INTRODUCTION CLASSIFICATION OF SUBMARINE EXHALATION VOLCANIC MASSIVE SULPHIDE DEPOSITS(VMS DEPOSIT) SEDIMENTARY EXHALATIVE DEPOSITS(SEDEX DEPOSIT) CONCLUSION REFERRENCE

1. SUBMARINE VOLCANIC
EXHALATION
SUBMITTED BY-
JYOTIRMAYEE MAHANTA
M.Sc. 1st year(2nd semester)
22GEOL019

2. CONTENTS
• INTRODUCTION
• CLASSIFICATION OF SUBMARINE EXHALATION
• VOLCANIC MASSIVE SULPHIDE DEPOSITS(VMS DEPOSIT)
• SEDIMENTARY EXHALATIVE DEPOSITS(SEDEX DEPOSIT)
• CONCLUSION
• REFERRENCE

3. INTRODUCTION
• This process involves exhalation of hydrothermal fluids at the surface,
usually under submarine conditions and generally producing
stratiform ore bodies.
• Deposits resulted from this process is known as VMS deposit.
• Volcanic associated massive sulphide deposit frequently show a close
spatial relationship to volcanic rocks but this is not the case all the
deposits, Example- Sullivan, Canada which is sediment hosted and
are referred to as SEDEX deposit.

4. https://images.app.goo.gl/BGb3E4FBcNv2243r8

5. CLASSIFICATION OF SUBMARINE EXHALATIVES
CONCORDANT MASSIVE
SULPHIDE DEPOSITS
VOLCANIC HOST
VMS
VHMS
SEDIMENT HOST
STRATIFORM
SEDEX
CARBONATE HOSTED IRISH TYPE
MISSISSIPPI VALLEY
TYPE

6. VOLCANOGENIC MASSIVE SULFIDE(VMS)DEPOSIT
These are exhalations of sulphide rich magma at the surface, usually
under marine conditions. The deposits formed from this process can be
known as volcanic exhalative deposit.
The ores show relationship to volcanic rock.
VMS deposits are the source of pyrite with varying amount of copper,
lead, zinc and barite .
VMS deposits are epigenetic.
Stratiform or stratabound nature of ore deposit.
Minor amount of gold and silver are also found.
VMS deposits are generally associated with black smokers.

7. Types of smokers or hydrothermal vents
• BLACK SMOKER- Iron sulphide (black)

8. Continued…
• WHITE SMOKER- Barite, Calcite(White)

9. MORPHOLOGY OF VMS DEPOSITS
VMS deposits have a wide variety of morphologies, with mound shaped and bowl shaped
deposits most typical. The bowl-shaped formations formed due to venting of hydrothermal
solutions into submarine depressions.
VMS deposits have an ideal form of a conical area of highly altered volcanic or
volcanogenic sedimentary rock within the feeder zone, which is called the stringer
sulfide or stockwork zone, overlain by a mound of massive exhalites, and flanked by
stratiform exhalative sulfides known as the apron.
Stockwork Zone- Vein hosted sulfides(chalcopyrite, pyrite, pyrrhotite) with quartz, chlorite
and lesser barite and calcite.
Mound Zone- laminated massive to brecciated pyrite, sphalerite (+/-galena), hematite,
and barite.
Apron Zone- generally more oxidised, manganese, barium and hematite enriched,
with cherts, jaspers.

10. A cross-section of a typical
volcanogenic massive sulfide
(VMS) ore deposit as seen in
the sedimentary record

11. Metal Zonation
Most VMS deposits show metal zonation, caused by the changing physical and
chemical environments of the circulating hydrothermal fluid.
Ideally, this forms a core of massive pyrite and chalcopyrite around the throat of
the vent system, with a halo of chalcopyrite-sphalerite-pyrite grading into a distal
sphalerite-galena and galena-manganese and finally a chert-manganese-
hematite facies.
 Most VMS deposits show a vertical zonation of gold, with the cooler upper
portions generally more enriched in gold and silver.
The mineralogy of VMS massive sulfide consists of over 90% iron sulfide, mainly
in the form of pyrite, with chalcopyrite, sphalerite and galena also being major
constituents.

13. Types of VMS deposit
A)On the basis of sulphide content and ore deposits and its
relation to the volcanic stratigraphy, it is of two types.
1)Massive type- sulphide mineral>60%,
stratiform and stratabound.
2)Stringer or vein type – sulphide mineral<20%,
crosscut stratigraphy.

