The Volcanic Evolution of Cerro Uturuncu: A High-K, Composite Volcano in the Back-Arc of the Central Andes of SW Bolivia
The Volcanic Evolution of Cerro Uturuncu: A High-K, Composite Volcano in the Back-Arc of the Central Andes of SW Bolivia
复制标题
乌图伦库山 (Cerro Uturuncu) 的火山演化：玻利维亚西南部安第斯山脉中部弧后的一座高 K 复合火山
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Wilder
中科院分区：
文献类型：
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作者：
G. Michelfelder;T. Feeley;A. Wilder
Cerro
位于玻利维亚西南部的乌图伦库火山是一座高钾钙碱性复合火山
建造在极厚的大陆地壳上，
安第斯中央火山带（CVZ）的弧前。喷发活动
发生在890 - 271 ka之间，在持续约620，000年的单一火山作用阶段
年建筑物由一个中央圆锥体和几个侧面通风口组成，
英安岩和安山质熔岩流和圆顶喷发。个体的数量
喷发单元范围为0.1 ~10 km 3;
乌图伦库为~89 km 3。在本文中，我们提出了新的领域，
岩石学和地球化学数据，以了解火山和
乌图伦库岩浆演化熔岩流和圆顶的范围有限，
全岩成分范围为61 wt% - 67 wt% SiO2;岩浆
包含在这些单元内的夹杂物具有53重量% - 64重量%的较大范围
二氧化硅。典型的斑晶组合为斜长石>
斜方辉石>黑云母>石英和铁钛氧化物。铅同位素比值
以高207 Pb/204 Pb为特征，
206 Pb/204 Pb和中~高208 Pb/204 Pb。
Sr和Nd同位素比值表明乌图伦库岩浆受到高87 Sr/86 Sr的改造
低143 Nd/144 Nd长英质基底岩性
岩浆迁移和分异在所有的喷发单位中，
岩石学和地球化学证据的岩浆混合和混合。在这
在这方面，岩浆混合和混合被认为是负责小
在整个火山喷发历史中，
中心
Cerro
Uturuncu, southwest Bolivia, is a high-K, calc-alkaline, composite volcano
constructed upon extremely thick continental crust approximately 125 km behind
the arc-front of the Andean Central Volcanic Zone (CVZ). Eruptive activity
occurred between 890 - 271 ka in a single phase of volcanism lasting ~620,000
years. The edifice consists of a central cone and several flank vents where
dacitic and andesitic lava flows and domes erupted. Volumes of individual
eruptive units range from 0.1 to ~10 km3; the composite volume of
Uturuncu is ~89 km3. In this paper, we present new field,
petrographic, and geochemical data in an effort to understand the volcanic and
magmatic evolution of Uturuncu. Lava flows and domes have a restricted range in
whole rock compositions ranging from 61 wt% - 67 wt% SiO2; magmatic
inclusions contained within these units have a larger range from 53 wt% - 64 wt%
SiO2. Typical phenocryst assemblages are plagioclase >
orthopyroxene > biotite >> quartz and Fe-Ti oxides. Pb isotope ratios
are characteristic of the southern CVZ by containing high 207Pb/204Pb
and 206Pb/204Pb and moderate to high 208Pb/204Pb.
Sr and Nd isotope ratios indicate that Uturuncu magmas were modified by high 87Sr/86Sr
and low 143Nd/144Nd felsic basement lithology during
magma migration and differentiation. In all eruptive units, there is
petrographic and geochemical evidence for magma mixing and mingling. In this
regard, magma mixing and mingling is considered to be responsible for the small
range in lava flow and dome compositions throughout the eruptive history of the
center.