Bulletin of the Geological Society of Malaysia, Volume 46, May 2003, pp. 485 – 489
1lnstitut Penyelidikan Tenaga Nuklear Malaysia (MINT), Bangi, 43000 Kajang, Malaysia
2Program Geologi, Pusat Pengajian Sains Sekitaran dan Sumber Alam, FST, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
Abstrak: Penyiasatan bawah tanah adalah sesebuah peringkat kajian yang penting dalam menentukan kesesuaian sesuatu kawasan yang akan dibangunkan. Satu kajian pencirian jasad batuan formasi Kenny Hill yang menggabungkan kaedah geofizik dan geologi kejuruteraan telah dijalankan pada dua buah potongan cerun pada batuan filit, batuan kuarzit dan selang-Iapis batuan filit dan kuarzit di tapak Kamsis H, Universiti Kebangsaan Malaysia (UKM). Kaedah geofizik yang digunakan adalah survei seismos biasan dan survei keberintangan geoelektrik, manakala kaedah geologi kejuruteraan melibatkan survei profil luluhawa. Berdasarkan data survei seismos biasan, empat lapisan dapat dikesan; lapisan pertama (penutup bumi) mempunyai nilai halaju sebenar gelombang P (Vp) yang berjulat antara 180 m/s-920 m/s, dengan kedalaman <1.5 m. Lapisan kedua mempunyai nilai Vp berjulat antara 510 m/s-1,280 m/s, pada kedalamannya di antara 0.5-4.0 m. Bagi lapisan ketiga nilai Vp ialah di antara 1,020 m/s-1,940 m/s pada kedalamannya di antara 3.0 m-11.0 m manakala lapisan keempat mempunyai Vp berjulat di antara 1,860 m/s-3,150 m/s. Berdasarkan nilai halaju sebenar gelombang P (Vp) yang diperolehi, terdapatnya perbezaan yang jelas antara batuan filit dan kuarzit dengan nilai 1,800 m/s-2,500 m/s untuk batuan filit dan 2,500 m/s-3,200 m/s untuk batuan kuarzit. Bagi survei keberintangan geoelektrik, terdapat tiga zon keberintangan yang utama iaitu zon berkeberintangan rendah berjulat 20 Wm-1,000 Wm, zon berkeberintangan sederhana berjulat antara 1,000 Wm-3,500 Wm dan zon berkeberintangan tinggi iaitu >3,500 Wm. Daripada kajian profil luluhawa, enam gred luluhawa daripada gred I hingga gred VI telah dapat dikelaskan dan dipetakan. Pengredan luluhawa ini dapat dibandingkan dan dikorelasikan dengan parameter geofizik.
Abstract: Investigation of the subsurface conditions is one of the important factors that is needed for the determination of the suitability of an area for development. A study to characterize the Kenny Hill formation was conducted by using geophysical and engineering geological methods at two different slope cuts at Kamsis H, Universiti Kebangsaan Malaysia (UKM). The lithologies consist of phyllite, quartzite and interbedded phyllite and quartzite. The geophysical methods employed were seismic refraction and geoelectrical resistivity surveys. Engineering geological survey of the weathering profile was carried out. Based on the seismic refraction surveys, four subsurface layers have been determined. Each of the layers are characterized by different true P-wave velocities, Vp, that ranges from 180 m/s to 920 m/s for the first layer, 510 m/s to 1,280 m/s for the second layer, 1,020 m/s to 1,940 m/s for the third layer and 1,860 m/s to 3,150 m/s for the fourth layer. The thicknesses of each of these layers were determined as <1.5 m, 0.5-4.0 m and 3.0-11.0 m. Based on the distribution of true P-wave velocities, phyllite and quartzite have distinctly different true P-wave velocities, Vp, that are 1,800 m/s to 2,500 m/s for phyllite and 2,500 m/s to 3,200 m/s for quartzite. Geoelectrical resistivity results show three main zones of different specific geoelectrical resistivities ranging from 20 Wm-1,000 Wm, 1,000 Wm-3,500 Wm and >3,500 Wm. From the weathering profile, six weathering grades from grade I to grade VI were classified and mapped. Each of the weathered layers can be correlated with the geophysical parameters.
