Journal Article

Vertically extensive and unstable magmatic systems

Blundy, Jonathan D., Sparks, R. Stephen J., Cashman, Katharine V.

2017

Overview

Shallow magma chambers either erupt as volcanoes or solidify as intrusive magma bodies. These magma bodies are traditionally considered to be long-lived and dominated by melt. Cashman et al. review the evidence that shallow magma chambers are actually assembled quickly from much larger, crystal-rich transcrustal magmatic systems. This paradigm helps explain many geophysical and geochemical features of volcanic systems. It also presents challenges for understanding the evolution of magma and provides insight into how and why volcanoes erupt. Science , this issue p. eaag3055 Shallow magma chambers are ephemeral expressions of larger transcrustal magmatic systems. Volcanoes are an expression of their underlying magmatic systems. Over the past three decades, the classical focus on upper crustal magma chambers has expanded to consider magmatic processes throughout the crust. A transcrustal perspective must balance slow (plate tectonic) rates of melt generation and segregation in the lower crust with new evidence for rapid melt accumulation in the upper crust before many volcanic eruptions. Reconciling these observations is engendering active debate about the physical state, spatial distribution, and longevity of melt in the crust. Here we review evidence for transcrustal magmatic systems and highlight physical processes that might affect the growth and stability of melt-rich layers, focusing particularly on conditions that cause them to destabilize, ascend, and accumulate in voluminous but ephemeral shallow magma chambers.

• Publisher: American Association for the Advancement of Science
• Subject: Chambers / Crusts / Evolution / Magma / Melts / Plate tectonics / REVIEW SUMMARY / Spatial distribution / Volcanoes