2. Ganesh Prasad and Suresh Prasad Yadav
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straight or nearly straight relationships that may be the expression of folds, fractures,
or faults in the subsurface (Sabins, 2000, Anderson, 2008) [1] Lineament in this study
is defined as a mappable, linear feature of a surface whose parts are aligned in a
rectilinear or slightly curvilinear relationship and which differ from the pattern of
adjacent features and presumably reflect some subsurface phenomenon. Lineament
analysis in hard-rock terrains has been performed widely as a means for groundwater
exploration (Mogaji, 2011) [5]. Identification of lineament using remote sensing
techniques is the common practice. But sub surface extension of lineament can not be
fully identified in satellite image. Electrical resistivity is one of the most effective
geophysical methods for investigating the 3D spatial pattern of lineament.
Identification and analysis of underground fractures and concealed lineaments are
crucial in hard-rock terrains (Mondal et al 2008) [4].
Two and three dimension electrical resistivity imaging is widely used for mapping
of an area having complex geological structure. Electrical resistivity imaging has been
proved an excellent tool for identification of horizontal and vertical extension of
buried litho- units and linear structure. The electrical prospecting method consists of
measuring the potential at the surface which results from a known current flowing
into the ground. A pair of current electrodes, A and B, and a pair of potential
electrodes, M and N, are used. The apparent resistivity (ρa) is given by
ρa = K ΔV / I
Where, K denotes a geometric coefficient dependent upon the electrode array, Δ V
denotes the measured potential difference and I denote the current intensity. By
expanding the current electrode array, the depth of investigation can be increased.
Such a data set provides a vertical log of apparent resistivity called a vertical electrical
sounding (VES). The sounding site is conventionally located at the centre between the
inner electrodes. Electrical profiling is used for generation of electrical resistivity
image. The electrode separation is kept constant and the electrode array is moved as a
whole with the center of the configuration occupying successive points along a
traverse in electrical profiling.
Electrical Resistivity Imaging (ERI) techniques is highly capable to generate a
realistic model of the subsurface in geologically complex areas Two and three
dimension (2D) electrical imaging are now widely used where conventional 1-D
resistivity sounding surveys are inadequate to map subsurface object. One
dimensional resistivity surveying is a point specific investigation that gives vertical
information in terms of resistivity with depth of layers laying in sub -surface to that
point. Therefore, No sub-surface information can be obtained by any shift or deviation
from surveying point in 1-D resistivity survey. Basically, Electrical Resistivity Image
(ERI) is the final result of mathematical stitching of all 1-D VES data generated at
closed spaced locations or stations on a line through suitable software in form of
pixels or contours.
2. OBJECTIVE
Following are main objectives:
• Identification of three dimensional spatial postion of fracture
• Determination of the hydrogeological character of the fracture.
3. THE STUDY AREA
3. Spatial Positioning of Fracture in Hard Rock
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The study area constitutes a part of Navadih village of Dhanbad District. The study
area is located in SW corner of Navadih village. The total area is about 240000 square
meters have been selected for present investigation. The Dhanbad district enjoys a hot
summer and cold winter. The temperature range from 8 °C in December to 45 °C in
May. The average annual rainfall is 1295.0 mm, most of which is precipitated during
the monsoon months. Monsoon arrives in Dhanbad in the third week of month of June
and end in the month of September. Geologically, the study area is the part of
Ghotatanagpur gneissic complexes. Quartzite is the main litho-unit. Hornblende
gneiss and quartz reef have been also noticed as linear outcrop in the study area
(Figure 1). Quartz reefs are emplaced along lines of crushing and faulting and the
fault plane marks a zone of shearing in which both horizontal and vertical
displacement took place. Central portion of the quartz reefs are massive, hard and
compact in the study area.
This central portion is 2 to 5 meter wide. Both sides of
quartz reef are fractured and closely associated with central portion. Central portion of
this quartz reef having bold topographic expression and can be easily identified in
field.
4. METHODOLOGY
Electrical resistivity survey was carried out at various sites in the study area,
employing Schlumberger profiling techniques for creation of Electrical resistivity
Image. Differential Global Portioning System (DGPS, Trimble R3) has been used to
know the altitude of various points in order to generate topographic map. A Direct
Current resistivity meter (SSR- MP-AT) was used to measure the apparent resistivity.
This instrument has been fabricated by M/s integrated Geo-instrument and service
private limited, Hyderabad. It measures the apparent resistivity directly in ohm-meter.
