Debris-flow deposits of Early Miocene age, Deadman Stream, Marlborough, New Zealand.

Detailed analysis is presented of a conformable succession of conglomerates and sandstones lying between massive marine mudstones. The coarse sediments reflect deposition by a spectrum of subaqueous debris-flow mechanisms during an early pulse of tectonism that ultimately resulted in Plio-Pleistocene eversion of the Kaikoura Mountains. Sparse pebbly mudstones and rare sandy conglomerates show disoriented clasts and reflect high-viscosity flows and slurry- creep flow mechanisms. Other deposits have little mud matrix, hence appear to reflect low-viscosity flow processes. Common sorted sandstones and some conglomeratic sandstones show diffuse parallel lamination. Other conglomeratic sandstones show trough cross-bedding which we attribute to entrained bedload movement during intersurge episodes of debris flow. - from Authors