vlf – em, magnetic and radiometric investigations in … · 1. introduction the eastern dharwar...

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International Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 5, September-October 2016, pp. 202–215, Article ID: IJCIET_07_05_022

Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=5

ISSN Print: 0976-6308 and ISSN Online: 0976-6316

© IAEME Publication

VLF – EM, MAGNETIC AND RADIOMETRIC

INVESTIGATIONS IN PARTS OF PEDDAVURA

GREENSTONE BELT AND RAMADUGU AREA,

NALGONDA DISTRICT, TELANGANA STATE, INDIA

G. Sriramulu, G. Ramadass, Dubba Vijay Kumar and S.V. Jagadish

Centre of Exploration Geophysics, Osmania University,

Hyderabad, Telangana, India.

ABSTRACT

The Archaean –Proterozoic Cuddapah basin, in parts of Eastern Dharwar craton of south

India peninsular shield comprising supra crustal (Schist belts, mafic dyke swarms, and younger

granites) within the gneissic basement is significant in terms of geological, geophysical and

economic interest. The schist belts and the gneissic terrain of Peninsular India are important in

determine the structural configuration of the regions as the geological nature and the

interrelationship of the volcano-sedimentary supra-crustal rocks help in understanding the tectonic

sedimentary environments of deposition.

Accordingly, the Peddavura schist belt, the only gold bearing schist belt and Ramadugu

Lamproite field occurring in Nalgonda District, Telangana State were identified for integrated

geophysical investigations include VLF-EM, magnetic and radiometric methods carried out along

six detailed traverses. The VLF filtered real and imaginary component anomalies identify major

geological interfaces suspected to be faults/fractured zones, which may reflect that VLF anomalies

are due to shear zones or alteration zones located along the contact between different rock types.

The VLF– EM results of the Fraser model filtered data plots, as well as Karous-Hjelt filter 2-D

inversion current density (Pseudo sections) plots for traverse (PS, V-I,V-II, R-I, R-II and SG ), are

presented in Figures (2 to 7). The data analysis revealed the presence of positive and negative

amplitude of filtered real and imaginary for possible identification of conductive and resistive

formations. The interpreted results of VLF-EM agree with magnetic and radiometric anomalies

qualitatively. In particular, the disposition and extent of the Peddavura schist belt and mafic dykes

swarms in Ramadugu Lamproites field are discontinuous at places was traced and its relation with

the other geological members of the region examined in terms of Lamproite locations.

Key words: Archaean–Proterozoic Cuddapah basin, Peddavura schist belt, Lamproites, VLF– EM,

Mafic dykes, Current density, Pseudo section.

Cite this Article: G. Sriramulu, G. Ramadass, Dubba Vijay Kumar and S.V. Jagadish, VLF – EM,

Magnetic and Radiometric Investigations in Parts of Peddavura Greenstone Belt and Ramadugu

Area, Nalgonda District, Telangana State, India. International Journal of Civil Engineering and

Technology, 7(5), 2016, pp.202–215.

http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=5



1. INTRODUCTION

The Eastern Dharwar craton is significant from both the geological and geophysical points of view

characterized as it is by a complex evolutionary history and a vast storehouse of valuable minerals. The

broad geological configuration of the Achaean to Proterozoic craton comprises a suite of greenstone belts,

volcanic, granitic rocks, Paleo to Mesoproterozoic plat formal sedimentary basins, mafic dyke swarms and

Mesoproterozoic kimberlitic and Lamproites (Ramakrishnan and Vaidyanadhan, 2008). The Dharwar

craton has a unique combination of special carbonic features in the form greenstone (schist) belts. The

distribution of these diverse supra crustal belts in three basic regimes of metamorphism resulted in the

division of cratonic region, into three blocks consist of three types of greenstone belts in Dharwar craton

viz, older greenstone of Sargur type (Western Dharwar), Chitradurga (intervening block), Ramadass et al

2006 and younger greenstones of Kolar type green stones or Eastern green stones (Eastern Dharwar

craton) belts.

The economic significance of greenstone belts of the Easter Dharwar Craton stems from the fact that

many of them are auriferous (gold- bearing ) eastern schist belts of the Dharwar craton (Kustagi, Hutti ,

Raichur, Sandur, Gadwal and Peddavura) two schist belts only occurring in Telangana State are the

Gadwal and Peddavura schist belts .

