Testing the hypothesis of the slab-plume interaction on the formation of the Yellowstone hotspot system

Yellowstone;plume;geodynamics

Leonard, Tiffany F.

关键词: Yellowstone;    plume;    geodynamics;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/78510/LEONARD-THESIS-2015.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Origin of the Yellowstone hotspot system remains debated. Proposed hypothesesfall into two main categories that involve either a deep mantle plume or only uppermantle processes. Recent seismic tomography images suggest the existence of hot mantleupwelling beneath the present-day Yellowstone, lending support to the plume hypothesis.However, the effect of the Farallon slab on the temporal evolution of the hypothesizedplume remains unclear. We use 4-D geodynamic models to investigate the temporalevolution of slab-plume interaction on the formation of the intra- plate volcanic provincethat includes the mid-Miocene Columbia River flood basalt (CRFB) and subsequentYellowstone and Newberry hotspot tracks. We find that the sinking slabs dominate thebuoyancy and dynamics of the system, and that evolution of the mantle upwelling issubject to that of the slabs. Our best-fit model with a hot upwelling starting at 35 Mabelow the present-day Yellowstone can match both the mid-Miocene flood basalt eventand the present-day lower mantle seismic image, suggesting a possible contribution ofdeep mantle to the CFRB. However, all models predict very little upper mantle residualhot anomaly, in contrast to the voluminous slow seismic anomalies, especially beneaththe Snake River Plain. These models also fail to generate a vertical plume conduit belowYellowstone as suggested by seismic tomography. We conclude that additionalmechanisms must be responsible for adding more heat to the western U.S. upper mantle.