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Thermodynamic
Modelling and
MT anomalies
National MT Workshop andAusLAMP South Australia
Klaus Regenauer-Lieb
And Team
UNSW, Sydney
Unconventional Geomechanics is physics
based data assimilation in space and time Time – SpaceAusLAMP
Linkage Project
LP170100233
Linkage Project
LP170100233
When there are lots of Fluids in the ductile realm strange things happen
Weinberg, R. F., and K. Regenauer-Lieb
(2010), Ductile fractures and magma
migration from source, Geology, 38(4),
363-366, doi:10.1130/G30482.1.
Weinberg, R., M. Veveakis, and K. Regenauer-Lieb (2015),
Compaction bands and melt segregation from migmatites,
Geology, 43(6), 471-474, doi:10.1130/G36562.1.
Can deep fluids sources be imaged by MT?
Conductors at depth sign of Deep Fluids ?
How do fluids flow through solid granites?
Granite sample
Permeability: Local Porosity theory
• 1.3 micron resolution CT scan
Fusseis et al. 2009 (Nature)
Just at percolation
threshold enables flow
Deep fluid transfer in shear zones
drive mineral forming processes
Dissolution Precipation of K-feldspar in mid-crustal granite mylonites
Luca Menegon, Giorgio Pennacchioni, Richard Spiess (2008)
Northern Flinders Ranges
Low resistivity proxy for fluid dissolution-precipitation reactions triggering dynamic permeable networks?
Why do the anomalies pond at the brittle ductile transition
Open Questions
But how can we model fluid transfer?
Sommer, K. Regenauer-Lieb, B. Gasharova, H. Jung, The
formation of volcanic centers at the Colorado Plateau in the
western United States. Journal of Geodynamics 61, 154-171 (2012).
The effect of material damage can be incorporated in a far from equilibrium Thermodynamics approach
No Equilibrium
Thermodynamics 1. The macroscopic kinetic energy of the
whole system is constant ✔
2. No exchange of matter takes place with
the outside world No
3. No work is done on the total system No
4. No heat flows out of the surroundings
into the system
Chemical Shear Zones | Thomas Poulet11 |
• Normalised and reduced system of equations
• Dimensionless Groups:
Lewis number 𝐿𝑒
Gruntfestnumber 𝐺𝑟
heat diffusion
mass diffusionLe
𝜕Δ𝑃
𝜕𝑡=
𝜕
𝜕𝑧
1
𝐿𝑒
𝜕Δ𝑃
𝜕𝑧+
Λ
𝑚𝜎′𝑛
𝜕𝑇
𝜕𝑡+ 𝜇𝑟 1 − 𝜙 1 − 𝑠 𝑒
−𝐴𝑟𝑐 𝛿𝑇1+𝛿𝑇
𝜕T
𝜕𝑡=
𝜕𝑇
𝜕𝑧2+ 𝐺𝑟 𝑒
−𝛼Δ𝑃+𝐴𝑟𝑚𝛿𝑇1+𝛿𝑇 − 𝐷𝑎 1 − 𝜙 1 − 𝑠 𝑒
−𝐴𝑟𝑐 𝛿𝑇1+𝛿𝑇
Damköhlernumber 𝐷𝑎
Arrhenius number 𝐴𝑟𝑐
Mathematical system
𝐷𝑎 =𝑑𝑖𝑓𝑓𝑢𝑠𝑖𝑜𝑛 𝑜𝑓 𝑚𝑎𝑠𝑠
𝑐ℎ𝑒𝑚𝑖𝑐𝑎𝑙 𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 𝑟𝑎𝑡𝑒
𝐺𝑟 =ℎ𝑒𝑎𝑡 𝑑𝑖𝑓𝑓𝑢𝑠𝑖𝑜𝑛
ℎ𝑒𝑎𝑡 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛
Da, Le and Gr define critical time scales for instabilities
Alevizos, S., T. Poulet, S. Walsh, T. M. Durdez, M.
Veveakis, and K. Regenauer-Lieb (2017), The dynamics
of multiscale, multiphysics faults: part II-episodic stick-
slip can turn the jelly sandwich into a crème brûlée,
Tectonophysics.
