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白石坝一带花岗岩具高硅低铝、富钾贫钠、非常低Sr(24.9×10~(-6)~82.9×10~(-6))高Yb(2.61×10~(-6)~5.74×10~(-6))的南岭型花岗岩特征,A/CNK介于0.91~0.98之间,σ在1.92~2.22之间。明显富集Rb、Th、K等大离子不相容元素,亏损Ba、Sr、P、Ti等元素,并具有弱Nb亏损,稀土元素分布曲线呈明显的“燕式”型,其形成可能来源于下地壳底部部分熔融与地壳物质发生混合形成的产物,源区深度较浅、水含量低和氧逸度低,处于还原状态下的伸展构造背景,有利于锡矿的萃取和富集,研究其区域构造-岩浆演化,对指导区域矿产预测和评价均具有重要的理论和实际意义。
The granites in the Shibanba area are characterized by high silicon and low aluminum, potassium-rich and sodium-depleted, and very low Sr (24.9 × 10 -6 ~ 82.9 × 10 -6) high Yb (2.61 × 10 -6 ~ 5.74) × 10 ~ (-6)), with A / CNK of 0.91 ~ 0.98 and σ of 1.92 ~ 2.22. It is obviously enriched in large ion incompatible elements such as Rb, Th, K and depleted in Ba, Sr, P, Ti and other elements and has a weak Nb depletion. The distribution curve of rare earth elements is obviously “Yan style” Probably derived from the mixing of the bottom part of the crust and the melting of the crust material, resulting in a shallow tectonic source zone with low water content and low oxygen fugacity, which is in a state of reduced tectonic extension conducive to the extraction and enrichment of tin ore , The study of its regional tectonic-magmatic evolution has important theoretical and practical significance for predicting and evaluating the mineral resources in the guiding region.