义县组（Yixian Fm）最初称义县火山岩类。主要分布于辽宁省西部，典型剖面位于辽宁省义县头道河子马神庙至前杨宋八户。义县组是一套厚度巨大的陆相火山岩及火山碎屑沉积岩系。其整个火山活动阶段自始至终构成一个从基性—中基性—中性—中酸性的完整喷发旋回。
河北省丰宁县北部侏罗系义县组底部首次发现鸟类化石。
Bird fossils were for the first time discovered in the bottom of the Jurassic Yixian Formation in the north of Fengning county, Hebei.
古生物学家在义县组发掘出了中华龙鸟，它是羽毛恐龙的首个直接物证
The Yixian Formation also yielded Sinosauropteryx, the first physical evidence of a feathered dinosaur.
辽西凌源地区张家口组是否存在及其与义县组之间关系的问题一直存在争议。
The problems of whether the Zhangjiakou Formation exists in the Lingyuan area, western Liaoning, and its relationships with the Yixian Formation , has long been in dispute.
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