Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina
Abstract The Pampean flat slab in central Chile and Argentina is characterized by the inland migration and subsequent cessation of arc volcanism since the mid‐Miocene. Slab flattening also affects the distribution and number of intermediate‐depth earthquakes and the evolution of the overlying contin...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2024-03-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2023GC011317 |
| _version_ | 1797205632818872320 |
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| author | Xiaowen Liu Lara S. Wagner Claire A. Currie Mark J. Caddick |
| author_facet | Xiaowen Liu Lara S. Wagner Claire A. Currie Mark J. Caddick |
| author_sort | Xiaowen Liu |
| collection | DOAJ |
| description | Abstract The Pampean flat slab in central Chile and Argentina is characterized by the inland migration and subsequent cessation of arc volcanism since the mid‐Miocene. Slab flattening also affects the distribution and number of intermediate‐depth earthquakes and the evolution of the overlying continental thermal structure. In this study, we combine thermal‐mechanical models with petrological models to examine temporal changes in pressure, temperature, and composition during flat‐slab subduction and estimate water carrying capacity, predicted melt distributions and predicted changes in melt composition. Model results indicate that the present‐day flattened Nazca plate carries water to ∼700 km inland from the trench and could cause flux melting if the material above the slab remains fertile. Observed slab seismicity matches areas where hydrated materials have ∼>3 wt% H2O in the oceanic crust and mantle lithosphere. Seismicity increases as slab water carrying capacity decreases (slab dehydration). As P‐T conditions and compositions of the rock trapped above the slab change during slab flattening, flux melting switches from a peridotite‐dominated early phase to a combined mid‐ocean ridge basalt/eclogite and peridotite melting at ∼8 Ma. The results provide broad consistency with known earthquake distributions, seismic velocities, and observed temporal and spatial changes in volcanic patterns above the Pampean flat slab and point toward the role of melt depletion in the decrease and ultimate cessation of arc volcanism in this region. |
| first_indexed | 2024-04-24T08:54:13Z |
| format | Article |
| id | doaj.art-4738a22074f24cb784babbda533481f2 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-04-24T08:54:13Z |
| publishDate | 2024-03-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-4738a22074f24cb784babbda533481f22024-04-16T08:35:30ZengWileyGeochemistry, Geophysics, Geosystems1525-20272024-03-01253n/an/a10.1029/2023GC011317Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and ArgentinaXiaowen Liu0Lara S. Wagner1Claire A. Currie2Mark J. Caddick3Department of Physics University of Alberta Edmonton AB CanadaEarth and Planets Laboratory Carnegie Institution for Science Washington DC USADepartment of Physics University of Alberta Edmonton AB CanadaDepartment of Geosciences Virginia Tech Blacksburg VA USAAbstract The Pampean flat slab in central Chile and Argentina is characterized by the inland migration and subsequent cessation of arc volcanism since the mid‐Miocene. Slab flattening also affects the distribution and number of intermediate‐depth earthquakes and the evolution of the overlying continental thermal structure. In this study, we combine thermal‐mechanical models with petrological models to examine temporal changes in pressure, temperature, and composition during flat‐slab subduction and estimate water carrying capacity, predicted melt distributions and predicted changes in melt composition. Model results indicate that the present‐day flattened Nazca plate carries water to ∼700 km inland from the trench and could cause flux melting if the material above the slab remains fertile. Observed slab seismicity matches areas where hydrated materials have ∼>3 wt% H2O in the oceanic crust and mantle lithosphere. Seismicity increases as slab water carrying capacity decreases (slab dehydration). As P‐T conditions and compositions of the rock trapped above the slab change during slab flattening, flux melting switches from a peridotite‐dominated early phase to a combined mid‐ocean ridge basalt/eclogite and peridotite melting at ∼8 Ma. The results provide broad consistency with known earthquake distributions, seismic velocities, and observed temporal and spatial changes in volcanic patterns above the Pampean flat slab and point toward the role of melt depletion in the decrease and ultimate cessation of arc volcanism in this region.https://doi.org/10.1029/2023GC011317flat‐slab subductionslab dehydrationarc volcanismnumerical model |
| spellingShingle | Xiaowen Liu Lara S. Wagner Claire A. Currie Mark J. Caddick Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina Geochemistry, Geophysics, Geosystems flat‐slab subduction slab dehydration arc volcanism numerical model |
| title | Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina |
| title_full | Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina |
| title_fullStr | Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina |
| title_full_unstemmed | Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina |
| title_short | Implications of Flat‐Slab Subduction on Hydration, Slab Seismicity, and Arc Volcanism in the Pampean Region of Chile and Argentina |
| title_sort | implications of flat slab subduction on hydration slab seismicity and arc volcanism in the pampean region of chile and argentina |
| topic | flat‐slab subduction slab dehydration arc volcanism numerical model |
| url | https://doi.org/10.1029/2023GC011317 |
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