The Cancañiri Formation, also named as Cancañiri Tillite, is a Katian to Hirnantian geologic formation of central Bolivia.

The pebbly, argillaceous sandstones, shales and siltstones of the up to 1,500 metres (4,900 ft) thick formation,[1] were deposited in a glacial foreshore to deep water turbiditic environment.

[2][3][4][5] The formation is named after Cancañiri, a mining town close to Llallagua, where a local legend of a possessed woman is believed.

[6] The formation overlies the San Benito Formation in Cochabamba and the Amutara Formation in other parts.

[7] The formation has provided the following fossils: