Imaging of a shallow magma conduit system based on a high-power frequency-domain controlled-source electromagnetic survey

Abstract

Mantle-derived magma may undergo lateral flow and emplacement through horizontal magma conduits; this occurs after magma from a deep source ascends through a vertical conduit. Regardless of this understanding, the characteristics of such shallow magma conduit systems remain unclear. We have developed an image of a shallow (5 km deep) magma conduit system based on the resistivity results of a high-power frequency-domain controlled-source electromagnetic survey in the Kalatongke magmatic-type Ni-Cu deposit. The magma upwelled and ascended along the vertical fault. At shallow depths, the magma moved horizontally along the tuff layer, laterally propagating in a horizontal magma conduit. Magma extending horizontally in the horizontal tuff layer could not break through the upper, conductive, and low-density carbonaceous layer. This image provides a conduit model with vertical magma ascent and lateral magma propagation. The model provides a basis for studying shallow magma conduit systems in orogenic belts on a global scale.