An integrated kinematic and geochemical model to determine lithospheric extension and mantle temperature from syn-rift volcanic compositions
An integrated kinematic and geochemical model to determine lithospheric extension and mantle temperature from syn-rift volcanic compositions
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DOI：
10.1016/j.epsl.2008.11.012
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发表时间：
2009-02
影响因子：
5.3
通讯作者：
S. Dean;B. Murton;T. Minshull;T. Henstock;R. White
中科院分区：
文献类型：
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作者：
S. Dean;B. Murton;T. Minshull;T. Henstock;R. White
我们提出了一个综合的运动学和地球化学模型，以确定大陆裂谷期间地幔减压熔融产生的熔体及其残余烃源岩的组成。我们的方法是构建一个统一的数值解，该解融合了确定熔融发生速度和深度的已建立的岩石圈拉伸模型，以及用于预测初级熔体组成的地幔熔融的几个成分参数化。我们还加入了稀土元素的参数化。利用我们的方法，我们能够在熔融过程中跟踪熔体组分和地幔残留物的组成。我们的统一模型表明，初级熔体成分对裂谷持续时间和地幔温度敏感，快速裂谷和较高的地幔温度比缓慢/较冷的裂谷产生更大的熔体成分，在更大的平均熔化压力下。将模型结果与北大西洋扩张脊和裂陷边缘的原始玄武岩进行对比，表明可以从适当的地球化学数据独立推断出裂谷持续时间和辐合地幔温度。
We present an integrated kinematic and geochemical model that determines the composition of melts and their residual source rocks generated by decompression melting of the mantle during continental rifting. Our approach is to construct a unified numerical solution that merges an established lithospheric stretching model which determines the rate and depth at which melting occurs, with several compositional parameterisations of mantle melting to predict the composition of primary melts. We also incorporate a parameterisation for the rare earth elements. Using our approach, we are able to track the composition of the melt fractions and mantle residues as melting progresses. Our unified model shows that primary melt composition is sensitive to rift duration and mantle temperature, with rapid rifting and higher mantle temperatures producing larger melt fractions, at a greater mean pressure of melting, than slower/cooler rifting. Comparison of the model results with primitive basalts recovered from oceanic spreading ridges and rifted margins in the North Atlantic indicates that rift duration and synrift mantle temperature can be inferred independently from the appropriate geochemical data.