Imperial College London
Alternate

Emeritus ProfessorHowardJohnson

Faculty of Engineering, Department of Earth Science & Engineering

Emeritus Professor of Reservoir Geology
 
 
 
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Contact

 

+44 (0)20 7594 6450h.d.johnson

 
 
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Location

 

3.48Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Steventon:2019:10.1111/bre.12337,
author = {Steventon, M and Jackson, C and Hodgson, D and Johnson, H},
doi = {10.1111/bre.12337},
journal = {Basin Research},
pages = {600--620},
title = {Strain analysis of a seismically-imaged mass-transport complex (MTC), offshore Uruguay},
url = {http://dx.doi.org/10.1111/bre.12337},
volume = {31},
year = {2019}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Strain style, magnitude, and distribution within mass-transport complexes (MTCs) is important for understanding the process evolution of submarine mass flows and for estimating their runout distances. Structural restoration and quantification of strain in gravitationally-driven passive margins have been shown to approximately balance between updip extensional and downdip compressional domains; such an exercise has not yet been attempted for MTCs. We here interpret and structurally restore a shallowly buried (c. 1500 mbsf) and well-imaged MTC, offshore Uruguay using a high-resolution (12.5 m vertical and 15x12.5 m horizontal resolution) 3D seismic-reflection survey. This allows us to characterise and quantify vertical and lateral strain distribution within the deposit. Detailed seismic mapping and attribute analysis shows that the MTC is characterised by a complicated array of kinematic indicators, which vary spatially in style and concentration. Seismic-attribute extractions reveal several previously undocumented fabrics preserved in the MTC, including internal shearing in the form of sub-orthogonal shear zones, and fold-thrust systems within the basal shear zone beneath rafted-blocks. These features suggest multiple phases of flow and transport directions during emplacement. The MTC is characterised by a broadly tripartite strain distribution, with extensional (e.g. normal faults), translational and compressional (e.g. folds and thrusts) domains, along with a radial frontally emergent zone. We also show how strain is preferentially concentrated around intra-MTC rafted-blocks due to kinematic interaction between these features and the underlying basal shear zone. Overall, and even when volume loss within the frontally emergent zone is included, a strain deficit between the extensional and compressional domains (c. 3-14%) is calculated, which we attribute to a combination of distributed, sub-seismic, ‘cryptic’ strain, likely related to de-watering, grain-
AU  - Steventon,M
AU  - Jackson,C
AU  - Hodgson,D
AU  - Johnson,H
DO  - 10.1111/bre.12337
EP  - 620
PY  - 2019///
SN  - 0950-091X
SP  - 600
TI  - Strain analysis of a seismically-imaged mass-transport complex (MTC), offshore Uruguay
T2  - Basin Research
UR  - http://dx.doi.org/10.1111/bre.12337
UR  - https://onlinelibrary.wiley.com/doi/abs/10.1111/bre.12337
UR  - http://hdl.handle.net/10044/1/66389
VL  - 31
ER  -
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