[PPT] - P-T-X evolution of paleo- hydrothermal systems related to PowerPoint Presentation

SLIDE 1

P-T-X evolution

f

paleo- hydrothermal systems related to granites and active geothermal systems : the data from fluid inclusion studies

M. Cathelineau and M.C. Boiron

Thanks to coll. with CNR-IGG , G. Gianelli,

G. Ruggieri, M. Puxeddu

Works on Larderello geothermal system from 1986 to 2007 and Alpi Apuane (Ch. Montomoli, Pisa Univ.) and coll. with O. Vanderhaeghe, J. Vallance, A.S. André on paleo-hydrothermal systems

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mantle

Crust

Crustal fluids

Meteoric fluids

Mantle fluids

SLIDE 3

SLIDE 4

Calcite
!

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Optical microscopy, IR, UV Water-gas-salt system

microthermometry

Raman : gas, Cl EOS Liquid-Vapour modelling

PTX

LIBS : cations, trace elts

λ λ λ λ (nm)

740 660 580

I (u.a)

3 8 6 4 2

Na Li Mg Ca Li Si

' ( % ) * ('' (+' %'' %+' )'' )+' *'' ,° ° ° °-

,.-

)'° ° ° °/0 *'° ° ° °/.

///

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('1

2 #/#2 32 4 2222!32 "2 2522 !2$% 24% 2

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Meteoric fluids

Crustal fluids

Meteoric fluids

Mantle fluids

mantle crust Thermal evolution of the continental crust in subduction zones

Development of accretion prism Low geothermal gradient Relief formation

SLIDE 8

Meteoric fluids

Crustal fluids

Transition from crustal thickening to crustal thinning formation of metamorphic core complexes, horts and grabens, crustal cooling during thinning

SLIDE 9

Meteoric fluids

Crustal fluids

Mantle fluids and heat

Partial melting High geothermal gradients Gravitational collapse

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Continental convergence Thickening, and accretion Incipient melting Increase of temperature due to radioactive decay Partial melting Formation of an anatectic layer Pervasive melt migration Network of granitic veins

(sills/ dykes feeding larger Intrusions)

Exhumation / crystallization

f the partially molten crust

Orogenic collapse Extension of the upper crust

Vanderhaeghe, 2001 Sense

f melt migration

SLIDE 11

Divergent collapse (Vanderhaeghe and Teyssier, 2001)

synchronous with late exhumation gravitanional collapse of the

verthickened crust

may be divergent or convergent with or without (brittle) extension of the upper crust Normal faulting Ductile thinning of the lower crust >> nearly isothermal decompression, followed by rapid cooling magma Shallow brittle to ductile transition

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Gravitational collapse accompanied by shallow intrusion of leucogranites >> nature of the fluids involved in the local heat transfer, and cooling ??

SLIDE 13

Northern Portugal Fluid typology in past geothermal systems related to granites

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10

10

km

WSW ENE

Anticlinal de Valongo (D1v) Complexe granitique de Minho-Beira Anticlinal de Marao (D1v) Batholite de Villa Real-Moncorvo Bassin de Morais Antiforme de Miranda do Douro (D3v) Synforme de Bragança (D3v)

Paraautochtone

Complexe gneissique Précambrien

Complexe Allochtone Aut ochtone

Allochtone supérieur Ordovicien moyen à Dévonien supérieur

Granites hercynien

Ophiolite Quartzites Chevauchements majeurs Allochtone inférieur Complexe grauwackeux Chevauchements secondaires

Fig. : Profil géologique Miranda do Douro (ENE) - Porto (WSW) (d’après Ribeiro et al., 1990, modifié)

Northern Portugal (Miranda do Douro-Porto cross-section; after Ribeiro et al., 90) Hercynian granites

SLIDE 15

Northern Portugal

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W E Valongo anticline

D3 shear zone (N130°E)

Syn to post D3 granite Post D3 granite Aplite

Mineralised zone N30-60°E faults N130°E fault

Au

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100 150 200 250 300 350 400 2 4 6 8 10 12 14 16 Salinity (% wt % eq. NaCl) N115-140 N90 Primary Unoriented samples N30-60 N5 Primary (H2O-Vol) Unoriented samples (H2O-Vol)

