Magma mixing at mid-ocean ridges: Evidence from basalts drilled near 22° N on the Mid-Atlantic Ridge
Magma mixing at mid-ocean ridges: Evidence from basalts drilled near 22° N on the Mid-Atlantic Ridge
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DOI：
10.1016/0040-1951(79)90334-2
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发表时间：
1979-05
期刊：
影响因子：
2.9
通讯作者：
J. Rhodes;M. Dungan;D. Blanchard;P. Long
中科院分区：
文献类型：
--
作者：
J. Rhodes;M. Dungan;D. Blanchard;P. Long
本文总结了深海钻探项目第45和46航次期间回收的玄武岩的详细岩石学、地球化学和实验研究结果，并提出了岩浆混合在这些和其他海底玄武岩演化中发挥重要作用的证据，沿着晶体分馏。三个主要的证据被认为是，包括斑晶矿物学，熔体包裹体成分，和整个岩石的主要和微量元素化学。两者合计，这一证据表明，“原始”岩浆及其伴随的斑晶是间歇性注入到分馏岩浆房含有更多的进化同生岩浆。这种岩浆反复注入、混合和分馏的稳定过程的主要产物是适度演化的洋底玄武岩。成分极端，包括“原始”，幔源原始岩浆和高度进化的分异产物，将是罕见的。这一模型解释了以前用部分熔融和晶体分馏过程不能充分解释的海底玄武岩的几个神秘的岩石学特征。因此，它建议，岩浆混合是一个基本的过程，是内在相关的海底玄武岩岩石成因中的晶体分馏。
This paper summarizes the results of a detailed petrological, geochemical and experimental study of basalts recovered during Legs 45 and 46 of the Deep Sea Drilling Project, and presents evidence that magma mixing has played an important role, along with crystal fractionation, in the evolution of these and other sea-floor basalts. Three major lines of evidence are considered, including phenocryst mineralogy, melt inclusion compositions, and whole rock major and trace element chemistry. Taken together, this evidence indicates that “primitive” magmas and their attendant phenocrysts are episodically injected into fractionating magma chambers containing more evolved cogenetic magmas. The dominant products of this steady-state process of repeated magma injection, mixing and fractionation are moderately evolved ocean floor basalts. Compositional extremes, including “primitive”, mantle-derived primary magmas and highly evolved differentiation products, will be rare. This model accounts for several enigmatic petrological characteristics of ocean-floor basalts previously inadequately explained by partial melting and crystal fractionation processes. Consequently, it is suggested that magma mixing is a fundamental process that is intrinsically interrelated with crystal fractionation in ocean-floor basalt petrogenesis.