The identification and discovery of meteorite impact structures are based on several observation on the field such as geomorphology, rock textures, mineral deformation, and stratigraphic relations. Based on the aerial photo and image, the geomorphology of Mahsuri Ring (MR) region in Langkawi shows a circular features that possibly indicate the existence of meteorite impact. Integrated geophysical survey was carried out to image and detect the structure at these two different locations (Mahsuri Ring, MR and Bukit Bunuh, BB). The geophysical survey were carried out with gravity and magnetic method survey cover approximately 10 km2 for both case studies area. The geophysicalsurvey also involved resistivity imaging method and seismic refraction methods acquire subsurface information and image the potential subsurface area. Based on geophysical survey at MR, the results from both magnetic and gravity survey shows relatively low anomaly at the center of the survey area which suspected meteorite impact area. The impact structure has been modelled by using integration of all the geophysical data (magnetic, gravity, resistivity and seismic) which produced were then used to produce simple type crater model with diameter of approximately 1.5 km and depth of up to 800 meters. While correlation of the integrated geophysical survey in Bukit Bunuh (BB) indicated that the crater has a diameter of approximately 2.5 km with depth up to 400 m. The interpretation of the subsurface structure in BB area indicates the formation of complex crater structure. In conclusion, integrated geophysical method shows the possible occurrences of complex impact craters at BB and indicates simple impact crater structure at MR.
D geoelectrical resistivity imaging using the Wenner configuration was conducted to investigate the weathering profile of a sedimentary rock cut slope at Lubuk Paku, Pahang. The rock which belongs to the Tembeling Formation was cut into· three terraces and it consists of, from bottom to top, thick layers of basal conglomerate, massive pebbly sandstone and highly weathered shale. The resistivity imaging results show that the rock cut slope can be characterised into several zones of low, moderately low, moderately high and high resistivities. The low resistivity zone which has resistivity values ranging from 150 to 500 Qm is associated with the residual soil with high water content. It is classified as grade VI according to the IAEG ( 1981) weathering index with an average layer thickness of about 1.8 m. A moderately low resistivity zone with weathering index of grade V shows resistivity values ranging from 650 to 800 Qm. This layer appears to have low water content and its thickness varies from 1.1 to 1. 7 m. Weathered rock material of grade IV shows resistivity values ranging from 800 to 1200 Qm. A zone of moderately high resistivity is represented by the weathered rock mass of grade III. The resistivity value for this particular zone is relatively high and ranges from 1232 to 2000 run. This zone is dominated by a slightly weathered layer of pebbly sandstone. A slightly weathered rock of grade II represents the high resistivity zone with values ranging from 2000 to 3000 Qm. This zone is correlated well with the massive and solid rocks of basal conglomerate and pebbly sandstone. The results of the present study illustrate empirically that the geoelectrical resistivity values decrease as the weathering grades of the rock material increase. The presence of discontinuities and fractures in the rock mass appears to have lowered the overall resistivity of the rock mass. This empirical correlation could be used to map zones of different grades of weathered sedimentary rock mass and to study other subsurface geological structures related to slope cuts. Abstrak: Survei pengimejan keberintangan geoelektrik dengan menggunakan susunatur Wenner telah dijalankan untuk mengkaji prof11 luluhawa potongan cerun batuan sedimen di Lubuk Paku, Pahang. Cerun batuan sedimen Formasi Tembeling ini telah dipotong kepada tiga teres dan batuan ini, dari bawah ke atas, terdiri daripada lapisan batuan konglomerat basal, batu pasir berpebel massif dan syal terluluhawa. lmej keberintangan yang dihasilkan menunjukkan jasad batuan di cerun kajian boleh dikategorikan kepada zon keberintangan rendah, sederhana rendah, sederhana tinggi dan tinggi. Zon keberintangan rendah yang berjulat daripada 150 hingga 500 Qm. adalah berasosiasi dengan tanah baki sedimen yang lembab. Tanah ini dikelaskan sebagai bahan bergred VI mengikut pengelasan IAEG ( 1981) dengan ketebalan purata 1.8 m. Zon berkeberintangan sederhana rendah yang diwaki1i oleh bahan bergred V menunjukkanjulat keberintangan 650 - 800 Qm. Lapisan ini mempunyai keteba1an sekitar 1.1 ke 1. 7 m dan kurang mengandungi air. Bahan terluluhawa bergred IV mempunyai nilai keberintangan daripada 800 ke 1200 Qm. Zon berkerintangan sederhana tinggi diwakili oleh bahan bergred III. Nilai keberintangan bahan ini relatif tinggi dengan ju1at 1232 ke 2000 Qm. Zon ini · didominasi oleh lapisan batu pasir berpebe1 yang sedikit ter1uluhawa. Jasad batuan gred II yang sedikit ter1u1uhawa mewakili zon berkeberintangan tinggi dengan julat daripada 2000-3000 Qm. Zon ini bo1eh dikorelasikan dengan jelas terhadap batuan dasar kong1omerat serta batu pasir massif. Hasil kajian yang dipero1ehi menunjukkan secara empirikal bahawa nilai keberintangan geoelektrik menurun dengan kenaikan gred luluhawa jasad batuan. Kehadiran fitur ketakselanjaran dan retakan juga didapati merendahkan keseluruhan ni1ai keberintangan da1am jasad batuan. Korelasi empirical yang diperolehi ini boleh digunakan untuk pemetaan zon-zon gred luluhawa batuan sedimen dan mengkaji struktur geologi bawah permukaan yang berkaitan dengan cerun potongan.
