The Seismic Reflection Moho in Continental Rifted Margins: Insights from the Mid-Norwegian Continental Shelf

The Moho designates the boundary that separates the Earth's crust from the underlying upper mantle. Lying at about 5-7 km in oceanic domains and 30-40 km in continental domains, the Moho is of global significance and a major term widely used in geosciences. Although the definition sounds straightforward, method-dependent observations of the Moho have varied significantly, indicating that the simple definition may be misleading.

This contribution proposes an analysis of the seismic reflection Moho in a modern rifted margin context. The mid-Norwegian Continental Shelf is one of the worldwide most used laboratories to study rifting processes and rifted margin architecture. Available datasets are dense, various and of good quality. However, since the basement is rarely imaged in its whole, major questions remain unanswered regarding the structural details and nature of rocks at depth. The Geoex MCG Regional Deep Imaging 2019 (RDI19) dataset propose a series of regional long-offset seismic reflection profiles, of high resolution and deep imaging (16 s-twtt). The dataset offers an unprecedented imaging of the entire margin architecture including deep basement units, Moho and upper mantle - from the proximal margin to the outer margin. Based on this, the seismic facies, reflectivity, geometries and structural details of the Moho can be described and discussed in terms of tectonic deformation pattern.

Peron-Pinvidic G., 2022 -- The seismic reflection Moho across the mid-Norwegian continental rifted margin. Nature Communication Earth & Environment, 3:133, https://doi.org/10.1038/s43247-022-00465-y

Figure: The different seismic reflection Mohos identified in the different margin structural domains. Schematic geosection summarizing the main structural characteristics of a standard rifted margin. The thick dashed white lines illustrate the different seismic reflection Mohos identified in this study, summarizing their main characteristics with keywords: diffuse in the proximal domain, convergent in the necking domain, focused in the hyperextension subdomain, transparent in the exhumation subdomain, and corrugated in the outer domain. The faults are color-coded based on their assumed tectonic evolution related to the deformation phases and margin structural domains.