Plume‐Lithosphere Interaction and Delamination at Yellowstone and Its Implications for the Boundary of Craton Stability

• Published in: Geophysical research letters Vol. 49; no. 2
• Main Authors: Shi, Ya‐Nan, Morgan, Jason P.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.01.2022
• Subjects: Basalt; Boundaries; craton lithospheric thinning; Cratons; Delamination; Fault lines; Hot spots; Hot spots (geology); Identification; Lava; Lithosphere; mantle plume; Melting; mid‐lithosphere discontinuity; numerical modeling; Ocean circulation; Plumes; Rivers; Seismic stability; Tectonics; Upwelling; Yellowstone hotspot; Columbia River
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2021GL096864

Delamination of the lower lithosphere has occurred under different tectonic settings, thereby inducing strong lateral lithospheric strength heterogeneities. Here, we examine a recent case of plume‐induced lithosphere delamination associated with the Yellowstone plume. We propose that interaction between the Yellowstone plume and western North American lithosphere is what led to delamination of the lower lithosphere beneath the Columbia River Basalt (CRB) roughly ∼17 Myr ago. The excess melting that occurred when this “hole” was being filled by Yellowstone plume material was the primary trigger for the CRB excess melting event. The delaminated lower lithosphere currently lies to the northeast of the CRB; it can be clearly identified in recent seismic tomographic models. We suggest that both weak zones, for example, lithosphere‐crossing faults or suture zones, or vertical weaknesses associated with hotspot tracks, and strong zones (regions not underlain by weak mid‐lithosphere discontinuity material) can become the lateral boundaries of lithosphere delamination. Plain Language Summary In a few regions the continental lithosphere is not stable and its lower part has been thinned and destroyed. However, the controls on the geometry and boundary of this modification process remain largely unknown. Here, we use the continental lithosphere around the Yellowstone hotspot track as an example to show how hot material rising from the deep mantle can lead to the modification of overriding lithosphere. We propose that interaction between the hot Yellowstone plume and western North American lithosphere led to thinning of the lower lithosphere beneath the Columbia River Basalt (CRB) roughly ∼17 Myr ago. The excess melting that occurred when this “hole” was being filled by upwelling hot material was the primary trigger for the CRB melting event. The lower lithosphere that was delaminated currently lies to the northeast of the CRB; it can be clearly identified in recent seismic tomographic models. We suggest that both weak zones, either lithosphere‐crossing faults or suture zones, or vertical weaknesses associated with hotspot tracks, and strong zones which lack a weak internal layer in the middle of the lithosphere will form natural lateral boundaries to the delamination of the lower lithosphere. Key Points The lower lithosphere beneath the Columbia River Basalt has been delaminated and currently lies in mantle transition zone to the northeast This location is consistent with absolute plate motions over the past 16 Myr The geometry of “vertical” pre‐existing weak zones and a weak mid‐lithosphere layer controls the pattern of lithospheric delamination