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首页> 外文期刊>Contributions to Mineralogy and Petrology >Evolution of pantellerite-trachyte-phonolite volcanoes by fractional crystallization of basanite magma in a continental rift setting, Marie Byrd Land, Antarctica
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Evolution of pantellerite-trachyte-phonolite volcanoes by fractional crystallization of basanite magma in a continental rift setting, Marie Byrd Land, Antarctica

机译：南极大陆裂谷背景下的玄武岩岩浆的分步结晶演化成的pantellerite-trachyte-vololite火山

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摘要

The Marie Byrd Land province includes 18 large (up to 1,800 km~3) central volcanoes distributed across an active volcano-tectonic dome. The typical volcano structure consists of a basal 1,000-5,000 m of basanite surmounted by trachyte and subordinate intermediate rocks, plus phonolite, or pantellerite, or comendite. The volumes of felsic sections are large (～ 30-700 km~3), but these rocks probably make up <10% of volcanic rock in the province. This paper describes pantellerite volcanoes in the Ames and Flood Ranges, which include a large and varied suite of these iron-rich, silica-poor rhyolites. Isotopic and trace element data, maintenance of isotopic equilibrium throughout the basalt-felsic range, and the results of modeling, all exclude significant crustal contamination and point to fractional crystallization as the process that controls magmatic evolution. The most unusual feature of these volcanoes is the apparent need to derive pantellerites from basanite, the long interval of fractionation at the base of the lithosphere and crust, involving kaersutite as the key phase in developing pantellerite, and a plumbing system that permitted coeval eruption of pantellerite and phonolite from the same edifice. Peralkalinity most likely developed in upper crustal reservoirs during the final 4-5% of magmatic history, by fractionating a high proportion of pla-gioclase under low pH_2O. Mantle plume activity appears to drive doming and volcanism. This, a stationary plate, and continental lithospheric structure seem to provide an optimal environment for the evolution of a diverse, large volume suite of felsic rocks by fractional crystallization.
机译：玛丽·伯德（Marie Byrd Land）省包括18个大型（长达1800 km〜3）大型中央火山，分布在活跃的火山构造圆顶上。典型的火山结构由1,000-5,000 m的basanite基底组成，该basanite基底由曲奇和次要的中间岩层覆盖，再加上方沸石，pantellerite或comonite。长岩段的体积很大（〜30-700 km〜3），但这些岩石可能占该省火山岩的不到10％。本文介绍了艾姆斯山脉和洪泛山脉中的pantellerite火山，其中包括各种各样的富含铁，贫硅的流纹岩。同位素和微量元素数据，在玄武岩-长石质范围内维持同位素平衡以及建模结果均排除了严重的地壳污染，并指出了部分结晶作用是控制岩浆演化的过程。这些火山的最不寻常的特征是，显然需要从玄武岩中提取出蝶粉岩，在岩石圈和地壳底部分馏的间隔很长，涉及到以斑岩为发育蝶粉岩的关键相，并且还存在一个管道系统，可以使该岩层同时喷发。相同建筑中的膨润土和方沸石。通过在低pH_2O下分馏高比例的pla-gioclase，最有可能在岩浆史的最后4-5％期间在上地壳储层中形成过碱性。地幔羽活动似乎推动了穹隆和火山活动。这种固定的板块和大陆性岩石圈结构似乎为通过分步结晶演化出多样化，大体积的长英质岩石提供了最佳的环境。

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