内蒙古、河北高级变质岩中锆石的成因矿物学研究

Minerageny of Zircons from High-Grade Metamorphic Rocks in Inner Mongolia and Hebei

本文对内蒙古上、下集宁群、河北桑干群紫苏花岗岩及麻粒岩中的锆石进行了形态、环带及成分分布的研究，发现这些岩石中存在岩浆成因和变质成因的锆石，论述了这两种锆石的成因矿物学特征，并对这些岩石的成因进行了探讨。

It is discovered that zircons(2400 Ma ±) from charnockite and granulite in LowerJining Group of Inner Mongolia and Sanggan Group of Hebei exhibit euhedral growthzoning and compositional zonation of increasing HfO_2 content and decreasing ZrO_2/HfO_2ratio from the core to the edge of a crystal,suggesting that these zircons grew duringmagmatic crystallization and differentiation. Nevertheless,the edges of these zirconsare rounded,and their compositional zonation shows resemblance to that of recrystallizedzircons in metamorphism,implying that these zircons have experienced metamorphism,with recrystallization growth along their edges.As for the charnockite studied in thispaper,the authors consider that its formation undewent a cycle of protolithmetamorphic rock magma (TTG type) TTG typegranite or charnockite (under high pressure)existing charnockite,which se-ems to be one of the materials exchange modes between the crust and the mantle andleads to the formation of the stratified structure of the earth.zircons of 1980 Ma±found in granulite of Upper Jining Group exhibit rounded growth zoning and composi-tional variation trend opposite to that of magmatogenic zircons,tending to decrease inHfO_2 and increase in ZrO_2/HfO_2 from the core to the edge of the crystal,which suggeststhat these zircons are of metamorphic recrystallization origin.