云南鲁春晚三叠世硅质岩的地球化学特征及成因

云南鲁春晚三叠世火山沉积盆地是在江达－维西火山弧的基础上，通过拉张作用形成的碰撞后拉张盆地，盆地内广泛发育一套由玄武岩和流纹岩组成的“双峰式”火山岩及与其相伴的硅质岩。硅质岩可分为灰质硅质岩和纹层状硅质岩两类。通过对两类硅质岩所进行的地球化学研究和分析，表明云南鲁春晚三叠世火山沉积盆地中的凝灰质硅质岩属火山沉积成因，在而纹层状硅质岩为海底喷流热液／热泉（热水）沉积成因的热水硅质岩。

The origin and geochemistry of the Late Triassic siliceous rocks in Luchun, Yunnan

The Luchun Late Triassic volcano-sedimentary basin in Yunnan is a post-collisional strike-slip extensional basin grounded upon the Jomda-Weixi volcanic arc. The basin is conspicuous by bimodal volcanic rocks composed of basalts and rhyrolites and by associated siliceous rocks. The siliceous rocks in the basin may fall into two categories: tuffaceous and laminated. The former is characterized by high ΣREE, enriched LREE, minor negative Ce anomaly and marked negative Eu anomaly, whereas the latter is typical of low ΣREE, slightly enriched LREE, minor negative Eu anomaly and marked negative Ce anomaly. The study of the geochemistry of the above-mentioned two siliceous rocks shows that the tuffaceous siliceous rocks have a volcano-sedimentary origin, while the laminated siliceous rocks are of submarine-exhalative or hydrothermal (hot-spring) sedimentary origin.