TY  - JOUR
A1  - Schmeling, Harro
A1  - Zulauf, Gernold
T1  - The physics of dyke and sill emplacement: Solidification, visco-elasticity, stress evolution, and melt migration
T2  - Tectonophysics
N2  - Highlights
• Solidification and cooling of an intruded dyke or sill within the middle or shallow crust generate stresses of order 200 MPa, which relax on time scales of a few years to million years.
• Stresses may exceed the brittle strength forming tensile fractures.
• Combined with the pressure gradient within the over-pressurized felsic melts, this explains the migration of felsic contact melt into shrinkage cracks (Sederholm-type veins).
Abstract
Rapid emplacement of a mafic dyke or sill at mid-crustal depth heats and possibly melts the felsic wall rock followed by solidification. Associated volume changes generate stresses, possibly enforcing brittle failure and melt migration. We model the evolution of melting, solidification, temperature, and stress including visco-elastic relaxation in 1D - dykes or -sills using realistic rock rheologies of the Weschnitz pluton (Odenwald). For deep emplacement (Case 1, 15.3 km) extensive contact melting of the wall rock occurs, for shallow emplacement (Case 2, 10 km) it is negligible. The stresses are zero at high melt fractions, but increase during solidification and cooling: The intrusion orthogonal stress is always zero. The intrusion parallel stress σ‖ within the intrusion is tensile (O(200 MPa)). It relaxes on a time scale between a few years (Case 1) and 0.6 m.y. (Case 2). Within the wall rock σ‖ is compressive during heating, but becomes tensile under solidification and cooling. Wall rock stresses relax on a time scale of months to 100 years. A Deborah number is defined based on viscous to thermal relaxation allowing generalization of our results. Adding lithostatic stresses, the total stresses of Case 1 remain below the brittle strength, while for Case 2 they may exceed it. Adding the lithostatic pressure to the melt pressure, the effective stresses exceed the brittle strength and intrusion orthogonal tensile fractures are predicted. Combined with the pressure gradient within the over-pressurized felsic melts generated in the wall rock, this explains the migration of felsic contact melt into shrinkage cracks of the mafic sill in the Weschnitz pluton.
KW  - Dykes and Sills
KW  - Magma emplacement
KW  - Physics of magma and magma bodies
KW  - Sederholm-type vein
KW  - Weschnitz pluton
KW  - Visco-elastic stress relaxation
Y1  - 2024
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/85766
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-857666
SN  - 0040-1951
VL  - 882
IS  - 230367
PB  - Elsevier
CY  - Amsterdam
ER  -