Introduction Condition Sources Classification Conclusion References

1. HYDROTHERMAL
MINERAL DEPOSIT
HYDROTHERMAL
MINERAL DEPOSIT
HYDROTHERMAL
MINERAL DEPOSIT
PRESENTED BY-
BIMALENDU BISWAL
ROLL NO-22GEOL026

2. CONTENTS:-
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Introduction
Condition
Sources
Classication
Conclusion
References

3. INTRODUCTION:-
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The concept of hydrothermal mineralization deposits related to uids derived from sources
other than magmatic solution.
For the more effective as a mineralization agents, hydrothermal or hot water need to circulate
through the earth’s crust. Due to this the solution of the hydrothermal uids interacts with large
volumes of rock (Dissolve and transport) to form hydrothermal ore deposits.
If we simplify the term hydrothermal it gives us
Hydro-Water
Thermal-Heat/Hot
Hydrothermal mineral deposits are accumulations of valuable mineral which formed from the
hot waters circulating in Earth’s crust through fractures or ssure.
It is a types of epigenetic deposit.

4. CONDITIONS:-
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Availability of hot water to dissolve and transport minerals that occurs over there.
Presence of interconnected openings spaces.
Presence of enough metal content.
Chemical reaction causing depositions of ore.
SOURCES:-
Such uids includes those formed from metamorphic dehydration reactions, from the
expulsion of pore uids during compaction of sediments and from the meteoric waters.
It also considers as sea water as a hydrothermal uids for the formations of base metal
deposits on the ocean oor.
Mainly the last product of magmatic crystallization that is the residual hot water.

5. Hydrothermal Mineral Deposit

6. CLASSIFICATION:-
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The term hydrothermal means hot water with possible temperature of 50° to
500° c . Fluids left during the later stage of crystallization of intrusive magma is
called as hydrothermal solution. It’s journey through the rocks loses heat and
metal contents with increased distance.
The hydrothermal solution move through cracks and opening present in the
rock and deposit their dissolved materials there.
Lindgren classied hydrothermal deposits On the basis of the temperature of
formation in three types-
Epithermal Deposit-
-Low temperature and shallow depth.
-Formed very much away from the intrusive body
-Temperature ranges from 50°c to 200°c

7. Mesothermal Deposit:
-Intermediate temperature and about 1.2 km to 3.5 km depth.
-Formed at some distance outward from the intrusive igneous mass.
-Temperature ranges from 200°c to 300°c.
-Example: native gold, bornite, sphalerite, galena etc
Hypothermal deposit:
-High temperature and greater depth about more than 10 km.
-Formed close to the intrusive body
-Temperature range from 300°c to 500°c .
-example: wolframite, arsenopyrite, native gold, chalcopyrite etc
Telethermal deposit:
-Low temperature (<100°c) and low depth.
-Far from the hydrothermal solution.
Xenothermal deposit:
-Formed at high temperature with shallow depth and low pressure
-Fault zone, Hot spring

8. On the basis of mode of formation hydrothermal deposit are classied
into two groups-
CAVITY FILLING DEPOSIT:-
-These deposits are formed due to deposition of hydrothermal solution mineral in the various
types of opening in rock.
-The walls of the cavity are lined rst by the rst mineral to be deposited.
-There is no replacement involved.
Characteristic features of the cavity lling deposit:
>Crustication- The mineral usually grow inward with development of crystal faces pointed
towards the supplying solution is called as Comb Structure. This process is continue called as
Crustication.
-Process is repeated until the lling is complete.
Types-
Symmetrical- Similar mineral crusts occur in both sides of the ssure.
Asymmetrical- Unlike layers are present on each side of crustication.
>Vugs- Open spaces are left in the centre such unlled spaces are called as Vugs.

9. Crustication Comb
Structure

10. Types of cavity lling deposits:-
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A.
a.
b.
c.
d.
e.
The following types of deposits may result due to the cavity lling process:
Fissure Vein Deposits:- A ssure lled with ore is called ssure vein.
-It is a tabular ore body which occupies one or more ssure with in a rock.
-Most ssure vein are narrow and their layer range from a few hundreds of
meter to few km.
-ore mineral are never equally distributed throughout the ssure vein.
-e.g.-Kolar Gold eld
Simple ssure vein- A single ssure whose walls are nearly straight and
parallel.
Chambered vein-Walls are irregular and brecciated.
Lenticular Vein- Generally schist shows this type of structure and such
lenses are called lenticular vein.
Sheeted veins- A group of closely spaced parallel veins.
Composite vein- Wide zone of nearly parallel ssure connected by
diagonal.