A geophysical survey was conducted to investigate contamination in a domestic waste-disposal site, at Ampar Tenang, Dengkil, Selangor. The objectives of the survey were to delineate and identify pathways for contaminant migration. Surface geophysical method employing 2-D DC resistivity imaging technique was used to locate potential leachate plumes. A total of six lines of 2-D resistivity images were established with three of them located on the waste pile while the other three situated outside the boundary of the dumping site. The objectives were successfully met, including delineation of buried waste and identification of the positions of contaminated subsurface soil and groundwater. In general the result of the survey shows that the resistivity value of the decomposed waste material is relatively low compared to those of the uncontaminated soil outside the dumping site. The electrically conductive anomaly on the dumping site was interpreted as leachate plumes which appears to have seeped at depth as far as 20 m below surface. Near surface low resistivity layer observed on the area east of the dumping site is interpreted to be associated with leachate runoff.
Geophysical surveys in particular ground penetrating radar (GPR), electrical resistivity tomography (ERT) and vertical resistivity probe (VRP) were used in mapping subsurface geological structures and groundwater contaminants at Sungai Kandis, Klang to identify the approximate boundaries of contaminant plumes and to provide stratigraphic information at this site. The study area was formerly an illegal dumping site of hydrocarbon and toxic waste. A good correlation exists between GPR signatures, ERT layers, vertical resistivity probe and the contaminated soil. The presence of contaminant plumes as well as the water table are also observed in the GPR and ERT sections at depths approximately of 0.5 to 1 m. In this study, a total of 16 GPR traverses and 10 ERT lines with lengths from 30 to 100 m were established. VRP measurements were conducted in 14 shallow boreholes with a maximum depth of about 1m. The VRP results show high apparent resistivity values ranging from 200 to 10000 Ωm associated with oil contaminated layer. The presence of this layer was also detected in the 2D resistivity sections as a thin band of high resistivity values ranging from 60 to 200 Ωm. In the GPR section, the oil contaminated layer exhibits discontinuous, subparallel and chaotic high amplitude reflection patterns.
Since the large earthquakes in Sumatera and Nias, there were some tremors incidents at Bukit Tinggi. Therefore, a study on the earth's crust movement and the effects of the earthquake in Indonesia on the tectonic blocks of Peninsular Malaysia have been carried out using GPS data analysis. GPS data from five MyRTKnet stations within Peninsular Malaysia have been analyzed to monitor the movement of two major tectonic blocks of Peninsular Malaysia which are the western belt represented by the Behrang (BEHR) and UPM Serdang (UPMS) stations and the central belt represented by Bentong (BENT), Jerantut (JRNT) and Temerloh (TLOH) stations. GPS data recorded from 2005 to 2010 were analysed based on horizontal and vertical displacements of the respective stations by using Trimble Business Centre (TBC) software. Based on the results of accumulated displacements of recorded GPS data from January 2006 to December 2013, it shows that the western belt which represented by UPMS has shifted 0.096m towards northwest with changes of ellipsoidal height of +0.030m while the central belt which represented by TLOH has shifted 0.080m towards northwest with changes of ellipsoidal height of −0.015m. Meanwhile, BENT station which is located on the Bentong-Raub suture zone turns to its original position as well as JRNT station. However, BEHR station which are located in western belt do not show any movements. All of these movements may be due to the influence of reactive faults in the stations area stimulated by several large earthquakes that occurred in 2005 to 2010. Study on using the GPS data analysis and combine with integrated geophysical methods are necessary to understand in detail about the tectonic evolution of Peninsular Malaysia.
