The fossiliferous Plio-Pleistocene fluvio-lacustrine sediments in the East Turkana Basin of northern Kenya were derived from two major source areas: (1) Ethiopian plutonic igneous and metamorphic rocks of the Precambrian basement and (2) Kenyan Cenozoic volcanic rocks. Interpretations of provenance are based on heavy mineral analyses of 123 sandstone samples and data collected during stratigraphic studies. Thirty heavy minerals have been identified in the East Turkana Basin and commonly compose 5–20% of the fine sand fraction which is compositionally representative of the entire heavy fraction. Morphological properties of the grains, geometric form, roundness and surface textures indicate that the mineral distribution primarily reflects source rocks lithology. Seven distinct heavy mineral associations have been distinguished which are grouped into two suites: a plutonic suite dominated by blue-green hornblende, apatite, sphene, garnet and clinozoisite-epidote and a volcanic suite dominated by augite and opaque minerals. Both suites form mappable heavy mineral provinces. Plutonic provinces occur throughout the basin interior, and volcanic provinces are distributed along the basin margin in association with alluvial fan deposits. Sedimentation began in the Pliocene following formation of the Turkana half-graben and the Chew Bahir (Stefanie) graben. The sediments are predominantly first cycle with limited reworking in fluvial and lacustrine environments. Two perennial stream systems transported plutonic detritus to the basin interior from basement rocks of high relief exposed to the northeast in the Chew Bahir basin and eastern Omo valley. Short ephemeral streams transported volcanic detritus to alluvial fans along the basin margins from volcanic rocks of low relief which border the basin to the east and south.