11. A)Chambered Vein B)Lenticular vein
C)Sheeted Vein D)Composite Vein Deposit
Fissure Vein
Deposit

12. B. Shear zone deposit-
-A shear zone with sheet like connected openings and they are zone of thin and closely
spaced parallel feature. Deposited as thin mineral plate.
-Opening are minute, the open space deposition is minor.
-e.g.- copper deposit, singhbhum shear zone
C. Ladder Vein Deposit-
-This type of deposit forms due to the transvers vein or fracture.
-Commonly found in dykes.
-They are short, transvers, roughly parallel fracture, that are lled
with the ore.
-They looks like a ladder so called as ladder vein.
-e.g.- magnesite deposit of Mysore.
D. Saddle reef Deposit-
-These are formed between rock beds at the crest anticline during folding.
-Ore are deposited in opening spaces.
-Because these ore deposits appear like saddle they are called as saddle reef.
-e.g.- quartz reef in Hutti gold eld.
Ladder Vein
Saddle Reef

13. E. Stockworks-
-A stockworks in a mass of rock traversed by a network of small ore bearing
veins.
-It form when the hydrothermal solution are percolate through vertical zone
of intense shattering which occur in certain igneous intrusions.
-Each vein is about 1 cm and spacing few cm to few km.
-E.g.-Lead and Zinc deposit, Zawar area of Rajasthan
F. Breccia Filling Deposit-
-Breccia offer opening spaces in between angular fragments.
-Mineralizing solution traverse through the opening space and form deposits.
-In this deposit the breccia are may be volcanic breccia, tectonic breccia or collapse breccia .
-e.g.-Wajrakakur kimberlite pipe, Andhra Pradesh
-fault breccia in singhbhum shear zone
G. Pitches and ats:
-Formed due to folding of brittle sedimentary bed.
-Deposit in a series of disconnected deposit.
-E.g.-Iron Ore Deposit Of Bailadela And Chotadungar, Bastar Dist., Mp
Stockwork

14. H. Vesicular llings-
-Vesicular lava ow being permeable from channel ways for mineralizing solution and site of mineral
deposit.
-E.g.-Copper deposit in Dras Volcanic, Kargil area
-Chalcedony, amethyst occur in Deccan Trap
I. Pore spaces lling-
-Many mineral deposits occur as pore space lling say in Sandstone.
-Oil, gas and water are the most important among all.
-E.g.- Quartzite of Zawar dist., Rajasthan
J. Cave deposit and Gash Vein-
-Solution cavities in the form of caves, galleries and gash veins may contain deposits of lead, zinc,
copper, mercury etc.
-They occur only in soluble rock.
-Occur along joints and bedding planes.
-Veins form when mineral constituents carried by an aqueous solution within the rock mass
are deposited through precipitation.

15. Vertical Gash vein Deposit Horizontal Gash Vein
Deposit

16.  REPLACEMENT
DEPOSIT-
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It is one of the important process in the formation of epigenetic mineral deposit.
Mineral deposit are formed by chemical processes that dissolve a rock and deposit
a new assemblage of minerals in it’s place.
The rate of replacement is dependent upon the rate of supply new material and
removal dissolved material.
For the large deposits, large channel ways are required for transporting large
quantities of replacing substance over long distance.
There are three types of replacement deposits :
1)Massive Deposit
2)Replacement
3)Disseminated Deposit

17. 1)Massive Deposit-
-These are irregular in form and variation in sized and they are generally occur in
limestone.
-The host rock is almost completely replaced and ore terminates abruptly against
the country rock.
-The ore may retain original texture and structure of the rock it places.
2)Replacement lode deposit-
-These are the high grade ore deposit.
-Formed when replacement localized along thin bed or ssure.
-Fissure wall replaced by ore.
-Lode deposit wider than ssure vein.
-Ore body may be wavy, irregular and gradational with the country rock.

18. REPLACEMENT DEPOSIT LOCALIZED BY FISSSURE

19. 3)DISSEMINATED DEPOSIT-
-These are low grade ore deposit where grains of ore mineral are found
scattered throughout the host rock.
-Large size ore deposit and it required large scale mining.
-The boundaries between ore and host rock is vague and gradational.
-E.g. Copper, Gold deposit.
TEXTURAL PROPERTIES IN REPLACEMENT DEPOSIT-
-Texture of replacement ore is dependent upon temperature and pressure of
formation and degree of replacement.
-Coarse texture is developed at high temperature and pressure.
-Fine grained texture is developed at low temperature and pressure.

20. REFERENCE-
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Economic Geology by Umeshwar Prasad
Principles of engineering Geology, K.M Bangar
Introduction to Ore forming processes by Laurence Robb
Ignou
Internet Source
Notes

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