冀北大庙斜长岩体中产出著名的大庙式铁矿。大庙式铁矿除浸染状贫铁矿外，还有大量富铁矿脉充填在钠黝帘石化斜长岩中的断裂裂隙中。钠黝帘石化与脉状富铁矿空间关系密切，但它们是否具有成因联系尚不明确，确定蚀变年代和成矿时代是关键。本申请以新发现的产于钠黝帘石化斜长岩中钛铁矿裂隙的锆石、富铁矿脉中的锆石、未蚀变斜长岩钛铁矿中的斜锆石为主要研究对象：通过锆石和斜锆石的外部形态、内部结构及与其它矿物的相互关系的系统岩相学观察，查明锆石和斜锆石的赋存状态，确定其成因；采用多种微区原位测试技术研究锆石及相关蚀变矿物组合的主微量元素特征，探讨钠黝帘石化蚀变流体性质、锆石Zr和Si来源、挥发份对Zr和Si活动性影响，揭示锆石的形成机制；采用针对性的单矿物挑选方法和高精度测年手段，测定锆石年代，确定蚀变与富铁矿化及蚀变与岩体成岩的时间关系，探讨它们的成因联系，为总结大庙式铁矿成矿规律、指导深边部铁矿找矿勘查服务。

The well-known Damiao-type iron deposits occur in the Damiao anorthosite complex in Chengde area, Hebei province. In addition to the orebodies composed of disseminated iron ores, there are also abundant orebodies composed of massive ores that generally fill the vertical fractures of the altered white-colored anorthosite as irregular dykes or veins with various shapes and sizes. The wall-rcok alteration is spatially related to vein-like mineralization, but it is not clear whether they have a genetic relationship or not. Determination the age of alteration and mineralization is of vital importance. This application is based on newly discovered zircon in the fracture of ilmenite of the altered white-colored anorthosite, zircon in massive ores, and baddeleyite in the unaltered dark-colored anorthosite. Systematic petrographical observation will be carried out to ascertain the internal structure and external morphology of zircon and baddeleyite, and then to identify the genesis. A variety of micro and in-situ analyses of major and trace element characteristics of zircon and associated mineral assemblages will be carried out to explore the formation of albitization and zoisitization of the anorthosite, Zr and Si source of zircon, the influence of volatile on the activity of Zr and Si, and then to reveal the mechanisms for generating zircon; Specific selection and high-precision zircon dating methods will be carried out to determine the age of alteration and high-grade mineralization, and then to discuss their relationship. The application can provide important support both to the regularity of ore formation and to deep prospecting for Damiao-type iron deposits.