Skip to content

Chemical differentiation, cold storage and remobilization of magma in the Earth’s crust

Research output: Contribution to journalLetter

Original languageEnglish
Pages (from-to)405-409
Number of pages5
JournalNature
Volume564
Issue number7736
Early online date3 Dec 2018
DOIs
DateAccepted/In press - 2 Oct 2018
DateE-pub ahead of print - 3 Dec 2018
DatePublished (current) - 20 Dec 2018

Abstract

The formation, storage and chemical differentiation of magma in the Earth’s crust is of fundamental importance in igneous geology and volcanology. Recent data are challenging the high-melt-fraction ‘magma chamber’ paradigm that has underpinned models of crustal magmatism for over a century, suggesting instead that magma is normally stored in low-melt-fraction ‘mush reservoirs’1–9. A mush reservoir comprises a porous and permeable framework of closely packed crystals with melt present in the pore space1,10. However, many common features of crustal magmatism have not yet been explained by either the ‘chamber’ or ‘mush reservoir’ concepts1,11. Here we show that reactive melt flow is a critical, but hitherto neglected, process in crustal mush reservoirs, caused by buoyant melt percolating upwards through, and reacting with, the crystals10. Reactive melt flow in mush reservoirs produces the low-crystallinity, chemically differentiated (silicic) magmas that ascend to form shallower intrusions or erupt to the surface11–13. These magmas can host much older crystals, stored at low and even sub-solidus temperatures, consistent with crystal chemistry data6–9. Changes in local bulk composition caused by reactive melt flow, rather than large increases in temperature, produce the rapid increase in melt fraction that remobilizes these cool- or cold-stored crystals. Reactive flow can also produce bimodality in magma compositions sourced from mid- to lower-crustal reservoirs14,15. Trace-element profiles generated by reactive flow are similar to those observed in a well studied reservoir now exposed at the surface16. We propose that magma storage and differentiation primarily occurs by reactive melt flow in long-lived mush reservoirs, rather than by the commonly invoked process of fractional crystallization in magma chambers14.

Download statistics

No data available

Documents

Documents

  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Springer Nature at https://doi.org/10.1038/s41586-018-0746-2 . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 781 KB, PDF document

    Licence: Other

DOI

View research connections

Related faculties, schools or groups