In the presence of random (non-coherent) earth noise, the signal to noise ratio can be
enhance by √N, where N is the number of stacked reading. SSR-MP-AT is a
microprocessor based signal stacking resistivity meter in which running average of
measurement [1,(1+2)/2,(1+2+3)/3.(1+2+3…+16)/16 ] up to the chosen stacks are
displayed and the final average is stored automatically in memory. It has resolution of
10-5.
The SSR MP-AT contains mainly two parts viz. current unit and microprocessor
based measuring unit built in single housing. The current unit sends bipolar signals
into ground at a frequency of about 0.5 Hz. The receiver has 4.5 digital dual slope
analog to digital converter unit which can measure the ground potential and current
with resolution up to 10 µV and 10 µA respectively. The microprocessor controls the
current unit, determines attenuation level for potential measurements, computes the
resistance values, average the measured values, keeps the data in memory display and
transfer the data to PC.
A switch box was used as an intermediate connecting device between resistivity
meter and electrodes. All electrodes have been coded by a specific number and
connected with same code number to the key of switch box. Apparent resistivity was
converted into absolute resistivity of various layers using inverse slope software i.e.
based on inverse slope principle proposed by Sankaranarayan and Ramanujachary
(1967) [7]. Resistivity with thickness and depth of each layer has been also
determined by using this software. Horizontal extension (i.e. length and breadth),
vertical extension (i.e. depth) and resistivity of layers were placed in A, B, C, and D
column respectively in the worksheet of Voxler software for generation of image.
Thereafter, all the data were transferred in data modules for griding, which is
important step before contouring, isoslicing and volrendering. Finally, 3D image has
been generated in form of pixel format (Figures 2 and 3)
4. Ganesh Prasad and Suresh Prasad Yadav
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5. RESULTS AND DISCUSSION
The lineament under study is indicated by a drainlet flowing from NW to SE
direction. This drainlet has darker tone in comparison to other parts of this area due to
presence of waterlogged by continuous seepage from adjacent upland. Vertical
Electrical Soundings (VES) have been performed at several location across the
lineament in order to know the three dimensional spatial pattern of fracture. The
coordinate of each VES location in terms of length, breadth, depth and resistivity of
layers have been used as input for generation of Electrical Resistivity Image (ERI).
The resistivity ranges are the bases for identification of different layers. The area
under investigation is comprises of linear outcrop of quartz reefs and fractured
quartzite. Quartzite is covered with thin soil and weathered product. Following
resistivity ranges on the basis of field experiences have been used to categorized the
above said geological litho-units (Table 1).
Table 1 Categorization of layers on the basis of resistivity ranges
Resistivity ranges in ohm meter Name of layers
Below 1200
Fractured rock/ water saturated/ weathered
product
1200- 2000 Partially fractured quartzite rock
More than 2000 Hard quartzite
The lineament representing the fracture having NW to SE trend in ERI also
(Figure 2a, 2b). Its Thickness is not uniform. This lineament is showing more than 75
meters thickness in the SE corner. The thickness is about 25 m in NW side due
emplacement of quartz reef (Figure 1a, 1b). It can be inferred from ERI that lineament
is vertical in nature and inclined towards SE direction. Groundwater flow might be
towards SE due to slope of lineament toward SE direction. Surface water is also
flowing in the same direction (Figure 1b). Volumetric Picture or image of this
lineament indicates its irregular shape within linear pattern (Figure 3a, 3b).On the
basis of volumetric dimension of lineament, high groundwater potentiality can be
identified from this fracture. Upland of the study area acts as natural recharging
system to this fracture through perennial seepage
Figure 1 a) Structural map showing lineament and quartz reef, VES sations have been shown
by white spot. b) DGPS data based topographic map of study site showing lineament
5. Spatial Positioning of Fracture in Hard Rock
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Figure 2 a) ERI lineament of surface b) various ERI sections showing sub surface orientation
of lineament.
Figure 3 a) ERI showing the 3D spatial pattern of lineament in blue color. Hard rocks are in
green, yellow and red colour b) ERI showing volume of lineament
6. CONCLUSION
A remote sensing technique is only suitable for tracing the two dimension of
lineament. ERI is capable to map the three-dimensional picture of lineament even in
complex geological environment. The lineament in the present study is older than
quartz reef.
