Projects - Magma Mixing
Petrology and Geochemistry Approach
The process of mixing is ubiquitous across all tectonic settings where magmas form and best recognized in arc magmatism. In arc systems we are often faced with a multitude of mixing events obscuring end-member compositions and the effects of individual recharge events. Thus, to make progress in our understanding of the assembly and differentiation of the continental crust we are limited by our restricted understanding of the dynamic templates and the frequency of magmatic recharge, overturn, and mixing that creates and destroys heterogeneity on the crystal to the outcrop scale.
My work has been mainly focussed on a well-characterized volcanic system (Volcán Quizapu) that serves as an excellent natural laboratory for investigating the effects of a single magma recharge event, thus providing important constraints on mixing efficiency and crystal dispersal during recharge. Volcán Quizapu in Chile is known for two large historic eruptions (1846-47 and 1932), which share many characteristics, while at the same time being distinct. The 1846-47 eruption is strongly affected by a recharge event just prior to eruption, whereas the 1932 eruption is almost free of recharge and mixing features.
I use this system to explore magma mixing on various scales and develop a rationalize that constrains under which conditions hybrid arc magmas are assembled and on what length scale this hybridization is effective. Furthermore, I work towards delineating the crystal time scale record that is constantly affected by magma mixing.
Relevant publication:
The effects of Magma mixing on creating Heterogeneity
Photos: Left, close up of a intra-crater tephra deposit from the 1963-65 eruption of Irazú volcano. Bottom, During magma mixing the crystals floating in the magma get dispersed and gathered. The chaotic pathway of the crystal may lead to gathering of crystal in the volume of a thin section from areas that cover the entire convective system.
In this study we investigated the length scale of individual crystal dispersal and the potential diverging histories individual crystals may record.
Fluid Dynamics Approach
Magma overturn and mixing redistributes the crystal cargo. We investigate using a numerical multiphase model how much a single gas-driven overturn affect the crystals that you can find in your common thin section.
The results showed that during a single overturn crystals that ultimately end up in the volume similar to a thin section or hand sample may originate from tens to hundreds of meters away. The crystals are basically passive tracers of the fluid flow during the fast overturn that is typical for large-density differences associated with degassing.
During magma mixing the crystals floating in the magma get dispersed and gathered. The chaotic pathway of the crystal may lead to gathering of crystal in the volume of a thin section from areas that cover the entire convective system.
In this study we investigated the length scale of individual crystal dispersal and the potential diverging histories individual crystals may record.
Relevant publication:
Find here some short summaries of some of these studies:
Magma mixing and its effect on crystal residence times