The Peninsular India with several Achaean-Proterozoic nuclei is crisscrossed by many deep-seated

fractures/faults. These nuclei, underlain by thick lithosphere mantle roots, have witnessed different events

of kimberlitic, Lamproites intrusions within cratons usually are localized (Ramesh Chandra Phani, 2015) in

zones of high magmatic permeability, as defined by the repeated intrusion of various types of igneous

rocks. While kimberlitic /Lamproites are generated in the mantle, often reactivated fault/fracture systems (

Sykes, 1978, Haggerty,1994) their intrusion into the crust, these intrusive tend to occur in cluster or fields,

within the large-scale distribution possibly controlled by shallow zones of weakness such as faults ( linear

lows) or the margins of databases dykes (Power and Hildes 2007). They are associated with large-scale

structural features like regional and local lineaments, the intersection of major lineaments, dome structures,

fracture corridors, disjunctive zones radial features and resultant structural features formed due to

emplacement of diaper granites (Rao 1996) opines that the regional trend of kimberlites/Lamproites rocks

in the Dharwar craton is possibly related to crustal warping and closely related deeply penetrating faults.

The Peddavura schist belt was not reported any detailed geophysical studies, keeping this in mind, the

present work is aimed at the need to obtain a clearer perception of structural configuration along chosen

profiles across the Peddavura schist belt and in parts of Ramadugu, Vattikod and Somavarigudem

lamproite fields, in the Northwestern part of Dharwar craton of Nalgonda district Telangana, India, by

carrying integrated geophysical studies by Total magnetic and VLF-EM and radiometric techniques.

2. GEOLOGICAL SETTING

The study area is located NW margin of the Cuddapah basin bounded by Longitudes 79◦ 5′ to 79

◦ 25′and

Latitudes 16◦42′ to 16

◦ 58′ (Figure. 1). Geologically the area forms a part of the Eastern Dharwar Craton

(EDC) which is recognized for its emplacement of numerous lamproite bodies. The geological formations

in the area (GSI, 1999) include unclassified granites and gneisses of Achaean age, Cumbum shales,

phyllites, Srisailam quartzites of the Cuddapah super group, and shales of the younger Kurnool group of

rocks. The hornblende schist and amphibolites (Older Metamorphic) which are oldest rocks occur, as rafts,

enclaves and discontinuous linear bands, within the Peninsular Gneissic Complex. The district comprises

migmatites, granites granodiorite, tonalitic-trondhjemite suite of rocks and hornblende-biotite schist, meta-

basalts, meta-rhyolite and banded hematite quartzite and Dharwar super group are exposed as linear belts

near Peddavura on the Hyderabad-Nagarjuna Sagar road. Figure.1shows the disposition of the Peddavura

schist belt lies in the Eastern Dharwar craton. The NW-SE trending Peddavura greenstone belt extends

over 25 km with a variable width of 0.5-2 km (Srinivasan 1991) and is flanked on both sides by granitoid

rocks whose ages 2551-+/- 19 Ma trending in the Nalgonda and Guntur districts of Telangana and Andhra

Pradesh state with a hooked shape (Jayananda et al 2013) . The belt is well exposed Vijayapuri north all

VLF – EM, Magnetic and Radiometric Investigations in Parts of Peddavura Greenstone Belt and Ramadugu

Area, Nalgonda District, Telangana State, India


along the Krishna River, downstream of Nagarjuna Sagar Dam and consists of dark- colored basalts, fine-

grained buff coloured felsic volcanic rocks and tuffs, and BIF that are interlayer with each other.

Peddavura schist belt lies 150 km south of Hyderabad near Nagarjuna Sagar dam. North of Jugudem, in the

north-west, the belt tapers down and vanishes in the gneisses. At the southeastern end, west of

Tummurukota, the belt takes a spectacular U-turn and younger Cuddapaha’s cover. The Northwestern half

of the narrow belt is flanked on either side by younger granite intrusive. The western arm of the schist belt

on the west is bounded by an NE-SE trending fault lineament.

