Canales JP, Detrick RS, Bazin S, Harding AJ, Orcutt JA
J. P. Canales and R. S. Detrick, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543, USA. S. Bazin, A. J. Harding, J. A. Orcutt, Institute of Geophysics and Planetary.
Science. 1998 May 22;280(5367):1218-21. doi: 10.1126/science.280.5367.1218.
Wide-angle seismic data along the Mantle Electromagnetic and Tomography (MELT) arrays show that the thickness of 0.5- to 1. 5-million-year-old crust of the Nazca Plate is not resolvably different from that of the Pacific Plate, despite an asymmetry in depth and gravity across this portion of the East Pacific Rise. Crustal thickness on similarly aged crust on the Nazca plate near a magmatically robust part of the East Pacific Rise at 17 degrees15'S is slightly thinner (5.1 to 5.7 kilometers) than at the 15 degrees55'S overlapping spreading center (5.8 to 6.3 kilometers). This small north-south off-axis crustal thickness difference may reflect along-axis temporal variations in magma supply, whereas the across-axis asymmetry in depth and gravity must be caused by density variations in the underlying mantle.
沿着地幔电磁与层析成像（MELT）阵列采集的广角地震数据显示，尽管东太平洋海隆这一部分在深度和重力上存在不对称性，但纳斯卡板块0.5至150万年历史的地壳厚度与太平洋板块的地壳厚度并无明显差异。在南纬17度15分处，靠近东太平洋海隆岩浆活动活跃区域的纳斯卡板块上，同样年龄的地壳厚度（5.1至5.7千米）比在南纬15度55分处的重叠扩张中心（5.8至6.3千米）略薄。这种南北向轴外地壳厚度的微小差异可能反映了岩浆供应沿轴向的时间变化，而深度和重力的轴不对称性必定是由下地幔密度变化引起的。
