KANDUNGAN (Contents)
Total Page:16
File Type:pdf, Size:1020Kb
Jil. 21, No.2 (Vol. 21, No.2) Mar-Apr 1995 KANDUNGAN (Contents) Umar Hamzah, Abdul Rahim Samsudin and Abdul Ghani Rafek: Shallow reflection seismics at 69 the Pekan Quaternary deposits Basir Jasin: Occurrence of bedded radiolarian chert in the Kubang Pasu FOl1l1ation, north Kedah, 73 Peninsular Malaysia :.: ... :... :.:.::::: ...................... ::::.: ... :..... :........... :....... :.:.: ... :.... ........................................................................................................................................................................... ,...... ................................... :;:;:;:;:;:;:;:;:;:;:;:;:;:;:::;:::::;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:::::;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;:;::::::::::::::::::::::=::::::::::::::::::::::::::.:.,.. :: .. geRt~tqY?fNg5RS~]Q :&N :: IM ·~~Vpg~ : §ffn€$9.gr§fY) :>.::::::: D.F. Strong: 1) Tectonic: Some metallogenic aspects of mineral deposits. 81 2) Some geochemical petrological aspects of mineral deposits 81 S.N. Wersching, Malek Musa, P.A. Smith and I.G. Edmonds: Preliminary site investigations of the 83 Kuala Lumpur International Airport Kuala Lumpur International Airport Sepang - Site Visit 85 Annual General Meeting & Annual Dinner 1995 - Report 86 Speech by Y. Bhg. Tan Sri Dato' Dr. Othman Yeop Abdullah 87 Minutes of the EGM of 17 February 1995 91 Minutes of the 28th Annual General Meeting 92 Reports 96 Keahlian (Membership) 115 Pertukaran Alamat (Change of Address) 115 Pertambahan Baru Perpustakaan (New Library Additions) 116 Local News 117 The Gros Morne Declaration: assessing rapid environmental change 127 26th Underwater Mining Institute 129 Kalendar (Calendar) 130 Majlis (Council) 1995/96 Presiden (President) KhalidNgah Naib Presiden (Vice-President) Ibrahim Komoo Setiausaha (Secretary) Ahmad Tajuddin Ibrahim Penolong Setiausaha (Asst. Secretary) Nik Ramli Nik Hassan Bendahari (Treasurer) Lee Chai Peng Pengarang (Editor) TehGuanHoe Presiden Yang Dahulu (Immediate Past President) : Fateh Chand 1995-97 1995-96 Khoo Kay Khean Abd. Ghani Mohd Rafek Hoh Swee Chee Abdul Rahim Samsudin Ibrahim Abdullah Effendy Cheng Abdullah Mohd Shafeea Leman Tan Boon Kong Jawatankuasa Kecil Pengarang (Editorial Subcommittee) Teh Guan Hoe (Pengerusi/Chairman) Dorsihah Mohamad Jais J.J. Pereira Fan Ah Kwai Ng Tham Fatt Lembaga Penasihat Pengarang (Editorial Advisory Board) AwPeck Chin Denis N.K. Tan Leong Lap Sau P.H. Stauffer Azhar Hj. Hussin Foo Wah Yang Mazlan Madon Tan Boon Kong K.R. Chakraborty C.A. Foss Ian Metcalfe Tan Teong Hing Choo Mun Keong N.S. Haile John Kuna Raj H.D. Tjia Chu Leng Heng C.S. Hutchison Senathi Rajah Yeap Cheng Hock Lee Chai Peng Shu Yeoh Khoon The Society was founded in 1967 with the aim of promoting the advancement of earth sciences particularly in Malaysia and the Southeast Asian region. The Society has a membership of about 600 earth scientists interested in Malaysia and other Southeast Asian regions. The membership is worldwide in distribution. Published by the Geologlc~1 Society of Malaysia, Department of Geology, University of Malaya, 59100 Kuala lumpur. Tel: 603-757 7036 Fax: 603-756 3900 Printed by Art Printing Works Sdn. Bhd., 29 Jolon Riong. 59100 Kuala Lumpur. Shallow reflection seismics at the Pekan Quaternary deposits UMAR HAMZAH, ABDUL RAHIM SAMSUDIN AND ABDUL GHANI RAFEK J abatan Geologi Universiti Kebangsaan Malaysia Bangi, Selangor D.E. Abstract: The applicability of the seismic reflection method for exploration at shallow depth « 100 m) has been investigated atPekan Quaternary deposits. A system comprising of a high frequency response seismograph and a hammer source was used. The reflection data provides information on the internal structure of the Quaternary deposits. The resolution and accuracy of the reflection data demonstrate the potential of this method in engineering geophysical investigations. Abstrak: Satukajian untukmelihatkebolehan teknikseismos pantulan di dalam penjelajahan struktur bawah tanah sehingga ke kedalaman di sekitar 100 meter telah dilakukan pada endapan kuaterner di Pekan. Sistem peralatan yang digunakan terdiri daripada seismograf rangsangan berfrekuensi tinggi dan tukul sebagai punca. Data pantulan menghasilkan maklumatstruktur dalaman endapan kuaterner. Resolusi dan ketepatan data menunjukkan bahawa kaedah ini berpotensi untuk penyiasatan geofizik kejuruteraan. INTRODUCTION bedrock. Lithologic sequence shows interlayering Recent modification of the seismic reflection of clay/silt and sand/gravel (Saffeen Baharuddin, technique (Hunter et al., 1984; Knapp and 1992). Steeples, 1986a; Pullan and MacAulay, 1987; Ali and Hill, 1991) has improved its applicability FIELD TECHNIQUE AND PROCESSING for exploration at shallow depths. The