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Content uploaded by Mark Jinmin
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All content in this area was uploaded by Mark Jinmin on Dec 09, 2020
Content may be subject to copyright.
Trilogy possible meteorite impact crater at Bukit Bunuh, Malaysia using 2-D electrical
resistivity imaging
M. Jinmin, S. Rosli, M. M. Nordiana, and S. Mokhtar
Citation: AIP Conference Proceedings 1861, 030012 (2017); doi: 10.1063/1.4990899
View online: http://dx.doi.org/10.1063/1.4990899
View Table of Contents: http://aip.scitation.org/toc/apc/1861/1
Published by the American Institute of Physics
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Trilogy Possible Meteorite Impact Crater at Bukit Bunuh,
Malaysia Using 2-D Electrical Resistivity Imaging
M. Jinmin1, a), S. Roslib), M. M. Nordianac), S. Mokhtar 2, d)
1Geophysics Section, School of Physics, 11800 Universiti Sains Malaysia, Penang, Malaysia
2Centre for Global Archaeological Research Malaysia, 11800 Universiti Sains Malaysia, Penang, Malaysia
amarkjinmin@hotmail.com
brosli@usm.my
cmmnordiana@usm.my
dmmokh@usm.my
a) Corresponding author email’s: markjinmin@hotmail.com
Abstract. Bukit Bunuh situated in Lenggong (Perak) is one of Malaysia’s most important areas for archeology that
revealed many traces of Malaysia’s prehistory. Geophysical method especially 2-D electrical resistivity imaging method
is non-destructive which is applied in geo-subsurface study for meteorite impact. The study consists of two stages which
are regional and detail study with a total of fourteen survey lines. The survey lines were conducted using Pole-dipole
array with 5 m minimum electrode spacing. The results of each stage are correlated and combined to produce detail
subsurface resistivity distribution of the study area. It shows that the area consists of two main layers which are
overburden and granitic bedrock. The first layer is overburden mix with boulders with resistivity value of 10-800 Ωm
while the second layer is granitic bedrock with resistivity value of >1500 Ωm. This study also shows few spotted
possibility of uplift (rebound) due to the high impact which suspected from meteorite. A lot of fracture were found within
the survey area which could be one of the effect of meteorite impact. The result suggest that Bukit Bunuh is under layer
by a complex crater with diameter of crater rim is approximately 5-6 km.
INTRODUCTION
Impact cratering plays a major role in surface forming and modifying of planetary bodies. The impact changes
the properties and characteristic of impacted soils and target rocks at the point of impact and surrounding area.
Geophysical survey in archaeological is a noninvasive method for aiding in identification of features within the
shallow subsurface for archaeological mapping or imaging. 2-D electrical resistivity imaging is non-destructive
method which is eco-friendly for environmental study. Electrical resistivity is one of the most sensitive geophysical
methods for monitoring changes of electrical properties in the subsurface. Resistivity results correlations with
borehole records were used to have valid interpretations. These are the important part for geophysicists in
archaeological prospect. Geophysical methods in archaeological study has gained wide acceptance in the past
decade within the general archaeological community.
1st International Geo-Electromagnetic Workshop (Geo-EM 2017)
AIP Conf. Proc. 1861, 030012-1–030012-4; doi: 10.1063/1.4990899
Published by AIP Publishing. 978-0-7354-1535-5/$30.00
030012-1
METHODOLOGY
In this paper, the survey used 2-D electrical resistivity imaging method in Bukit Bunuh. The resistivity
measurements are normally made by injecting current into the ground through two current electrodes, C1 and C2, and
measuring the resulting voltage difference at two potential electrodes, P1 and P2. Electrical Imaging System is now
mainly carried out with a multi-electrode resistivity meter system connected with SAS4000 (ABEM Instrument).
Resistivity method basically measures the resistivity distribution of the subsurface materials. The resistivity of a soil
or rock is dependent on factors that include porosity, amount of total dissolved solid such as salts and minerals
composition as clays and amount on interconnected pore water. Igneous and metamorphic rocks typically have
higher resistivity values than sedimentary rocks. Table 1 shows alluvium has a significantly lower resistivity value
than granite.
TABLE 1. Resistivity value of common rocks and soil materials.
Material
Resistivity (ohm-m)
Alluvium
10 to 800
Sand
60 to 1000
Clay
1 to 1000
Groundwater (fresh)
10 to 100
Sandstone
8 - 4 x 105
Shale
20 - 2 x 105
Limestone
50 - 4 x 105
Granite
5000 to 1,000,000
Pole-dipole array was used with minimum electrodes spacing on the surface of 5.0 m. The pole-dipole array has
relatively very good horizontal coverage, but it has a significantly higher signal strength compared with dipole-
dipole and it is not as sensitive to telluric noises as the pole-pole array. A least-squares inversion of the resistivity
data was conducted using finite element mesh with surface topography to generate 2-D model of resistivity versus
depth. The data were then outputted into RES2Dinv software for gridding, contouring and interpretation. The results
for resistivity pseudo-section and bedrock contour map are produced using Surfer 13 software for final
interpretation.
