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Seismic Imaging of Mantle Transition Zone Suggests a Hot Deep Plume Underneath the Iceland-Mid-Atlantic Ridge Region
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DOI：10.1029/2025JB033003.png)
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Abstract
En 中文
Iceland has long been a focus of geophysical studies due to its potential link to a deep mantle plume. However, the source region, morphology, and compositional characteristics-particularly the role of water-remain debated. We analyze a new SS precursor data set containing over 3,000 high-quality waveforms and apply a multi-dimensional reconstruction method to improve the robustness of travel-time (depth) measurements used to image the mantle transition zone (MTZ). Our imaging results reveal a thin MTZ (231 5 km) centered beneath Iceland, extending southward along the Mid-Atlantic Ridge to the Reykjanes Ridge. This thinning is mainly caused by a similar to 11 km uplift of the 660 km discontinuity (642 3 km), whereas the 410 km discontinuity (412 5 km) remains near the global mean. Temperature estimates from discontinuity topography indicate a 194 56 K anomaly at 660 km, while the lack of a thermal anomaly at 410 km contradicts a conventionally warm mantle plume environment, implying that additional factors flatten the discontinuity. We suggest that a moderate water content (similar to 0.2-0.5 wt%) can compensate for the expected thermal depression at 410 km, causing reduced S410S amplitudes (similar to 0.02). In contrast, the large S660S amplitudes (similar to 0.06) are consistent with a model of relatively dry thermal plume beneath Iceland originating from the lower mantle. This deep plume may interact with a hydrated MTZ, entraining volatiles during ascent. Our results underscore the critical roles of temperature and hydration in controlling plume expression and interpreting MTZ structure beneath oceanic hotspots.
Keywords:
mantle transition zone
the Iceland plume
seismic imaging
mantle temperature
mantle water content
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J
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4.1
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182
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