Stratigraphy and sedimentology of the chert unit of the Semanggol Formation

Excavation of rocks in the Semanggol Formation exposed more rock succession, making it feasible to study in detail the stratigraphical distribution of the rocks, their age and relationship among the units in the formation. Five Permian and four Triassic radiolarian biozones were recognized. Discovery of Permo-Triassic radiolarian faunas indicates the chert unit is partly equivalent in age to the rhythmite and conglomerate units. The chert unit is divided into eight sedimentary facies, which were deposited in an open-deep marine environment under the influence of different transport mechanisms. It is evident that there were widespread volcanogenic sediments prior to the deposition of the chert in the Semanggol Formation. Abstrak: Pengorekan batuan di Formasi Semanggol telah mendedahkan lebih banyak jujukan batuan yang membolehkan kajian terperinci sebaran stratigrafi, usia, dan hubungan unit-unit dalam formasi ini. Lima biozon Perm dan empat biozon Trias radiolaria telah dikenal pasti. Penemuan radiolaria Perm dan Trias menunjukkan unit rijang ini sebahagiannya setara dengan unit berirama dan konglomerat. Unit rijang boleh dibahagikan kepada lapan fasies endapan yang diendapkan dalam sekitaran samudera laut dalam di bawah pengaruh mekanisme pengankutan yang berbeza. Bukti juga menunjukkan kewujudan endapan volkanogen yang meluas sebelum berlakunya pengendapan rijang Formasi Semanggol.