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Abstract Studying the driving force of intracratonic uplifts is important in understanding the deformation mechanism of continental lithosphere and the role of mantle dynamics. The Adirondack Mountains are located at the eastern Laurentian margin in the northeastern United States forming a distinct domal uplift. Subsurface structural constraints on their uplift mechanism are limited. Here we construct a high‐resolution velocity model for the crust and mantle lithosphere using full‐wave ambient noise tomography. A distinct low shear velocity anomaly with a diameter of ~70–100 km is imaged beneath the Moho at the Adirondack Mountains. This anomaly is connected with the large‐scale low‐velocity volume beneath southern New England and eastern New York at greater depths. The observed low‐velocity anomalies may reflect asthenosphere upwelling induced by a combined effect of the Great Meteor hot spot and edge‐driven mantle convections. The buoyancy of upwelling asthenosphere, together with possible thermal expansion, may have uplifted the Adirondack Mountains.
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Mantle thermochemical variations beneath the continental United States through petrologic interpretation of seismic tomography
The continental lithospheric mantle plays an essential role in stabilizing continents over long geological time scales. Quantifying spatial variations in thermal and compositional properties of the mantle lithosphere is crucial to understanding its formation and its impact on continental stability; however, our understanding of these variations remains limited. Here we apply the Whole-rock Interpretive Seismic Toolbox For Ultramafic Lithologies (WISTFUL) to estimate thermal, compositional, and density variations in the continental mantle beneath the contiguous United States from MITPS_20, a joint body and surface wave tomographic inversion for Vp and Vs with high resolution in the shallow mantle (60–100 km). Our analysis shows lateral variations in temperature beneath the continental United States of up to 800–900 °C at 60, 80, and 100 km depth. East of the Rocky Mountains, the mantle lithosphere is generally cold (350–850 °C at 60 km), with higher temperatures (up to 1000 °C at 60 km) along the Atlantic coastal margin. By contrast, the mantle lithosphere west of the Rocky Mountains is hot (typically >1000 °C at 60 km, >1200 °C at 80–100 km), with the highest temperatures beneath Holocene volcanoes. In agreement with previous work, we find that the chemical depletion predicted by WISTFUL does not fully offset the density difference due to temperature. Extending our results using Rayleigh-Taylor instability analysis, implies the lithosphere below the United States could be undergoing oscillatory convection, in which cooling, densification, and sinking of a chemically buoyant layer alternates with reheating and rising of that layer.
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- Award ID(s):
- 1952642
- PAR ID:
- 10389593
- Editor(s):
- Hans Thybo
- Date Published:
- Journal Name:
- Earth and planetary science letters
- ISSN:
- 0012-821X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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