Sains Malaysiana 49(7)(2020): 1509-1520

http://dx.doi.org/10.17576/jsm-2020-4907-04

Estimation of Earth Structure by Satellite Gravity Analysis of Peninsular Malaysia

(Anggaran Struktur Bumi melalui Analisis Graviti Satelit di Semenanjung Malaysia)

NURUL FAIRUZ DIYANA BAHRUDIN^1,2*, UMAR HAMZAH¹ & WAN ZUHAIRI WAN YACCOB¹

¹Geology Programme, School of Environmental Sciences and Natural Resources, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi Selangor Darul Ehsan, Malaysia

²Environmental Tracer Application Group Waste, Technology and Environmental Division, Malaysian Nuclear Agency, Bangi, 43000 Kajang, Selangor Darul Ehsan, Malaysia

Diserahkan: 31 Mei 2019/Diterima: 8 Mac 2020

ABSTRACT

Power spectral analysis was successfully carried out on satellite gravity data along 10 East-West profiles of about 140 to 320 km length across Peninsular Malaysia beginning from its border with the Straits of Malacca towards the South China Sea coastline. Power spectrum curves obtained clearly indicate the presence of three major slopes corresponding to four type of materials with different dominant densities. Depth curves computed from all these profiles produced three major dominant peaks beginning with the deepest one at about 33 to 42 km, followed by intermediate depth of 18 to 26 km and the shallowest peaks at about 3 to 10 km. The shallowest depth is interpreted as representing geological formation such as the Mesozoic and Palaeozoic deposits including the granite intrusion classified as basement. Underlying the basement is the upper crustal material extending to Conrad discontinuity at depth of about 18 to 26 km. Earth materials below the Conrad discontinuity constitutes of the lower crustal material overlying the border of upper mantle at depth of 33 to 42 km representing the Mohorovicic discontinuity.

Keywords: Earth structures; satellite gravity data; spectral analysis

ABSTRAK

Analisis kuasa spektrum telah dijalankan ke atas data graviti satelit sepanjang 10 garis rentas timur-barat Semenanjung Malaysia. Panjang garis rentas berjulat antara 140 hingga 320 km. Lengkung kuasa spektrum menunjukkan kehadiran tiga kecerunan utama yang mewakili empat bahan yang mempunyai ketumpatan yang berbeza. Lengkung kedalaman yang diperoleh daripada kecerunan tersebut menghasilkan tiga puncak dominan bermula daripada kedalaman maksimum 33 hingga 42 km diikuti dengan kedalaman sederhana 18 hingga 26 km dan puncak paling cetek pada kedalaman 3 hingga 10 km.  Kedalaman paling cetek ditafsirkan mewakili formasi geologi yang berusia Mesozoik dan Paleozoik termasuk granit yang dikelaskan sebagai besmen. Lapisan besmen ini menindih lapisan kerak atas yang didasari oleh satah ketakselarasan Conrad pada kedalaman 18 hingga 26 km. Bahan bumi di bawah ketakselarasan Conrad terdiri daripada kerak bawah yang menindih sempadan mantel atas pada kedalaman 33 hingga 42 km yang ditafsirkan sebagai satah ketakselarasan Mohorovicic.

Kata kunci: Analisis kuasa spektrum; data graviti satelit; struktur bumi

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*Pengarang untuk surat-menyurat; email: nurulfairuz@nuclearmalaysia.gov.my