Proposal for a mechanical model of mobile shales
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Show full item recordEditorial
Nature
Date
2021-12-10Referencia bibliográfica
Soto, J.I., Heidari, M. & Hudec, M.R. Proposal for a mechanical model of mobile shales. Sci Rep 11, 23785 (2021). [https://doi.org/10.1038/s41598-021-02868-x]
Sponsorship
Applied Geodynamics Laboratory (AGL) Industrial Associates programAbstract
Structural systems involving mobile shale represent one of the most difficult challenges for
geoscientists dedicated to exploring the subsurface structure of continental margins. Mobile-shale
structures range from surficial mud volcanoes to deeply buried shale diapirs and shale-cored folds.
Where mobile shales occur, seismic imaging is typically poor, drilling is hazardous, and established
principles to guide interpretation are few. The central problem leading to these issues is the poor
understanding of the mechanical behaviour of mobile shales. Here we propose that mobile shales
are at critical state, thus we define mobile shales as “bodies of clay-rich sediment or sedimentary
rock undergoing penetrative, (visco-) plastic deformation at the critical state”. We discuss how this
proposition can explain key observations associated with mobile shales. The critical-state model can
explain the occurrence of both fluidized (no grain contact) shales (e.g., in mud volcanoes) and more
viscous shales flowing with grain-to-grain contact (e.g., in shale diapirs), mobilization of cemented
and compacted shales, and the role of overpressure in shale mobility. Our model offers new avenues
for understanding complex and fascinating mobile-shale structures.