The use of mafic dike swarms in identifying and locating mantle plumes
The use of mafic dike swarms in identifying and locating mantle plumes
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DOI：
10.1130/0-8137-2352-3.247
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
R. Ernst;K. Buchan
中科院分区：
文献类型：
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作者：
R. Ernst;K. Buchan
岩墙群，特别是长达300 km的巨型岩墙群，是识别和定位地幔柱的重要工具。虽然与前中生代羽流有关的火山成分往往会因侵蚀或构造过程而消失，但岩脉可能会幸存下来。到目前为止，大约有30个巨大的岩墙群被确认形成辐射状分布。这些巨大的辐射状岩脉群被认为聚集在到达的羽状头中心上方，并为洪水玄武岩提供食物。超出羽流产生的隆起（1000公里，从羽流中心）的辐射群的一部分摆动到羽流产生的隆起外部的区域应力场的方向，因此，只提供有限的信息羽流中心的位置。地幔柱中心通常位于大陆分裂边界附近。在这种情况下，只有一部分的辐射图案被保存在一个单一的大陆片段，和古大陆重建需要重新组装整个群。到达海洋地壳之下的羽流产生了海洋高原，也许还有巨大的辐射群。大洋高原的大部分都在俯冲过程中消失了，但岩墙群的一部分可能会在附近的大陆上保存下来。在100个已被编入目录的巨型线状星群中，有许多可能是未被识别的巨型辐射星群的一部分。提出了使用这些线性群来帮助限制羽状头中心位置的标准。更进一步的推测是，一些巨大的弧形星团可能部分地包围了羽状头区域，因此有助于确定其中心。最后，岩脉群与大陆下方的羽状尾位于尾部上方，但有一个外部区域应力场控制的方向。
Dike swarms, especially giant dike swarms with lengths 300 km, are an important tool for identifying and locating mantle plumes. Although the volcanic component associated with pre-Mesozoic plumes is often lost to erosion or tectonic processes, the dikes may survive. About 30 giant dike swarms have so far been recognized to form radiating distributions. These giant radiating dike swarms are thought to converge above the centers of arriving plume heads and feed flood basalts. The part of a radiating swarm beyond the plume-generated uplift (1000 km from the plume center) swings into the direction of the regional stress field external to the plume-generated uplift and, therefore, provides only limited information on the location of the plume center. The plume center is often located near a continental breakup boundary. In such cases, only a portion of the radiating pattern is preserved on a single continental fragment, and a paleocontinental reconstruction is needed to reassemble the whole swarm. Plumes arriving beneath oceanic crust generate oceanic plateaus and perhaps giant radiating swarms. Most of an oceanic plateau is lost to subduction, but parts of the dike swarm could be preserved on nearby continents. Many of 100 giant linear swarms that have been catalogued may represent parts of unrecognized giant radiating swarms. Criteria are proposed for using these linear swarms to help constrain the location of the center of the plume head. More speculatively, some giant arcuate swarms may partly circumscribe the plume-head region and, hence, help define its center. Finally, dike swarms associated with plume tails beneath continents are located above the tail but have an orientation controlled by the external regional stress field.