EXPLORATION FOR GEOTHERMAL RESOURCES USING GEOLOGICAL STRUCTURES-FAULTS BY CHARLESON NAMANDWA ELIYASI GEOLOGICAL SURVEY OF MALAWI 1
EXPLORATION FOR
GEOTHERMAL RESOURCES
USING GEOLOGICAL
STRUCTURES-FAULTS
BY
CHARLESON NAMANDWA ELIYASI
GEOLOGICAL SURVEY OF MALAWI
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OUTLINE
• Introduction
• Structural setting of the study area
• Surface manifestations
• Methodology
• Relationship between faults and geothermal springs
• Fault density analysis
• Discussion
• Conclusion
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INTRODUCTION
MALAWI’S GEOGRAPHICAL
LOCATION
• Located in the SE part of
Africa
• Within within latitudes 90s and
180s and longitudes 32
0e and
360e
• The Study area is located to
the Northern part of Malawi
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Source: Google map
STRUCTURAL SETTING
• The area lies at the meeting point of three major
mobile belts formed during the orogenic
episodes.
• The Ubendian mobile belt: originates from the
Sw-Tanzania and extend into Malawi in a SE
direction.
• Irumide belt of Zambia: well pronounced in the N
& and Southern province of the Malawi rift.
• The Mozambique is the last mobile belt that
affected the country including northern Malawi.
• This was followed by the rifting episodes and
initiated the Malawi rifting.
• Geothermal occurrences in Malawi are
influenced by these tectonic activities.
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SURFACE
MANIFESTATIONS
• Surface
indicators/manifestations
are in form of warm and
hot springs.
• Surface temperatures
ranging from 300C to over
700C
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Source: Field photo
CHIWETA
METHODOLOGY FLOW CHART
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FAULTS ORIENTATION AND RELATIONSHIP
BETWEEN FAULTS AND GEOTHERMAL
SPRING OCCURENCES
Faults overlain on
SRTM DEM (A)) and
Rose diagram (B)
showing two main
prominent NE-SW,
NW-SE trending
pattern and less
prominent NS
trending pattern
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FAULT SETS ASSOCIATED WITH
GEOTHERMAL SPRINGS
• Known geothermal
spring locations and
their temperature,
border faults and major
faults were overlain on
SRTM DEM (arrows
show areas where
higher temperatures
were recorded)
• High temperature
geothermal springs
located within border
faults (above 700C)
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FAULT DENSITY ANALYSIS
• Fault density analysis is a method that is used to calculate the number
of faults per unit area
• Areas with more faults per unit area are considered as high fault
density areas while those with less faults per unit area , low density
areas
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FAULT DENSITY ANALYSIS CONT’D
• The Density analysis
showed high occurrence of
geothermal springs in high
density areas, followed by
medium density areas.
• In terms of percentage: out
of 12 geothermal spring
sites 50% of them occur in
high density areas, 42% in
medium density areas and
8% in low density areas
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DISCUSSION
• The study has shown that the orogenic processes that affected the
area resulted into formation of structures such as faults which have
two main NW-SE, and NE-SW general orientation and less pronounced
N-S orientation.
• It was also noted that the general occurrence of geothermal springs
mainly follows a similar trend.
• Geothermal spring occurrences in the study area are mainly controlled
by two sets of faults namely major faults and border faults.
• High temperature geothermal springs are located in border fault zones
• Exploration for geothermal resources in the study area should be
concentrated in high and medium fault density zone areas.
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CONCLUSION
• It is possible to use geological structures such as faults for
geothermal exploration
• The technique can be applied to other areas of similar geological
setting.
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THANK YOU ALL FOR YOUR ATTENTION
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STRUCTURAL SETTING
• The area lies at the meeting point of
three major mobile belts formed during
the orogenic episodes.
• The orogenic episode was followed by
rifting and faulting within the Malawi rift.
• Ubendian –originates from the Sw-
Tanzania
• Irumide belt of Zambia
• The Mozambique
• This was followed by the rifting episodes
and initiated the Malawi rifting.
• Geothermal occurrences in Malawi are
influenced by these tectonic activities.
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FAULTS
• Faults were digitized from the geological map of Malawi using arc Gis
software 10.2 and a shapefile was created. it was displayed on SRTM
DEM data to see how it correlates spatially with the structural features
(figure 5a). the shapefile containing faults was exported from arc gis to
PCI Geomatica software and saved as AutoCAD vectors in a data
interchange file (dxf) format in order to be compatible with rockworks
software where the rose diagrams were plotted. the rose diagram
(figure 5b) was plotted in rockworks using the linear algorithm under
the utilities function.
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ROSE DIAGRAM
• A Rose diagram is a circular histogram plot which displays directional
data and frequency of each class (PRABU ET AL., 1964). These
diagrams have been used in many studies to define structural trend.
for instance CHENRAI, (2012) used rose diagrams to interpret
geological structures in koh samui area in gulf of thailand. further,
prabu et al., (2013) used rose diagrams to analyse orientation of
lineaments in the mapping of lineaments for groundwater study in
india.
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• SRTM-SHUTTLE RADAR TOPOGRAPHY MISSION
• A HALF-GRABEN IS A GEOLOGICAL STRUCTURE BOUNDED BY A FAULT ALONG ONE SIDE OF
ITS BOUNDARIES, UNLIKE A FULL GRABEN WHERE A DEPRESSED BLOCK OF LAND IS BORDERED
BY PARALLEL FAULTS.
•
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OROGENIC PROCESS
• OROGENY REFERS TO FORCES AND EVENTS LEADING TO A LARGE STRUCTURAL
DEFORMATION OF THE EARTH'S LITHOSPHERE (CRUSTAND UPPERMOST MANTLE) DUE TO THE
INTERACTION BETWEEN TECTONIC PLATES. OROGENS OR OROGENIC BELTS DEVELOP WHEN A
CONTINENTAL PLATE IS CRUMPLED AND IS PUSHED UPWARDS TO FORM MOUNTAIN RANGES,
AND INVOLVE A GREAT RANGE OF GEOLOGICAL PROCESSES COLLECTIVELY
CALLED OROGENESIS.[1][2]
•
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