Constructing magma plumbing systems

Abstract

The structure of magma plumbing systems controls a variety of processes that are critical to keeping people safe, secure, and prosperous. These processes include the: (i) location, threat, and early warning signals of volcanic eruptions; (ii) accumulation of magma-related ore deposits; and (iii) distribution of subsurface heat. Yet magma plumbing systems are themselves controlled by a multitude of geological factors, such as host rock lithology and structure, and magma dynamics, each of which unique to different geological settings. Deciphering how entire magma plumbing systems are constructed is thus challenging: at active volcanoes we cannot see the subsurface geology at a high resolution, and exposed ancient intrusions only provide a snapshot of the systems evolution. We therefore have to infer how magma plumbing systems are constructed, and use various modelling approaches to test these interpretations. These models underpin many recent advances in volcanology but, by necessity, are simplified compared to natural magmatic systems and their host rock.In this presentation, we will explore how ground deformation is used to understand the structure and growth of subsurface magma plumbing systems. In particular, we will demonstrate how seismic reflection data, which provides ultrasound-like images of Earth’s crust, and structural geological mapping of active and ancient systems can be integrated to test model-based hypotheses concerning how magma emplacement translates into ground deformation. For example, graben-bounding, dyke-induced faults are commonly observed on Earth and many planetary bodies, but can we assume that their surficial graben properties (e.g. width and cumulative extension) reflect the underlying dyke depth and thickness? Similarly, how do surface uplift patterns relate to subsurface magma plumbing system structure? Overall, this presentation will emphasise the need to integrate geological, geophysical, and modelling-based approaches to advance our understanding of plumbing system construction.