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南澜沧江结合带云县花岗岩体的岩石类型主要为黑云二长花岗岩,SiO2平均为68.57%,K2O/Na2O平均为1.67,相对富钾,岩石属高钾钙碱性系列。其岩石酸、碱度低于同类岩石平均值;而镁铁组分高于平均值,显示岩石偏中性,与同碰撞构造环境形成的花岗岩特征类似。Al2O3平均为13.66%,含量较高,ACNK平均为1.1,呈铝过饱和。CIPW计算结果,都出现标准矿物刚玉分子(>1%)。岩石总体上相对富集大离子亲石元素,亏损高场强元素。稀土元素总量(ΣREE)较高,平均240.75×10-6。岩体轻稀土元素富集,重稀土亏损,(La/Yb)N为8.88～9.41,分异不是很大;Eu为中等负异常,δEu为0.52～0.57,经多种相关图解判别,岩石属S型花岗岩。其构造环境相当于大陆碰撞花岗岩类(CCG)。锆石颗粒U-Pb测年结果显示,源岩的形成年龄最晚是晋宁期(>778Ma),岩体主体形成于华力西晚期-印支期。0206024-5k号锆石是岩浆成因锆石,该样品的206Pb/238U和207Pb/235U两个年龄(49Ma和61Ma)反映在云县岩体中可能存在喜山期岩浆活动。
The rock types of the southern Lancangjiang belt-associated Yunxian granite body are mainly black-monzonitic granite with an average of 68.57% of SiO2 and an average K2O / Na2O of 1.67, which are relatively potassium-rich and belong to the high-K calc-alkaline series. The acidity and alkalinity of the rocks are lower than the average values of the rocks of the same type. However, the composition of the mafic rocks is higher than the average value, indicating that the rock is of a neutral nature similar to that of the granite formed in the same collision structural environment. The average content of Al2O3 is 13.66%, and the content is high. The average ACNK is 1.1, which is supersaturated with aluminum. CIPW calculation results, there are standard mineral corundum molecules (> 1%). The rock is generally relatively enriched in large ion lithophile elements, loss of high field strength elements. The total rare earth elements (ΣREE) higher, with an average of 240.75 × 10-6. The light rare earth elements in the rock mass are enriched, and the heavy rare earth loss is (La / Yb) N 8.88 ~ 9.41, which shows little difference; Eu is moderately negative anomaly and δEu is 0.52 ~ 0.57. According to various correlation diagrams, S-type granite. Its tectonic environment is equivalent to Continental Collision Granitoid (CCG). U-Pb dating of zircon grains shows that the earliest formation age of the source rocks is the Jinning period (> 778Ma), and the main body of the rock mass is formed in the late Variscan-Indosinian period. Zircon 0206024-5k is magmatic zircon. The 206Pb / 238U and 207Pb / 235U ages (49Ma and 61Ma) indicate that there may exist Himalayan magmatism in the rock mass of Yunxian.