Moho structure of northeastern Canada using receiver function analysis

This study investigates variations in Mohorovi£i¢discontinuity (Moho) depth across the northeastern segment of the Canadian Shield using the receiver function (RF) technique. The study area encompasses a range of geologically distinct terranes, including both Archean and Proterozoic domains, making it an ideal setting for investigating the evolution of the continental crust from the Paleoarchean era to the emergence of plate tectonic activity in the Paleoproterozoic. Central to this investigation is the Trans-Hudson Orogen (THO) — a Paleoproterozoic suture zone situated between the Superior Craton in the southeast and the Rae and Hearne Cratons in the northwest. This region retains a complex geological history that offers key insights into processes of crustal growth and continental assembly. We utilize teleseismic earthquakes with magnitudes (M > 5.5) recorded by both permanent and temporary seismic stations to compute Receiver Functions (RF) and estimate Moho depth beneath each station. While the standard RF method remains central to this work, we compare our findings with previous studies and models (e.g., Crust 1.0) to validate our interpretations. Although we attempted to assess azimuthal variation in Moho depth, our efforts were limited by the uneven azimuthal distribution of incoming seismic waves. This restricted our ability to reliably separate directional effects such as dipping interfaces or seismic anisotropy, particularly in geologically complex areas like the Trans-Hudson Orogen. Despite the methodological strengths, our analysis is constrained mainly by the limited azimuthal distribution of seismic events, which hampers our ability to robustly resolve directional variations in Moho depth and distinguish between seismic anisotropy and structural dips. Moho depth estimates in the Superior Province (Archean) range from 34 to 40 km, reflecting relatively simple crustal structure. In contrast, the THO exhibits more variation, with Moho depths between 35 and 43 km. While some of our stations reveal sharp receiver function peaks indicative of well-defined Moho boundaries, others display more complex or ambiguous patterns—likely influenced by uneven data coverage, crustal anisotropy, topographic variations in the Moho, or differences in its nature, ranging from sharp to gradational transitions. Regional patterns also emerge from our analysis. In Greenland, Moho depth increases from north to south, while in the Canadian Shield, more spatially variable trends are evident. Overall, this work demonstrates the value of receiver functions in probing crustal structure across a geologically complex region, while also emphasizing the importance of dense seismic coverage and integrated methodologies. Future studies would benefit from the inclusion of complementary techniques (e.g., joint inversion, gravity or magnetotelluric (MT) surveys) to better resolve anisotropic features and refine Moho depth estimates in areas with limited seismic data.

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