A
clastic dike is a seam of
sedimentary material that fills an open
fracture in and cuts across
sedimentary rock strata or layering in other rock types. Clastic dikes form rapidly by fluidized injection (mobilization of pressurized pore fluids) or passively by water, wind, and gravity (sediment swept into open cracks).
Diagenesis may play a role in the formation of some dikes. Clastic dikes are commonly vertical or near-vertical. Centimeter-scale widths are common, but thicknesses range from millimetres to metres. Length is usually many times width.