The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes
The origin and crust/mantle mass balance of Central Andean ignimbrite magmatism constrained by oxygen and strontium isotopes and erupted volumes
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DOI：
10.1007/s00410-015-1152-5
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发表时间：
2015-06-01
影响因子：
3.5
通讯作者：
Woerner, Gerhard
中科院分区：
文献类型：
--
作者：
Freymuth, Heye;Brandmeier, Melanie;Woerner, Gerhard
安第斯山脉中央火山带（CVZ）新近纪的火山作用产生了（1）成层火山，（2）流纹岩至流纹岩熔结凝灰岩，体积通常小于300 km（3）和（3）大体积的单调英安岩熔结凝灰岩，可达数千立方公里。我们提出的模型，这些岩浆类型的起源，使用O和Sr同位素来限制壳/幔比例的大体积熔结凝灰岩和探索安第斯地壳的演化关系。为了避免次生蚀变的影响，在斑晶上测量了氧同位素比值。我们的研究结果表明，在Sr-O同位素组成的熔岩从成层火山和低容量的流纹质熔结凝灰岩以及老（>9马）大容量的英安质熔结凝灰岩的完全重叠。这表明地壳和地幔成分的质量平衡基本相似。相比之下，年轻人（
Volcanism during the Neogene in the Central Volcanic Zone (CVZ) of the Andes produced (1) stratovolcanoes, (2) rhyodacitic to rhyolitic ignimbrites which reach volumes of generally less than 300 km(3) and (3) large-volume monotonous dacitic ignimbrites of up to several thousand cubic kilometres. We present models for the origin of these magma types using O and Sr isotopes to constrain crust/mantle proportions for the large-volume ignimbrites and explore the relationship to the evolution of the Andean crust. Oxygen isotope ratios were measured on phenocrysts in order to avoid the effects of secondary alteration. Our results show a complete overlap in the Sr-O isotope compositions of lavas from stratovolcanoes and low-volume rhyolitic ignimbrites as well as older (>9 Ma) large-volume dacitic ignimbrites. This suggests that the mass balance of crustal and mantle components are largely similar. By contrast, younger (