Abstract: In the north of Zunhua, plentiful structural lenses of basic and ultra-basic rocks including metamorphosed diabases (amphibolites), layer gabbros, ultramafic cumulates and mantle peridotites, are scattered in the strongly sheared Neoarchaean gneiss. The basic and ultra-basic rocks are comparable to a modern ophiolite suite and make up of an ophiolitic mélange in the strongly deformed gneiss. The podiform chromite associated with these structural lenses is only reported in ophiolites. Therefore, it is a convincing evidence for the existence of a Neoarchaean ophiolite in China. The Zunhua Neoarchaean ophiolitic mélange proves the operation of plate tectonics in North China 2500Ma ago.

Key words: Neoarchaean, ophiolite mélange belt, podiform chromites, plate tectonics

摘要： 在遵化北部，有大量的基性岩超基性岩构造透镜体，包括变质辉绿岩（斜长角闪岩）、层状辉长岩、堆积杂岩、地幔橄榄岩等散布在新太古代片麻岩中。这些岩石组合与现代蛇绿岩套一致，和强烈剪切变形的片麻岩一起构成典型的蛇绿岩混杂岩。蛇绿岩套中的豆荚状铬铁矿提供了中国存在新太古代蛇绿岩的确切证据。遵化新太古代蛇绿混杂岩带的发现，证明25亿年以前板块构造运动已经出现。

关键词: 新太古代, 蛇绿混杂岩, 豆荚状铬铁矿, 板块构造