Episodic Tremor and Slip
THE OSCILLATOR
A.Creeping shear post-failure
B.Shear Heating in creeping chemical process zone
C.Chemical reaction/ decomposition of the skeleton (excess pore pressure)
D.Reverse chemical reaction
Poulet, T., E. Veveakis, K. Regenauer-Lieb, and D. A. Yuen (2014), Thermo-Poro-Mechanics of chemically active creeping faults. 3: The role of Serpentinite in Episodic Tremor and Slip sequences, and transition to chaos, Journal of Geophysical Research: Solid Earth, 119(6), 4606–4625 doi:10.1002/2014JB011004.
Cascadia Episodic Tremor and Slip ETS
THCM effects in rocks | E. Veveakis
Rogers, 2003
Brudzinski, 2007
Nonvolcanic tremor is observed in close association with geodetically observedslow-slip events in subduction zones.
Predicted Serpentinite oscillator
THCM effects in rocks | E. Veveakis
Predicted: Serpentinite oscillator solid line (2003/2004 perturbation of GPS station)
Observed: Blue dots GPS data
Does cyclical deep fluid release provide a key to understanding Earth surface instabilities?
A fundamental thermo-chemo-mechanical oscillator characterized by shear heating, fluid release, fast slip and slow backward reaction in carbonates, serpentinites, sediments and granites.
The oscillator can explain episodic ductile localization in large thrust systems (Glarus) Episodic Tremor and Slip in Subduction Zones (Cascadia, Hikurangi Trench), buckling of the interior of the Australian continent (Musgrave, Arunta) and creep fractures in the Geodynamics Deep Geothermal Well in Australia Cooper Basin .
We propose it as a universal mechanism connecting geodynamic and seismological time-scales
Shelly and Hardebeck 2010
Far from equilibrium model 2 or 3-DUsing simplification from high-T material sciences: damage mechanics
Creep Fractures are well known in Ceramics
The test checks the creep fracture strength of samples ranging from sizes smaller than a matchstick down to samples of diameter 100mm.
Early stage
creep fracture
Creep fractures in Ceramics
A. C. F. Cocks and M. F.
Ashby, progress in
materials science, 1982,
Vol. 27, pp. 189 to 244
Incre
asin
g s
train
Micro-
pores/cracks
on grain
boundaries
fibre pullout
SiC-SiCf Ceramic
Matrix Composite
1300º C
Integrating the Oscillator over time allows 2D/3D modeling, here granitic composition
400-500∘C Redbank shear zone creep
fractures, dissolution-precipitation traces
Regenauer-Lieb et al. 2009
Numerical model of the shear zone
with chemical reactions
Veveakis et al. 2013
Temperature
pre
ssure
etime
Sandiford et al. 2004, Quigley et al. 2010
Compression atextremely low strain rates
<10-16 s-1
CollisionHot Granite
under
strong
compression
Geodynamic Driver for creep fractures
Deep
Well
The Clean Base LoadEnergy Dream
Example Geothermal
Reservoir
“GEODYNAMICS”
PROJECT
In Australia
Hydrogen Embrittlement
Ruptured through 7 m concrete
How can we understand deep permeability?
Televiewer image of a
permeable zone @
~250°C4.5 km depth
Is permeability triggered
by dissolution
precipitation reactions?
Fluid
pathway
Courtesy of
Geodynamics
Model versus Observations
images courtesy of Geodynamics Ltd
First fracture at 4134m No fracture at
top ~of granite
Key Observations
• Fractures only exist and can be stimulated for
temperatures > 230° C
• Fractures do not propagate into the sediments
• In excess of 35 MPa fluid overpressure
• Fluid equilibrated within pegmatitic granite
Conclusion: Fractures appear to be generated by a mineral dissolution reaction driven by geodynamic work
<4,100 m depth
500 Myrs compression of Australia
1Regenauer-Lieb, K., M. Veveakis, T. Poulet, and Ali Karrech (2015), Multiscale, Multiphysics
Geomechanics for Geodynamics applied to Buckling Instabilities in the Middle of the Australian Craton, Philosophical Magazine, 95(28-30), 3055-3077.
Conductors delineate the mechanism of buckling
UNSW Team: Dynamic Modelling of MT-Anomalies in the Crust • Flinders Case• Gawler Case• Northern Territory (Cloncurry case study)
Macquarie Team: 3D Probabilistic Inversion for the Entire Model,• End of Q2 2019 1D Inversion Australia wide• End Q1 2020 3D Inversion on a case study (TISA)
Where to go from here? January 2019 – July 2020
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