Samoa reinstated as a primary hotspot trail
Samoa reinstated as a primary hotspot trail
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DOI：
10.1130/g24630a.1
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发表时间：
2008-06-01
期刊：
影响因子：
5.8
通讯作者：
Hart, Stanley R.
中科院分区：
文献类型：
--
作者：
Koppers, Anthony A. P.;Russell, Jamie A.;Hart, Stanley R.
产生热点轨迹的经典模型认为，静止的深层地幔柱撞击上覆构造板块，从而产生火山岛和海山的年龄渐进轨迹。萨摩亚在否定这一模型和地幔柱存在的过程中扮演了关键角色，因为早期的年代学工作未能证明沿着这一岛链的线性年龄增长。特别是在萨瓦伊岛，大部分的陆上火山岩是年轻的0.39马，比5.1马的年龄从经典的热点模型和恒定的7.1厘米/年的太平洋板块运动预测年轻得多。这种差异导致了替代的岩浆产生机制，涉及萨摩亚群岛下方的岩石圈破裂，作为附近汤加海沟产生的伸展制度的结果。在这里，我们报告40 Ar/39 Ar年龄从萨瓦伊岛的海底侧翼显示，其火山建设早在5.0马开始，并在一个真正的板内设置。这恢复萨摩亚作为一个主要的热点线索与深地幔柱和线性年龄进展。
The classical model for the generation of hotspot tracks maintains that stationary and deep-seated mantle plumes impinge on overriding tectonic plates, thereby generating age-progressive trails of volcanic islands and seamounts. Samoa has played a key role in discrediting this model and the very existence of mantle plumes, because early geochronological work failed to demonstrate a linear age progression along this chain of islands. Specifically on Savai'i Island, the bulk of the subaerial volcanics is younger than 0.39 Ma, much younger than the 5.1 Ma age predicted from the classical hotspot model and a constant 7.1 cm/yr Pacific plate motion. This discrepancy led to alternative magma-producing mechanisms that involve the cracking of the lithosphere beneath the Samoan islands, as a result of the extensional regime generated by the nearby Tonga Trench. Here we report 40Ar/39Ar ages from the submarine flanks of Savai'i Island showing that its volcanic construction began as early as 5.0 Ma and in a true intraplate setting. This reinstates Samoa as a primary hotspot trail associated with a deep mantle plume and a linear age progression.