Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Seafloor Massive Sulfides (SMS)

Global characteristics, distribution,

and regional Pacific potential

Sven Petersen

(IFM-GEOMAR)

SPC-EU EDF

Deep Sea Minerals Workshop, Nadi, Fiji, 06.-08. June 2011

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

influx of cold seawater (recharge)

H2O = H+ + OH- Mg2+ + OH- = Mg(OH)2 precipitation excess H+

pH drop to ~ 4-5

heating of seawater to > 400°C leaching of Cu, Zn, Fe, Au, S etc. from the surrounding rock

formation of hydrothermal precipitates due to mixing of hot fluid with seawater

150°C

375°C

Reaction Zone

Gabbro

Dike Section

Extrusives

Magma

Recharge

Discharge

>30% water

<1% water

fluid is hot, buoyant, weakly acid, reduced & metal+sulfur-rich

How do they form ?

source: Comou et al., 2008

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen Hydrothermal sites in the

South Atlantic

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

distribution of seafloor hydrothermal systems in the world ocean

Where do they form ?

latest discoveries: Cayman Trough

Wallis & Futuna

Northern Matas

Piterskoe

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

distribution of seafloor hydrothermal systems in the world ocean

Russian exploration claim area

Chinese exploration claim area

Manafe & DFI

mining liscence

Nautilus

mining liscence

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• >350 known sites of hydrothermal activity

• 270 sites of polymetallic sulfide deposits

• 180 sites of high-temperature hydrothermal activity

(black smokers)

• 57% at mid-ocean ridges

(64,000 km)

• 28% in back-arc environments

15% on submarine volcanic arcs

(combined 25,000 km)

• <1% on intraplate volcanoes

Basic Facts

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Examples are known in very different tectonic settings:

• mid-ocean ridges

(superfast, fast, intermediate, slow, ultraslow spreading centers)

• off-axis volcanoes

• intracontinental rifts & rifted margins

• intraoceanic back-arc basins

• intracontinental back-arc basins

• volcanic island arcs

(Hannington et al., 2005)

Basic Facts

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

other factors: water depth, distance to land, EEZ ?

massive sulfides as a

resource ?

•how many ?

•grade ?

•tonnage?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• 1.8 x 1012 W of heat flux at young crust (Mottl, 2003)

• 10% at black smoker temperatures; the rest is diffuse

• 2 to 5 MW for a single black smoker (Converse et al, 1984)

• 50,000 to 100,000 black smokers (at least 1 every km of ridge axis)

• 200 to 500 MW for a large field (500 to 1,000 fields)

• ~ 15% of the hydrothermal fields are currently known

How many black smokers are there?

Sou

rce: S

OE

ST

(Haw

aii)

>80 % look like this !

© NOAA

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

at fast-spreading ridges

• short lived hydrothermal activity

• cyclic volcanic and hydrothermal activity

• quick burial by extrusives

• 90% of the metals lost to the plume

massive sulfides at

mid-ocean ridges

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

1 cm

pyrite - chalcopyrite - sphalerite

1 cm isocubanite -

pyrrhotite - wurtzite

average geochemistry of MORB-

hosted massive sulfides

mainly pyrite with

5 % Cu

9 % Zn

0.3 ppm Au (strong bias due to sampling of chimneys)

massive sulfides at

mid-ocean ridges

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• systems at slow-spreading ridges tend to be larger !

•commonly located off-axis

•deep penetrating faults allow long-lasting fluid flow

• some sites associated with mantle rocks

massive sulfides at

mid-ocean ridges

N

0 5 10 km

basaltic lava floor

mantle rocks

Logatchev

Logatchev hydrothermal field 2 hydrothermally active fields

largest field 800x300 m

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Logatchev hydrothermal field

1 cm

64ROV-11D

• hosted in mantle rocks • water depth 3000m • very high Cu and Au grades !

