Definition of volcaniclastic

The general term ‘volcaniclastic’ was introduced by Fisher (1961) and redefined in Fisher and Smith (1991) to include ‘the entire spectrum of clastic materials composed in part or entirely of volcanic fragments, formed by any particle- forming mechanism (e.g. pyroclastic, hydroclastic, epiclastic, autoclastic, transported by any mechanism, deposited in any physiogeographic environment or mixed with any other volcaniclastic type or with any nonvolcanic fragment types in any proportion’. The term volcanogenic is used by other authors and has a broadly similar meaning. To be classified as ‘volcaniclastic’, we suggest that a rock or unconsolidated deposit must have more than 10% by volume of volcanic debris. Volcanic debris is defined as fragments originating by volcanic processes, either primary or after redeposition. Many volcaniclastic rocks and sediments can also be classified within the scheme for ‘Sedimentary rocks and sediments’.

FISHER, R V. 1961. Proposed classification of volcaniclastic sediments and rocks. Geological Society of America Bulletin, Vol. 72, 1409–1414.
FISHER, R V, AND SCHMINKE, H U. 1984. Pyroclastic rocks. (Berlin: Springer-Verlag.)
FISHER, R V, AND SMITH, G A . 1991. Volcanism, tectonics and sedimentation, 1–5 in Sedimentation in volcanic settings. SEPM (Society for Sedimentary Geology) Special Publication, No. 45.