Analogue simulation of pyroclastic density current deposition: internal complexity from a waxing and waning flow

Pyroclastic density currents (PDCs) are globally and historically represented by a wide range of scales, sizes and rheologies, ultimately producing a vast spectrum of deposit types. Use of relatively simple analogue flume experiments has been able to reproduce a number of typical PDC deposit features. These include overpassed and perched pumice horizons, internal lithic lenses, pumice levees, and complex internal 3D structure such as axial channels. By using multiple charges from a lock-gate release mechanism, a wide variety of features can be produced in a single deposit, with implications for field observations of primary versus re-worked PDC material, as well as progressive aggradation versus plug flow.