Post on 07-Apr-2018
8/6/2019 2011 SOPAC Meeting Fiji Petersen
1/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Seafloor Massive Sulfides (SMS)Seafloor Massive Sulfides (SMS)
Global characteristics, distribution,Global characteristics, distribution,and regional Pacific potentialand regional Pacific potential
Sven PetersenSven Petersen
(IFM-GEOMAR)(IFM-GEOMAR)
SPC-EU EDFDeep Sea Minerals Workshop,
Nadi, Fiji, 06.-08. June 2011
8/6/2019 2011 SOPAC Meeting Fiji Petersen
2/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
influx of cold seawater (recharge)
H2O = H+ + OH-
Mg2+ + OH- = Mg(OH)2precipitation
excess H+ pH drop to ~ 4-5heating of seawater to > 400C
leaching of Cu, Zn, Fe, Au, S etc. from
the surrounding rockformation of hydrothermal precipitates
due to mixing of hot fluid with seawater
150C
375C
Reaction Zone
Gabbro
DikeSection
Extrusives
Magma
Recharge
Discharge
>30% water
8/6/2019 2011 SOPAC Meeting Fiji Petersen
3/42
Modern SeafloorMassive Sulfide
Deposits
S. PetersenHydrothermal sites in theSouth Atlantic
8/6/2019 2011 SOPAC Meeting Fiji Petersen
4/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
distribution of seafloor hydrothermal systems in the world ocean
Where do they form ?
latest discoveries:Cayman TroughWallis & FutunaNorthern MatasPiterskoe
8/6/2019 2011 SOPAC Meeting Fiji Petersen
5/42
Modern SeafloorMassive 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
Nautilusmining liscence
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
6/42
8/6/2019 2011 SOPAC Meeting Fiji Petersen
7/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Examples are known in very different tectonicExamples are known in very different tectonicsettingssettings::
mid-ocean ridges(superfast, fast, intermediate, slow, ultraslow spreading centers)
off-axis volcanoes
intracontinental rifts & rifted margins
intraoceanic back-arc basins
intracontinental back-arc basinsvolcanic island arcs
(Hannington et al., 2005)
Basic Facts
8/6/2019 2011 SOPAC Meeting Fiji Petersen
8/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
other factors: water depth, distance to land, EEZ ?
massive sulfides as aresource ?
how many ?
grade ?
tonnage?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
9/42
8/6/2019 2011 SOPAC Meeting Fiji Petersen
10/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
S
ource:SOE
ST(Hawaii)
>80 % look like this !
NOAA
8/6/2019 2011 SOPAC Meeting Fiji Petersen
11/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
at fast-spreading ridgesat fast-spreading ridges
short lived hydrothermal activityshort lived hydrothermal activity
cyclic volcanic and hydrothermal activitycyclic volcanic and hydrothermal activity
quick burial by extrusivesquick burial by extrusives
90% of the metals lost to the plume90% of the metals lost to the plume
massive sulfides atmid-ocean ridges
8/6/2019 2011 SOPAC Meeting Fiji Petersen
12/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
1 cm
pyrite - chalcopyrite - sphalerite
1 cmisocubanite -
pyrrhotite - wurtzite
average geochemistry of MORB-
hosted massive sulfides
mainly pyrite with5 % Cu9 % Zn
0.3 ppm Au
(strong bias due to sampling of chimneys)
massive sulfides atmid-ocean ridges
8/6/2019 2011 SOPAC Meeting Fiji Petersen
13/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
systems at slow-spreadingsystems at slow-spreadingridges tend to be larger !ridges tend to be larger !
commonly located off-axiscommonly located off-axis
deep penetrating faults allowdeep penetrating faults allowlong-lasting fluid flowlong-lasting fluid flow
some sites associated withsome sites associated with
mantle rocksmantle rocks
massive sulfides atmid-ocean ridges
ne
8/6/2019 2011 SOPAC Meeting Fiji Petersen
14/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
N
0 5 10 km
1520'
Nfrac
turezo
ne
basaltic lava floor
mantle rocks
Logatchev
Logatchev hydrothermal field2 hydrothermally active fields
largest field 800x300 m
8/6/2019 2011 SOPAC Meeting Fiji Petersen
15/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Logatchev hydrothermal field
1 cm
64ROV-11D
hosted in mantle rockswater depth 3000mvery high Cu and Au grades !
23 % Cu
4 % Zn
11 ppm Au
Is it possible to utilize this ?
atth
esurf
ace
8/6/2019 2011 SOPAC Meeting Fiji Petersen
16/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
-u rich chimneyu rich chimney
wasteaste
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
17/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersenmassive sulfides inback arc basins
Hydrothermal sites in
Papua New Guinea
8/6/2019 2011 SOPAC Meeting Fiji Petersen
18/42
Modern SeafloorMassive 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 rhyolithewater depth: 1650m
Yeats (CSIRO)
atth
esurf
ace
8/6/2019 2011 SOPAC Meeting Fiji Petersen
19/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
58-GTVA
altered dacitealtered dacite
8/6/2019 2011 SOPAC Meeting Fiji Petersen
20/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
exploring companies: exploring countries:Nautilus South KoreaBluewater, and others Russia China
(France/Germany)
PacManus
20102010
Susu Knolls
=1. mine site ?