GEOLOGY AND STUDY AREA
The study was conducted at Bukit Bunuh, which located at one kilometer from the Kota Tampan, Lenggong, Perak.
The study area which is approximately 11.5 km East-West and 11.5 km North-South with total of fourteen survey
lines. The regional study consists of four lines and detail study consists of ten survey lines. The survey area covered
approximately 132.25 km2 with undulating terrain that consists mainly palm estate towards the west and east of the
survey area, it covered by primary jungle. The survey lines run parallel and across Sungai Perak and between two
ranges, Bintang Range and Tititwangsa Range. Lenggong Valley consists of few unit of lithology such as alluvium,
tefra dust and granitic rock. The alluvium unit is situated along the river. The topography of Bukit Bunuh is 600ft
above MSL. The granitic rock is from Jurassic End-Carbonaceous low era being dominated the whole of Lenggong
valley and originated from Bintang Range at the west of Lenggong [1].
RESULTS AND DISCUSSION
Total of fourteen survey lines were conducted around the possible rim of the meteorite impact. The results of the 2-
D electrical resistivity imaging survey are presents as contoured pseudo-section. Figure 1 shows one of the
030012-2
resistivity section from regional study with lots of fractures were detected due to the meteorite impact.2-D electrical
resistivity imaging show the study area was divided into two main zones which are alluvium with resistivity value of
10-800 Ωm and granitic bedrock value of >1500 Ωm with depth of 5-50 m. Table 2 shows one of the borehole data
which located at the study area that assists in data interpretation. From the resistivity results, it shows alluvium with
10-800 Ωm and granitic bedrock with resistivity of >1500 Ωm were confirmed by the borehole record which
identify literate at range from 1.50 m to 3.00 m and granitic bedrock was identified at 4.00 m depth. From regional
study, the results were convincing to identify the bedrock subsurface changes due to the meteorite impact at the
study area. More survey lines were then conducted in detail study at the high possibility of uplift zones for further
understanding and interpretation. To producecomplete bedrock topography map, bedrock depths were then digitized
from all resistivity section with granitic bedrock value >1500 Ωm and varies from 5-50 m depth. All digitized
bedrock depth will be presenting in a contour mapusing Surfer 13 for detail interpretation.Trilogy from regional to
detail study shows convincing evidence for interpretations to identify crater rims which approximately 5-6 km
diameter. Few possibility spots of high elevated bedrock appeared as rebound zones are suspected to be the uplift
effect due to the impact as in Fig.2.The layered bedrock type uplift defined as a central uplift of pre-existing
relatively flat-lying layered bedrock that was exhumed from depth, tilted, and fractured during the impact process
[2].
FIGURE 1. Resistivity section North-West to South-East line with fractures in dotted line.
TABLE 2.Borehole BH3 at Bukit Bunuh with lithology.
Sample depth (m)
Lithology
Color (Munsell chart)
Details
1.50
Literate
Yellowish brown and
light grey
Weathered granite to
literate. Existing of pyrite
and mica
3.00
Literate
Lighter grey, yellowish
brown and greenish grey
Weathered granite to
literate. Existing of
courser quartz and pyrite
and mica mineral
4.00
Weathered granite
Granite impact (Bedrock)
5.00
Granite
Granite impact (Bedrock)
6.00
Granite
Granite impact (Bedrock)
7.10
Granite
Granite impact (Bedrock)
113
5 m
Fracture
Fracture
Road
Fracture
Road
030012-3
FIGURE 2. 3-D view of ground topography (top) and bedrock depth with rebound (R) zones (bottom).
CONCLUSION
The 2-D electrical resistivity imaging method conducted at Bukit Bunuh can be used as indication of the geological
mapping tool to provide detail image of subsurface characteristic due to meteorite impact. This paper shows trilogy
research starting regional until detail study which is suspect Bukit Bunuh as a complex meteorite impact area. The
results presented in this paper are promising to identify possible rebound and fractures which can be one of possible
causes of the impact. The existing geotechnical borehole log refined the 2-D electrical resistivity imaging results.
ACKNOWLEDGMENTS
The authors would like to thank all students and staff involved in this research including Centre for Global
Archaeological Research (CGAR) Universiti Sains Malaysia for sponsoring this research.
REFERENCES
[1] Mokhtar S 1993 “Kajian perbandingan tapak Paleolitik Kampung Temelong dengan Kota Tampan dan
sumbangannya terhadap kebudayaan zaman Pleistosein akhir di Asia Tenggara” (Malaysia Museum Journal,
Vol. 32).
[2] Caudill C M, Tornabene L L, McEwen A S, Byrne S, Ojha L and Mattson S 2012 “Layerede Mega Blocks in
the central uplifts of impact craters.”(Icarus 221).
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