Asthenospheric low-velocity zone consistent with globally prevalent partial melting

Hua, Junlin; Fischer, K. M.; Becker, T. W.; Gazel, Esteban; Hirth, Greg

doi:10.1038/s41561-022-01116-9

Cited by 35 publications

(47 citation statements)

References 82 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…So far, most of the observational constraints of MLDs come from SRFs. In addition to the well-known sensitivity of the S-to-P amplitude in SRFs to isotropic V s changes, the amplitude is also affected by changes in radial anisotropy (e.g., extended Figure 6 in Hua et al, 2023), with the dependence involving both anisotropy amplitude and Kawakatsu's fifth parameter (η κ ; Kawakatsu, 2018). Despite the broad application of the SRF technique to studying MLDs, it also has three well-known limitations: First, the depth resolution is limited due to the low frequency range of teleseismic S waves and the small temporal separations between the S-to-P phases generated at different interfaces (Figure 1e in T. Liu & Shearer, 2021).…”

Section: Methods For Studying Mlds and Future Directionsmentioning

confidence: 99%

Strong Physical Contrasts Across Two Mid‐Lithosphere Discontinuities Beneath the Northwestern United States: Evidence for Cratonic Mantle Metasomatism

Liu,

Chin,

Shearer

2023

AGU Advances

View full text Add to dashboard Cite

Mid‐lithosphere discontinuities are seismic interfaces likely located within the lithospheric mantle of stable cratons, which typically represent velocities decreasing with depth. The origins of these interfaces are poorly understood due to the difficulties in both characterizing them seismically and reconciling the observations with thermal‐chemical models of cratons. Metasomatism of the cratonic lithosphere has been reported by numerous geochemical and petrological studies worldwide, yet its seismic signature remains elusive. Here, we identify two distinct mid‐lithosphere discontinuities at ∼87 and ∼117 km depth beneath the eastern Wyoming craton and the southwestern Superior craton by analyzing seismic data recorded by two longstanding stations. Our waveform modeling shows that the shallow and deep interfaces represent isotropic velocity drops of 2%–8% and 4%–9%, respectively, depending on the contributions from changes in radial anisotropy and density. By building a thermal‐chemical model including the regional xenolith thermobarometry constraints and the experimental phase‐equilibrium data of mantle metasomatism, we show that the shallow interface probably represents the metasomatic front, below which hydrous minerals such as amphibole and phlogopite are present, whereas the deep interface may be caused by the onset of carbonated partial melting. The hydrous minerals and melts are products of mantle metasomatism, with CO2‐H2O‐rich siliceous melt as a probable metasomatic reagent. Our results suggest that mantle metasomatism is probably an important cause of mid‐lithosphere discontinuities worldwide, especially near craton boundaries, where the mantle lithosphere may be intensely metasomatized by fluids and melts released by subducting slabs.

show abstract

Section: Methods For Studying Mlds and Future Directionsmentioning

confidence: 99%

Strong Physical Contrasts Across Two Mid‐Lithosphere Discontinuities Beneath the Northwestern United States: Evidence for Cratonic Mantle Metasomatism

Liu,

Chin,

Shearer

2023

AGU Advances

View full text Add to dashboard Cite

show abstract

“…However, this is a heavily debated topic with several proposed hypotheses. Some studies proposed that the asthenosphere results from the presence of small amounts of partial melts in the upper mantle (Anderson & Spetzler, 1970; Chantel et al., 2016; Debayle et al., 2020; Hua et al., 2023), while others consider that the region is better explained by a subsolidus regime associated with rheological weakening of mantle rocks under temperatures that are close to the solidus (Karato, 2012; Takei, 2017). For the latter hypothesis, it has been suggested that dissolved water in olivine could effectively reduce the viscosity (Hirth & Kohlstedt, 1996).…”