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
21/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
NOAA
massive sulfides atisland arc volcanoes
8/6/2019 2011 SOPAC Meeting Fiji Petersen
22/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
mid-ocean ridges island/back arcsbasalt exposed mantle interm. - felsic
Fe, Cu, Zn Cu, Fe Cu, Zn, Pb, Ba
Co Au, Co, Ni, Sn As, Hg, Sb, Au, Ag~1 ppmAu 3-10 ppmAu 530 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 aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
23/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
high grade (CuAuZn) or large deposits
massive sulfides as aresource ?
TAG
Middle Valley
Manus
Suiyo
KrasnovSemyenov
Kairei
13N, EPR
Atlantis II
Logatchev
8/6/2019 2011 SOPAC Meeting Fiji Petersen
24/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Will these deposits by of commercial interest ?
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
25/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Uchaly + Novo Uchaly (>220 Mio t)
compared to those on land ?
Gay (>380 Mio t)
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
26/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
NOAA
Kelley et al., 2001
(C
)Nationa
lGeograph
ic1
992
MARUM
massive sulfides as aresource ?
8/6/2019 2011 SOPAC Meeting Fiji Petersen
27/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
typical EPR chimneys 0.x Mio t
Atlantis II Deep (Red Sea) 94 Mio t drilledore mud from brine pool
Middle Valley (JFR) 8-10 Mio t drilledlarge sulfide lenses in sediments (Fe dominated)
13N 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 aresource ?
M d S fl
8/6/2019 2011 SOPAC Meeting Fiji Petersen
28/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
high grade or large deposits
XX
XFe-only
Xtoo small
X
too deep ?
size ?
X
too deep ?low grade ?
X
too small
size ?
TAG
Middle Valley
Manus
Suiyo
KrasnovSemyenov
Kairei
13N, EPR
Atlantis II
Logatchev
massive sulfides as aresource ?
M d S fl
8/6/2019 2011 SOPAC Meeting Fiji Petersen
29/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Mining seafloor massiveMining seafloor massivesulfides needs: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?Will mining of seafloor massive sulfides replace land mining?
massive sulfides as aresource ?
M d S fl
8/6/2019 2011 SOPAC Meeting Fiji Petersen
30/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
worldwide VMS Districts (>> 6 billion tonnes)
GSC
massive sulfides as aresource ?
50 % in only 50 deposits of >50 mio t
M d S fl
8/6/2019 2011 SOPAC Meeting Fiji Petersen
31/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
a snapshotin 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 aresource ?
M d S fl
8/6/2019 2011 SOPAC Meeting Fiji Petersen
32/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Most seafloor sites: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 beeconomically feasible
massive sulfides as aresource ?
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
33/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersenregional Pacific potential
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
34/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersenregional Pacific potential
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
35/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Opportunities:
There is still a large potential for newdiscoveries using regional surveys!
regional Pacific potential
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
36/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Back-arc spreading centers still have large potential todiscover new sites ! By far most of those will be small.
Intra-plate volcanoes are underexplored but have limitedpotential for sulfide deposits.
Island-arc volcanoes have large potential, but frequent
eruptions and shallow water depth may limit sulfidepotential near the seafloor.
Where are the large deposits
in the Pacific region ?
regional Pacific potential
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
37/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
Current research and exploration ismainly related to active deposits at ornear spreading axis.
many deposits are buried underneathsediments or lava.
Systematic surveys for hidden depositsare lacking.
Regional geological and geophysicalexploration using towed systems orAUVs is necessary to define resource
potential.
seafloor hydrothermal systemsseafloor hydrothermal systems
Challenges
Modern Seafloor IFM GEOMAR
8/6/2019 2011 SOPAC Meeting Fiji Petersen
38/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
6000m depth rating, 4Kn max. speed24 h station timeturbidity sensor (ECO), Eh-sensor (NIST
Japan), CTD, 120/410 kHz side-scansonar (Edgetech), ADCP
3 konfigurations200/400 kHz multibeam (RESON 7125D)or sub-bottom profileror b/w digital camera + flash
underwater navigation:transponder (LBL, USBL)inertial navigation (Kearfott)
IFM-GEOMARsAUV ABYSS
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
39/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
central part= 65 km !
Reson Seabat 7125400 kHz
AUV-basedbathymetry
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
40/42
Modern SeafloorMassive Sulfide
Deposits
S. PetersenAUV-basedbathymetry
Modern Seafloor
8/6/2019 2011 SOPAC Meeting Fiji Petersen
41/42
Modern SeafloorMassive Sulfide
Deposits
S. Petersen
8/6/2019 2011 SOPAC Meeting Fiji Petersen
42/42