Longchahe porphyritic granite is the largest pluton within the western Gejiu complex, a series of mainly intermediate to felsic alkali intrusions in southwestern China. Our research indicates that the pluton intruded during the Late Cretaceous (82–84 Ma). The pluton is primarily a medium- to coarse-grained porphyritic granite, which shows weakly peraluminous (A/CNK = 0.92–1.82, with an aver…