23 % Cu 4 % Zn 11 ppm Au

Is it possible to utilize this ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Cu-rich chimney

waste

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen massive sulfides in

back arc basins

Hydrothermal sites in

Papua New Guinea

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

PacManus samples

10.3 % Cu

22.6 % Zn

0.5 % Pb

205 ppm Ag

14 ppm Au

PACMANUS hydrothermal field host rocks: volcanic suite from basalt to rhyolithe

water depth: 1650m

Yeats (CSIRO)

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

58-GTVA

altered dacite

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

exploring companies: exploring countries:

• Nautilus South Korea

• Bluewater, and others Russia

• China

(France/Germany)

PacManus

2010

Susu Knolls

=

1. mine site ?

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

© NOAA

massive sulfides at

island arc volcanoes

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

mid-ocean ridges island/back arcs basalt exposed mantle interm. - felsic

Fe, Cu, Zn Cu, Fe Cu, Zn, Pb, Ba

Co Au, Co, Ni, Sn As, Hg, Sb, Au, Ag

~1 ppm Au 3-10 ppm Au 5–30 ppm Au!

deep water deep water shallow water

source: geochemical differences in the rocks themselves

+ additional factors (magmatic input, biology, zone refining, ... )

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

high grade (Cu±Au±Zn) or large deposits

massive sulfides as a

resource ?

TAG

Middle Valley

Manus

Suiyo

Krasnov Semyenov

Kairei

13°N, EPR

Atlantis II

Logatchev

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Will these deposits by of commercial interest ?

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Uchaly + Novo Uchaly (>220 Mio t)

… compared to those on land ?

Gay (>380 Mio t)

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

© NOAA

Kelley et al., 2001

(C)

Nation

al

Geogra

phic

1992

© MARUM

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• typical EPR chimneys 0.x Mio t

• Atlantis II Deep (Red Sea) 94 Mio t drilled ore mud from brine pool

• Middle Valley (JFR) 8-10 Mio t drilled

large sulfide lenses in sediments (Fe dominated)

• 13°N Seamount (EPR) 5-10 Mio t ?

• Krasnov, Semyenov ~ 15 Mio t ? large pyrite mounds (Fe dominated)

• TAG (MAR) 4 Mio t drilled (low grade in interior)

• Suzu Knolls; Manus Basin >2 Mio t drilled (indicated + inferred)

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

high grade or large deposits

X X

X Fe-only

X too small

X too deep ?

size ?

X

too deep ?

low grade ?

X

too small

size ?

TAG

Middle Valley

Manus

Suiyo

Krasnov Semyenov

Kairei

13°N, EPR

Atlantis II

Logatchev

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Mining seafloor massive

sulfides needs:

•2 mio tonnes of ore /year

(~ 200x200x20m)

• life-time of 10 years

(= 20 mio t of ore !) (may be contained in several orebodies !)

Currently not known !

Will mining of seafloor massive sulfides replace land mining?

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

worldwide VMS Districts (>> 6 billion tonnes)

GSC

massive sulfides as a

resource ?

21. Avoca 37 Mt

20. Iberian Pyrite Belt 1000 Mt

19. Central Nfld. 75 Mt18. Bathurst 250 Mt

16. Abitibi 600 Mt

15. Ladysmith -Rhineland 80 Mt

14. Sturgeon Lake 35 Mt13. Geco-Manitouwadge 60 Mt

12. Flin Flon -Snow Lk 150 Mt

11. Ruttan , Manitoba 70 Mt

45. Mt. Read Tasmania 150 Mt32. Central Urals >100 Mt10. Slave 20 -30 Mt

44. Lachlan Fold Belt31. Southern Urals >400 Mt9. Tambo Grande 200 Mt

43. Central Queensland30. Semail Oman 30 Mt8. Central Mexico 120 Mt 41-42. WA >75 Mt29. Saudi Arabia 70 Mt7. Jerome, Arizona 40 Mt

40. Philippines 65 Mt28. Turkey, Black Sea 200 Mt6. Shasta, Klammath 35 Mt

39. Besshi Japan 230 Mt27. Troodos Cyprus 35 Mt5. Myra Falls 30 Mt

38. Hokuroku Japan 80 Mt25. Bergslagen -Orijarvi 110 Mt4. Northern Cordillera 100 Mt35. Bawdwin -Laochang >40 Mt24. Outokumpu -Pyhslm 90 Mt3. Windy Craggy 300 Mt

