Full‐Wave Seismic Tomography in the Northeastern United States: New Insights Into the Uplift Mechanism of the Adirondack Mountains

Yang, Xiaotao; Gao, Haiying

doi:10.1029/2018gl078438

Cited by 32 publications

(35 citation statements)

References 69 publications

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“…The boundaries of the yellow domain appear to be aligned with the slow feature at greater depths seen in most tomographic studies with sensitivity to the 50-to 150-km range (Shen & Ritzwoller, 2016;Yang & Gao, 2018; Figure 12b). The feature is located beneath Vermont and New Hampshire, and spatially coincides with the deeper NAA anomaly.…”

Section: Comparison With Other Geological and Geophysical Observablesmentioning

confidence: 57%

“…To explain the timing of emplacement of anorthosite bodies in the Adirondacks, Mclelland et al (2010) proposed an episode of lithospheric foundering and replacement, a process likely recorded in the residual lithospheric fabric. Additionally, the lithosphere of this domain may be experiencing a modern-day alteration, as suggested by the surface wave imaging by Yang and Gao (2018).…”

Section: Comparison With Other Geological and Geophysical Observablesmentioning

confidence: 99%

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Localized Anisotropic Domains Beneath Eastern North America

Levin

Elkington

et al. 2019

Geochem Geophys Geosyst

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Seismic anisotropy beneath eastern North America likely reflects both the remnant lithospheric fabrics and the present‐day deformation of the asthenosphere. We report new observations of splitting in core‐refracted shear phases observed over 3–5 years at 33 sites in New Jersey, New York, and states in the New England region and also include data from eight previously studied locations. Our data set emphasizes back azimuthal coverage necessary to capture the directional variation of splitting parameters expected from vertically varying anisotropy. We report single‐phase splitting parameters as well as station‐averaged values based on splitting intensity technique that incorporates all observed records regardless of whether they showed evidence of splitting or not. Trends of averaged fast shear wave polarizations appear coherent and are approximately aligned with absolute plate motion direction. The general disparity between the fast axes and the trend of surface tectonic features suggests a dominant asthenosphere contribution for the observed seismic anisotropy. Averaged delay values systematically increase from ~0.5 s in New Jersey to ~1.4 s in Maine. Splitting parameters vary at all sites, and neighboring stations often show similar patterns of directional variation. We developed criteria to group stations based on their splitting patterns and identified four domains with distinct anisotropic properties. Splitting patterns of three domains suggest a layered anisotropic structure that is geographically variable, outlining distinct regions in the continental mantle, for example, the Proterozoic lithosphere of the Adirondack Mountains. A domain coincident with the North Appalachian Anomaly displays virtually no splitting, implying that the lithospheric fabric was locally erased.

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Section: Comparison With Other Geological and Geophysical Observablesmentioning

confidence: 57%

Section: Comparison With Other Geological and Geophysical Observablesmentioning

confidence: 99%

Localized Anisotropic Domains Beneath Eastern North America

Levin

Elkington

et al. 2019

Geochem Geophys Geosyst

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“…In comparison with the initial reference model (Yang & Gao, 2018), our new shear‐wave velocity model in this study provides more detailed structure of the southern New England crust (Figure 2). Beneath the SEISConn array, we are able to resolve seismic features at a horizontal scale of 30–40 km (Figure S5), a significant improvement over the horizontal resolution (~50 km) of Yang and Gao (2018). At depths greater than about 30 km, the major velocity features in our velocity model are primarily inherited from the reference model (Figure S6).…”

Section: Resultsmentioning

confidence: 97%

“…The model grid extends from −75° to −69.8° in longitude, from 40.5° to 43.48° in latitude, and from the Earth's surface down to 131 km depth; (2) measurement of the Rayleigh wave phase delays between the observed empirical Green's functions and the synthetic waveforms through cross‐correlation in seven overlapping period bands, including 20–40, 15–30, 10–20, 8–15, 5–10, 4–8, and 3–5 s; and (3) calculation of three‐dimensional, finite‐frequency sensitivities of Rayleigh waves and inversion for velocity perturbations. We chose the regional shear‐wave velocity model of the northeastern United States that was recently constructed by Yang and Gao (2018) as the initial reference model, which extends from the surface down to the depth of about 220 km, with the best vertical resolution at the depth range of 15–120 km.…”

Section: Methodsmentioning

confidence: 99%

Seismic Evidence for Crustal Modification Beneath the Hartford Rift Basin in the Northeastern United States

