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The lithospheric structure of the Mendocino Triple Junction: Implications of receiver function analysis
Levander, Alan R.
Master of Science
This thesis presents a 3-D Common Conversion Point (CCP) image to examine the lithospheric structure in the Mendocino Triple Junction (MTJ) region. I have used 186 teleseismic earthquakes recorded in the Flexible Array Mendocino Experiment (FAME) to generate the stacked CCP image of PdS receiver functions. The resulting image not only shows the existence of a slab window beneath the northern Coast Ranges, as proposed by the slab window hypothesis, but also reveals the slab window structure in detail for the first time. The slab window is identified as a complex low velocity body with its top connected to the Gorda lithosphere-asthenosphere boundary (LAB). The asthenospheric mantle might upwell as shallow as ∼50 km near Clear Lake and Lake Pillsbury, resulting in high heat flow and basalt intrusions respectively. This work can help develop a dynamic model of the three plates involved in the MTJ's migration.