Th (° ° ° °C) Aqueous fluids in metamorphic rocks

N30-60° ° ° °E N115- 140° ° ° °E N90° ° ° °E Primary

Aqueous carbonic fluids

Castromil

SLIDE 18

50 100 150 200 250 300 100 150 200 250 300 350 400 450 500 T (° ° ° °C) P (MPa) 400 405 331 366 365 335 357 312 284 Greisen stage Q1/Q2 Fe-S-As stage Q3 gold stage Reequilibrated fluid inclusions (metamorphic fluids) Aplite intrusion

Castromil

10 km lithostatic P 7 km lithostatic P 4 km lithostatic P 4 km hydrostatic P

SLIDE 19

250-300° ° ° °C Blackschists >450° ° ° °C 400-450° ° ° °C H2O- CO2 δ δ δ δ 18 O =9-12‰ 0.0015<Br/Cl<0.005 Aqueous-carbonic fluids Geopressured pseudo-metamorphic fluids Residual hot aqueous fluids 1-3 eq.wt% NaCl Local unmixing CH4-N2 Recharge fluids: Meteoric waters Mixing zone Au-ore deposit 180-250° ° ° °C δ δ δ δ 18 O = 0/+6‰ Resident aqueous fluids 1-3 eq.wt% NaCl δ δ δ δ 18 O = -1/+4‰ 0.0003<Br/Cl<0.001 120-150° ° ° °C

!

+

SLIDE 20

ASA96-6

520 522 521 519 524 116 114 113 112

N

PENY

805 132 138 140

MARGNAC FANAY RAZES

500 m

ASA96-4

. F.RN20

ASA96-7

F . N

é

m i e

Lac de St Pardoux ASA96-3

Late intrusion in French Massif Central : Intense microfracturing and fluid percolation

samples Granite γ1 - coarse grained Granite γ2 - Granite γ3 − fine grained faults Large hydrothermal pipes

SLIDE 21

Aqueous-carbonic 3 phases Lc-w1

N

. . . . . . . . . . .

°

Aqueous - carbonic 2 phases Lc-w2 + Aqueous inclusion Lw2, low salinity

. .

Aqueous inclusions Vw and Lw1

ASA96-3

N N

Aqueous inclusions Lw2, low salinity

N N

N=27 N=9 N=20

N=56

All data

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100 200 150 50 100 200 300 400 500 600 250 300

320 Ma 305 Ma

P (MPa) T (° ° ° °C)

(a) 325 Ma (b)

700

Litho.P Hydro.P Lw2 Lc-w1 Lc-w2 90°C/Km (Litho) 9 ° C / K m ( H y d r

)

(c) V/L

SLIDE 23

Metamorphic peak conditons

P T

Progressive exhumation

Decompression and abnormal heat flows

Local abnormal heat flows

Effects of quick penetration

f cold meteoric waters

25° ° ° °C/km

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65

SLIDE 25

5

&
(%))

&

53

5 57 7 %*+ ,*+ 7, 7,# #-

* .

) /* 0 )

8

8 12 3+ II-1 II-4 II-5 II-3 IV

4

Works in progress in coll. C. Montomoli, G. Ruggieri

SLIDE 26

50 100 150 200 250 300 5 10 15 20 25 30

salinity (wt % eq. NaCl) TH (°C)

isothermal mixing

diluted fluid saline fluid $5 4* $5 #6*

metamorphic fluid

$5 $5 $5 0* &6*

Northern Apennines

4!

SLIDE 27

Northern Apennines

55

7 7 8 8* 1 2*

5

57 7* 1 * '7," '

Montomoli et al., 2001

SLIDE 28

8 "9:;

:; 8

:;

(Larderello)

8; ; #;

SLIDE 29

20 µm 10 µm 10 µm

QuickTime™ et un décompresseur Photo - JPEG sont requis pour visualiser cette image.

