江西宜丰县大港超大型含锂瓷石矿床地质特征及成因机制探讨

大港含锂瓷石矿床产于宜丰钽铌锂稀有金属成矿带甘坊花岗岩岩体内，属典型的含锂云母碱长花岗岩型矿床。含锂瓷石矿体厚度21.62~148.88 m，其中w（Al₂O₃）为15.38%~23.97%，w（Li₂O）为0.30%~1.06%，同时伴生Rb、Cs、Ta、Nb等稀有金属。矿石矿物组成为钠长石、锂云母或锂白云母，白度达80%以上。化学组成上，表现出富硅，贫铁、镁、钛，高磷的特征；铝饱和指数A/CNK值大于1.20，Zr/Hf比值（< 12）与Nb/Ta比值（< 2）极低，表明具有高分异的过铝质S型花岗岩特性。由构造环境判别图解可知，大港含锂云母碱长花岗岩应形成于同碰撞或后碰撞早期阶段的伸展构造背景下，极低的CaO/Na₂O比值（< 0.2），指示岩体的源区应为富黏土矿物的变质泥质岩。

A discussion on geological characteristics and genetic mechanism of Dagang superlarge lithium-bearing porcelain stone deposit in Yifeng County, Jiangxi Province

The Dagang lithium-bearing porcelain stone deposit occurs in Ganfang granite pluton of the tantalum-niobium-lithium rare metal metallogenic belt in Yifeng County. It is a typical alkali-feldspar granite deposit which contains lepidolite. The prospective resource is expected to exceed 100 million tons. The thickness of lithium-bearing porcelain ore body is in the range of 21.62~148.88 m, in which the content of w(Al₂O₃) is 15.38%~23.97%, the content of w(Li₂O) is 0.30%~1.06%, and some rare metals such as Rb, Cs, Ta and Nb are concentrated as well. The mineral composition of the ore consists of albite, lepidolite and lithium muscovite with whiteness over 80%. The granite is rich in silicon and phosphorus, but poor in iron, magnesium, and titanium. The A/CNK value of Al saturation index is beyond 1.20, and the ratio of Zr/Hf (< 12) and Nb/Ta (< 2) is very low, which indicates that the granite is of peraluminous S-type with high differentiation. According to the diagrams of tectonic environment discrimination, Dagang alkali-feldspar granites should have been formed under the extensional tectonic setting of the early stage of co-collision or the early stage of post-collision, and the very low ratio of CaO/Na₂O (< 0.2) indicates that the source area of the granites might have been metamorphic mudstone.