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| Titel |
New interpretation of the deep mantle structure beneath eastern China |
| VerfasserIn |
Pengfei Ma, Shaofeng Liu, Chengfa Lin, Xiang Yao |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250126430
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| Publikation (Nr.) |
 EGU/EGU2016-6149.pdf |
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| Zusammenfassung |
| Recent study of high resolution seismic tomography presents a large mass of high velocity
abnormality beneath eastern China near the phase change depth, expanding more than
1600km-wide in East-west cross-section across the North China plate. This structure high is
generally believed to be the subducted slab of Pacific plate beneath the Eurasia continent,
while its origin and dynamic effect on the Cenozoic tectonic evolution of eastern China
remain to be controversial. We developed a subduction-driven geodynamic mantle
convection model that honors a set of global plate reconstruction data since 230Ma to
help understand the formation and evolution of mantle structure beneath eastern
China. The assimilation of plate kinematics, continuous evolving plate margin,
asymmetric subduction zone, and paleo seafloor age data enables the spatial and
temporal consistency between the geologic data and the mantle convection model, and
guarantees the conservation of the buoyancy flux across the lithosphere and subducted
slabs. Our model achieved a first order approximation between predictions and the
observed data. Interestingly, the model suggests that the slab material stagnated above
discontinuity didn’t form until 15Ma, much later than previous expected, and the fast
abnormality in the mid-mantle further west in the tomographic image is interpreted to
be the remnants of the Mesozoic Izanagi subduction. Moreover, detailed analysis
suggests that the accelerated subduction of Philippine Sea plate beneath Eurasia plate
along the Ryukyu Trench and Nankai Trough since 15Ma may largely contribute to
extending feature above 670km discontinuity. The long distance expansion of the slab
material in the East-west direction may be an illusion caused by the approximate
spatial perpendicularity between the cross-section and the subduction direction of the
Philippine Sea plate. Our model emphasizes the necessity of the re-examination on the
geophysical observation and its tectonic and geodynamic implication in eastern China. |
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