Limited latitudinal mantle plume motion for the Louisville hotspot
Limited latitudinal mantle plume motion for the Louisville hotspot
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DOI：
10.1038/ngeo1638
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发表时间：
2012-12-01
影响因子：
18.3
通讯作者：
Williams, R.
中科院分区：
文献类型：
--
作者：
Koppers, Anthony A. P.;Yamazaki, Toshitsugu;Williams, R.
当构造板块在其位置上移动时，在深部地幔的热物质上涌的羽流上方形成的热点通常会留下火山海山的狭窄痕迹。这些海底山的痕迹是地球深部活动的极好记录者，使我们能够解开古代地幔柱运动的谜团。在上升过程中，地幔柱很可能被地幔对流力推离其垂直上升流轨迹。有人提出，在大约8000万到5000万年前，太平洋上存在着一种被称为地幔风的大规模横向位移，它使夏威夷的地幔柱向南移动了大约15度的纬度。在这里，我们使用与南太平洋路易斯维尔热点相关的四个海山的40Ar/39Ar年龄测定和古地磁倾角数据来表明该热点在其位置方面相对稳定。具体来说，路易斯维尔热点——南半球的夏威夷——在7000万到5000万年前，一直保持在与现在的南纬51度相差3-5度的范围内。虽然我们不能排除在此之前有更显著的南移，但我们认为路易斯维尔和夏威夷的热点是独立移动的，而不是作为太平洋大规模地幔风的一部分。
Hotspots that form above upwelling plumes of hot material from the deep mantle typically leave narrow trails of volcanic seamounts as a tectonic plate moves over their location. These seamount trails are excellent recorders of Earth's deep processes and allow us to untangle ancient mantle plume motions. During ascent it is likely that mantle plumes are pushed away from their vertical upwelling trajectories by mantle convection forces. It has been proposed that a large-scale lateral displacement, termed the mantle wind, existed in the Pacific between about 80 and 50 million years ago, and shifted the Hawaiian mantle plume southwards by about 15 degrees of latitude. Here we use 40Ar/39Ar age dating and palaeomagnetic inclination data from four seamounts associated with the Louisville hotspot in the South Pacific Ocean to show that this hotspot has been relatively stable in terms of its location. Specifically, the Louisville hotspot-the southern hemisphere counterpart of Hawai'i-has remained within 3-5 degrees of its present-day latitude of about 51 degrees S between 70 and 50 million years ago. Although we cannot exclude a more significant southward motion before that time, we suggest that the Louisville and Hawaiian hotspots are moving independently, and not as part of a large-scale mantle wind in the Pacific.