In the study area, sulphide and oxide ore minerals are concentrated within the quartz veins that are

traversing the Amphibolites metavolcanic are associated gangue minerals are Pyrite, Pyrrhotite,

Arsenopyrite, Chalcopyrite, Sphalerite Magnetite, Quartz, Native Gold etc. Gold mineralization is

structurally controlled and is confined in association with sulphides. A number of dolerite dykes and quartz

reefs traverse these rocks trending N-S.E-W, NE-SW and NW-SE direction, Lamproites occurs as dykes

and trend essentially NW-SE as discontinuous isolated outcrops associated with intrusive contact with the

basement granitoid .

3. GEOPHYSICAL INVESTIGATIONS

The Ramadugu study area lies in between latitude 160

42′ to 16

0 57′ N and longitude 79

0 05′ E to 79

0 23′ E.

Very low frequency (EM) , Total magnetic and radiometric investigations carried out in detail using

ABEM WADI VLF equipment , Model 600 Proton precession magnetometer and ECIL- Scintillometer

type SM141 instrument, along six detailed traverses with 10 m station to station distance were conducted

at the Peddavura schist belt (PS), Vattikod (V), Ramadugu (R) and Somavarigudem (SG) Lamproites field

(Figure.1). The length of these traverses varied between 160m 450 m were taken perpendicular to the

geological formations. The frequency use in the present investigation is 18 KHz (VLF), Global Position

System (GPS) was used to locate the observation points and elevation to ensure reliability and accuracy of

the radiometric and GPS elevation, location of geographic coordinates several observations (20 %) are

repeated. The overall effective accuracy obtained for elevation, the magnetic data, radiometric data and

VLF data is 1m, +/- 1nT, 2µR/hr and 2% respectively. The N-S and E-W extend of this area that falls

under Survey of India (SOI) Topo sheet No. E44T1, E44T2 and E44T5, in Nalgonda district of Telangana

state, India.

Figure 1 Geological map of the study area along with the VLF traverses.



Interpretation of VLF (EM) data is complicated by the relatively high transmitter frequency which

results in secondary fields from many geological features (Philips and Richards 1975). Further, the three-

dimensional nature of real geologic structures may complicate, the two-dimensional inversion of real data

modeling is useful for interpretation of VLF-EM data and routinely done. VLF (EM) data are useful for

obtaining a qualitative view of the structure, particularly after filtering the data and analyzing the apparent

current density pseudo section. The Fraser and Karous Hjelt (1977, 1983) linear filtering techniques allow

geophysicist to filter the real (in phase) and generate an apparent current density pseudo section, therefore,

image the geological subsurface structure. The VLF method generally yields considering the EM

anomalies, even over poor conductors such as sheared contacts, fracture zones and faults. Hence this

method has been the most popular tool for the rapid mapping of near- surface geological structures (Parker

1980, Philips and Richards 1975, Sayadam 1975). The peaks of the real component can be interpreted as

conductors (Sunderarajan et al, 2006, Ogilvi and Lee., 1991).

The VLF-EM real and imaginary components are presented in the form of a profile, the crossover in

real and imaginary filtered components are inferred to be the conductor (Ramesh Babu et al 2007, Wright,

1988) where positive amplitudes of filtered real crossover the inflection points of the raw real reflects fault

or fractures. Further, the symmetry in the real and imaginary components is caused to the dipping nature of

conductors, wherein the larger anomaly peak identities the down-dip side (Coney, 1977). The real part

component will always show peak above a conductors (Sundararajan et al 2007 ) while the imaginary part

can show as well as a positive or negative peak depending on the conditions of the overburden or soil type

of VLF data associated with fault/ fractures. The symmetry of these conductive anomalies suggests that the

conductive structures are dipping. Also, the anomaly patterns exhibit varying amplitudes, which are

controlled by the depth of the body to the surface, its geometry and attitude mapped as on the profiles.

Fraser filtered from various lengths of the filter is the better the response of the deeper sources. The current

density pseudo section provides good visualization of targets such as mineralized veins, fractures (Fischer

et al, 1983) zones.

The real and imaginary components of all traverses are subjected to both Fraser and Karous-Hjelt filter

processed using RAMAG (VLF) software. The corresponding pseudo sections of station intervals versus

depth are shown in Figures 2 to 7. The inferred depth from the pseudo section ranges from 20 to 100 m

using a skin depth of 100m. The set of the pseudo section for real and imaginary components and graph for

same were presented Red colour indicates the high current density and black colour indicated low current

density reflects the non-conductors or resistive formation.

