A teleseismic shear-wave splitting study to investigate mantle flow around South America and implications for plate-driving forces
A teleseismic shear-wave splitting study to investigate mantle flow around South America and implications for plate-driving forces
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DOI：
10.1046/j.1365-246x.2002.01636.x
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发表时间：
2002-04
影响因子：
2.8
通讯作者：
G. Helffrich;D. Wiens;E. Vera;S. Barrientos;P. Shore;S. Robertson;Rodrigo Adaros
中科院分区：
文献类型：
--
作者：
G. Helffrich;D. Wiens;E. Vera;S. Barrientos;P. Shore;S. Robertson;Rodrigo Adaros
摘要 太平洋盆地因其周围板块的汇聚而封闭，其中一些板块具有深厚的大陆根源，这意味着太平洋下的地幔存在净质量通量。在这里，我们报告了一项剪切波分裂研究，旨在测试其南缘周围应该有流动的预测。我们的结果显示没有证据表明当今南美洲南部尖端有流动。相反，结果表明，即使在南极洲下方，当今南大西洋的流动方向也与南美绝对板块运动方向平行。研究结果还为洋盆尺度地幔流的基底阻力驱动的绝对板块运动提供了证据，并表明南美洲和南极洲下方存在约200公里厚的流动边界层，并证明从当今的板块形态无法可靠地推断地幔流方向。
SUMMARY Closure of the Pacific Ocean basin by the convergence of its surrounding plates, some of which have deep continental roots, implies that there is net mass flux out of the mantle under the Pacific. Here we report on a shear-wave splitting study designed to test the prediction that there should be flow around its southern margin. Our results show no evidence for present-day flow around the tip of southern South America. Instead, the results suggest present-day flow directions in the southern Atlantic that parallel the South American absolute plate motion direction, even under Antarctica. The results also provide evidence for absolute plate motion driven by the basal drag of ocean basin-scale mantle flow, and suggest that ∼200 km thick flow boundary layers exist under South America and Antarctica, and also demonstrate that mantle flow directions cannot be reliably inferred from present-day plate morphology.