FIRST RESULTS OF DATING OF ANABAR SHIELD ANORTHOSITES BY THE SM-ND ISOCHRON METHOD

Abstract

Anorthosite of the independent type is a typical component of Precambrian granulite-gnesis, and the determination of its origin is very intimately related to a fundamental problem of geology, namely ascertaining the mode of evolution of the ancient continental crust. The popular radiometric dating methods do not work with anorthosite. which is a virtually monomineralic rock. In such a situation, Sm-Nd radiometric dating provides the most reliable results. The authors studied the Sm-Nd system in a simple of anorthosite from the Kotuykan group of plutons, confined to the Kotuykan zone of shear and diaphthoresis. Study methods and results are discussed.