modifications include the seismic source (Miller The system used comprised of a high et al., 1992; Meekes, 1992), seismic detectors frequency ABEM 24 channel seismograph with (Gendzwill and Brehm, 1993) and field built in data storing facility. An approximately techniques (Frappa and Molinier, 1993). The 5 kilogram sledgehammer was used as a source aim is to generate, extract and record high of seismic energy. The 14 Hz Mark products resolution seismic data and eliminate noise geophones were used to receive the signals. especially low-frequency high amplitude source 100 Hz analogue low-cut filters were employed generated ground 1'011. to attenuate low-frequency source generated ground roll and enhance the high frequency This paper shows how this method was content of the signal. One half a kilometer used to delineate the internal structure within profile with CMP coverage was recorded at quaternary deposits and the granite bedrock. Pekan (Fig. 1). The common mid-point 'CMP' geometery (Umar Hamzah and King, 1988) GEOLOGY which provides multifold coverage data was used throughout the survey. The Pekan area consists of old Quaternary alluvium ranging from Pleistocene to Holocene The main processes applied to the seismic in age. The thickness of alluvium from drilling data included gain recovery, velocity analysis, data is from 18 to 107 meters overlying granite normal move out correction and common mid ISSN 0126-5539 Warta Gcologi, Vol. 21, No.2, Mar-Apr 1995, pp. 69-72 70 UMAR HAMZAH, ABDUL RAHIM SAMSUDIN AND ABDUL GHANI RAFEK point stacking. Stacking velocities were used .,...C\J r0 in normal move out correction of the data. 0::0:: ~ : I II I j CMP stacking of all profiles enhanced the quality :=...-...:::- ~~:>.: -t~ of the seismic data by increasing the signal to noise ratio. Static correction was not applied since the survey areas are flat. INTERPRETATION ::E o on N Case 1: Pekan (a) Seismic horizons which are identified as reflections are marked on the stacked seismic section (Fig. 2). Reflections recognized where the quality of data is good include two continuous and slightly undulating reflections Rl and R2 and continuous to discontinuous R3 and R4 which are generally parallel to earlier two reflections. Besides these reflections there are some short and weak alignments which may be reflections, such as indicated by reflection R5. Geological interpretation is very sensitive ,'. -:~ to velocities especially in depth conversion. Since interval velocity are not available, depth w conversion is carried out by using stacking (J ::E Z ~ ~ (J) r---~~~----~~-r~------------'3· 2i ~o' - ~ '.' ,.. I~ ..t o:: ~ ~3 ,r' ~', 3· 3" =. 40 40' . -'r: .:., , i".;: ,:.I&' ,• 3" 30' li 0 , , 1 , , ! KILOMETRE z~E v~ ~ ~ o , "'I' • Borehole position m Survey area J.. '".... ... Figure 1. Location of the survey area. (W)Hl.d30 War/a C"%gi, Vo/. 21, No, 2, Mar-Apr 1995 SHALLOW REFLECTION SEISMICS AT THE PEKAN QUATERNARY DEPOSITS 71 meter meter Survevarea / BH7 R. Pahang o ·~;.ili ~t~~;f~ .~~Fiz~ ~~3t~~R§~ ~1~~~~i~i~~~~-: 1 0 -. ~-:... :-.--:-.-:-:' .: ... :.~.:-,-~ .~~~......... ~.:::.:::::-: ... "":.:':': ,': -2~~.,.· ......... :.. :.:.:.: .................... :.:.:.:.~ .;.~ ................ :.: .. ~ ..... ,'725 + .:.:.:.: ............... ~: ~~:.:.:.:.: ....................:.:.:.:.: .........:..:..-:..:. + + ~ ....... ,:,:,:.:.:',;t ~ ...:. ..:.: ....... :.'.:.: .. :.:.:.: .... :.:~~ ~--: &0 + + ., '.' .......,- ""'-.... ~~...:,. .,. ~5-.-.- . .. ., -~ .... +'Cw:": ':':':':':-.-:- -:::: •.•• :•• :-: •• :~~ + 1IIl.. • .. .. .. .... .. .........'. :-r:--:.. .... ............................ ::-•..• :.:.:-:.:.: -:-'0.. + + "i. ............. .. .....' .......................... ,' ,' ......... ' ... + + -.:.:-:.:-:.:: :.:::.:.:.:.:.:.:.:.:.: .. :.:.:.::.:.:.:-:-:-:-:.:;::-- :.: -75 + + ~:':-:':-:'....... ' ...: ........................... -: ....... :-. :.:-:-:. ... ......... :..: - .;,....... + + + + -7' + + ~:-:-: .. : -:'.,:.:.:-:-:,:.:-:,;. '';:''''-+ + -100 + ,... ................ : ............, . - + + + + -100 + + .:.: :-:·:·:·:·:·v .... + + + +"\t . .:':-:"'4 ++ + -125 + + .o..:~ + -12' + + ++ + m Siltyclays r,::.:;.::1 Sand and gravels 1+++ I Granite bedrock Figure 3. Geological cores section based on boreholes. velocity obtained from velocity analysis. An Quaternary structure especially when estimated value of about 1,000 ms·1 was used correlation with existing borehole data is carried for the conversion and production of stacked out. section. Boreholes 7 and 13 on the north and south of the profiles (Fig. 3) were used for ACKNOWLEDGEMENT geological interpretations. Layer above reflection R1 which is approximately 25 m thick correlate The authors wish to thank the Malaysian with silty clays. Below R1 is sand and gravel government for the IRPA 4-07 -03-03 grant, JKR of