Mass and Heat Flux From Miocene to Present at Aucanqvilcha Volcano, Andes of Northern Chile

98149441 grunder俯冲带构造活动与火山活动之间的联系仍然是地质学中的基本问题。本研究的目的是对安第斯山脉中部一座大型长寿火山进行体积和时间限制分析，以期评估这一经典大陆俯冲带背景下的质量和热通量。奥坎奎尔查火山和周围的火山群跨越了至少940万年的火山历史，喷发量约为170立方公里。由于长期的干旱气候，从中新世到现在保存下来的火山大厦记录是无与伦比的。奥坎奎尔查群的组成和同位素特征符合区域趋势，是这一显著大陆弧的典型代表。本研究的方法是：(1)通过广泛的测绘和辐射测年来记录体积和成分的变化；(2)识别各阶段岩石作用过程和地壳储层，并获得随时间变化的物质平衡；(3)计算由质量通量决定的热量收支，评估地壳增厚和基性岩浆输入地壳的时间变化。重点是通过地质和地质年代学数据将所有过程置于时间背景下。正是因为火山作用提供了岩浆过程的连续采样，所以计划中的方法有望解决与大陆弧背景下岩浆作用有关的基本未解决问题。

9814941GrunderThe links between subduction-zone tectonic activity and volcanism remain fundamental problems in geology. The object of this study is a volume and time-constrained analysis of a large and long-lived volcano in the Central Andes with a view toward evaluating the mass and heat flux in this classic continental subduction zone setting.Aucanquilcha volcano and the surrounding cluster of volcanoes span at least 9.4 million years of volcanic history and constitute an erupted volume of about 170 km3. The preserved record of volcanic edifices from Miocene to present is unparalleled due to a prolonged arid climate. Compositionally and isotopically the Aucanquilcha cluster conforms with regional trends and so is typical of this remarkable continental arc. The approach to this study is: (1) to document changes in volume and composition in time through extensive mapping and radiometric dating; (2) to identify the petrologic processes and crustal reservoirs at each stage and to obtain a mass balance through time; and (3) to calculate the heat budget dictated by the mass flux and evaluate temporal variations in crustal thickening and mafic magma input into the crust. The emphasis is to place all processes in a temporal context through geologic and geochronologic data. It is precisely because volcanism provides sequential sampling of magmatic processes that the planned approach yields significant promise of addressing fundamental unresolved issues pertaining to magmatism in continental arc settings.