4. TRAVERSE - PS (PEDDAVURA SCHIST BELT)

The VLF-EM Radiometric Investigation and magnetic measurements were made along traverse the

Peddavura Schist belt (16043′03.9″to 16

043′05.1″ and longitude 79

011′38.4″ to 79

011′39.6″) total length

440 m trending NE-SW direction. The filtered real and imaginary components along the traverse-PS are

shown in Figure 2d. The traverse-PS reveal high and low amplitudes along traverse indicate one main

conductor in real components, whereas imaginary is reciprocal of this, the crossover points of inflection

noted as faults or fractures, the distance between them are identified as shear zones. The Peddavura schist

belt is dipping vertically Figure 2(e) VLF is the apparent current density pseudo section of traverse-PS

revives the presence of anomaly between station No 1 to 5, 35 to 55 Stations. The inversion of traverse-PS

demonstrates the presence of one conductor and resistivity body and three Faults Zone Fr1, Fr2 and Fr3 at

station 40 m, 50 m and 90 m respectively are in vertical dipping. Peddavura Schist is characterized by high

resistivity is in vertically dipping in long distance. The width of the schist belt (dyke like body dominated)

is characterize by moderated current density distribution and one small is conductive body possibly

indicating a lead, zinc and copper association within the schist belt, as a fault-related depression zones are

sometimes recognized as shear zone (Bormann et al 1986), the VLF data are useful obtain a qualitative

view of the structure.




The radiometric measurements obtained (Figure.2a) over the conductive body is higher values over

Peddavura Schist belt but there is no Lamproite indication. The Peddavura Schist belt within the belt one

fault identified. The distinct features along the traverse marked Fr1 to Fr3 representing geological contact,

faults, shear zones etc. The broad high of 10 to 55 µR/hr corresponds to the NW –SE trending schist belt

(10-30 µR/hr) within which quartz & pegmatite veins are clearly demarcated. Western and eastern margins

of this belt are sheared and faulted and are reflected by sharp peaks. The highs flanking the low over the

schist belt can attribute to younger granites and peninsular gneisses with the former registering higher

radio activities (20.73-36.67 µR/hr) as compared to the later (11.32-27.08 µR/hr). Pegmatite’s found in fair

concentrations in the region are also reflected by relatively high radio activities. These features correspond

to quartz veins and local litho variations and are less apparent from traverse to which set a limit to the NW-

SE extent of the inferred causatives.

The Total magnetic intensity along the traverse-PS map shows (Figure.2b) an acute variation in the

magnetic intensity indicating variations in the magnetic intensity. These variations are possibly related to

the zones of structural variations based on the geological investigations. While the comparison of the

magnetic signatures with the geology of the region not many inferences are made because the various

forms of granites (migmatites, gneisses, pink / grey granites and / or Biotite granites) are magnetically not

much distinctive. The magnetic highs and lows are in conjunction of subsurface faults in the granitic

terrain. Not with the composition of the granites, the study area covers various forms of granites along with

little Peddavura schist.

A few basic / ultra- basic dykes are available as intrusive rocks, and NW-SE trend to NE-SW

(Srinivasan, 1991) trends fault axis is evident in highs and lows in Figure.2b. Two other trends of magnetic

high responses are also running in the same direction.

There are only two schist belts only occurring in Telangana State are the Gadwal and Peddavura schist

belts are auriferous (Anand Murthy and Bhattacharji 1997, Ramadass et al 2007) reported gold

mineralization from bedrock pegmatites and soil samples (0.035 to 0.25 ppm), and in a shear zone (0.035

to 4.25 ppm), and also the gold specks are in the form of disseminated specks are reported from Peddavura

schist samples. Effect of shearing is well evident by the presence of mylonite. Morphologically the size of

native gold is variable and ranges from 3-10 microns.

C1Fr1 Fr2

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)



Figure 2 (a) Radiometric, (b) Total Magnetic Intensity, (c) Fraser filter Real and Imaginary Components (VLF) and

(d, e) Karous Hjelt current density pseudo section along the profile: 1, from west side of the Vattikod village.

