Segment tip geometry of sheet intrusions, II: Field observations of tip geometries and a model for evolving emplacement mechanisms

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Authors

Tara Louise Stephens , Richard J Walker, David Healy, Alodie Bubeck

Abstract

Igneous sheet intrusions are segmented across several orders of magnitude, with segment tip geometry commonly considered indicative of the propagation mechanism (brittle or non-brittle). Proposed propagation mechanisms are inferred to represent host rock mechanical properties during initial magma emplacement; typically, these models do not account for segment sets that show a range of tip geometries within the same lithology. We present a detailed structural characterization of basaltic sill segments and their associated host rock deformation from the Little Minch Sill Complex, Isle of Skye, UK, and a broader comparison with segment geometries in three additional intrusive suites (Utah, USA; and Mull and Orkney, UK). Each separate host lithology shows multiple tip geometries and styles of host rock deformation, from elastic-brittle fracture, to viscous indentation and fluidisation. We attribute this range of host rock deformations to evolving conditions that occur at the tips both during sheet growth and arrest.

DOI

https://doi.org/10.31223/X5SW28

Subjects

Earth Sciences, Geology, Volcanology

Keywords

deformation, sheet intrusion

Dates

Published: 2020-11-03 06:46

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
Data & supplemental files are available on request

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