LAUSR

We use analogue experimentation to test the hypothesis that host rock competence primarily determines the morphology of kimberlite pipes, which are subdivided into three classes: Class 1 pipes are steep-sided diatremes emplaced into crystalline rock; Class 2 pipes have a wide, shallow crater emplaced into sedimentary rock overlain by unconsolidated sediments; Class 3 pipes comprise a steep-sided diatreme with a shallow-angled crater emplaced into competent crystalline rock overlain by unconsolidated sediments. We use different configurations of three analogue materials with varying cohesions to model the contrasting geological settings proposed to explain kimberlite pipe morphology. Pulses of compressed air, representing the energy of the gas-rich head of a kimberlitic magma, are used to disrupt the experimental substrate. In the case of an eruption of a gas containing no particles or fluids, the organization of the analogue materials controls the excavation processes as well as the final shape of the ana...