14. Continued...
B)On the basis of host rock, metal content and alteration
assemblage there are six types.
Mafic(Cyprus type)
Bimodal Mafic(Noranda type)
Mafic Siliciclastic(Besshi type)(aka Pelitic Mafic)
Bimodal Felsic(Kuroko type)
Felsic Siliciclastic(Bathurst type)
Hybrid Bimodal Felsic/Siliciclastic(Eskay Creek type)

15. Continued…
Mafic(Mafic- Backarc)
Ophiolite- hosted.
Forearc or backarc.
Basalts and sheeted dyke
hosted.
Cu-(Zn-Au) rich.
Global Examples
Cyprus
Oman
NL Ophiolites

16. Continued...
Bimodal Mafic
Mafic-dominated
settings
Deposits often hosted by
felsic rocks.
Cu-Zn-(Au) rich.
Global Examples
Noranda
Flin Flon
Rambler-Ming

17. Continued…
Mafic Siliciclastic
 Mafic rocks and
sediments
 Mafic or ultramafic
intrusions.
 Cu-(Zn, Co, Au)rich.
 Global Examples
Besshi(Japan),
Windy Craggy(British
Columbia)

18. Continued…
Bimodal Felsic
 Felsic dominated
settings.
 Flow dominated
environments.
 Bimodal.
 Zn-Pb-Cu rich.
 Global Examples
Kuroko, Hellyer
Buchans

19. Continued…
Felsic Siliciclastic
 Sediment rich.
 Felsic volcaniclastic
rocks.
 Abundant felsic and
mafic sills.
 Graphitic shales+/- iron
formations/exhalations
 Tabular deposits.
 Zn-Pb-(Ag, Au) rich.
 Global Examples
Bathurst, IPB

20. Continued…
Hybrid Bimodal Felsic
 Felsic & mafic rocks
with sediments.
 Characteristics of
epithermal and VMS.
 Aluminous alteration
occurs.
 Zn-Pb rich(VMS).
 Hg-Bi-Sb-As-Au-Ag-S
rich.
 Global Examples
Eskay Creek
Rambler

21. SEDEX DEPOSITS
Sedimentary exhalatives (SEDEX).
These deposits are formed by release of ore bearing hydrothermal
fluids into the ocean resulting in the precipitation of stratiform ore.
Laminated sulfide deposits of Pb-Zn.
Lacks in volcanic components and absence of hydrothermal
alteration.
Also known as bimetallic deposits.
Hosted largely by clastic rocks deposited in intra-continental rifts or
failed rift basins and passive continental margins.
Important source of Pb, Zn and major contributor o f Ag, Cu, Au, Bs,
W.

22. Banded ore with Chalcopyrite,
Galena, Sphalerite, Pyrite, from
the SEDEX Rammelsberg
deposit, Germany
 Main economic minerals are
sphalerite(Zns) & galena(Pbs).
 Indian Example
Mochia-Rajpura-Dariba

23. CARBONATE HOSTED DEPOSITS
• Two types- Irish type & Mississippi valley type
Irish Type
• Pb- Zn deposits, strata bound sphalerite galena and iron sulfide
accompanied by dolomite, calcite and barite as gangue hosted in
carbonate sedimentary rocks.
Mississippi Valley Type(MVT)
• Epigenetic deposits.
• Strata bound in nature.
• Carbonate hosted ore bodies.
• Originate from saline bearing metalliferous fluids.

25. CONCLUSION
Both the SEDEX & VMS deposits are products of submarine hot springs.
VMS deposits are dominantly copper and zinc.
SEDEX deposits are dominantly zinc and lead but generally less common than
VMS deposits.
In VMS deposits the metals are usually zoned with copper near the vent and then
zinc and lead more distant to that.
These deposit types are major global sources of base metals particularly zinc.

26. REFERRENCES
• Volcanogenic Massive sulfide deposits : ALAN G. GALLEY, D.HANNINGTON
AND IAN R. JONASSON
• https://www.scribd.com/presentation/282329080/6-SEDEX-VMS-MVT
• https://www.911metallurgist.com/blog/difference-between-sedex-vs-vms-
deposits
• https://en.wikipedia.org/wiki/Volcanogenic_massive_sulfide_ore_deposit

27. THANK YOU