RUI: Volcanic, Petrologic, and Geochemical Evolution of Darwin Volcano, Galapagos

加拉帕戈斯群岛西部是地球上最活跃的火山地区之一。对达尔文火山的火山学、岩石学和地球化学研究旨在检验关于加拉帕戈斯型盾状火山生长及其地球化学变化的相互竞争的假设。它们独特的“倒过来的汤盘”形态的起源不仅仅是一个地方问题：加拉帕戈斯型盾可能是许多海底山和地外火山的特征。人们对达尔文火山所知甚少，但从最底部的几个侦察标本中发现，它主要由玄武岩组成，其同位素组成介于中洋脊喷发的熔岩和热点喷发的熔岩之间。尽管它们具有同位素特征，但同样的熔岩富含不相容元素，更典型的是洋岛玄武岩。之所以选择达尔文火山进行这项研究，是因为尽管它实际上还没有被研究过，但它位于伊莎贝拉岛上的阿尔塞多火山和沃尔夫火山两个研究得很好的火山之间。在地球化学变化、海拔、形状和火山口深度方面，阿尔塞多火山和沃尔夫火山代表了加拉帕戈斯群岛西部的两个末端成员，对达尔文火山的研究将允许测试和改进预测这些不同地球化学系统和火山形态起源的模型。该项目的目标是深入了解海洋-岛屿岩浆作用的基本过程。这包括：1)记录火山喷发过程以及形成达尔文火山的喷发年表、分布和数量；2)确定达尔文熔岩的岩石学和地球化学变化，以记录岩浆的产生、储存和喷发过程；3)将达尔文火山与其他得到充分研究的西加拉帕戈斯火山进行比较，以验证每个火山的岩浆供应率不仅是熔岩地球化学变化的主要控制因素，而且是每个火山独特的大小、形状和火山口形态的主要控制因素。

NaumannEAR-0207962The western Galapagos archipelago is one of the most active volcanic areas on Earth. This volcanologic, petrologic, and geochemical study of Darwin volcano is designed to test competing hypotheses for the growth of Galapagos-type shield volcanoes and their geochemical variations. The origin of their distinct "overturned soup plate" morphology is not merely a provincial issue: Galapagos-type shields may be characteristic of many seamounts and extraterrestrial volcanoes. Little is known of Darwin volcano, but several reconnaissance specimens from the lowermost flanks indicate that it is mostly made up of basalts with isotopic compositions are between those of lavas erupted from mid-oceanic ridges and those erupted from hotspots. Despite their isotopic character, the same lavas are rich in incompatible elements, more typical of ocean-island basalts. Darwin volcano was chosen for this study because although it remains virtually unstudied, it is situated between the two well-studied volcanoes of Alcedo and Wolf on Isabela Island. Alcedo and Wolf volcanoes represent two end members in the western Galapagos with respect to geochemical variation, elevation, shape, and caldera depth, and the study of Darwin volcano will allow for testing and refinement of models that predict the origin of these diverse geochemical systems and volcano morphologies.The goals of this project seek insights into the fundamental processes of ocean-island magmatism. These include: 1) documentation of the eruptive processes and the chronology, distribution and volume of eruptions that have constructed Darwin volcano; 2) determination of the petrologic and geochemical variation of Darwin's lavas in order to document the processes involved with the generation, storage, and eruption of magmas; and 3) a comparison of Darwin volcano with other well-studied western Galapagos volcanoes in order test the hypothesis that the magma supply rate to each volcano is the dominant control not only of the geochemical variation of lavas but also each volcanoes unique size, shape and caldera morphology.