Talur technical report,geological presentation.

1. GEOLOGICAL ASPECTS AND MINERALOGICAL
FEATURES OF ULTRAMAFIC- HOSTED VEIN- TYPE
MAGNESITE MINERALIZATION IN TALUR AREA,
MYSORE DISTRICT, KARNATAKA, INDIA.
REPORT
PRESENTATION
UNDER THE GUIDANCE OF-
PROF M S SETHUMADHAV
PROF A BALASUBRAMANIAN
DOS IN ERTH SCIENCE
MANASAGANGOTHRI
PRESENTED BY-
VINAY.C
MSC GEOLOGY
DOS IN EARTH SCIENCE

2. CONTENTS
 AIM & OBJECTIVE
 THE STUDY AREA
 METHODOLOGY
 FIELD TRAVERSING
 EQUIPMENT'S TO CARRY OUT THE FIELD WORK
 PETROLOGICAL INVESTIGATIONS IN THE FILED
 MINERALOGICAL INVESTIGATION
 GENESIS OF MAGNESITE IN TALUR
 CONCLUSION
 REFERENCE

3. AIM AND OBJECTIVE
AIM
 The aim of the present work is to decipher the genesis of
magnesite mineralization based on field and laboratory
investigations.
OBJECTIVE
The objectives of the present study are:
 To study the mode of occurrence of magnesite
mineralization and its relationship with the host rocks.
 To determine the mineralogy of host rocks and associated
mineralization.
 To arrive at the genesis of magnesite mineralization in the
study area.

4. THE STUDY AREA
 The study area - Talur (12° 10’ 00”, 76° 38 ‘30” toposheet
No. 57D/12) is located about 17 kilometers south of
Mysore city.
 The study area is a part of Sargur schist belt.
Geographically, the Sargur schist belt is located in a
prograde transition zone, trending in a N-S direction. It
extends from Yelwala near Mysore to Shigebetta near
the Karnataka-Kerala state boundary and beyond. The
Sargur belt is ~70 km long and ~10 Km wide.

5. Younger basic and granulite dykes
Pink porphyritic granites /pegmatites
>3000 Ma old gneissic complex
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Ultramafic-mafic rocks
Banded iron stone
Amphibolite (Meta basic flows and tuffs?)
Crystalline limestone, dolomite and calc-silicate rocks
Pelitic schists and paragneisses
Fuchsite quartzite and quartz schsits
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Basement not known (may be partly sialic)
Table 3.1: Stratigraphy of the Talur area
The stratigraphy of the prevailing rocks in the area shown below:

6. METHODLOGY USED
 Field traversing
 Equipments to carry out the field work
 Petrological investigations in the field.
 Mineralogical investigations.
 Study related to the origin of magnesite

7. FIELD TRAVERSING
 To determine the host rocks of magnesite mineralization,
 To study the nature of serpentinization of ultramafic/mafic rocks in
the area and their variation in the vertical sections in the miners,
 To observe the relationship between magnesite veins and the host
rocks
 To identify the textural varieties of magnesite,
 To collect samples of host ultramafic/mafic rocks, serpentinites and
magnesite.

8. EQUIMENTS CARRIED IN THE FIELD
THEIR USES
 BASE ON TOPOSHEET
 BRUNTON COMPASS
 GPS INSTRUMENTS
 HAMMER AND HAVERSACK

9. BASE MAP ON TOPOSHEET
BRUNTON COMPASS
GPS INSTRUMENTS HAMMER AND HAVERSACK

10. PETROLOGICAL INVESTIGATION IN FIELD
TYPE OF MAGNESITE TEXTURE SEEN
 We have seen two type of magnesites in the field-
a) GRANULAR MAGNESITE
b) MASSIVE MAGNESITE
GRANULAR
MAGNESITE
MASSIVE MAGNESITE

11. GRANULAR MAGNESITE
• In the granular type of magnesites we can observe the individual grains having
the size ranges from 0.5mm-4mm.
• The granular type is most common in the area.
• It is greenish white in colour , porous and is often composed of closely spaced
cryptocrystalline spherules of Magnesite.
MASSIVE MAGNESITE
• Massive type is cryptocrystalline, hard, compact and milky white in color.
• It exhibits porcellaneous luster, breaks with a conchoidal to subconchoidal
fracture and is next in abundance to the granular variety.

12. TEXTURE & MODE OF OCCURANCE OF MAAGNESITE IN TALUR
Magnesite occuring in a variety of forms ranging from tiny blebs to large veins.

