An experimental study in the structure of convective flows of magma melts in a complete system: Mantle chamber-intermediate chamber-volcano

Abstract

A continuous interrelationship of melts in intermediate and mantle chambers is found by experiment. The interrelationship occurs due to the presence of two melt counter currents within the supply channel (conduit) of the intermediate chamber. In the upper part of the intermediate chamber horizontal rolling flows are found to go from the center to the periphery and backward horizontal flows over the entire bottom of the intermediate chamber travel from the periphery to the center (the conduit), then become an annular descending flow. Due to thermal interaction with the central ascending flow, the annular descending flow heats and becomes undersaturated relative to precipitated crystals, thus excluding encrustation of the conduit walls. The mechanism of continuous interaction between the melts in the mantle and intermediate chambers provides a quasisteady-state of the system irrespective of volcanic activity. It is thought that horizontal layering in large basic intrusives forms similarly to the described process of development and accumulation of cumulus at the bottom of the intermediate chamber.