Meteorite impact crater subsurface study at Bukit Bunuh, Lenggong, Perak using 2-d electrical resistivity method
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Date
2014
Authors
Bin, Mark
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Abstract
Geophysical measurement is an important and integral component of geophysical investigations connected with environmental problems. 2-D electrical resistivity imaging (2-DERI) method has progressed rapidly which provides resistivities and depth at a certain point. The survey is to identify the features and the subsurface resistivity distribution by making measurement on the ground surface. Hence, true resistivity of subsurface can be estimated. The development of the 2-DERI tomography was rapidly developed for environmental, construction and archaeological interest. The geophysical survey for archaeology most often refers to the ground-based physical sensing methods used for mapping or imaging. The method is neither invasive nor destructive for environmental. The 2-DERI was conducted at Bukit Bunuh, Lenggong, Perak. The main objectives are determining the thickness and features of the subsurface and bedrock depth, associate meteorite impact with support of borehole records. The study consists of two stages which is regional and detail study, which covering area of 132.25 km2 . The detail study was executed by the results of regional study. The survey was carried out using 'roll-along' technique. The data were processed and analysed using RES2DINV, Excel, Surfer and Strater softwares in order to produce electrical resistivity tomography for qualitative interpretations. 2-D resistivity results show the study area was divided into two main zones, overburden consists of alluvium and embedded boulders with resistivity value of 10-800 Ωm, and bedrock with resistivity value of >1500 Ωm and depth of 5-70 m with borehole records correlation. There are lots of fractured zones identified in the study area. The low level bedrock was circulated by high-level bedrock which is interpreted as crater rim. The uplift or rebound zones were also identified at the centre of the crater rim. Lots of fractures and faults were found in the crater and crater boundary. This indicated that the 2-DERI has the capability of retrieving the meteorite impact subsurface at the studied area.