Crust and Lithospheric Structure - Hot Spots and Hot-Spot Swells

McNutt, Marcia; Caress, David W.

doi:10.1016/b978-0-444-53802-4.00212-8

Cited by 2 publications

(2 citation statements)

References 152 publications

(187 reference statements)

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“…This model includes the 3D mantle densities obtained from the conversion of the S-wave velocity anomalies of the SL2013sv model (Schaeffer and Lebedev, 2013), from 50 to 200 km depth, published by Gómez-García et al (2019a, b). In this approach, the density conversion is performed following a modified version of Goes et al (2000) method, using a pressure-and temperature-dependent expansion coefficient (Hacker and Abers, 2004;Meeßen, 2017). Figures S3 and S4 present the S-wave velocities at different depths (from 50 to 200 km, every 25 km) and their associated densities, respectively.…”

Section: Initial Lithospheric Configuration and The Mantle Density Effect On The Gravity Signalmentioning

confidence: 99%

The preserved plume of the Caribbean Large Igneous Plateau revealed by 3D data-integrative models

Gómez-García¹,

Breton²,

Scheck‐Wenderoth

et al. 2021

Solid Earth

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Abstract. Remnants of the Caribbean Large Igneous Plateau (C-LIP) are found as thicker than normal oceanic crust in the Caribbean Sea that formed during rapid pulses of magmatic activity at ∼91–88 and ∼76 Ma. Strong geochemical evidence supports the hypothesis that the C-LIP formed due to melting of the plume head of the Galápagos hotspot, which interacted with the Farallon (Proto-Caribbean) plate in the eastern Pacific. Considering plate tectonics theory, it is expected that the lithospheric portion of the plume-related material migrated within the Proto-Caribbean plate in a north–north-eastward direction, developing the present-day Caribbean plate. In this research, we used 3D lithospheric-scale, data-integrative models of the current Caribbean plate setting to reveal, for the first time, the presence of positive density anomalies in the uppermost lithospheric mantle. These models are based on the integration of up-to-date geophysical datasets from the Earth's surface down to 200 km depth, which are validated using high-resolution free-air gravity measurements. Based on the gravity residuals (modelled minus observed gravity), we derive density heterogeneities both in the crystalline crust and the uppermost oceanic mantle (<50 km). Our results reveal the presence of two positive mantle density anomalies beneath the Colombian and the Venezuelan basins, interpreted as the preserved fossil plume conduits associated with the C-LIP formation. Such mantle bodies have never been identified before, but a positive density trend is also indicated by S-wave tomography, at least down to 75 km depth. The interpreted plume conduits spatially correlate with the thinner crustal regions present in both basins; therefore, we propose a modification to the commonly accepted tectonic model of the Caribbean, suggesting that the thinner domains correspond to the centres of uplift due to the inflow of the hot, buoyant plume head. Finally, using six different kinematic models, we test the hypothesis that the C-LIP originated above the Galápagos hotspot; however, misfits of up to ∼3000 km are found between the present-day hotspot location and the mantle anomalies, reconstructed back to 90 Ma. Therefore, we shed light on possible sources of error responsible for this offset and discuss two possible interpretations: (1) the Galápagos hotspot migrated (∼1200–3000 km) westward while the Caribbean plate moved to the north, or (2) the C-LIP was formed by a different plume, which – if considered fixed – would be nowadays located below the South American continent.

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Section: Initial Lithospheric Configuration and The Mantle Density Effect On The Gravity Signalmentioning

confidence: 99%

The preserved plume of the Caribbean Large Igneous Plateau revealed by 3D data-integrative models

Gómez-García¹,

Breton²,

Scheck‐Wenderoth

et al. 2021

Solid Earth

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“…The seismic structure of the crust beneath ocean island volcanoes gives key information about the mechanical and thermal properties of the oceanic lithosphere, the potential role of magmatic underplating and the controls of the crust on the formation of tectonic swells in marine settings (e.g. McKenzie et al 2005;McNutt & Caress 2007). Moreover, a good knowledge of the shallow crustal structure of oceanic islands is crucial for reliable seismic hazard assessment, notably for accurate ground motion simulations (e.g.…”

Section: Introductionmentioning

confidence: 99%

Crustal structure of the Azores Archipelago from Rayleigh wave ellipticity data

Ferreira

Marignier

Attanayake

et al. 2020

Geophysical Journal International

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SUMMARY Determining the crustal structure of ocean island volcanoes is important to understand the formation and tectonic evolution of the oceanic lithosphere and tectonic swells in marine settings, and to assess seismic hazard in the islands. The Azores Archipelago is located near a triple junction system and is possibly under the influence of a mantle plume, being at the locus of a wide range of geodynamic processes. However, its crustal structure is still poorly constrained and debated due to the limited seismic coverage of the region and the peculiar linear geometry of the islands. To address these limitations, in this study we invert teleseismic Rayleigh wave ellipticity measurements for 1-D shear wave speed (VS) crustal models of the Azores Archipelago. Moreover, we test the reliability of these new models by using them in independent moment tensor inversions of local seismic data and demonstrate that our models improve the waveform fit compared to previous models. We find that data from the westernmost seismic stations used in this study require a shallower Moho depth (∼10 km) than data from stations in the eastern part of the archipelago (∼13–16 km). This apparent increase in the Moho depth with increasing distance from the mid-Atlantic ridge (MAR) is expected. However, the rate at which Moho deepens away from the MAR is greater than that predicted from a half-space cooling model, suggesting that local tectonic perturbations have modified crustal structure. The 1-D VS models obtained beneath the westernmost seismic stations also show higher wave speeds than for the easternmost stations, which correlates well with the ages of the islands except Santa Maria Island. We interpret the relatively low VS profile found beneath Santa Maria Island as resulting from underplating, which agrees with previous geological studies of the island. Compared to a recent receiver function study of the region, the shallow structure (top ∼2 km) in our models shows lower shear wave speed, which may have important implications for future hazard studies of the region. More generally, the new seismic crustal models we present in this study will be useful to better understand the tectonics, seismicity, moment tensors and strong ground motions in the region.

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Crust and Lithospheric Structure - Hot Spots and Hot-Spot Swells

Cited by 2 publications

References 152 publications

The preserved plume of the Caribbean Large Igneous Plateau revealed by 3D data-integrative models

The preserved plume of the Caribbean Large Igneous Plateau revealed by 3D data-integrative models

Crustal structure of the Azores Archipelago from Rayleigh wave ellipticity data

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