A Global View of Upper Mantle Stratification: CRISP-RF

Our planet’s mantle is the largest rock-layer by volume. Across its old and stable Archean and Proterozoic terranes, seismological evidence suggests ubiquitous, spatially variable, and puzzling discontinuities, within, across and beneath the upper mantle lithosphere (~50- 350 km). A variety of explanations have been proposed, including phase transformations, melting and compositional anomalies, anisotropy, and elastically accommodated grain. To evaluate these, and other models, it is crucial to improve our threshold for detecting such discontinuities especially in reverberant and noisy environments. Here, we present a new method for sifting through the echoes and reverberations: CRISP-RF (Clean Receiver function Imaging with Sparse Radon Filters). With a global dataset of Ps converted waves, we use CRISP-RF to isolate hard-to-detect wave conversions buried in reverberations and noise. This refined, high-resolution, global view of upper mantle stratification will ensure robust evaluation of proposed models of upper mantle structure, evolution, and dynamics.