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Constraining input and output fluxes of the southern-central Chile subduction zone: water, chlorine and sulfur

Constraining input and output fluxes of the southern-central Chile subduction zone: water, chlorine and sulfur
Constraining input and output fluxes of the southern-central Chile subduction zone: water, chlorine and sulfur
In this paper, we constrain the input and output fluxes of H2O, Cl and S into the southern-central Chilean subduction zone (31°S–46°S). We determine the input flux by calculating the amounts of water, chlorine and sulfur that are carried into the subduction zone in subducted sediments, igneous crust and hydrated lithospheric mantle. The applied models take into account that latitudinal variations in the subducting Nazca plate impact the crustal porosity and the degree of upper mantle serpentinization and thus water storage in the crust and mantle. In another step, we constrain the output fluxes of the subduction zone both to the subcontinental lithospheric mantle and to the atmosphere–geosphere–ocean by the combined use of gas flux determinations at the volcanic arc, volume calculations of volcanic rocks and the combination of mineralogical and geothermal models of the subduction zone. The calculations indicate that about 68 Tg/m/Ma of water enters the subduction zone, as averaged over its total length of 1,480 km. The volcanic output on the other hand accounts for 2 Tg/m/Ma or 3 % of that input. We presume that a large fraction of the volatiles that are captured within the subducting sediments (which accounts for roughly one-third of the input) are cycled back into the ocean through the forearc. This assumption is however questioned by the present lack of evidence for major venting systems of the submarine forearc. The largest part of the water that is carried into the subduction zone in the crust and hydrated mantle (accounting for two-thirds of the input) appears to be transported beyond the volcanic arc.
Subduction input, Forearc dewatering, Arc magmatism, Volcanic volatile output rates, Subduction fluids, Southern volcanic zone of Chile
1437-3254
2129-2153
Völker, David
f2b8a74f-9346-407a-8129-a90140ee5d3a
Wehrmann, Heidi
b5e430b9-0a69-46b4-b9ea-d38bee0283b7
Kutterolf, Steffen
79205a5c-9c0d-4ac2-a008-95efc5421963
Iyer, Karthik
8c8aff5f-c752-4e7d-a1c3-8ba96c3c4b42
Rabbel, Wolfgang
e0f229fe-093f-4656-b2be-55f716ab1b78
Geersen, Jacob
abcf5f76-3608-4322-ab54-7bfb8dfcaf2d
Hoernle, Kaj
fac56dc7-cb52-463d-bd03-0b2fc9e76eeb
Völker, David
f2b8a74f-9346-407a-8129-a90140ee5d3a
Wehrmann, Heidi
b5e430b9-0a69-46b4-b9ea-d38bee0283b7
Kutterolf, Steffen
79205a5c-9c0d-4ac2-a008-95efc5421963
Iyer, Karthik
8c8aff5f-c752-4e7d-a1c3-8ba96c3c4b42
Rabbel, Wolfgang
e0f229fe-093f-4656-b2be-55f716ab1b78
Geersen, Jacob
abcf5f76-3608-4322-ab54-7bfb8dfcaf2d
Hoernle, Kaj
fac56dc7-cb52-463d-bd03-0b2fc9e76eeb

Völker, David, Wehrmann, Heidi, Kutterolf, Steffen, Iyer, Karthik, Rabbel, Wolfgang, Geersen, Jacob and Hoernle, Kaj (2014) Constraining input and output fluxes of the southern-central Chile subduction zone: water, chlorine and sulfur. International Journal of Earth Sciences, 103 (7), 2129-2153. (doi:10.1007/s00531-014-1002-0).

Record type: Article

Abstract

In this paper, we constrain the input and output fluxes of H2O, Cl and S into the southern-central Chilean subduction zone (31°S–46°S). We determine the input flux by calculating the amounts of water, chlorine and sulfur that are carried into the subduction zone in subducted sediments, igneous crust and hydrated lithospheric mantle. The applied models take into account that latitudinal variations in the subducting Nazca plate impact the crustal porosity and the degree of upper mantle serpentinization and thus water storage in the crust and mantle. In another step, we constrain the output fluxes of the subduction zone both to the subcontinental lithospheric mantle and to the atmosphere–geosphere–ocean by the combined use of gas flux determinations at the volcanic arc, volume calculations of volcanic rocks and the combination of mineralogical and geothermal models of the subduction zone. The calculations indicate that about 68 Tg/m/Ma of water enters the subduction zone, as averaged over its total length of 1,480 km. The volcanic output on the other hand accounts for 2 Tg/m/Ma or 3 % of that input. We presume that a large fraction of the volatiles that are captured within the subducting sediments (which accounts for roughly one-third of the input) are cycled back into the ocean through the forearc. This assumption is however questioned by the present lack of evidence for major venting systems of the submarine forearc. The largest part of the water that is carried into the subduction zone in the crust and hydrated mantle (accounting for two-thirds of the input) appears to be transported beyond the volcanic arc.

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More information

e-pub ahead of print date: February 2014
Published date: October 2014
Keywords: Subduction input, Forearc dewatering, Arc magmatism, Volcanic volatile output rates, Subduction fluids, Southern volcanic zone of Chile
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 363144
URI: http://eprints.soton.ac.uk/id/eprint/363144
ISSN: 1437-3254
PURE UUID: 7dbf66c6-a16b-46e6-a29d-2803ce928eee

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Date deposited: 17 Mar 2014 15:27
Last modified: 14 Mar 2024 16:19

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Contributors

Author: David Völker
Author: Heidi Wehrmann
Author: Steffen Kutterolf
Author: Karthik Iyer
Author: Wolfgang Rabbel
Author: Jacob Geersen
Author: Kaj Hoernle

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