Role of lithospheric melt transport in controlling the assembly of magmatic systems
Abstract
The processes responsible for transporting melt from the asthenosphere to the crustal magmatic reservoirs have not received as much attention as their crustal counterparts owing to both the paucity of direct observations and complex visco-elasto-plastic rheology of the lithospheric mantle. However, the rate, intermittency, and duration over which magma intrudes into the crust plays a critical role in controlling both the volume and eruptibility of individual magma reservoirs (e.g. Degruyter & Huber 2014) as well as the ability of large magma bodies to aggregate in a thermally maturing crust (Karakas et al. 2017, Karlstrom et al. 2017). Thus, understanding the first-order controls on the processes that convert quasi-steady melt percolation in the asthenosphere to sporadic melt injections into the lower crustal magma bodies is critical for assessing whether a volcanic system has the capability to cause large eruptions and at what frequency. We develop a new model for dynamic initiation and propagation of dikes and diapers at the lithosphere-asthenosphere boundary (LAB) and through the lithosphere, building upon and generalizing previous studies (Havlin et al. 2013, Lucantonio et al. 2015). We couple a simplified two-phase model to a dike model at LAB/through the lithosphere and allow dynamic transition to a diaper style melt transport if the magma buoyancy in the dike is sufficient. We find that a diking event locally influences the lithospheric thermal structure and the consequent change in rheological properties can, for certain parameters, allow significantly longer dike propagation distances and wider dikes. In addition, we find that allowing successive generations of dikes to be re-injected into prior partially solidified dikes, as is observed for sheeted dike complexes in mid-ocean ridge settings, is key to allow thermally viable magma transport from the LAB over multiple kilometers. Finally, we use our results as inputs into a magma chamber box model (Degruyter & Huber 2014; Mittal & Richards, in review) incorporating volatile degassing and a coupled poro-thermo-elastic crust to analyze how the lithospheric melt transport processes affect the assembly of large magma bodies and their eruptibility.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.V43H0227M
- Keywords:
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- 1009 Geochemical modeling;
- GEOCHEMISTRYDE: 1160 Planetary and lunar geochronology;
- GEOCHRONOLOGYDE: 3618 Magma chamber processes;
- MINERALOGY AND PETROLOGYDE: 3640 Igneous petrology;
- MINERALOGY AND PETROLOGYDE: 3640 Igneous petrology;
- MINERALOGY AND PETROLOGYDE: 3660 Metamorphic petrology;
- MINERALOGY AND PETROLOGYDE: 8434 Magma migration and fragmentation;
- VOLCANOLOGYDE: 8439 Physics and chemistry of magma bodies;
- VOLCANOLOGY