Section: Discussionmentioning

confidence: 99%

The Mantle Viscosity Structure of Venus

Maia

Wieczorek

Plesa

2023

Geophysical Research Letters

View full text Add to dashboard Cite

The long‐wavelength gravity and topography of Venus are dominated by mantle convective flows, and are hence sensitive to the planet's viscosity structure and mantle density anomalies. By modeling the dynamic gravity and topography signatures and by making use of a Bayesian inference approach, we investigate the viscosity structure of the Venusian mantle by constraining radial viscosity variations. We performed inversions under a wide range of model assumptions that consistently predicted the existence of a thin low‐viscosity zone in the uppermost mantle. The zone is about 235 km thick and has a viscosity reduction of 5–15 times with respect to the underlying mantle. Drawing a parallel with the Earth, the reduced viscosity could be a result of partial melting as suggested for the origin of the asthenosphere. These results support the interpretation that Venus is a geologically active world predominantly governed by ongoing magmatic processes.

show abstract

“…Understanding the lithospheric evolution and origin of the Lithosphere‐Asthenosphere Boundary (LAB) is fundamentally important and widely debated. Popular hypotheses include thermal weakening of mineral structures (Chapman & Pollack, 1977), elastically accommodated grain boundary sliding (Karato, 2012; Karato et al., 2015); change in anisotropy (Rychert & Shearer, 2011; Rychert et al., 2007), stress induced amorphization at olivine grain boundaries (Samae et al., 2021) and the presence of partial melt (Debayle et al., 2020; Hua et al., 2023; Kovács et al., 2021; Rychert et al., 2020). Furthermore, the LAB contributes to our understanding of geodynamic processes in tectonically complex areas such as the Eastern‐Alps‐Carpathians‐Pannonian‐Dinarides region (ACPDR; Horváth et al., 2015; Rychert et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Lithospheric Structure of the Circum‐Pannonian Region Imaged by S‐To‐P Receiver Functions

Kalmár,

Petrescu,

Stipčević

et al. 2023

Geochem Geophys Geosyst

View full text Add to dashboard Cite

The lithosphere‐asthenosphere boundary and mid‐lithospheric discontinuities are primary attributes of the upper mantle. The Pannonian region is an extensional sedimentary basin enclosed by collisional orogens. Here, we estimate the negative phase depth of S‐to‐P receiver functions to image the lithospheric thickness and other discontinuities with high resolution, based on the recent dense seismological broadband networks. The lithosphere‐asthenosphere boundary is relatively shallow (<90 km) in the Pannonian Basin system, and deeper (∼90–140 km) in the surrounding orogens, where average surface heat flow values are higher (120 mW/m2) and lower (50–70 mW/m2), respectively. The 1D and 2D common conversion point migration with 3D velocity model provide comparable but different resolution images beneath the wider region of the Pannonian Basin. We obtained deeper values in the Western (∼120 km) and Southern‐Carpathians orogens (∼135 km). Furthermore, we provide new information on the lithospheric thickness and its seismic properties in the eastern part of the study region (e.g., Apuseni Mountains (∼95 km), Eastern‐Carpathians (∼120 km), Moesian Platform (∼90 km) and Transylvanian Basin (∼85 km). The shallower negative phase depth can be interpreted as the lithosphere‐asthenosphere boundary beneath the Pannonian Basin system in agreement with its high heat flow values. In contrast, the deeper negative phase depth estimates in the colder surroundings can be interpreted as intra‐ or mid‐lithospheric discontinuities, when compared with local seismic tomography models. In this region, the correlation with heat flow implies that the observed negative phase depth is of thermo‐chemical or rheological nature.

show abstract

Asthenospheric low-velocity zone consistent with globally prevalent partial melting

Cited by 35 publications

References 82 publications

Strong Physical Contrasts Across Two Mid‐Lithosphere Discontinuities Beneath the Northwestern United States: Evidence for Cratonic Mantle Metasomatism

Strong Physical Contrasts Across Two Mid‐Lithosphere Discontinuities Beneath the Northwestern United States: Evidence for Cratonic Mantle Metasomatism

The Mantle Viscosity Structure of Venus

Lithospheric Structure of the Circum‐Pannonian Region Imaged by S‐To‐P Receiver Functions

Contact Info

Product

Resources

About