The importance of rift history for volcanic margin formation
The importance of rift history for volcanic margin formation
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DOI：
10.1038/nature09063
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发表时间：
2010-06-17
期刊：
影响因子：
64.8
通讯作者：
Minshull, Tim A.
中科院分区：
文献类型：
--
作者：
Armitage, John J.;Collier, Jenny S.;Minshull, Tim A.
裂谷和岩浆活动是塑造我们星球表面的基本地质过程。两者之间的关系被广泛承认，但其确切性质一直困扰着地球科学家，并仍存在争议。根据对北大西洋的详细观察，地幔温度被确定为控制岩浆生成的主要因素1，大多数作者试图用断裂时的地幔温度来解释在断裂边缘观察到的火山活动变化（2，3）。然而，随着在世界范围内其他裂陷边缘进行更详细的观察，这种解释的有效性以及控制破裂样式的其他因素的重要性一直备受争议（4-7）。一个这样的观察是从印度洋西北部，在那里，尽管一个陆上溢流玄武岩省，大陆分裂和热点轨道导致一个活跃的海洋岛屿火山之间的明确联系，相关的大陆边缘显示很少岩浆活动（5，8）。在这里，我们调和这些意见，通过应用一个数值模型，明确说明早期事件的扩展的影响。我们的方法使我们能够直接比较在不同地点产生的破裂岩浆活动，从而分离出关键的控制因素。我们发现，无论是在西北印度洋和更知名的北大西洋边缘，裂谷相关的岩浆活动产生的量，不仅取决于地幔温度，但在类似的程度上，裂谷的历史。继承的伸展历史可以抑制或增强熔体的产生，这可以解释以前神秘的观察。
Rifting and magmatism are fundamental geological processes that shape the surface of our planet. A relationship between the two is widely acknowledged but its precise nature has eluded geoscientists and remained controversial. Largely on the basis of detailed observations from the North Atlantic Ocean, mantle temperature was identified as the primary factor controlling magmatic production 1, with most authors seeking to explain observed variations in volcanic activity at rifted margins in terms of the mantle temperature at the time of break-up(2,3). However, as more detailed observations have been made at other rifted margins worldwide, the validity of this interpretation and the importance of other factors in controlling break-up style have been much debated(4-7). One such observation is from the northwest Indian Ocean, where, despite an unequivocal link between an onshore flood basalt province, continental break-up and a hot-spot track leading to an active ocean island volcano, the associated continental margins show little magmatism(5,8). Here we reconcile these observations by applying a numerical model that accounts explicitly for the effects of earlier episodes of extension. Our approach allows us to directly compare break-up magmatism generated at different locations and so isolate the key controlling factors. We show that the volume of rift-related magmatism generated, both in the northwest Indian Ocean and at the better-known North Atlantic margins, depends not only on the mantle temperature but, to a similar degree, on the rift history. The inherited extensional history can either suppress or enhance melt generation, which can explain previously enigmatic observations.