13. Thick parallel to subparallel veins of magnesite disposed subhorizontally.

14. A thick magnesite veins is nearly25cm with a folded like structure.

15. Magnesite vein with the weathered serpentine weathered regolith

16. MINERALOGCAL INVESTIIGATION
MINERALOGY
 Magnesite is a refractory mineral with the chemical formula
MgCO3, is a member of calcite group of mineral. Magnesite
having molecular weight 84.31 gm is a mixture of 47.80 % MgO
and 52.20 % CO2. In total 100% Magnesite 28.23% is Mg, 14.25% is
Carbon and 56.93% is the Oxygen.
HAND SPECIMEN STUDY
 Magnesite crystallizes in Trigonal system, massive,
cryptocrystalline, white in colour, shows perfect cleavage, it is
brittle and shows conchoidal fracture, moderately hard ( 4 on
Moh’s scale), dull luster, white streak, translucent, its Specific
gravity is 2.98.

17. alteration in olivine shows mesh
texture
olivine shows mesh texture with mesh serpentinization of olivine along
fracture Center and mesh rim
elongated magnetite and chromite grains in serpentine

18. XRD DETERMINATION
 X-ray studies were carried out in massive, granular type of
magnesite aand quartz. The X-ray defraction pattern & results are
provided below.
x-ray difffraction of magnesite and quartz

19. X-ray difffraction of massive magnesite
Mineralogical investigations using X-ray diffractions studies of magnesite and petrological
studies within the hand specimen have revealed the mineral under consideration are
A) Magnesite with granural structure
B) Magnesite showing massive structure

20. GENESIS OF MAGNESITE
 Magnesite mineralisation is associated with ultramafic rocks.
 Ultramafic body hosting the magnesite deposits of Karnataka was subjected to a
near-surface low temperature serpentinisation and during subsequent weathering,
downward percolating CO2 rich meteoric waters reacted with the host rocks under
ambient temperature conditions to produce magnesite.
SOURCE OF MAGNESIUM
 Ultramafic rocks are considered to be the source of magnesium required for the
vein type magnesite deposits in different parts of the world. Magnesium is
released during weathering and serpentinisation of dunite and peridotite.
SOURCE OF CARBON
 Various models are in vogue regarding the source of CO2 for the formation of vein-
type magnesite deposits. Of these, magnesite formation as a result of reaction of
ultramafic rocks with ascending CO2- rich diagenetic metamorphic fluids derived
from decarbonation of deep-seated carbonates or decarboxylation of organic rich
sediments

21. Mg2SiO4 + H2O+ SIO2 =
MG3Si2O5(OH)4
olivine water quartz serpentine
Mg3Si2O5(OH)4 + CO2 = MgSi4O10(OH02
serpentine talc
MgCO3 + H2O
magnesite

22. Cauliflower textured magnesite, Minor fracture filling in the host
SAMPLE COLLECTION
Slicken slides found in magnesite
Magnesite vein in sharp
contact with host rock

23. CONCUSION
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24.  The magnesite-bearing ultramafic body exhibits varying degrees of
serpentinization and weathering.
 Magnesite is extracted by open-pit mining. The extraction is semi-
mechanised.
 Alteration / weathering of serpentine of serpentinized ultramafic
rocks has been invoked in majority of the cases for the formation of
ultramafic-hosted vein-type magnesite deposits.

25. REFERENCE
 B.P.Radhakrishna and R.Vaidyanadhan, 1994, Geology of Karnataka, Published by Geology of India,
Pp 1-41
 Edward Salisbury Dana, 1976, A textbook of mineralogy, Published by H.S.Poplai for Wiley Eastern
Limited, New Delhi, Pp 493, 517-519
 B.P. Radhakrishna, 1996, Mineral Resources of Karnataka, Geological Society of India, Bangalore,
Pp 123, 139-140, 372-378
 B. Krishna Rao, M.S. Sethumadhav, M. Hanuma Prasad, T.D. Mahabeleshwar, Ashok V. Rao and H.
Albert Gilg (1999) Features and genesis of vein-type magnesite deposit in Dodalakanya area of
Karnataka, India, Jour. Geological Society of India Volume-54, nov.1999, Pp 449-465
 Berry Mason Dietrich, 2004, Mineralogy, CBS Publishers and distributors PVT. LTD, Pp 202-205,
426-427, 334, 506, 525
 John Sinkankas, 1966, Mineralogy, Van Nostrand Reinhold Company, Pp- 35, 3648)CHADWICK,
B.,RAMAKRISHNAN, M.and VISWANATHA,M.N.(1978) structural and metamorphic relations
between Sargur and Dharwar supracrustal rocks and peninsular gneiss in central Karnataka.
Jour.Geol.Soc.India, v.19, pp. 531-549
 Swaminath J. And Ramakrishnan, M (1981) Early Precambrian Supracrustal of Southern Karnataka,
Men.Geol.Surv.India, v. 112
 Shrikantappa, C.Raith, M. and Ackermand, D. (1985) High grade Regional metamorphism of
ultramafic and mafic rock from the Archean Sargur Terrain, Karnataka, South India. Precambrian
Research, v.30, pp. 189-210