5. TRAVERSE- V1 (VATTIKOD)

Traverse-V1 (Figure-3) across the East- West direction running away from the Vattikod Village (latitude

16055′13.5″ to 16

055′14.1″, longitude 79

005′37.4″ to 79

005′43.2″) at a total length of 410m and (Figure.3c)

shows the linearly Filter Real and Imaginary Component, of the VLF data along with the Vertical

Magnetic and Radiometric data. The current density Pseudo Section (Figure.3d) shows one C1, conductors

at distance 60 m , two faults Fr1 and Fr2 faults/fractures (Fr) at 80m and 280m are indicated on the real

positive amplitude and crossover of the real and imaginary components., the positive response to the real

components value indicates the presence of conductive subsurface structures ,while low are negative

values are Indicate of all resistive formation. One dyke with a 100 m is responding with a high resistive

body extending vertically. There are no Indication of Lamproites along the traverse, however magnetic

(Figure.3b) responses low recorded at the station no 75 and 100 stations at the contacts at two faults

remaining part the radiometric (Figure.3a) no appreciable variation is observed. Figure.e is the current

density Pseudo section of imaginary components is the inversion of real component.

6. TRAVERSE-V2 (VATTIKOD)

This traverse V2 runs 1.5km away from Vattikod Village towards Pochampally (latitude 160

55′9.6″ to 160

55′ 10.1″, longitude 79005′08.2″ to 79

005′08.2″) village a total length of 440 m, the VLF, magnetic and

radiometric observations obtained at every 10meters. Figure (4d) shows current density Pseudo section has

been constructed distinct to traverse to show the vertical variation of a current density, and consequently to

derive the change of conductivity with depth qualitatively. It is possible to differentiate between

conductive and resistivity formations using apparent current density pseudo section and plots of real and

imaginary components (Figure 4c) locates the three dipping conductors (C1, C2 and C3) identified along

the traverse at 110m, 220m and 330m and three dipping fault/fractures (Fr1, Fr2 and Fr3) at 130m, 230 m

and 350m, two mafic dykes are traced in between 15-180m and 250-350m. Based on the moderate current

Dep

th in

Un

its

1 Unit = 1.6 m

Dep

th in

Un

its

(c)

(d)

(e)

(%)

Distance (m)

DYKE

WEST C1 EAST

C-Conductor

Fr-Fracture

Fr1 Fr2




density distributions occur in between gneisses and dykes contact Figure (4d) might be a possibility of the

location of Lamproites. The bedrock photography is varying traverse 30m to 80m at station 200 deeper

basement is traced.

The magnetic behavior (Figure.4b) over this traverse lows and high evaluates are recorded at 50-80m

and 300-350m respectively. The Radiometric (Figure.4a) response over this location also corroborated

with survey response.

7. TRAVERSE- RM1 (RAMADUGU)

Traverse RM1 lies under the bridge of Ramadugu trending NE-SW extending (latitude 16050′33.6″ to

16050′33.6″ to 16

050′33.8″ and longitude 79

017′ 52.8″ to 79

017′55.1″) east of Ramadugu village, the total

length of 370m station interval is 10m at near Ramadugu bridge (Halia river). From (5d) VLF on real and

imaginary component of the VLF-EM pseudo section (Figure 5e) revived the across the major conductive

zone identified, is varying from 48m to 250m, further east only one dyke with low conductivity zone is

identified fracture-zone at distance 100 and 250m at a depth of 60m to 100m there are only conductor best

of 100 station and broad conductors 50 to 250m identified a resistivity body at station 275 to 320m with

curves 50m width body only limited depth exclusive body. The magnetic evidence is the small conductive

absent at contact of the dyke.

8. TRAVERSE- RM2 (RAMADUGU)

This traverse (Figure.6) lies in (latitude 16050′12.2″ to16

050′14″ and longitude 79

0 16′ 44.5″ to 79

0

16′48.3″) located along the road side of at a distance of 1.7km west of Ramadugu village trends NE-SW

across a narrow mafic dykes. The VLF real and imaginary components (Figure.6d) a cross-over at

approximately 240m along the traverse. The imaginary response, on the other hand, shows an inverse

relationship with the real component. There are two conductors are identified C1 and C 2 at 50m and 200m

extending deeply at only one fracture/conductor. The total magnetic intensity is oscillatory and a

radiometric response is uniform intensity observed along this traverse, two shallow mafic dykes are traced

along the traverse station 210-240 and 280-310 in shallow station.

