Abstract
This paper studies numerically the rise of diapirs and the consequences of diapir-driven crustal flow. The ascent of diapirs imposes a convective flow pattern concentrated mostly in the low-viscosity lower crust in which the rocks immediately surrounding the diapir are dragged upwards and rocks a few radii to the sides of the diapir are pushed downwards to fill the gap left by the rising mass. There are two main consequences of this flow. One, warm and water undersaturated rocks may undergo decompression melting when dragged upwards. This is shown to enhance the ability of a diapir to intrude the crust, because the partially molten wall rocks gain buoyancy and add to the total buoyancy of the diapir, which regains part of the energy it spent on heating and dragging the surroundings. Two, the downward flow of rocks renews the magma source with potentially fertile rocks, which may undergo melting and give rise to a new diapir which will follow the same path as the first one and repeat the process, giving rise to a sequence of diapirs. Whereas source renewal is a direct result of diapirism, magma transport through dykes leads to the accumulation of refractory restite in the source which will eventually prevent further melting. Diapirism and decompression melting may lead to strong recycling of the lower crust and give rise to large volumes of melt. Sequential diapirism may explain nested plutons and multipulse mid- to upper-crustal batholiths.
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call