1. Temperature evolution of an oceanic fracture zone
Xiaopeng Tong & Janine Bühler

2. Outline Background Lithosphere flexure at Fracture zone
Mathematical derivation
Temperature & bathymetry
Comparison between the model and the data
Conclusion

3. Background
An oceanic fracture zone is the boundary between lithosphere of different ages.
A fracture zone is a linear oceanic feature--often hundreds, even thousands of kilometers long--resulting from the action of offset mid-ocean ridge axis segments. They are a consequence of plate tectonics. Lithospheric plates on either side of an active transform fault move in opposite directions; here, strike-slip activity is possible. Fracture zones extend past the transform faults, away from the ridge axis; seismically inactive (because both plate segments are moving in the same direction), they display evidence of past transform fault activity.

4. Lithosphere flexure at FZ
Phenomenon
Flexure near the FZ in the oceanic litho
Reason
Permanence of the initial bathymetric step across the FZ
Difference subsidence rate on either side of the FZ

5. Modeling Calculate the flexure Consistent with the observed data!
Elastic plate model
Thickness He(T)
Consistent with the observed data!

6. But…
They ignore the thermal conduction completely !

7. Problem
Ridge
Transform fault FZ t t0 x
Ridge

8. Mathematical derivation 1
T -- temperature
Tm -- temperature of the mantle
x -- distance vertical to FZ
z -- depth
t0 -- the age offset
t -- age of the older seafloor
t-t0 -- age of the younger one
The solution to this problem for an arbitrary initial temperature distribution can be expressed as a two-dimensional
Convolution of the initial temperature with a line source Green’s function
Green function method (Carslaw and Jaeger , 1959)

9. Mathematical derivation 2

10. Mathematical derivation 3
substitution
First part of the integration

11. Mathematical derivation 4
Second part of the integration
By Magic math

12. Final solution of temperature

13. Temperature evolution

14. Numerical approach...

15. Topography of the FZ 1 Ridge Local isostatic balance Transform faultx
Ridge

16. Topography of the FZ 2

17. Topography of the FZ 3
Final solution of the topography

20. Comparison

21. Conclusions
Topography calculations solely based on local isostatic compensation can not explain the observed data
We need to consider elastic flexure of the lithosphere (ie coupled fracture zones, fixed topographic step)
New studies use dynamic models that allow the fault zones to freely slip