Imperial College London
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DrRebeccaBell

Faculty of Engineering, Department of Earth Science & Engineering

Reader in Tectonics
 
 
 
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Contact

 

+44 (0)20 7594 0903rebecca.bell

 
 
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Location

 

2.37aRoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Harold:2020:10.1029/2019TC005965,
author = {Harold, L and Fagereng, A and Meneghini, F and Morgan, J and Savage, H and Wang, M and Bell, R and Ikari, M},
doi = {10.1029/2019TC005965},
journal = {Tectonics},
title = {Mixed brittle and viscous strain localisation in pelagic sediments seaward of the Hikurangi margin, New Zealand},
url = {http://dx.doi.org/10.1029/2019TC005965},
volume = {39},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Calcareouspelagic input sediments are present at several subduction zones and deform differently to their siliciclastic counterparts. We investigate deformation in calcareouspelagic sediments drilled ~20 km seaward of the Hikurangi megathrust toe at Site U1520 during IODP Expeditions 372 and 375. Clusters of normal faults and subhorizontal stylolites in the sediments indicate both brittle faulting and viscous pressure solution operated at <850 m below sea floor. Stylolite frequency and vertical shortening estimated using stylolite mass loss, porosity change, and distribution increase with carbonate content. We then use U1520 borehole data to constrain a PTt history for the sediments, and apply an experimentallyderived pressure solution model to compare with strains calculated from stylolites. Modelled strains fail to replicate stylolitehosted strain distribution or magnitude, but comparison shows porosity, composition, and grainscale effects in diffusivity and mass transfer pathway width likely exert a strong influence on pressure solution localisation and strain rate. Stylolite and fault clusters concentrate clay in these sediments, creating weak volumes of clay within carbonates, that may localise slip where the plate interface intersects the carbonates at <5 km depth. Plate interface slip character and rheology will be influenced by the deformation of intermixed phyllosilicates and calcite, occurring by variablystable frictional slip and pressure solution of calcite. Pressure solution of calcite is therefore important at the shallow plate interface, waning at the base of the slowslipping zone because calcite solubility is low at temperatures > 150°C where frictional (possibly seismic) slip likely predominates.Plain Language SummaryThe type of sediments entering subduction zones will influence the way the plates in the subduction zone slide past one another. We looked at limestones in sediments drilled before they reach the subduction zone an
AU  - Harold,L
AU  - Fagereng,A
AU  - Meneghini,F
AU  - Morgan,J
AU  - Savage,H
AU  - Wang,M
AU  - Bell,R
AU  - Ikari,M
DO  - 10.1029/2019TC005965
PY  - 2020///
SN  - 0278-7407
TI  - Mixed brittle and viscous strain localisation in pelagic sediments seaward of the Hikurangi margin, New Zealand
T2  - Tectonics
UR  - http://dx.doi.org/10.1029/2019TC005965
UR  - http://hdl.handle.net/10044/1/82946
VL  - 39
ER  -
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