1. Coupled trace element mobilisation and strain softening in quartz during retrograde fluid infiltration in dry granulite protolihts
Bjørn Eske Sørensen,
PhD 27. June 2007
Department of Geology and Mineral Resources Engineering
Supervisors Rune B. Larsen (IGB)
Håkon Austrheim (UIO)
Presented at the 33IGC, August in Oslo, Norway

2. Introduction Parameters controlling the retrograde behaviour of Qz
Influence of
Fluids
Deformation
PT-conditions
Ti-Al-B drop correlates with progressive recrystallisation seen in SEM-CL images
Relates to fluid infiltration and deformation
Fluids relate to regional alteration processes in other rock types and ore fm.
Arendal

3. Lecture outline Textural and chemical evolution of quartz
PTXfluid evolution from phase diagram modelling
Main conclusions

4. Lecture outline Textural and chemical evolution of quartz
PTXfluid evolution from phase diagram modelling
Main conclusions

5. SEM-CL summary Qz
Qz2
Qz1
Qz3
1mm

6. Coarse domains
Microfaults

7. SEM-CL quartzite Qz2 Qz1 Qz3 5 mm Owerview near micro-fault zones
3 qtz types
5 mm

8. SEM-CL quartzite
Qz1
Qz2
Qz3
Zoom on SEM-Cl picture
1 mm

9. Optical texture of quartzite
Optical picture of the same area as the previous slide
Note the partial alteration of Bt grains
Partial poltgonisation
Fine grained mica in aparrently homogeneous qtz grains
SGR Sb Sa
1 mm

11. d
quartzite
Vein + leocosome

13. Conclusion Qz1 & Qz2

14. Conclusion Qz3 cracking

15. Conclusion SGR Qz3 only

16. Lecture outline PTXfluid evolution from phase diagram modelling
Textural and chemical evolution of quartz
PTXfluid evolution from phase diagram modelling
Main conclusions

17. Fluid inclusions, FIA3
qz+bt+ru+(ttn)
qz+chl+mu +ttn+(ru)
3 cm

18. Typical FIA3 LVS-inclusion
Qz2
Qz3
Qz1
10 mm
Typical FIA3 LVS-inclusion
Halite
H2O
Vapour
250 mm
Qz3
Qz2
Qz1
FIA3 inclusions

19. Modified after Kornerup-Madsen (1979)
Sørensen (2007)
Modified after Kornerup-Madsen (1979)

20. PT-Xfluid path(Sørensen 2007)
PERPLEX, HP98 dataset

21. Lecture outline Main conclusions
Textural and chemical evolution of quartz
PTXfluid evolution from phase diagram modelling
Main conclusions

22. Conclusions
Quartz recrystallisation controlled by discrete fluid influxes during retrogression of dry high temperature quartz
Quartz recrystallisation events can be related to a revised retrograde PT-Xfluid path and discrete pulses of fluid influx
Qz1 – dry high metamorphic grade quartz – 750ºC, 7 kb
Qz2 – rehydration of dry brittle quartz causing brecciation and dissolution-reprecipitation
Qz3 – influx of aqueous brines along fracture causes recrystallisation, with resulting trace element depletion and strain softening changing rheological behaviour from brittle to plastic with SGR
Important process during exhumation and uplift, where quartz only deforms in H2O rich environments
Exhumation 100ºC lower than earlier estimates: from 7-6 kb down to 3-4 kb at ºC

23. Conclusions
High purity quartz purifications occurs on a localised scale in relation to scapolitisation and metasomatic alteration of biotite to muscovite
Devolatisation during HT metamorphism
Fluid saturated rocks dominated by greenshist facies are better sources of high quantities
It is important to understand quartz purification in the geological framework
New resources
Field investigation methods
New types of quartz resources for solar grade silicon require research on aggregation methods, processing etc.

24. Thanks for the attention 
That’s all for today
More info in my thesis and in forthcoming papers…..
Link to thesis: