Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico

Abstract Subduction zones play a crucial role in controlling interactions between the oceanic crust and mantle, generating fluid and hydrous melt, and facilitating subsequent volatile and mass transfer to mantle depths. In the Acatlán Complex, Mexico, trace elements, Sr–Nd isotopes, petrological mod...

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Main Authors: Fabián Gutiérrez-Aguilar, Sofía Jiménez-Barranco, Peter Schaaf, Alfredo Victoria-Morales
Format: Article
Language:English
Published: Nature Portfolio 2025-04-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-025-93279-9
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author Fabián Gutiérrez-Aguilar
Sofía Jiménez-Barranco
Peter Schaaf
Alfredo Victoria-Morales
author_facet Fabián Gutiérrez-Aguilar
Sofía Jiménez-Barranco
Peter Schaaf
Alfredo Victoria-Morales
author_sort Fabián Gutiérrez-Aguilar
collection DOAJ
description Abstract Subduction zones play a crucial role in controlling interactions between the oceanic crust and mantle, generating fluid and hydrous melt, and facilitating subsequent volatile and mass transfer to mantle depths. In the Acatlán Complex, Mexico, trace elements, Sr–Nd isotopes, petrological modeling coupled with time evolving models, and geochemical modeling in blueschists, retrograde eclogites, and garnet-bearing mica-schists provide evidence that mineral dehydration triggered fluid-rock interaction processes in a cold and mature paleo-subduction zone. Blueschists from the Acatlán Complex exhibit an enrichment, compared to the Mid-Ocean Ridge Basalts and the Altered Oceanic Crust, in Pb and Sr, a positive correlation between K/Th and Ba/Th, low Ce/Pb and 1/Pb ratios, and high 87Sr/86Sr( 350Ma) isotope ratios. We propose that such metasomatic characteristics were acquired during the interaction between the mafic subducted oceanic crust and both external and in-situ fluids along the transition from free sinking to mature stage in the paleo-subduction zone. We show that along this tectonic stage, the sedimentary portion of the Acatlán Complex produced external fluids through the dewatering of epidote, chlorite, and likely lawsonite enriched in Cs, Rb, Ba, Th, La, Pb, Sr, and 87Sr/86Sr, while being depleted in Nb, Sm, and Y. In contrast, the mafic portion generated in-situ fluids primarily enriched in Cs, Pb, and Sr, with a minor enrichment in Sm, through the breakdown of lawsonite and chlorite. Both external and in-situ fluids interacted with the mafic subducted oceanic crusts at 1.9–2.0 GPa and 477–555 °C. Based on petrophysical results, these external and in-situ fluids can be influenced by the expansion of the system (positive ΔVr solids + fluids) and changes in permeability, facilitating the migration of fluids parallel to the NE-SW foliation, as recorded in the Acatlán Complex blueschists.
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spelling doaj-art-6ea3b34759fb4ad8a64fc0000075978d2025-08-20T02:17:10ZengNature PortfolioScientific Reports2045-23222025-04-0115111510.1038/s41598-025-93279-9Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, MexicoFabián Gutiérrez-Aguilar0Sofía Jiménez-Barranco1Peter Schaaf2Alfredo Victoria-Morales3Facultad de Ingeniería, Universidad Nacional Autónoma de MéxicoPosgrado en Ciencias de la Tierra, Instituto de Geología, Universidad Nacional Autónoma de MéxicoLUGIS, Instituto de Geofísica, Universidad Nacional Autónoma de MéxicoFacultad de Ingeniería, Universidad Nacional Autónoma de MéxicoAbstract Subduction zones play a crucial role in controlling interactions between the oceanic crust and mantle, generating fluid and hydrous melt, and facilitating subsequent volatile and mass transfer to mantle depths. In the Acatlán Complex, Mexico, trace elements, Sr–Nd isotopes, petrological modeling coupled with time evolving models, and geochemical modeling in blueschists, retrograde eclogites, and garnet-bearing mica-schists provide evidence that mineral dehydration triggered fluid-rock interaction processes in a cold and mature paleo-subduction zone. Blueschists from the Acatlán Complex exhibit an enrichment, compared to the Mid-Ocean Ridge Basalts and the Altered Oceanic Crust, in Pb and Sr, a positive correlation between K/Th and Ba/Th, low Ce/Pb and 1/Pb ratios, and high 87Sr/86Sr( 350Ma) isotope ratios. We propose that such metasomatic characteristics were acquired during the interaction between the mafic subducted oceanic crust and both external and in-situ fluids along the transition from free sinking to mature stage in the paleo-subduction zone. We show that along this tectonic stage, the sedimentary portion of the Acatlán Complex produced external fluids through the dewatering of epidote, chlorite, and likely lawsonite enriched in Cs, Rb, Ba, Th, La, Pb, Sr, and 87Sr/86Sr, while being depleted in Nb, Sm, and Y. In contrast, the mafic portion generated in-situ fluids primarily enriched in Cs, Pb, and Sr, with a minor enrichment in Sm, through the breakdown of lawsonite and chlorite. Both external and in-situ fluids interacted with the mafic subducted oceanic crusts at 1.9–2.0 GPa and 477–555 °C. Based on petrophysical results, these external and in-situ fluids can be influenced by the expansion of the system (positive ΔVr solids + fluids) and changes in permeability, facilitating the migration of fluids parallel to the NE-SW foliation, as recorded in the Acatlán Complex blueschists.https://doi.org/10.1038/s41598-025-93279-9Subduction zonesBlueschistsAcatlán complexGeochemical modelingSr–Nd isotopesPetrological modeling
spellingShingle Fabián Gutiérrez-Aguilar
Sofía Jiménez-Barranco
Peter Schaaf
Alfredo Victoria-Morales
Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
Scientific Reports
Subduction zones
Blueschists
Acatlán complex
Geochemical modeling
Sr–Nd isotopes
Petrological modeling
title Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
title_full Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
title_fullStr Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
title_full_unstemmed Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
title_short Fluid-rock interaction processes in ancient subduction zones evidenced by the high-pressure–low-temperature Acatlán complex, Mexico
title_sort fluid rock interaction processes in ancient subduction zones evidenced by the high pressure low temperature acatlan complex mexico
topic Subduction zones
Blueschists
Acatlán complex
Geochemical modeling
Sr–Nd isotopes
Petrological modeling
url https://doi.org/10.1038/s41598-025-93279-9
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