Bulletin of the Geological Society of Malaysia, No. 66, December 2018, pp. 75 – 80
Nelisa Ameera Mohamed Joeharry1,*, Mohd Shafeea Leman1,2, Che Aziz Ali1,2 & Kamal Roslan Mohamed1,2
1Geology Programme, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia
2Institute for Environment and Development (LESTARI), Universiti Kebangsaan Malaysia, 43600 Bangi, Malaysia
*Corresponding author email address: nelisa166@yahoo.com
Abstract: The search for the critical Permian-Triassic Boundary (PTB) in Malaysia focuses on limestone hills in the Lipis district since the 1990s. The recent paleontological findings at Gua Panjang hill in Merapoh, Pahang state, has constrained the presence of PTB to be between 6.50 m to 9.00 m from the base of the logged section at the eastern cliff. Late Permian foraminifera such as Colaniella sp., Ichtyofrondina sp., and Palaeotextularia sp. were observed 6.50 m from the base of the logged section, where the microfacies is characterized as bioclastic grainstone deposited within a shallow open shelf environment during Late Permian. Located 2.50 m above the Late Permian horizon is a highly dolomitized horizon with the presence of earliest Triassic conodonts such as Hindeodus parvus and Isarcicella staeschi. Between the height of 6.50 m and 9.00 m, analyses on δ13C and δ18O of the whole rock composition have shown slight decrease in both isotopes to 1.18‰ (VPDB) and 18.23‰ (SMOW), respectively. However, a negative carbon isotope excursion, which is the signature in most PTB sections worldwide, was not observed in the Gua Panjang limestone section potentially due to the large-spaced sampling. Therefore, a high precision research on the 10.00 m logged section at the eastern cliff of the Gua Panjang hill is crucial to identify the precise position of the first PTB in Malaysia.
Keywords: Permian-Triassic Boundary, limestone, Gua Panjang, Merapoh, Lipis district, Pahang, Malaysia
Abstrak: Pencarian Sempadan Perm-Trias (SPT) yang kritikal di Malaysia telah tertumpu kepada singkapan-singkapan batu kapur di daerah Lipis sejak 1990an lagi. Penemuan paleontologi terkini pada bukit Gua Panjang di Merapoh, negeri Pahang, telah mengehadkan lokasi SPT pada ketinggian antara 6.50 m hingga 9.00 m daripada dasar log sedimen pada bahagian tebing timur Gua Panjang. Foraminifera Perm Akhir seperti Colaniella sp., Ichtyofrondina sp., dan Palaeotextularia sp. telah ditemui pada ketinggian 6.50 m daripada dasar log sedimen, di mana mikrofasies dikelaskan sebagai batu butir berbioklas yang diendap pada sekitaran pelantar cetek terbuka ketika Perm Akhir. Terletak 2.50 m pada bahagian atas jujukan Perm Akhir ini ialah jujukan yang hampir mengalami proses pendolomitan penuh dan mengandungi konodon-konodon Trias Awal seperti Hindeodus parvus dan Isarcicella staeschi. Di antara ketinggian 6.50 m hingga 9.00 m ini, analisis-analisis δ13C dan δ18O terhadap komposisi keseluruhan batuan telah menunjukkan sedikit penurunan pada kedua-dua isotop, masing-masing kepada nilai 1.18‰ (VPDB) dan 18.23‰ (SMOW). Namun, penurunan puncak karbon yang menjadi penunjuk bagi kebanyakan SPT di seluruh dunia, tidak ditemui pada singkapan batu kapur Gua Panjang berkemungkinan kerana jarak persampelan yang besar. Oleh itu, kajian terperinci terhadap 10.00 m singkapan yang dilog pada tebing timur bukit Gua Panjang ini adalah sangat penting bagi menentukan kedudukan sebenar SPT pertama di Malaysia dengan lebih tepat.
https://doi.org/10.7186/bgsm66201810
