Hawaiian alkaline volcanism
Hawaiian alkaline volcanism
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夏威夷碱性火山作用
DOI：
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发表时间：
1987
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影响因子：
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通讯作者：
D. Clague
中科院分区：
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作者：
D. Clague
摘要 夏威夷火山在四个喷发阶段中的三个阶段喷发碱性熔岩。第 1 阶段的特点是碱性玄武岩和玄武岩海底喷发，然后是拉斑玄武岩，仅在第 2 阶段喷发。第 3 阶段包括火山口塌陷后的碱性玄武岩盖层和相关分化。第四阶段包括碱性玄武岩、红硅岩、霞石和黄长石的侵蚀后喷发。喷发率和体积从第 1 阶段到第 2 阶段不断增加，然后在第 3 阶段和第 4 阶段下降。第 1 阶段和第 4 阶段熔岩含有深层二辉橄榄岩捕虏体（甚至在第 4 阶段熔岩中含有一些含石榴石捕虏体），而第 2 阶段熔岩仅含有非常浅的堆积物、矿脉、岩脉和岩基；第三阶段熔岩主要含有纯橄榄岩、韦尔岩和各种堆积物。捕虏体组合反映了岩浆储存库的发育，岩浆储存库充当水力过滤器，去除岩浆储存库下方夹带的任何捕虏体。岩浆储存系统的发展是对四个喷发阶段不同岩浆供应率的直接响应。微量元素、同位素和稀有气体数据都表明夏威夷熔岩是由至少由三种不同成分组成的异质源产生的。来源或源自这些来源的部分熔体的混合是不可避免的；然而，混合端部件的特性并没有得到很好的限制。一般而言，早期和晚期熔岩是由富含不相容元素较少的来源的小程度熔融产生的，而大量的盾状拉斑玄武岩是由富含不相容元素较多的来源的大程度熔融生成的。
Summary Hawaiian volcanoes erupt alkalic lavas during three of four eruptive stages. Stage 1 is characterized by submarine eruption of alkalic basalt and basanite followed by tholeiitic basalt which is exclusively erupted during stage 2. Stage 3 consists of a post-caldera-collapse capping of alkalic basalt and related differentiates. Stage 4 consists of post-erosional eruptions of alkalic basalt, basanite, nephelinite and melilitite. Eruption rates and volumes increase from stage 1 to stage 2 and then decline through stages 3 and 4. Stage 1 and 4 lavas contain deep-seated lherzolite xenoliths (even some garnet-bearing xenoliths in stage 4 lavas) whereas stage 2 lavas contain only very shallow cumulates, veins, dykes and sills; stage 3 lavas contain mainly dunite, wehrlite and various cumulates. The xenolith assemblages reflect the development of magma storage reservoirs which act as hydraulic filters in removing any xenoliths entrained below the magma storage reservoirs. The development of the magma storage system is a direct response to varying magma supply rates during the four eruptive stages. Trace-element, isotopic and rare-gas data all indicate that Hawaiian lavas are generated from heterogeneous sources consisting of at least three distinct compositions. Mixing of the sources or of partial melts derived from these sources is inevitable; however, the characteristics of the mixing end-members are not well constrained. In a general way, early and late lavas are generated by small degrees of melting of sources enriched with less incompatible elements, whereas the voluminous shield tholeiites are generated by large degrees of melting of sources enriched with more incompatible elements.