Gao

Yang

Long

et al. 2020

Geophysical Research Letters

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Extensive Mesozoic rifting along the eastern North American margin formed a series of basins, including the Hartford basin in southern New England. Nearly contemporaneously, the geographically widespread Central Atlantic Magmatic Province (CAMP) was emplaced. The Hartford basin provides an ideal place to investigate the roles of rifting and magmatism in crustal evolution, as the integration of the dense SEISConn array and other seismic networks provides excellent station coverage. Using full‐wave ambient noise tomography, we constructed a detailed crustal model, revealing a low‐velocity (Vs = 3.3–3.6 km/s) midcrust and a high‐velocity (Vs = 4.0–4.5 km/s) lower crust beneath the Hartford basin. The low‐velocity midcrust may correspond to a layer of radial anisotropy due to extension and crustal thinning during rifting. The high‐velocity crustal root likely represents the remnant of magmatic underplating resulting from the CAMP event. Our findings shed light on crustal modification associated with supercontinental breakup, rifting, extension, and magmatism.

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“…Previous studies using the full-wave ambient noise tomography method in various tectonic settings (Covellone et al, 2015;Emry et al, 2019;Gao, 2018;Savage et al, 2017;Yang & Gao, 2018), as well as Figure S4 in the supporting information, demonstrate that the final tomographic model does not rely on seismic features in the initial reference model. Comparing with the initial model, the final model reveals seismic features showing tight correlations with the major elements of the AASZ ( Figure S4), which we describe in detail in this section.…”

Section: Improvements Over the Reference Modelmentioning

confidence: 84%

Segmentation of the Aleutian‐Alaska Subduction Zone Revealed by Full‐Wave Ambient Noise Tomography: Implications for the Along‐Strike Variation of Volcanism

Yang

Gao

2020

JGR Solid Earth

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The along-strike variations of the velocity, thickness, and dip of subducting slabs and the volcano distribution have been observed globally. It is, however, unclear what controls the distribution of volcanoes and the associated magma generation. With the presence of nonuniform volcanism, the Aleutian-Alaska subduction zone (AASZ) is an ideal place to investigate subduction segmentation and its relationship with volcanism. Using full-wave ambient noise tomography, we present a high-resolution 3-D shear wave velocity model of the AASZ for the depths of 15-110 km. The velocity model reveals the distinct high-velocity Pacific slab, the thicker, flatter, and more heterogeneous Yakutat slab, and the northeasterly dipping Wrangell slab. We observe low velocities within the uppermost mantle (at depth <60 km) below the Aleutian arc volcanoes, representing partial melt accumulation. The large crustal low-velocity anomaly beneath the Wrangell volcanic field suggests a large magma reservoir, likely responsible for the clustering of volcanoes. The Denali volcanic gap is above an average-velocity crust but an extremely fast mantle wedge, suggesting the lack of subsurface melt. This is in contrast with the lower-velocity back-arc mantle beneath the adjacent Buzzard Creek-Jumbo Dome volcanoes to the east. The back-arc low velocities associated with the Pacific, the eastern Yakutat, and the Wrangell slabs may reflect subduction-driven mantle upwelling. The structural variation of the downgoing slabs and the overriding plate explains the change of volcanic activity along the AASZ. Our findings demonstrate the combined role of the subducting slab and the overriding plate in controlling the characteristics of arc magmatism. Plain Language Summary The subduction of oceanic plates underneath the continent plate is a complicated, three-dimensional process. The geometry of the downgoing plate and the associated volcanic activity vary along the subduction margin. It is not clearly understood what controls the distribution of arc volcanoes. We utilize an advanced seismic imaging technique to construct a detailed seismic velocity model of the Aleutian-Alaska margin, from crust to the uppermost mantle. The velocity model reveals multiple downgoing slabs, with various seismic velocities, thicknesses, and dip angles. The imaged Pacific slab, Yakutat slab, and Wrangell slab correlate spatially with the Aleutian arc volcanoes, the Buzzard Creek-Jumbo Dome volcanoes, and the Wrangell volcanoes, respectively. The mantle wedge, the wedge-shaped space below the overriding crust and above the downgoing slab, is characterized by different seismic velocities below these three volcanic areas. The Denali volcanic gap, a region with the absence of volcanic activity, is located above a seismically fast mantle wedge and an average crust. There is no melt below this volcanic gap based on our observations. Our findings explain the along-strike variation of volcanic activity along the Aleutian-Alaska subduction zone and demonstrate the combined role of the s...

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Full‐Wave Seismic Tomography in the Northeastern United States: New Insights Into the Uplift Mechanism of the Adirondack Mountains

Cited by 32 publications

References 69 publications

Localized Anisotropic Domains Beneath Eastern North America

Localized Anisotropic Domains Beneath Eastern North America

Seismic Evidence for Crustal Modification Beneath the Hartford Rift Basin in the Northeastern United States

Segmentation of the Aleutian‐Alaska Subduction Zone Revealed by Full‐Wave Ambient Noise Tomography: Implications for the Along‐Strike Variation of Volcanism

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