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为探讨川东北元坝地区长兴组岩石中钠长石矿物的成因,对其进行了利用电子显微镜、能谱仪及稀土元素测定等分析测试。结果表明,显微镜下钠长石主要呈分散状分布,明显的聚片双晶现象,交代早期成岩矿物;钠长石与石英、黄铁矿伴生;稀土元素总量较低,分布曲线较缓,轻稀土相对富集、重稀土元素相对亏损,正Eu异常。研究认为,钠长石的成因与深部热液活动有关。根据川东北地区晚二叠世拉张构造背景,推测其是在二叠世晚期峨眉地裂运动玄武岩喷发的构造背景下生成的,钠长石的发现为研究该区长兴期构造、岩浆活动、“热事件”等研究具有重要的地质意义。
In order to investigate the origin of albite minerals in the rocks of Changxing Formation in Yuanba area, northeastern Sichuan, the analysis was carried out by using electron microscope, energy dispersive spectrometer and rare earth element analysis. The results show that the microscopic albite is mainly distributed in the form of scattered polycrystal twin phenomenon, account for early diagenetic minerals; albite associated with quartz and pyrite; the total amount of rare earth elements is relatively low, the distribution curve is slow, Light rare earth is relatively enriched, heavy rare earth elements are relatively depleted, and Eu is anomalous. The study suggests that the origin of albite is related to deep hydrothermal activity. Based on the Late Permian extensional tectonic setting in northeastern Sichuan, it is presumed that it was formed in the tectonic setting of Emei earth-fissure movement basalt eruption in the late Permian. The discovery of albite is of great significance for the study of Changxing period tectonism, magmatism, “Hot incident ” and other research has important geological significance.