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元古宙伸展构造环境产出的壳幔型熊耳群火山岩系 ,具有向碱性演化的趋势。晚期有石英正长斑岩、霓辉正长岩、正长辉长岩产出 ,赋存在熊耳群中上部。应用单锆石U Pb法测定年龄 ,石英正长斑岩谐和年龄为 ( 1731± 2 9)Ma ,霓辉正长岩、正长辉长岩上交点年龄分别为( 1644± 14)Ma、( 1750± 65)Ma。1650～ 170 0Ma是碱性岩浆活动热构造事件的标志 ,石英正长斑岩被中元古代晚期的高山河组不整合覆盖 ,故以 1650～ 170 0Ma作为熊耳群的上限。1650～ 170 0Ma热构造事件是华北地块重大地质事件 ,有可能是进一步划分中元古代重要的年龄界限。
Proterozoic extensional tectonic environment derived from the crust-mantle Xiong ear group volcanic rocks, with a tendency to evolution. Late quartz quartzite porphyry, Nepheline syenite, Zhenggong gabbro output, presence in the upper ear Xiong ear group. Single zircon U Pb method was used to determine the age. The coincidence age of quartz positive porphyry is (1731 ± 2 9) Ma, Nefon syenite and Zhenggai gabbro are 1644 ± 14 Ma, 1750 ± 65) Ma. 1650-170 Ma is a sign of tectonic events of alkaline magmatic activity. Quartz-positive porphyry is unconformably covered by the late Paleoproterozoic Gaoshanhe Formation, so 1650-170 Ma is the upper limit of the Xiong’er group. The 1650-170 Ma thermal tectonism is a major geological event in the North China block and may be an important age boundary for the further division of the Proterozoic.