34-36. China >500 Mt23. Skellefte Sweden 70 Mt2. Finlayson, Yukon 20 Mt

33. Rudny Altai >100 Mt22. Tondheim Norway >100 Mt1. Alaska, Brooks Range 33 Mt

21. Avoca 37 Mt

20. Iberian Pyrite Belt 1000 Mt

19. Central Nfld. 75 Mt18. Bathurst 250 Mt

16. Abitibi 600 Mt

15. Ladysmith -Rhineland 80 Mt

14. Sturgeon Lake 35 Mt13. Geco-Manitouwadge 60 Mt

12. Flin Flon -Snow Lk 150 Mt

11. Ruttan , Manitoba 70 Mt

45. Mt. Read Tasmania 150 Mt32. Central Urals >100 Mt10. Slave 20 -30 Mt

44. Lachlan Fold Belt31. Southern Urals >400 Mt9. Tambo Grande 200 Mt

43. Central Queensland30. Semail Oman 30 Mt8. Central Mexico 120 Mt 41-42. WA >75 Mt29. Saudi Arabia 70 Mt7. Jerome, Arizona 40 Mt

40. Philippines 65 Mt28. Turkey, Black Sea 200 Mt6. Shasta, Klammath 35 Mt

39. Besshi Japan 230 Mt27. Troodos Cyprus 35 Mt5. Myra Falls 30 Mt

38. Hokuroku Japan 80 Mt25. Bergslagen -Orijarvi 110 Mt4. Northern Cordillera 100 Mt35. Bawdwin -Laochang >40 Mt24. Outokumpu -Pyhslm 90 Mt3. Windy Craggy 300 Mt

34-36. China >500 Mt23. Skellefte Sweden 70 Mt2. Finlayson, Yukon 20 Mt

33. Rudny Altai >100 Mt22. Tondheim Norway >100 Mt1. Alaska, Brooks Range 33 Mt

12

34

10

5

6

7

8

1112

14

15

13 16

17

18 19

9

26

20

21

22

25

23

24

28

27

29 30

32

31

3334

35

46

39

3836

37

40

43

44

45

41

42

50 % in only 50 deposits of >50 mio t

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

a snapshot

in time

At most the modern oceans contain only 175 million years worth of metal !

Current exploration is considering only young crust !

One giant deposit every 200 mio years !

Why is the geologic record so well endowed?

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Most seafloor sites:

• are too small

• are of low grade

• occur too deep

• are too far from land

• occur in the „Area“ (politics)

• or are active and „too hot“

but: mining of few sites might be

economically feasible

massive sulfides as a

resource ?

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen regional Pacific potential

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen regional Pacific potential

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

Opportunities:

There is still a large potential for new

discoveries using regional surveys!

regional Pacific potential

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• Back-arc spreading centers still have large potential to

discover new sites ! By far most of those will be small.

• Intra-plate volcanoes are underexplored but have limited

potential for sulfide deposits.

• Island-arc volcanoes have large potential, but frequent

eruptions and shallow water depth may limit sulfide

potential near the seafloor.

• Where are the large deposits

in the Pacific region ?

regional Pacific potential

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• Current research and exploration is

mainly related to active deposits at or

near spreading axis.

• many deposits are buried underneath

sediments or lava.

• Systematic surveys for hidden deposits

are lacking.

• Regional geological and geophysical

exploration using towed systems or

AUV’s is necessary to define resource

potential.

seafloor hydrothermal systems

Challenges

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

• 6000m depth rating, 4Kn max. speed

• 24 h station time

• turbidity sensor (ECO), Eh-sensor (NIST

Japan), CTD, 120/410 kHz side-scan

sonar (Edgetech), ADCP

3 konfigurations

• 200/400 kHz multibeam (RESON 7125D)

• or sub-bottom profiler

• or b/w digital camera + flash

underwater navigation: • transponder (LBL, USBL)

• inertial navigation (Kearfott)

IFM-GEOMAR’s

AUV ABYSS

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen

central part

= 65 km² !

Reson Seabat 7125

400 kHz

AUV-based

bathymetry

Modern Seafloor

Massive Sulfide

Deposits

S. Petersen AUV-based

bathymetry

Thank You !