Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate
Abstract In the Mesozoic, the age of Paleo‐Pacific plate that flatly subducted beneath the South China was ∼80 Ma, resulting in a cold and dense oceanic slab. The transition process from flat to steep subduction of this old slab and factors that affect it are still unclear. Using 2‐D thermomechanica...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Wiley
2022-12-01
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| Series: | Geochemistry, Geophysics, Geosystems |
| Online Access: | https://doi.org/10.1029/2022GC010523 |
| _version_ | 1797638042082607104 |
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| author | Jiawei Jiang Yadan Mao Xiangyun Hu |
| author_facet | Jiawei Jiang Yadan Mao Xiangyun Hu |
| author_sort | Jiawei Jiang |
| collection | DOAJ |
| description | Abstract In the Mesozoic, the age of Paleo‐Pacific plate that flatly subducted beneath the South China was ∼80 Ma, resulting in a cold and dense oceanic slab. The transition process from flat to steep subduction of this old slab and factors that affect it are still unclear. Using 2‐D thermomechanical numerical models, we investigate the dependence of the transition mode on the size of TOC (length and thickness) and the subduction rate. The results indicate that under low subduction rates (e.g., 1 cm/yr), even a 100‐km long eclogitized TOC can induce slab delamination beneath continental lithosphere. The maximum subduction rate for slab delamination to occur increases with an increasing length or thickness of TOC. However, when the subduction rate is over a certain critical value (e.g., ≥4 cm/yr), oceanic slab rolls back. The presence of the TOC delays the initial rollback time, as compared to cases with no TOC. In addition, with a TOC of small size (e.g., 100‐km length and 20‐km thickness) under a certain range of subduction rate, an 80‐Ma old slab can maintain a long‐lasting flat subduction. The comparisons between the numerical results and global plate motion models indicate that the northwestward motion of South China Block since ca. 195 ± 5 Ma induced the delamination of oceanic slab. The arrival of the TOC in the Paleo‐Pacific Plate to the continental arc should be later than the previously estimated ca. 250 Ma. Determination of the TOC size requires three‐dimensional simulations and more detailed geological records. |
| first_indexed | 2024-03-11T12:57:01Z |
| format | Article |
| id | doaj.art-df78d92e8d1045b7aaf76224b49aa081 |
| institution | Directory Open Access Journal |
| issn | 1525-2027 |
| language | English |
| last_indexed | 2024-03-11T12:57:01Z |
| publishDate | 2022-12-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj.art-df78d92e8d1045b7aaf76224b49aa0812023-11-03T17:00:34ZengWileyGeochemistry, Geophysics, Geosystems1525-20272022-12-012312n/an/a10.1029/2022GC010523Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction RateJiawei Jiang0Yadan Mao1Xiangyun Hu2Hubei Subsurface Multiscale Imaging Key Laboratory School of Geophysics and Geomatics China University of Geosciences Wuhan ChinaHubei Subsurface Multiscale Imaging Key Laboratory School of Geophysics and Geomatics China University of Geosciences Wuhan ChinaHubei Subsurface Multiscale Imaging Key Laboratory School of Geophysics and Geomatics China University of Geosciences Wuhan ChinaAbstract In the Mesozoic, the age of Paleo‐Pacific plate that flatly subducted beneath the South China was ∼80 Ma, resulting in a cold and dense oceanic slab. The transition process from flat to steep subduction of this old slab and factors that affect it are still unclear. Using 2‐D thermomechanical numerical models, we investigate the dependence of the transition mode on the size of TOC (length and thickness) and the subduction rate. The results indicate that under low subduction rates (e.g., 1 cm/yr), even a 100‐km long eclogitized TOC can induce slab delamination beneath continental lithosphere. The maximum subduction rate for slab delamination to occur increases with an increasing length or thickness of TOC. However, when the subduction rate is over a certain critical value (e.g., ≥4 cm/yr), oceanic slab rolls back. The presence of the TOC delays the initial rollback time, as compared to cases with no TOC. In addition, with a TOC of small size (e.g., 100‐km length and 20‐km thickness) under a certain range of subduction rate, an 80‐Ma old slab can maintain a long‐lasting flat subduction. The comparisons between the numerical results and global plate motion models indicate that the northwestward motion of South China Block since ca. 195 ± 5 Ma induced the delamination of oceanic slab. The arrival of the TOC in the Paleo‐Pacific Plate to the continental arc should be later than the previously estimated ca. 250 Ma. Determination of the TOC size requires three‐dimensional simulations and more detailed geological records.https://doi.org/10.1029/2022GC010523 |
| spellingShingle | Jiawei Jiang Yadan Mao Xiangyun Hu Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate Geochemistry, Geophysics, Geosystems |
| title | Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate |
| title_full | Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate |
| title_fullStr | Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate |
| title_full_unstemmed | Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate |
| title_short | Factors on the Mesozoic Transition From Flat to Steep Subduction of the Paleo‐Pacific Plate Beneath South China: Thickened Oceanic Crust and Subduction Rate |
| title_sort | factors on the mesozoic transition from flat to steep subduction of the paleo pacific plate beneath south china thickened oceanic crust and subduction rate |
| url | https://doi.org/10.1029/2022GC010523 |
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