Fr1 Fr2 Fr3C1

C2C3

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)




(d,e) Karous Hjelt current density pseudo section along the profile:2, 1.5km away from profile:1 (Vattikod village).

9. TRAVERSE- SG (SOMVARIGUDAM)

This Traverse ( Figure.7) is a total length of 480 m running from (16052′15.4″ to 16

052′19.8″ and longitude

79021′27.4″ to 79

021′29.2″) the Figure-7 difference shows the VLF-EM section over flatted and shows the

Pseudo sections of Figure.9d relative current density radiation with depth. The Fraser and KH Filter-aided

in the identification of conductive and resistive structure there are three positive amplitude real component

and four negative amplitude negative representative conductive resistivity bodies.

Dep

th in

Un

its

1 Unit = 1.6 m

Dep

th in

Un

its

(c)

(d)

(e)

Distance (m)

(%)

Shear zone

Fr1Fr2 Fr3

DYKE DYKE

C1C2 C3

BEDROCKBEDROCK

WESTEAST

C-Conductor

Fr-Fracture

Fr1

C1

Fr2

Fr3

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)





(d, e) Karous Hjelt current density pseudo section along the profile: 3, Peddavura Schist Belt.

The conductive bodies red colour resistivity is in black colour (Figure.7d). The cross over the point is

the positive amplitude of real and imaginary component indicates one Fr1 fracture at 220m and three

conductors C1, C2 and C3 identified stations 20, 200m and 300m along the traverse, the subsurface

bedrock thickness are varying from 60 to 100m. Two Lamproite dykes are traced at 148-200, and 290-300

with a subsurface fault which is a possible indicator of Lamproites. The magnetic and radiometric

responses are corroborative with VLF results.

Dep

th in

Un

its

1 Unit = 5m

Dep

th in

Un

its

(c)

(d)

(e)

(%)

Distance (m)

Shear zone Shear zone

Fr1

C1

Fr2

SCHIST BELT

Fr3

C-Conductor

Fr-Fracture

C1 C2 C3

Fr1

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)




(d, e) Karous Hjelt current density pseudo section along the profile: 4, Nearby Somvarigudam.

Dep

th in

Un

its

1 Unit = 1.25 m

Dep

th in

Un

its

(c)

(d)

(e)

(%)

Distance (m)

C1C2

C3Fr1

BEDROCK BEDROCK

DYKEDYKE

C-Conductor

Fr-Fracture

FF

F FFault

C1

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)





(d, e) Karous Hjelt current density pseudo section along the profile: 5, under the bridge at Ramadugu Village.

Dep

th in

Un

its

1 Unit = 1.6 m

Dep

th in

Un

its

(c)

(d)

(e)

(%)

Distance (m)

C1

BEDROCK BEDROCK

C-Conductor

C2

C1Fr1

µr/h

r

Distance (m)

Distance (m)

nT

(a)

(b)




(d, e) Karous Hjelt current density pseudo section along the profile: 6, 1.7km away from Ramadugu Village.

10. CONCLUSION

The interpretation of VLF, Total magnetic and radiometric data has clearly brought out the subsurface

fractures associated with the conducting auriferous mineralization. Crossover of the real and imaginary

components demarcate the conductors, from the current density Pseudo section of the six traverses –PS,V1,

V2 RM1, RM2 and SG helps in determining the conductors dip attitude and nature of the conductors the

fractures inferred from VLF-EM are conductive in peddavura due to sulfide and oxide ore minerals are

concentrated within the quartz veins that are traversing the Amphibolites metavolcanic are associated

gangue minerals are Pyrite, Pyrrhotite, Arsenopyrite, Chalcopyrite, Sphalerite Magnetite, Quartz, Native

Gold etc. This approach clearly demarcated boundaries in between peninsular gneisses and mafic dyke

swarms/fractures associated with Lamproites in Ramadugu, Vattikod and Somavarigudem Lamproites

clusters.

ACKNOWLEDGEMENT

The authors gratefully acknowledge the financial support extended by the UGC, New Delhi for granting

Emeritus Professor.

Dep

th in

Un

its

1 Unit = 1.6 m

Dep

th in

Un

its

(c)

(d)

(e)

(%)

Distance (m)

C2C1

Fr1

C-Conductor

Fr-Fracture




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