Premium
Numerical Modeling of Dike Propagation Out of Continuously and Episodically Growing Midcrustal Magma Chambers
Author(s) -
Chen Yanying,
Nabelek Peter I.
Publication year - 2020
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2019jb019021
Subject(s) - magma chamber , dike , geology , magma , overpressure , petrology , buoyancy , volcano , geochemistry , mechanics , thermodynamics , physics
In the continental crust, the probability of dike propagation out of magma chambers is governed by thermal, rheological, and pressure conditions of magma chamber‐wall rock systems. Incremental injection of melt into an average‐size, laccolith‐shaped, midcrustal magma chamber produces a volume of mobile magma at the bottom of the chamber that has the potential to escape as dikes through the upper, immobile portion of the chamber and the roof. Here we numerically model the conditions needed for dike propagation out of a magma chamber during continuous and episodic injections of melt into the chamber. The roles of magma buoyancy and overpressure from melt injections in generating dikes are explored within 1.78 × 10 4 to 1.78 × 10 8 Pa·s range of magma viscosities ( μ mag ), 10 to 40 GPa range of elastic moduli ( E ) of the immobile top portion of the magma chamber, and 10 and 20 kyr durations of chamber growth. During episodic, high‐flux melt injections (tens of km 3 /yr), magma overpressure can reach >100 MPa and initiate dike propagation even when μ mag and E are near the high ends of the examined ranges. The probability of generating dikes diminishes when the injection flux is lower. Continuous low‐flux injections favor magma accumulation because injection overpressure never exceeds 20 MPa. During either continuous or episodic growth of magma chamber, there is never a sufficient amount of mobile magma in the chamber for dikes to be induced by magma buoyancy alone.