imaging of the base of the Pacific plate as it descends beneath New Zealand discloses a 10-kilometre-thick channel that decouples the plate from underlying upper mantle. See Letter p.85 Tim Stern and co-authors use explosion-generated seismic waves to form a high-resolution image of the base of an oceanic plate that is subducting beneath North Island, New Zealand. They find an abrupt seismic wave-speed transition less than a kilometre thick at a depth of 100 km, dipping at an angle of 15°. The presence of a parallel, 10 km deeper, reflection event shows that the decrease in compressional wave speed is confined to a channel at the base of the plate, which the authors interpret as a sheared zone of ponded partial melts or volatiles. They conclude that this is independent evidence for a low-viscosity channel at the lithosphere–asthenosphere boundary that decouples plates from mantle flow beneath, and allows plate tectonics to take place.
影响因子：
3.9
作者：
Rychert, Catherine A.;Shearer, Peter M.
通讯作者：
Shearer, Peter M.