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通过野外调研和相关地球化学研究,表明出露于阿尔泰造山带南缘富蕴地区喀腊曼哲一带的中泥盆统阿勒泰组火山岩由玄武岩和流纹岩组成,为一套典型的双峰式火山岩组合。其中,玄武岩多变质为钠长阳起片岩、绿帘透闪片岩等,属拉斑玄武岩系列,低SiO2、K2O,高Ti,稀土配分曲线显示轻稀土略富集的平坦型,无明显Eu异常(δEu=0.92~1.08),富Th、U等,Nb负异常;流纹岩属钙碱性系列,高SiO2,低K2O,为钠质型,稀土配分曲线显示Eu负异(δEu为0.29~0.58)的右倾型,富集Th、U、La、Ce和Hf,亏损Sr、Nb、Ta、Zr、P、Ti。二者地球化学特征存在明显差异,表明酸性火山岩并不是由基性岩浆分离结晶产生,而可能是与基性下地壳经不同程度的部分熔融有关;基性火山岩为经俯冲流体改造的亏损地幔部分熔融的产物。岩石地球化学分析结果虽然显示其兼具洋中脊和岛弧火山岩的地球化学特征,但结合区域地质背景,其可能并不是形成于弧后盆地环境,而是岛弧裂谷的产物,属于成熟岛弧。
Field research and related geochemical studies show that the Middle Devonian Aletai Group volcanic rocks exposed in the Kelamanzhe area of the Fuyun area in the southern margin of the Altay orogenic belt are composed of basalts and rhyolite. Volcanic rock assemblage. The basalts are mostly metamorphic to the Changyangqi schist and the greenscreen Zhechuanchitian, which belong to the tholeiite series. The distribution curves of low SiO2, K2O, high Ti and rare earth show that the light rare earth is enriched in a flat type with no obvious Eu anomaly δEu = 0.92-1.08), rich in Th, U and other Nb negative anomalies; rhyolite is a series of calcium and alkaline, high SiO2, low K2O, sodium type, rare earth distribution curve shows Eu negative differences (δEu 0.29 ~ 0.58 ), And enriched in Th, U, La, Ce and Hf and depleted in Sr, Nb, Ta, Zr, P and Ti. The geochemical characteristics of the two are obviously different, indicating that the acidic volcanic rocks are not separated and crystallized by the basic magma but may be related to the partial melting of the lower crust by different degrees. The basic volcanic rocks are the part of the depleted mantle remodeled by the subducting fluid Melted product. Though the geochemical analysis results show that it has the geochemical characteristics of mid-ocean ridge and island arc volcanic rocks, it may not be formed in the backarc basin environment but the product of the island arc rift, which belongs to the mature Island arc.