Fault inversion can accommodate ground deformation above inflating igneous sills

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Authors

James Norcliffe, Craig Magee , Christopher Aiden-Lee Jackson, Jonas Kopping, Bailey Lathrop

Abstract

Magma emplacement is commonly accommodated by uplift of the overburden and free surface. By assuming this deformation is purely elastic, we can invert the shape and kinematics of ground deformation to model the geometry and dynamics of underlying intrusions. However, magma emplacement can be accommodated by viscoelastic and/or inelastic processes. We use 3D seismic reflection data to reconstruct how elastic bending and inelastic processes accommodated emplacement of a Late Jurassic sill offshore NW Australia. We restore syn-emplacement ground deformation and compare its relief to sill thickness, showing that: (i) where they are equal, elastic bending accommodated intrusion; but (ii) where sill thickness is greater, inversion of a pre-existing fault and overburden compaction contributed to magma accommodation. Our results support work showing inelastic processes can suppress ground deformation, and demonstrate magmatism can modify fault displacements. Reflection seismology is thus powerful tool for unravelling links between magma emplacement, ground deformation, and faulting.

DOI

https://doi.org/10.31223/X5GC76

Subjects

Physical Sciences and Mathematics

Keywords

Inversion, Sill, Fault, Magma, Forced fold

Dates

Published: 2020-11-09 13:05

License

CC BY Attribution 4.0 International

Additional Metadata

Conflict of interest statement:
None

Data Availability (Reason not available):
The seismic reflection and borehole data is publicly available from https://www.ga.gov.au/nopims

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