Microanalysis of Oxygen Isotope Ratios in Zircon from Metamorphosed Igneous Rocks

9628260谷这项研究是工作的继续，以开发和应用新技术的稳定同位素比的微观分析。 PI将分析来自北卡罗来纳州格伦维尔和上级省变质火成岩中锆石的氧同位素比。美国参考在格伦维尔，锆石研究的一个目标是绘制斜长岩套岩浆活动的高火成岩（18 O）值范围的界限，据信这代表了地壳深部的异常情况。在上级省，锆石的初步分析表明，（18）O的显着差异，似乎与地壳污染的数量。在关键地区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~（18）O分带或继承性，用电子探针分析锆石的分带和蚀变。 初步研究表明，不同的域和（18 O）的差异将被发现，锆石的分析将有广泛的意义，加拿大地盾的关键部分的磁演化。这可能会导致新的标准来评估构造组装的格伦维尔，或各种增生板块构造过程，现在提出的地壳形成的上级省。

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.