Larderello

Vc-w Lw-c Aqueous carbonic inclusions Lw- c -h Saline inclusions Aqueous inclusions Lw

10 µm

SLIDE 30

20 40 60 40 60 80 20 40 60

CH4 N2 CO2

Larderello

<

*

',

38*
5

$59" $5

%*' 8:;/ < 5 )

' ,

!' 4' + group 1 '* , 03%3=%7,7'; >'>77+ group 2

SLIDE 31

CH4 10 2 30 40 50 60 70 80 90 100 H2 O 10 20 30 40 50 60 70 80 9 100 CO2 10 20 30 40 50 60 70 80 90 100 L u m3 110 S P O9 2700 B ru2443 B ru3138 S as 104027 B ad 3 65 4 C an352 3 V C112946 S p er2240 P ad2 782 M V3 3577 M V530 46 CH4 H2 O 7 80 90 100 CO2 10 20 30 400 450 500

Larderello

10 µm 10 µm

Lw-c Vc-w

CO2 rich end-member

5# #=

SLIDE 32

Na/K Na/Li

300°C 250°C 200°C 150°C 100°C

1 10 100 1000 1 10 100

Serrazzano1 Padule SASSO San Pompeo 9 Bruciano Monteverdi Canneto Cerreta

480°C 400°C

320°C 500 1000 1500 2000 2500 3000 10 20 30 40 50

Na/Li Cl/Br Seawater Magmatic fluids Evaporites

Ion Chemistry

SLIDE 33

# '* ) :,77° !5' ? '9,9'* @ 15 A+ #5 ! B 5))+ B 5*+ 9 !1

"

SLIDE 34

S N

250° ° ° °C 3 ° ° ° ° C 3 5 ° ° ° ° C 350° ° ° °C 4 ° ° ° ° C 1000 2000 3000 4000 m C-rich host rocks

CO2 - CH4

evaporitic level Lw-h H2O Vc-w,Lc-w Lw-(c), Lw present-day steam reservoir H2O Lw, Vw Lw-(c), Vw-(c) meteoric waters

Li-brines

saline Vw Lw-h*

Chlorite zone Biotite zone K-horizon 2 km

Larderello

Neogene seds

Flysch complex

Tuscan nappe

basement

Chl Biot

SLIDE 35

T (° ° ° °C) P (MPa) Monteverdi 3 - 3577 150 100 50 300 400 500 600 mu+chl And+bio+qz+H

2

O p.l.P p.d.l.P Lw-h L1w Lc-w Vc1w Vc2w p.d.h.P L2w p.d.T. b io ∆ ∆ ∆ ∆ P 1 1 1 1 2 2 2 2 Bruciano - 3138 P (MPa) T (° ° ° °C) 40 80 120 160 250 300 350 400 450 500 p.l.P p.d.l.P Vc-w Lw p.l.T p.d.h.P P (MPa) T (° ° ° °C) Badia - 3564 200 150 100 50 400 450 500 55

qz+mu+bio

Crd+Kf+H

2

O Vc-w p.l.P p.d.l.P p.d.h.P

SLIDE 36

Ruggieri et al.,99 Chlorite zone (intermediate levels)

Boiling and fluid mixing (condensation, mixing of the products

f boiling, and parent fluids

SLIDE 37

P (Mpa) T°C

300 600 500 400 150 100 50 Past L. P p.d. L. P p.d. H. P

1- Early stages

T°C = f(distance to the intrusion)

Litho > hydro hydro > L/V >vapor cooling

SP SAS SER BRU MV3

Deep levels Shallow levels

SLIDE 38

P (Mpa) T°C 300 600 500 400 150 100 50 Past L. P p.d. L. P p.d. H. P 1- Early stages T°C = f(distance to the intrusion) Litho > hydro hydro > L/V >vapor cooling SP SAS SER BRU MV3 Deep levels Shallow levels

50 100 150 200 250 300 100 150 200 250 300 350 400 450 500 T (° ° ° °C) P (MPa) 400 405 331 366 365 335 357 312 284 Greisen stage Q1/Q2 Fe-S-As stage Q3 gold stage Reequilibrated fluid inclusions (metamorphic fluids) Aplite intrusion Castromil 10 km lithostatic P 7 km lithostatic P 4 km lithostatic P 4 km hydrostatic P

SLIDE 39

Similarities between

ld and active geothermal areas

Link with collision events, and MCC style deformation Abnormal heat flows in relation with late partial melting Penetration of cold meteoric waters and cooling of the overheated crust Mixing of pseudo-metamorphic or contact metamorphism fluids with meteoric waters (and secondary brines when evaporites) Geometry of active systems (size, fluid percolation style) may be deduced from past systems and conversely

Crustal fluids