Melting and storage conditions of rhyolites in the Snake River Plain Province , USA

美国蛇河平原省流纹岩的融化和储存条件

• 批准号: 398667061
• 负责人: Professor Dr. Francois Holtz, Ph.D.
• 金额: --
• 依托单位: Institut für Mineralogie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/398667061?language=en
• 关键词: Melting; storage; conditions; rhyolites; Snake; Melting; storage; conditions; rhyolites; Snake

The Snake River Plain-Yellowstone province preserves a unique record of bimodal magmatism (basalt-rhyolite) resulting from basaltic magma underplating and subsequent crustal recycling. The proposed project focuses on the generation and storage of rhyolites in the Snake River Plain (SRP) and is designed to clarify the “crustal recycling” processes occurring at depth as a result of basaltic magma underplating. A variety of generation models are currently proposed (fractionation, assimilation, partial melting) but they are not tested experimentally and, as a consequence tend to remain qualitative. Starting from one end-member hypothesis and assuming that rhyolites are formed from partial melting of crustal material, high pressure experiments will be conducted to determine the geochemical signature (major and trace elements) of partial melts produced from typical protoliths. Two main source types which are under debate will be tested: hydrothermally altered rhyolites and mafic basaltic rocks. The experimental results and the composition of the experimental melts will be compared with the composition of glasses in natural samples from the ICDP cores and from selected eruptive units covering the 16 Ma activity of the SRP. The geochemical compositions of the natural glasses will also be used to apply a new barometer recently calibrated by the proponents. Selected samples from a few eruptive units (e.g., Kimberley and Sugar City core) will be used to check if large eruptions result from different magma batches stored at various P-T conditions. The results will contribute to understand the nature of the source rocks of the rhyolites, the conditions of melting and of magma storage prior to eruption (depth, temperature, volatile contents), and the evolution of magma storage conditions in space and time.

蛇河平原石省保留了由玄武岩岩浆底层和随后的地壳回收产生的独特双峰岩浆作用（玄武岩 - 丝状石）的独特记录。拟议的项目着重于在蛇河平原（SRP）中产生和存储，并旨在阐明由于玄武岩岩浆的底板而导致的“地壳回收”过程。目前提出了各种一代模型（分馏，同化，部分熔化），但未通过实验进行测试，因此，它们往往保持定性。从一个末端成员的假设开始，并假设有节奏是由地壳材料的部分熔化形成的，将进行高压实验，以确定典型的Protoliths产生的部分熔体的地球化学特征（主要和微量元素）。将测试两种正在争论的主要源类型：氢化改变的节奏和镁铁质基本岩石。将将实验结果和实验熔体的组成与来自ICDP核心的天然样品中的玻璃的组成以及涵盖SRP 16 MA活性的选定喷发单元的组成。天然眼镜的地球化学组成也将用于应用支持者最近校准的新晴雨表。将使用来自一些喷发单元（例如金伯利和糖城核心）的选定样品来检查是否在各种P-T条件下存储的不同岩浆批次引起大型喷发。结果将有助于了解节奏的源岩的性质，喷发前熔化和岩浆存储的条件（深度，温度，挥发物内容）以及空间和时间中岩浆存储条件的演变。