Volatiles and the tempo of flood basalt magmatism
© 2016 Elsevier B.V. Individual flood basalt lavas often exceed 103km3in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas implies correspondingly large magma reservoirs within or at the base of the crust. To erupt, some...
Published in: | Earth and Planetary Science Letters |
---|---|
Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
eScholarship, University of California
2017
|
Subjects: | |
Online Access: | http://www.escholarship.org/uc/item/7mm1q3v1 |
id |
ftcdlib:qt7mm1q3v1 |
---|---|
record_format |
openpolar |
spelling |
ftcdlib:qt7mm1q3v1 2023-05-15T17:52:10+02:00 Volatiles and the tempo of flood basalt magmatism Black, BA Manga, M 130 - 140 2017-01-15 application/pdf http://www.escholarship.org/uc/item/7mm1q3v1 english eng eScholarship, University of California qt7mm1q3v1 http://www.escholarship.org/uc/item/7mm1q3v1 public Black, BA; & Manga, M. (2017). Volatiles and the tempo of flood basalt magmatism. Earth and Planetary Science Letters, 458, 130 - 140. doi:10.1016/j.epsl.2016.09.035. UC Berkeley: Retrieved from: http://www.escholarship.org/uc/item/7mm1q3v1 article 2017 ftcdlib https://doi.org/10.1016/j.epsl.2016.09.035 2018-11-02T23:53:26Z © 2016 Elsevier B.V. Individual flood basalt lavas often exceed 103km3in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas implies correspondingly large magma reservoirs within or at the base of the crust. To erupt, some fraction of this magma must become buoyant and overpressure must be sufficient to encourage failure and dike propagation. The overpressure associated with a new injection of magma is inversely proportional to the total reservoir volume, and as a large magma body heats the surrounding rocks thermally activated creep will relax isotropic overpressure more rapidly. Here, we examine the viability of buoyancy overpressure as a trigger for continental flood basalt eruptions. We employ a new one-dimensional model that combines volatile exsolution, bubble growth and rise, assimilation, and permeable fluid escape from Moho-depth and crustal chambers. We investigate the temporal evolution of degassing and the eruptibility of magmas using the Siberian Traps flood basalts as a test case. We suggest that the volatile inventory set during mantle melting and redistributed via bubble motion controls ascent of magma into and through the crust, thereby regulating the tempo of flood basalt magmatism. Volatile-rich melts from low degrees of partial melting of the mantle are buoyant and erupt to the surface with little staging or crustal interaction. Melts with moderate volatile budgets accumulate in large, mostly molten magma chambers at the Moho or in the lower crust. These large magma bodies may remain buoyant and poised to erupt—triggered by volatile-rich recharge or external stresses—for ∼106yr. If and when such chambers fail, enormous volumes of magma can ascend into the upper crust, staging at shallow levels and initiating substantial assimilation that contributes to pulses of large-volume flood basalt eruption. Our model further predicts that the Siberian Traps may have released 1019–1020g of CO2during a number of brief (∼104yr) pulses, providing a plausible trigger for warming and ocean acidification during the end-Permian mass extinction. The assimilation of carbon-rich crustal rocks strongly enhances both flood basalt eruptibility and CO2release, and the tempo of eruptions influences the environmental effects of CO2, SO2, and halogen degassing. The eruptive dynamics of flood basalts are thus inextricably linked with their environmental consequences. Article in Journal/Newspaper Ocean acidification University of California: eScholarship Earth and Planetary Science Letters 458 130 140 |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
description |
© 2016 Elsevier B.V. Individual flood basalt lavas often exceed 103km3in volume, and many such lavas erupt during emplacement of flood basalt provinces. The large volume of individual flood basalt lavas implies correspondingly large magma reservoirs within or at the base of the crust. To erupt, some fraction of this magma must become buoyant and overpressure must be sufficient to encourage failure and dike propagation. The overpressure associated with a new injection of magma is inversely proportional to the total reservoir volume, and as a large magma body heats the surrounding rocks thermally activated creep will relax isotropic overpressure more rapidly. Here, we examine the viability of buoyancy overpressure as a trigger for continental flood basalt eruptions. We employ a new one-dimensional model that combines volatile exsolution, bubble growth and rise, assimilation, and permeable fluid escape from Moho-depth and crustal chambers. We investigate the temporal evolution of degassing and the eruptibility of magmas using the Siberian Traps flood basalts as a test case. We suggest that the volatile inventory set during mantle melting and redistributed via bubble motion controls ascent of magma into and through the crust, thereby regulating the tempo of flood basalt magmatism. Volatile-rich melts from low degrees of partial melting of the mantle are buoyant and erupt to the surface with little staging or crustal interaction. Melts with moderate volatile budgets accumulate in large, mostly molten magma chambers at the Moho or in the lower crust. These large magma bodies may remain buoyant and poised to erupt—triggered by volatile-rich recharge or external stresses—for ∼106yr. If and when such chambers fail, enormous volumes of magma can ascend into the upper crust, staging at shallow levels and initiating substantial assimilation that contributes to pulses of large-volume flood basalt eruption. Our model further predicts that the Siberian Traps may have released 1019–1020g of CO2during a number of brief (∼104yr) pulses, providing a plausible trigger for warming and ocean acidification during the end-Permian mass extinction. The assimilation of carbon-rich crustal rocks strongly enhances both flood basalt eruptibility and CO2release, and the tempo of eruptions influences the environmental effects of CO2, SO2, and halogen degassing. The eruptive dynamics of flood basalts are thus inextricably linked with their environmental consequences. |
format |
Article in Journal/Newspaper |
author |
Black, BA Manga, M |
spellingShingle |
Black, BA Manga, M Volatiles and the tempo of flood basalt magmatism |
author_facet |
Black, BA Manga, M |
author_sort |
Black, BA |
title |
Volatiles and the tempo of flood basalt magmatism |
title_short |
Volatiles and the tempo of flood basalt magmatism |
title_full |
Volatiles and the tempo of flood basalt magmatism |
title_fullStr |
Volatiles and the tempo of flood basalt magmatism |
title_full_unstemmed |
Volatiles and the tempo of flood basalt magmatism |
title_sort |
volatiles and the tempo of flood basalt magmatism |
publisher |
eScholarship, University of California |
publishDate |
2017 |
url |
http://www.escholarship.org/uc/item/7mm1q3v1 |
op_coverage |
130 - 140 |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
Black, BA; & Manga, M. (2017). Volatiles and the tempo of flood basalt magmatism. Earth and Planetary Science Letters, 458, 130 - 140. doi:10.1016/j.epsl.2016.09.035. UC Berkeley: Retrieved from: http://www.escholarship.org/uc/item/7mm1q3v1 |
op_relation |
qt7mm1q3v1 http://www.escholarship.org/uc/item/7mm1q3v1 |
op_rights |
public |
op_doi |
https://doi.org/10.1016/j.epsl.2016.09.035 |
container_title |
Earth and Planetary Science Letters |
container_volume |
458 |
container_start_page |
130 |
op_container_end_page |
140 |
_version_ |
1766159534829600768 |