华北克拉通下地壳麻粒岩的Pb同位素组成

项目名称： 华北克拉通下地壳麻粒岩的Pb同位素组成

项目编号： No.41473003

项目类型： 面上项目

立项/批准年度： 2015

项目学科： 天文学、地球科学

项目作者： 张宏福

作者单位： 西北大学

项目金额： 110万元

中文摘要： 本项目以华北克拉通典型地区显生宙玄武质岩石携带的下地壳麻粒岩捕虏体和前寒武纪地体麻粒岩为研究对象，采用西北大学最新引进的飞秒激光原位分析技术，通过对这些下地壳麻粒岩捕虏体和前寒武纪地体麻粒岩中斜长石的原位Pb同位素系统分析，并结合详细的岩石学和麻粒岩中锆石的U-Pb定年以及相应的锆石氧同位素和Hf同位素地球化学研究，来探讨华北下地壳的Pb同位素组成、时空分布和演化规律，古老下地壳的破坏和改造过程及其机理、以及参与改造的底侵熔体的性质和来源。从而为我国华北岩石圈下地壳的破坏和改造过程提供Pb同位素地球化学约束。

中文关键词： Pb同位素；飞秒激光；麻粒岩；下地壳；华北克拉通

英文摘要： The project, as target on lower crust granulite xenoliths entrained in Phanerozoic basaltic rocks occurred in the typical regions of the North China Craton as well as Archean granulites exposed in the Precambrian terrane and utilizing the recently-imported sophisticated Femtosceond laser analytical technique in the Northwest University, is designed to probe the Pb isotopic composition and its temperal-spatial distribution of the lower crust beneath the North China Craton, the processes involved in the destruction and modification of the ancient lower crust of the North China Craton and its mechanism, as well as the nature and origin of the underplated melts involved in modification, through the systematic in-situ Pb isotopic analyses on the plagioclases of these lower crust granulite xenoliths and Archean granulites from the Precambrian terrane, in combination with detailed studies on granulite petrology and geochemistry such as U-Pb dating,oxygen and Hf isotopes of zircons from these garnulies. This project finally tries to provide the Pb isotopic constraints on the destruction and modification processes of the ancient lower crust of the North China Craton from a new view of plagioclase Pb isotopes.

英文关键词： Pb isotope;Femtosceond laser;Granulite;Lower crust;North China Craton