87Sr/86Sr as an Isotopic Ratemeter for Dynamic Processes in High-Rb/Sr Zoned Magma Bodies: Application to the Bandelier Tuff

9316477沃尔夫拟议的研究项目将利用可测量的演化87 Sr/86 Sr的生命周期的一个大型流纹岩岩浆系统非常高的Rb/Sr，调查和限制的速度和性质的过程中造成成分环带。 研究的流纹岩系是新墨西哥州杰梅斯山班德利尔凝灰岩Otowi段（或下段）在1.51 Ma喷发形成的流纹岩系。 要遵循的程序依赖于分析长石，基质玻璃和玻璃夹杂物的小样品中非常少量的Sr（低至1 ng）。 这项工作的结果将使各种过程中所涉及的成分分带（封闭系统分异，斑晶积累，围岩污染，岩浆补给）的Otowi成员岩浆的贡献进行量化。 更重要的是，任何贡献的时间，速度和机制，从封闭系统分异可以更密切地限制比可能在一个传统的地球化学研究。

9316477 Wolff The proposed research project will exploit the measurable evolution of 87Sr/86Sr over the lifetime of a large rhyolitic magma system with very high Rb/Sr, to investigate and constrain the rates and nature of processes causing compositional zonation. The rhyolitic system to be studied is that which erupted at 1.51 Ma to form the Otowi (or Lower) Member of the Bandelier Tuff, Jemez Mountains, New Mexico. The procedure to be followed relies on analyzing very small amounts of Sr (down to 1 ng) in small samples of feldspar, matrix glass, and glass inclusions. The results of this work will enable the contribution of various processes involved in compositional zonation (closed-system differentiation, phenocrysts accumulation, wall-rock contamination, magmatic recharge) of the Otowi Member magma to be quantified. More significantly, the timing, rates, and mechanism of any contribution from closed-system differentiation can be constrained more closely than is possible in a conventional geochemical study.