The quaternary caldera volcano emuruangogolak, kenya rift, and the petrology of a bimodal ferrobasalt-pantelleritic trachyte association
The quaternary caldera volcano emuruangogolak, kenya rift, and the petrology of a bimodal ferrobasalt-pantelleritic trachyte association
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肯尼亚裂谷第四纪火山口火山 emuruangogolak 和双峰铁玄武岩-潘泰里晶粗面岩组合的岩石学
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发表时间：
1977
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通讯作者：
S. Weaver
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作者：
S. Weaver
埃穆鲁安戈戈拉克火山是一座第四纪玄武岩火山，位于肯瓦裂谷北部的苏古塔地块，可能于本世纪初喷发。在建造早期粗面盾状火山之后，发生了两次破火山口坍塌事件。每一次之前都有爆炸性的碎裂活动。后加莱拉火山作用由玄武岩和粗面岩交替喷发组成。基性熔岩是中等碱性的过渡成分的高钛铁玄岩，粗面岩是过碱性和过饱和的。存在明显的成分双峰性，在49-59°范围内没有岩石。SiO，已被发现。常量元素和微量元素分析表明，粗面岩与玄武岩有成因上的联系。埃塞俄比亚出现了几乎相同的熔岩组合。Pantelleria和Azores，但存在中间阶段，分离结晶是目前首选的解释粗面岩起源的机制。“戴利缺口”可能是结晶过程的结果，这种结晶过程限制了任何时候可用的中间岩浆的体积。此外，不同岩浆的物理性质和空间分布可能不同于中间成分熔岩的破裂。
Emuruangogolak is a Quaternary basalitrachyte volcano situated in the Suguta graben of the northern Kenva rift, and probably erupted last early in this century. Following the construction of an early trachytic shield volcano, two episodes of caldera collapse occurred. each preceded by explosive pvroclastic activity. Post-calelera volcanism consisted of alternating phases of basalt and trachyte eruption.The basic lavas are high-Ti ferrobasalts of a mildly alkaline ‘transitional’ composition and the trachytes are peralkaline and oversaturated. A distinct compositional bimodality exists and no rocks in the range 49–59°. SiO, have been found. Major and trace element analyses suggest that the trachytes are genetically related to the basalts. Associations of almost identical lavas occur in Ethiopia. Pantelleria and the Azores but with the presence of intermediate terms Fractional crystallization is the mechanism currently preferred to account for the origin of the trachytes. The ‘Daly gap’ may be a consequence of a crystallization process which limits the volume of intermediate magma available at any time. In addition, the physical properties and spatial distribution of the different magmas probably discriminate against the cruption of lavas of intermediate composition.