STM, ITM and Stages of ME - JKA
STM, ITM and Stages of ME - JKA
STM, ITM and Stages of ME - JKA
Stages of ME
J. K. Aravind
Senior Geologist
Petrology Division
Geological Survey of India
Training Institute
Mission-V
“Field work is not always a fashionable geological
activity, but it remains as the life blood of Earth
science. It is the only sound way of discovering
reality, making observations which stimulate the
mind and which lead to the postulation of better
models, whose predictions can subsequently be
tested by further geological and geophysical
methods”
Ramsay, J.G., 1997
The field is where the truth resides. Models are essential
figments of imagination which must be tested by
observation. Those who do no field work and do not gather
data will never understand ‘Geology’
✓Stratigraphy
✓Tectonic set-up
✓Crustal evolutionary trend
✓Metallogeny / Ore localization
✓Environmental analysis
✓Natural hazard recognition &
risk management
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Concept of OGP
• Out of the total area of India, 6.88 lakh sq km has been identified
as mineral prognosticated area or Obvious Geological Potential
(OGP)
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Obvious Geological Potential Area
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National Geochemical Mapping
(1:50,000 scale)
Regional Exploration
UNFC stage of G4 is being carried out mainly by GSI and further promising
blocks are developed through G3 & G2 stage of exploration.
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The geological assessment (G) as per UNFC norms has four codes in order of increasing details:
Detailed
Exploration (G1)
General
Exploration (G2)
Preliminary
Exploration (G3)
Reconnaissance
Survey (G4)
➢ In general, mineral exploration begins from G4 stage (prospect scale) with an area of about 10 km x 10 km.
➢ As per the MEMC norms, some area upgraded to G3 and subsequently a few to G2 / G1 based on the geological
potentiality established during the successive stages of exploration.
➢ Each stage generate resource data with a clearly defined degrees of geological assurance.
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Reconnaissance Survey (G4)
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G4 (Reconnaissance Survey) Collection and consultation of all baseline reports
of target area (General Geology, STM, NGCM,
Work Components: NGPM etc.) Regional traverses.
Work Flow
Geochemical Survey: i) Grab, chip sampling (ii) Recording of
broad geomorphology, drainage etc.
LSM of ~100 sq. km. on 1:12,500. collection of PS,
Geophysical Survey: Ground Geophysical survey. PCS, SSS, BRS etc. & Lab study. Selection of area
for trenching, pitting, scout drilling etc. (~1 to 5
Technological: i) Pitting/Trenching: one or two to expose sq. km.)
mineralized zone at ideal location ii) Scout drilling: A few
boreholes to know the existence of mineral iii) Sampling:
Regional and random chip samples. Narrowing down target block by interpretations based
on chemical results, structure, geophysics etc. Trenching
Petrographic and mineralogical studies: To determine (25 to 50 cu. m), Pitting ~30 to 50 nos, channel sampling,
principal rock types, mineral assemblage, identification of groove sampling, dense stream sediment sampling etc.
mineral of interest. Suggested for G3 stage, if the block is promising.
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G3 (Preliminary Exploration)
Consultation of G4 report and other relevant
Work Components: literature. Study of target block for mineralization and
collection of surface samples for petrography, ore-
Geological Surveys: i) Mapping on 1:5000/ 2,000 or larger microscopy, chemical analysis etc.
scale ii) Linking of prepared maps with topogrid iii) Assessment
of lithology, structure, surface mineralization, analysis of old
workings etc. Preliminary petrographic and ore-microscopic
Geochemical Survey: Geochemical sampling rock type wise, studies.
Initiation of Geophysical Survey.
soil survey.
Work Flow
Geophysical Survey: Detailed ground geophysical work,
borehole logging. Detailed Mapping by Total Station Survey Instrument
Technological: i) Pitting/trenching to explore mineralized zone (1:2000 / 1:1000 scale) with 1m contour interval.
Ground Geophysical Mapping on the same scale.
ii) Drilling borehole spacing as per MEMC, 2015: Gold & PGE Trenching, Pitting and collection of BRS, PCS, SSS.
200 - 100m or closer interval. Interpretations and borehole planning/ drilling.
Work Flow
product elements.
3. Geophysical survey: i) Borehole geophysical survey ii)
special survey for problem solving.
Geophysical well logging, sampling (bulk, chip, core
4.Technological : i) Systematic pitting / trenching, ii) Drilling etc). Laboratory analysis of cores. Understanding and
interpretation of Geophysical data sets.
Borehole spacing as per MEMC, 2015: Gold & PGE 100 - 50m
or closer interval.
5. Sampling: Systematic pit/trench and core sampling iv) Bulk
sampling, if necessary
Better define ore body shape, size, grade, mineral
6. Collection of geo-environmental parameters. beneficiation studies etc. Preparation of borehole
sections, Cross and Longitudinal sections, Level plans
7.Petrographic studies. and Resource estimation. Suggested for Mining License
or G1 stage, if the block is promising.
8.Beneficiation test.
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Preliminary Exploration (G3) General Exploration (G2) Detailed Exploration (G1)
Narrowing down areas of General Exploration involves Detailed Exploration involves
promising enhanced mineral the initial delineation of an the detailed three‐dimensional
potential. identified deposit. delineation of a known deposit.
The objective is to identify a The objective is to establish the Size, shape, structure, grade,
deposit which will be the target main geological features of a and other characteristics of the
for further exploration. deposit, giving a reasonable deposit are established with a
indication of continuity and high degree of accuracy.
providing an initial estimate of
size, shape, structure and
grade.
Quantities estimated for the Quantities estimated for the Quantities estimated for the
deposits are with a low level of deposits are with a moderate deposits are with a high level of
confidence. (medium) level of confidence. confidence.
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Summary
➢ GSIs teams are engaged in mineral targeting projects (Craton scale to Mineral
District scale followed by Prospect scale and Deposits scale) by using its baseline
geoscience and mineral exploration data.
➢ Deposit discovery is becoming a challenge all across the globe. In this regard,
geoscience agencies have to look for concealed and deep seated deposits as
majority of near surface deposits have already been developed.
➢ GSI is evolving with time by applying new developments in mineral targeting
methodologies in collaboration with national and international geoscience agencies,
especially for covered and Greenfield Regions to enhance the rate of mineral deposit
discoveries.
➢ In order to keep the supply of potential G4 stage mineral exploration blocks,
concentrated efforts are being made by taking up Data Integration and Regional
Mineral Targeting Projects.
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धन्यवाद / Thank You
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