Microanalysis of Oxygen Isotope Ratios in Zircon from Metamorphosed Igneous Rocks

这项研究是开发和应用稳定同位素比率微分析新技术工作的继续。PI将分析北美格伦维尔省和苏必利尔省变质火成岩中锆石的氧同位素比率。在格伦维尔，锆石研究的一个目标将是绘制出高火成岩（18O）值的斜长岩套岩浆活动区域的边界，据信这代表了地壳深处的异常情况。在苏必利尔省，对锆石的初步分析显示（18O）的显著差异似乎与地壳污染的数量有关。在关键地区进行的有限实地工作和对共存矿物的分析将检验数据的独特性或普遍性。用离子探针分析单个锆石的（18O）分带或继承，用电子探针分析锆石的分带和蚀变。初步研究表明，将发现明显的磁域和（18O）差异，锆石分析对加拿大地盾关键部分的磁演化具有广泛意义。这可能为评估格伦维尔的构造组合提供新的标准，或者为苏必利尔省的地壳形成提出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.