The upper mantle beneath Asia from seismic tomography, with inferences for the mechanisms of tectonics, seismicity, and magmatism

Dou, Hui; Xu, Yihe; Lebedev, Sergei; Chagas de Melo, Bruna; van der Hilst, Robert D.; Wang, Baoshan; Wang, Weitao

doi:10.1016/j.earscirev.2024.104841

Cited by 2 publications

References 243 publications

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Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum‐Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical‐Petrological Thermochemical Inversion

El‐Sharkawy,

Hansteen,

Clemente‐Gomez

et al. 2024

Geochem Geophys Geosyst

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We compile an extensive catalog comprising geochemistry and ages of Cenozoic volcanic provinces in the Mediterranean region, distinguishing between three groups according to the geochemistry of magmatic rocks: intraplate (IVP), subduction‐related (SRVP), and mixed‐origin volcanic provinces (MVP; intraplate with subduction imprint). In order to relate their spatial distribution to properties of the lithosphere‐asthenosphere system, we determine temperature‐depth profiles by integrated geophysical‐petrological inversion at representative locations, using Rayleigh and Love wave phase velocities, heat flow, rock densities, and accounting for thermochemical conditions. The results confirm the occurrence of thin lithosphere (<100 km) above warm asthenosphere (>1,300°C) in areas of low shear‐wave velocities in the shallow upper mantle. Nine shallow asthenospheric volumes (SAVs) between 70 and 300 km depths are identified, forming a partly interconnected belt across the Circum‐Mediterranean. A remarkable colocation exists between the SAVs and the intraplate and mixed‐origin volcanic provinces (IMVPs). Whereas dense networks of IMVPs have formed above the SAVs, IMVPs are absent in areas of thick mantle lithosphere. Magmatic activity in IMVPs at 60–70 Ma indicates that several SAVs existed already in the Paleogene (Central European, Adriatic, Western Mediterranean, and Moesian SAVs). The formation of SAVs is related either to asthenospheric upwelling caused by slab rollback and back‐arc extension (Aegean‐Anatolian, Moesian, Pannonian, Western Mediterranean SAVs), or to thermal upwelling (Adriatic, Central European, Middle East [MEA], North African, Rhine‐Rhone SAVs), with some of the latter coupled partly with continental rifting (Central European, MEA, North African, Rhine Rhone SAVs).

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Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum‐Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical‐Petrological Thermochemical Inversion

El‐Sharkawy,

Hansteen,

Clemente‐Gomez

et al. 2024

Geochem Geophys Geosyst

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Himalayan sub-Moho earthquakes suggest crustal faults trigger eclogitized-drip tectonics

Song,

Klemperer

2024

Preprint

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Along the 1400-km Himalayan arc, 100 + sub-Moho earthquakes have been detected from their Sn/Lg amplitude ratios or S-P delay times, concentrated densely beneath a ~ 300-km segment in south Tibet where they reach ~ 110-km depth. Explanations for these earthquakes include Moho-penetrating faults and the dripping of eclogitized lower crust. We estimate the geological strain-rates, temperatures, and timescales for these two processes from seismological, thermal, geological, and geodetic datasets. We constrain the eclogite viscosity to \(\:\lesssim\:\)1–5×1021 Pa⋅s through numerical modeling of viscous Rayleigh-Taylor dripping within the available geological timescale (~ 20 Ma). Thermal analysis shows it is unlikely that brittle failure in olivine-dominated lithospheric mantle occurs below the 70-km Moho, hence a deeply penetrating fault cannot by itself explain the 70–110-km seismicity. Stronger eclogitized lower crust at upper-mantle depths would enable brittle failure, but an eclogite drip by itself cannot explain the dominating dextral-slip focal mechanisms. We propose that eclogitization of mafic granulites in the Indian lower crust occurs along lower-crustal shear zones associated with active faults and fluid intrusion, creating the density anomaly that drives Rayleigh-Taylor instability. As the eclogite drip grows, high strain within the drip creates brittle faulting to upper-mantle depths, albeit in what are crustal lithologies.

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The upper mantle beneath Asia from seismic tomography, with inferences for the mechanisms of tectonics, seismicity, and magmatism

Cited by 2 publications

References 243 publications

Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum‐Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical‐Petrological Thermochemical Inversion

Cenozoic Volcanic Provinces and Shallow Asthenospheric Volumes in the Circum‐Mediterranean: Evidence From Magmatic Geochemistry, Seismic Tomography, and Integrated Geophysical‐Petrological Thermochemical Inversion

Himalayan sub-Moho earthquakes suggest crustal faults trigger eclogitized-drip tectonics

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