Microanalysis of Oxygen Isotope Ratios in Zircon from Metamorphosed Igneous Rocks

9628260山谷这项研究是开发和应用稳定同位素比率微量分析新技术的继续工作。PI将分析北美格伦维尔和苏必利省变质火成岩中的锆石中的氧同位素比率。在格伦维尔，锆石研究的目标之一将是绘制高火成岩区域的界限(斜长岩系列岩浆活动的18O值，据信代表地壳深部的异常条件)。在苏必利省，对锆石的初步分析表明，(18O)存在显著差异，这似乎与地壳污染量有关。关键地区有限的实地工作和对共存矿物的分析将考验数据的独特性或普遍性。单个锆石将通过离子探针进行分带或(18O)的继承分析，并通过电子探针进行分带和蚀变分析。初步研究表明，将发现不同的磁区和(18O)差异，对锆石的分析将对加拿大地盾关键部分的磁演化具有广泛的意义。这可能会导致新的标准来评估格伦维尔的构造组合，或者现在被提议用于上位省地壳形成的各种增生板块构造过程。

9628260 Valley This research is a continuation of work to develop and apply new techniques for micro-analysis of stable isotope ratios. The PI will analyze oxygen isotope ratios in zircons from metamorphosed igneous rocks of the Grenville and Superior Provinces of N. America. In the Grenville, one goal of the zircon research will be to map the limits of a domain of high igneous (18O values for anorthosite-suite magmatism, believed to represent anomalous conditions in the deep crust. In the Superior Province, preliminary analysis of zircons show significant differences in (18O that appear to correlate to the amounts of crustal contamination. Limited field work in key areas and analysis of co-existing mineral will test the uniqueness or generality of the data. Individual zircons will be analyzed by ion probe for zonation or inheritance of (18O and by electron probe for zonation and alteration. Preliminary studies suggest that distinct domains and (18O differences will be found and that the analysis of zircons will have broad significance for the magnetic evolution of critical portions of the Canadian Shield. This may lead to new criteria for assessing the tectonic assembly of the Grenville, or various accretionary plate tectonic processes that are now proposed for crust formation in the Superior Province.