大兴安岭南段西沙拉地区出露大量的中生代新民组（J₂x）和满克头鄂博组（J₃m）地层，由于其岩石组合中流纹岩的存在，易混淆地层的划分，导致该流纹岩的地层归属存在争议。因此，以流纹岩为研究对象，进行锆石U-Pb测年，地球化学特征分析，并开展了新民组和满克头鄂博组地层剖面对比研究，进而探讨流纹岩的形成时代、构造背景及地层归属问题。研究指出西沙拉流纹岩的地球化学特征为高硅（SiO₂平均含量为75.74%）、富碱（Na₂O+K₂O平均含量为7.69%），并且镁、钙含量较低，属过铝质、高钾钙碱性系列；球粒陨石标准化的稀土元素配分模式呈右倾型，轻稀土元素相对富集，重稀土元素相对亏损，（La/Yb）_N介于10.61~14.21，显示出较强的负铕异常（δEu介于0.44~0.53）；大离子亲石元素（large ion lithophilic elements, LILE） Rb、Ba和K相对富集，同时高场强元素（high field strength elements, HFSE） Nb、Ta和Ti相对亏损，这说明岩浆起源于地壳物质；LA-ICP-MS锆石U-Pb测年结果显示流纹岩年龄为（167.7±2.6） Ma，形成于中侏罗世，是蒙古-鄂霍茨克洋闭合后伸展构造作用所形成的产物；结合区域地质、剖面岩石组合类型对比研究认为该流纹岩应归属为满克头鄂博组。

In the southern Great Xing'an Range, the Xishala area exposes a substantial amount of Mesozoic strata of Xinmin Formation (J₂x) and Manketouebo Formation (J₃ m). However, due to the presence of rhyolite in the rock association, it is easy to confuse the stratigraphic division and lead to disputes of the stratigraphic attribution of rhyolite. Therefore, zircon U-Pb dating and geochemical characteristic analysis of the rhyolites were conducted, and stratigraphic sections of the Xinmin and Manketouebo Formations were compared to explore the formation age, tectonic setting, and stratigraphic attribution of the rhyolites. The results indicate that the geochemical characteristics of the riolites in Xishala area are high SiO₂ content (The value of mean is 75.74%.), rich alkali content [mean(Na₂O + K₂O) = 7.69%] and low Mg and Ca content, belonging to peraluminous and high-K calc-alkaline series. The Chondrite-normalized REE pattern is right-dip type, with relative enrichment of LREE and relative depletion of HREE, the value of (La/Yb) _Nis between 10.61 ~ 14.21 and strong negative Eu anomaly (The value of δEu is between 0.44 ~ 0.53.). LILE(large ion lithophilic elements) such as Rb, Ba and K are relatively enriched, while HFSE(high field strength elements) such as Nb, Ta and Ti are relatively depleted, indicating that the magma originated from crustal materials. The LA-ICP-MS zircon U-Pb dating results show that the age of the rhyolite is (167.7 ± 2.6) Ma, belonging to the Middle Jurassic, and it formes in the extensional tectonic action after the closure of the Mongolian-Okhotsk ocean. Based on the comparative study of regional geology and sectional rock assemblage types, the rhyolite belongs to the Manketouebo Formation.