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滇东早寒武世梅树村期含磷岩系中出现的十多层浅色粘土岩层为酸性火山灰蚀变而成的变斑脱岩，它们是火山喷发事件和事件地层对比的标志。这些浅色粘土岩层中稳定微量元素Ｈｆ、Ｎｂ、Ｙ、Ｔｈ、Ｚｒ含量高于非火山成因的粘土，而Ｆｅ、Ｎｉ、Ｃｏ、Ｃｒ含量低于筇竹寺组泥岩。ＴｉＯ２／Ａｌ２Ｏ３、Ｚｒ／Ｈｆ、Ｔｉ／Ｔｈ比值属于酸性岩浆范围，球粒标准化稀土元素配分模式和具中至大的Ｅｕ负异常类似于花岗岩稀土配分模式。岩浆判别图指示了梅树村期变斑脱岩具板内花岗岩位置的亚碱性流纹岩和粗面岩岩浆亲缘性。变斑脱岩在地层序列上和区域上分布表明扬子地台西缘早寒武世初期火山活动频繁，火山喷发事件与古大陆解体和板内拉张构造运动有关
More than a dozen of light-colored clay rocks in the Pashu period of the Pudong area of the eastern Yunnan Province were altered by volcanic ash. They are the hallmarks of volcanic eruptions and event stratigraphic correlations. The contents of trace elements Hf, Nb, Y, Th and Zr in these light-colored clay stratums are higher than those of non-volcanic ones, while the contents of Fe, Ni, Co and Cr are lower than those of Qiongzhusi formations. The ratios of TiO2 / Al2O3, Zr / Hf and Ti / Th belong to the range of acidic magmatism. The normalized REE patterns of spherulites and the moderate to negative Eu anomalies are similar to the granite REE patterns. The magmatic discriminant map indicates the affinity of subbasic rhyolite and trachyte for the granitic rocks in the Meishucun Periodically-altered plaque. The distribution of variatitic rocks in stratigraphic sequences and regions shows that volcanic activity was frequent during the early Early Cambrian in the western margin of the Yangtze Platform, and volcanic eruptions were associated with the disintegration of the Paleo-Continental and the intraplate extensional tectonics