Gravity Data Analysis and Interpretation of Sirt Basin, Libya Ahmed Saheel; Ahmed Saheel School of Environment and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia Search for other works by this author on: This Site Google Scholar Abdul Rahim Bin Samsudin; Abdul Rahim Bin Samsudin School of Environment and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia Search for other works by this author on: This Site Google Scholar Umar Bin Hamzah Umar Bin Hamzah School of Environment and Natural Resource Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia Search for other works by this author on: This Site Google Scholar Paper presented at the North Africa Technical Conference and Exhibition, Cairo, Egypt, February 2010. Paper Number: SPE-127789-MS https://doi.org/10.2118/127789-MS Published: February 14 2010 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Saheel, Ahmed , Bin Samsudin, Abdul Rahim, and Umar Bin Hamzah. "Gravity Data Analysis and Interpretation of Sirt Basin, Libya." Paper presented at the North Africa Technical Conference and Exhibition, Cairo, Egypt, February 2010. doi: https://doi.org/10.2118/127789-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE North Africa Technical Conference and Exhibition Search Advanced Search Abstract The produced Bouguer gravity map shows prominent NW-SE and N-NW trends.Total horizontal derivative gravity map of the study area shows strong horizontal gradient anomalies that are located in eastern and central parts of the area. The central part of the basin can be divided into four zones the eastern zone shows many short anomalies of NW-SE orientation; the southern zone shows N-S orientation; the northern zone shows NW-SE orientation trends; in the western zone strong NW-SE trends cut with NE-SW changing to E-W trends. Isostatic residual map is characterized by a dominant northwest – southeast trend in the study area. This is clearly evident in the isostatic residual. The main trending anomalies are in the northern and southeastern parts of the study area with NW-SE orientation. A strong NW-SE trend is truncated by E-W trending in the southeastern and southwestern parts of the area. This is consistent with change of tectonic zones. Keywords: gravity map, geology, anomaly, sequence, upstream oil & gas, gravity data analysis, study area, spe 127789, reservoir characterization, information Subjects: Reservoir Characterization Copyright 2010, Society of Petroleum Engineers You can access this article if you purchase or spend a download.
A geophysical investigation was conducted at the UKM's matriculation centre in Kuala Pilah, Negeri Sembilan by the Department of Geology, Universiti Kebangsaan Malaysia. The study was initiated as a result of water shortage in the area. The normal supply of piped water by Jabatan Bekalan Air (JBA) is either insufficient or totally cut off for several days especially during dry season. The aim of the study was to look for groundwater as a possible source of back up water supply for the centre. Geoelectrical resistivity sounding and seismic methods were adopted for assessment of the groundwater potential of the site and to determine the subsurface conditions of the area. A total of eleven sounding stations and eight seismic profiles were established. A layer of low resistivity « 100 ohm-m) was detected at eight sounding localities within the study area. This conductive layer could be associated with a near surface water saturated zone or aquifer. However based on seismic data and by taking velocity of 1,600 to 1,700 mls for the water saturated zone, only one location (S4ISP3) was found to be favourable. The potential water saturated layer has a resistivity value and a seismic velocity of about 80 ohm-m and 1,690 mls respectively. Both geoelectrical and seismic results show good agreement in term of depth below surface (- 2 metres) and layer thickness (- 30 metres). However, these results need to be confirmed by drilling.
Shallow seismic reflection is one of the surface geophysical techniques to investigate indirectly subsurface structures within depths of 200 meters. Structures such as faults, sedimentary features, hydrogeological aquifers, depth to bedrock and limestone sinkholes are always related to the geological mapping. This paper presents some of the shallow seismic reflection results in imaging subsurface structures at a few selected localities. The presence of a limestone sinkhole as small as 20 ´ 5 meters was imaged at the old limestone quarry in Batu Caves, Kuala Lumpur. Sedimentary structures, aquifers and thickness of alluvium on granite bedrock were imaged from surveys at Pekan, Pahang and Bacok, Kelantan. Faults have also been detected using the same technique from a survey in Midland, England. Currently a minimum depth obtained is approximately 20 meters and the vertical resolution is approximately 5 meters.
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