REFERENCE
[1] Anderson, J. F. Lineament mapping and analysis in the northern Wiliston basin of
Noerth Dakota, DMR Newsletter, 96(1). 2008
[2] Fox, C. S. The Jharia coalfield, Mem. G. S. I., 19(56), 1930
6. Ganesh Prasad and Suresh Prasad Yadav
http://www.iaeme.com/IJARET/index.asp 42 editor@iaeme.com
[3] Henriksen, H. Fracture lineaments and their surroundings with respect to
groundwater flow in the bedrock of Sunfjord, western Norway. Norwegian
journal of geology, 86, 2006, pp-373–386.
[4] Mondal, N.C., Rao, V.A., Singh, V. S. and Sarwade, D. V. Delineation of
concealed lineaments using electrical resistivity imaging in granitic terrain.
Current science, 94(8), 2008.
[5] Mogaji, K. A., Aboyeji, O. S. and Omosuyi, G. O. 2011 Mapping of lineaments
for groundwater targeting in the basement complex region of Ondo State,
Nigeria, using remote sensing and geographic information system (GIS)
techniques, International Journal of Water Resources and Environmental
Engineering, 3(7), August 2011, pp. 150–160.
[6] Rao, M. K. Bull. I. S. M. Geophycs. Soc., 1970.
[7] Sankaranarayan, P. K. and Ramanujachary, K. R. Short Note – An Inverse slope
Method of Determining Absolute Resistivity. Geophysics, 32 (6), pp. 1036–1040,
1967
[8] Van Nostrand, R. G and Cook, K. L. Interpretation of Resistivity data, Geological
Survey prof. paper, US Geological survey, 1996, pp. 499.
![Ganesh Prasad and Suresh Prasad Yadav
http://www.iaeme.com/IJARET/index.asp 38 editor@iaeme.com
straight or nearly straight relationships that may be the expression of folds, fractures,
or faults in the subsurface (Sabins, 2000, Anderson, 2008) [1] Lineament in this study
is defined as a mappable, linear feature of a surface whose parts are aligned in a
rectilinear or slightly curvilinear relationship and which differ from the pattern of
adjacent features and presumably reflect some subsurface phenomenon. Lineament
analysis in hard-rock terrains has been performed widely as a means for groundwater
exploration (Mogaji, 2011) [5]. Identification of lineament using remote sensing
techniques is the common practice. But sub surface extension of lineament can not be
fully identified in satellite image. Electrical resistivity is one of the most effective
geophysical methods for investigating the 3D spatial pattern of lineament.
Identification and analysis of underground fractures and concealed lineaments are
crucial in hard-rock terrains (Mondal et al 2008) [4].
Two and three dimension electrical resistivity imaging is widely used for mapping
of an area having complex geological structure. Electrical resistivity imaging has been
proved an excellent tool for identification of horizontal and vertical extension of
buried litho- units and linear structure. The electrical prospecting method consists of
measuring the potential at the surface which results from a known current flowing
into the ground. A pair of current electrodes, A and B, and a pair of potential
electrodes, M and N, are used. The apparent resistivity (ρa) is given by
ρa = K ΔV / I
Where, K denotes a geometric coefficient dependent upon the electrode array, Δ V
denotes the measured potential difference and I denote the current intensity. By
expanding the current electrode array, the depth of investigation can be increased.
Such a data set provides a vertical log of apparent resistivity called a vertical electrical
sounding (VES). The sounding site is conventionally located at the centre between the
inner electrodes. Electrical profiling is used for generation of electrical resistivity
image. The electrode separation is kept constant and the electrode array is moved as a
whole with the center of the configuration occupying successive points along a
traverse in electrical profiling.
Electrical Resistivity Imaging (ERI) techniques is highly capable to generate a
realistic model of the subsurface in geologically complex areas Two and three
dimension (2D) electrical imaging are now widely used where conventional 1-D
resistivity sounding surveys are inadequate to map subsurface object. One
dimensional resistivity surveying is a point specific investigation that gives vertical
information in terms of resistivity with depth of layers laying in sub -surface to that
point. Therefore, No sub-surface information can be obtained by any shift or deviation
from surveying point in 1-D resistivity survey. Basically, Electrical Resistivity Image
(ERI) is the final result of mathematical stitching of all 1-D VES data generated at
closed spaced locations or stations on a line through suitable software in form of
pixels or contours.
2. OBJECTIVE
Following are main objectives:
• Identification of three dimensional spatial postion of fracture
• Determination of the hydrogeological character of the fracture.
3. THE STUDY AREA](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)