Dyke cooling upon intrusion: Subsequent shape change, cooling regimes and the effect of further magma input
Abstract
Upon emplacement of a dyke, the magma may crystallise immediately and block the dyke (blocking) or begin to melt the surrounding country rock prior to crystallisation (meltback). A numerical model is used to investigate the prevalence of these regimes and the change in shape (of horizontal cross-section) of the dyke's solidus and mobile melt extent (MME) isotherms. For static magma, the solidus narrows from its initial shape throughout cooling while the MME initially narrows prior to widening. Magma reinjection leads to widening of the MME after each injection, with a lesser to no response in the solidus aspect ratio. For static magma, the minimum dyke width at which meltback occurs is inversely proportional to the country rock temperature (with no meltback for country rock below specific temperatures determined by the specific magma properties). Considering reinjection allows for meltback at significantly lower country rock temperatures and a power law relationship is determined between this meltback width and the reinjection period. Injection of superheated magma gives rise to further widening of the MME during cooling with no effect on the solidus shape, as well as decreasing the country rock temperature required for meltback.
- Publication:
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Earth and Planetary Science Letters
- Pub Date:
- September 2022
- DOI:
- 10.1016/j.epsl.2022.117687
- Bibcode:
- 2022E&PSL.59317687L
- Keywords:
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- dyke intrusion;
- dyke shape change;
- heat-flow;
- thermal modelling