The pegmatite district of El Quemado (NW Pampean Ranges, NW Argentina) hosts several Ordovician pegmatite bodies of the LCT (Li, Cs, Ta) type. We present paragenetic assemblages for a set of samples from two of the El Quemado pegmatite groups, Santa Elena and Tres Tetas, and mineral chemistry analyses for gahnite, columbite-group minerals, tourmaline, micas, albite, microcline, and discuss the relation between their major element composition and the degree of evolution of pegmatite melts. The chemical composition of rare element minerals allows recognizing an evolutive trend reaching highly differentiated compositions, with complex paragenetic assemblages including Li-, Zr-, U-, Zn-, P-, Mn- and Ta-bearing minerals. The temperature of crystallization during the magmatic phase was below 400 °C. Non-pervasive hydrothermal alteration, testified by a moderate presence of phyllosilicates, affected the pegmatite bodies. Chlorite geothermometry indicates that the circulation of post-magmatic hydrothermal fluids occurred at a temperature ranging between 200 °C and 250 °C. The mineralogical features recognized in the El Quemado pegmatite rocks have implications for the metallogenesis of the region, suggesting that the pegmatites potentially contributed to the genesis of Ta-Nb oxide placer mineralizations.

El Quemado的伟晶岩区（西北西北部的庞毕山脉）拥有LCT（Li，Cs，Ta）类型的奥陶纪伟晶岩体。我们介绍了来自两个El Quemado伟晶岩组，Santa Elena和Tres Tetas的一组样品的共生组合，以及针铁矿，co钴族矿物，电气石，云母，云母，钠长石，微斜纹岩的矿物化学分析，并讨论了它们之间的关系。主要元素组成和伟晶岩熔体的演化程度。稀有元素矿物的化学成分使人们认识到具有高度分化成分，具有复杂的共生组合（包括含Li，Zr，U，Zn，P，Mn和Ta的矿物）的演变趋势。岩浆阶段的结晶温度低于400°C。非普遍性的热液蚀变，适度的页硅酸盐的存在证明，伟晶岩体受到影响。亚氯酸盐地热测定表明，岩浆后热液的循环发生在200°C至250°C的温度范围内。El Quemado伟晶岩中公认的矿物学特征对该地区的成矿意义重大，这表明伟晶岩可能有助于Ta-Nb氧化物砂矿成矿作用的成因。