Deformation-related volcanism in the Pacific Ocean linked to the Hawaiian–Emperor bend
Deformation-related volcanism in the Pacific Ocean linked to the Hawaiian–Emperor bend
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DOI：
10.1038/ngeo2416
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发表时间：
2015-05
影响因子：
18.3
通讯作者：
J. O’Connor;K. Hoernle;R. Müller;J. Morgan;N. Butterworth;F. Hauff;D. Sandwell;W. Jokat;J. Wijbrans;P. Stoffers
中科院分区：
文献类型：
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作者：
J. O’Connor;K. Hoernle;R. Müller;J. Morgan;N. Butterworth;F. Hauff;D. Sandwell;W. Jokat;J. Wijbrans;P. Stoffers
人们认为海洋岛屿、海山和火山脊是在地幔柱之上形成的。然而，这种机制无法解释太平洋海底的许多火山特征，有些可能是由与板块运动重组相关的洋壳裂缝引起的。夏威夷-皇帝火山链的独特弯曲与太平洋板块运动方向的变化、夏威夷羽流的运动或两者的组合有关。然而，这些联系是不确定的，因为没有独立的记录可以精确确定影响太平洋板块的构造事件的日期。在这里，我们分析了从音乐家山脊（靠近夏威夷-皇帝弯形成的火山海山线）采集的熔岩样本的地球化学特征。我们发现这些熔岩的地球化学特征与典型的洋岛玄武岩不同，而是类似于洋中脊玄武岩。我们推断，这些海山与地幔柱活动无关，而是在太平洋板块变形的拉张环境中形成的。40Ar/39Ar测年表明，音乐家海脊是在夏威夷-皇帝弯曲形成时间的两个时间窗口（53-52年和48-4700万年前）形成的。我们得出的结论是，夏威夷-皇帝弯曲是由板块-地幔重组形成的，可能是由太平洋板块边缘的一系列俯冲事件引发的。
Ocean islands, seamounts and volcanic ridges are thought to form above mantle plumes. Yet, this mechanism cannot explain many volcanic features on the Pacific Ocean floor and some might instead be caused by cracks in the oceanic crust linked to the reorganization of plate motions,,. A distinctive bend in the Hawaiian–Emperor volcanic chain has been linked to changes in the direction of motion of the Pacific Plate,, movement of the Hawaiian plume,,, or a combination of both. However, these links are uncertain because there is no independent record that precisely dates tectonic events that affected the Pacific Plate. Here we analyse the geochemical characteristics of lava samples collected from the Musicians Ridges, lines of volcanic seamounts formed close to the Hawaiian–Emperor bend. We find that the geochemical signature of these lavas is unlike typical ocean island basalts and instead resembles mid-ocean ridge basalts. We infer that the seamounts are unrelated to mantle plume activity and instead formed in an extensional setting, due to deformation of the Pacific Plate.40Ar/39Ar dating reveals that the Musicians Ridges formed during two time windows that bracket the time of formation of the Hawaiian–Emperor bend, 53–52 and 48–47 million years ago. We conclude that the Hawaiian–Emperor bend was formed by plate–mantle reorganization, potentially triggered by a series of subduction events at the Pacific Plate margins.