兴安地块呼伦湖东岸白音高老组主要由凝灰岩和流纹岩组成，其形成时代和构造背景一直存在较大争议。通过对采自白音高老组的流纹岩进行LA-ICP-MS锆石U-Pb定年，结果显示其结晶年龄为144.3±0.6 Ma（MWSD=0.74），属早白垩世。岩石地球化学特征表明白音高老组流纹岩属高钾钙碱性系列，亏损Ba、Sr、Ti元素，Rb、Th、Pb等相对富集，稀土元素配分模式为轻稀土富集右倾型，轻重稀土分馏明显，具有明显Eu负异常。综合研究表明，呼伦湖东岸白音高老组的流纹岩岩浆来源于下地壳基性岩石的部分熔融，应形成于非造山板内伸展构造环境中。%The Hinggan massif Bayan Gol Formation in the east coast of Hulun Nur consists of mainly tuff and rhyolite;its formation age and tectonic setting have a lot of controversy. Through the sampling of rhyolite in Bayan Gol Formation carried out LA-ICP-MS zircon U-Pb dating. The result has shown that its crystallization age is 144.3 ± 0.6 Ma(MWSD=0.74), belongs to early Cretaceous. The rock geochemical features have shown that the rhyolite in the formation belongs to high potassium-calcium alkaline series, Ba, Sr and Ti de⁃ficient, Rb, Th and Pb relatively enriched. REE distribution pattern is LREE enrichment right deviation type, fractional distillation of LREE and HREE clear with obvious Eu negative anomaly. Integrated study shows that rhyolite magma in Bayan Gol Formation in east coast Hulun Nur is derived from partial melting of lower crustal basic rocks should be formed in non-orogenic intra plate extensional tectonic environment.
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