Gravitational Instability in Coexisting Layered Magmas: Isle au Haut, Maine

这项提案寻求为缅因州豪特岛上的花岗岩-闪长岩-辉长岩协会的综合野外、地球化学和岩石学研究提供资金。这些岩石是更广泛的缅因湾火成岩杂岩的一部分。这项研究的主要关注点将是记录和了解层状辉长岩和闪长岩单元的惊人暴露序列，我们认为这些单元是一系列共存熔体的冻结遗迹。场关系清楚地表明，这些层中的几个是重力不稳定的，处于倾覆和混合过程中。最近将流体动力学应用于岩浆室模型的理论研究表明，成分带岩浆室、层状岩浆层和不同岩浆类型的混合在火成岩的形成中起着重要作用。在Au Haut岛上，我们可能是第一次有一个前所未有的机会，获得关于分层岩浆室中共存岩浆的系统岩石学和地球化学数据。根据这些数据，我们将能够评估最近的流体动力学和实验研究预测的岩浆储集层中发生的许多岩浆过程。

This proposal seeks funding for an integrated field, geochemical and petrographic study of a granite-diorite-gabbro association on the island of Isle au Haut, Maine. These rocks are part of the more extensive Bays-of-Maine Igneous Complex. A major concern of this research will be to document and understand a spectacularly exposed sequence of layered gabbro and diorite units which we believe to be the frozen relics of a sequence of coexisting melts. Field relationships show clearly that several of these layers were gravitationally unstable, and were in the process of overturning and mixing. Recent theoretical studies applying fluid dynamics to magma chamber models predict that compositionally zone magma chambers, stratified magmatic layers, and mixing of distinct magma types play important roles in the petrogenesis of igneous rocks. On Isle au Haut we have, perhaps for the first time, an unprecedented opportunity to obtain systematic petrographic and geochemical data on coexisting magmas within a stratified magma chamber. From this data we will be able to evaluate many of the magmatic processes predicted to occur in magma reservoirs by recent fluid dynamics and experimental studies.