Some fluid mechanical constraints on crystallization and recharge within sills

Abstract

The injection of hot magma into a sill can lead to heating and melting of the walls and roof of the reservoir while the injected magma cools and crystallizes. If the crystals are relatively dense, they will try to sediment from the injected magma to form a cumulate layer. In this cumulate layer, the crystals form a porous framework which traps the melt as it is built up. As the melt within the sill continually cools and precipitates dense crystals, there will be a gradual reduction in the density of the remaining silicate liquid. As a result, the melt which is progressively trapped in the pore space of the cumulate layer will become stably stratified in density. Using an idealized model of the fluid mechanical and thermodynamical principles, we explore some of the controls on the thickness and density stratification of cumulate layers following replenishment of a sill-like magma chamber. We show the balance between jamming of the crystal laden melt to form a homogeneous layer and the formation of a stratified cumulate zone depends on the cooling time scale compared to the sedimentation time scale. A key finding is that the composition and stratification in a packed crystal–melt suspension and the associated cumulate layer formed by cooling an intrusion of hot melt injected into the crust may have considerable variability, depending on the properties of the overlying roof melt and the size and hence fall speed of crystals which form in the melt. This article is part of the Theo Murphy meeting issue ‘Magma reservoir architecture and dynamics’.

Thermal and Chemical Evolution of Small, Shallow Water Bodies in Europa's Ice Shell

“…Analogously to the high‐density saline liquid at the bottom of our liquid water chamber, the low‐density minerals and fluids are buoyantly trapped at the roof and will solidify there. This tends to cause the roofs of these magma chambers to have a decreasing density profile with depth (Marsh, 2015; Sparks & Huppert, 1984; Turner, 1980; Woods & Stock, 2019; Worster et al., 1993). Reciprocally to magma chambers, the density of entrained salts at the floor should increase as the freezing front moves upward from the base of the modeled liquid bodies due to the increasing salinity of the liquid.…”

Architecture and dynamics of magma reservoirs

“…Crystal mush with a touching framework of crystals can support a stress. Intrusion of a liquid-rich magma into the crystal mush, however, may dilate it sufficiently to mobilize the suspension, thereby allowing new melt to intrude [219]. The heterogeneity in crustal architecture produced by successive intrusions then controls the loci of successive intrusions, and the ability of magmas to ascend through the crust [219].…”

“…Magma intrusion into pre-existing, partially solidified sills, can create complex density profiles, as reviewed by Woods & Stock [219]. For example, density-stratified cumulate layers may be interspersed with more homogeneous layers.…”

“…Intrusion of a liquid-rich magma into the crystal mush, however, may dilate it sufficiently to mobilize the suspension, thereby allowing new melt to intrude [219]. The heterogeneity in crustal architecture produced by successive intrusions then controls the loci of successive intrusions, and the ability of magmas to ascend through the crust [219]. Other factors that may affect the local formation and ascent of magmas include compaction waves and buoyancy layers in the mush (which may be melts or exsolved volatiles) which may be unstable and overturn, reviewed by Sparks et al [2,17].…”

Continuous Flow Vortex Fluidic Transformation of Kombucha Cellulose into More Compact and Crystalline Fibers

“…The increase was quantified by the crystallinity degree (X c ) which can be calculated using different methods, with debate ongoing regarding the most rigorous method. In the present study, the ratio of the intensities was employed using the equation, X c = A crystalline peaks /(A crystalline peaks + A amorphous scattering ), where A crystalline peaks and A amorphous scattering stand for the area of the diffraction peaks and amorphous scattering, respectively 25 (Figure 5). This revealed the degree of crystallinity of untreated kombucha cellulose, kombucha cellulose produced from homogenization at 12k rpm, and kombucha cellulose produced from VFD at 6k rpm to be 52.6, 55.3, and 69.8%, respectively.…”