Radiolarian Biostratigraphy of Peninsular Malaysia and Implications for Regional Palaeotectonics and Palaeogeography

Abstract

1,289 samples of chert and siliceous argillite from 78 localities in the Bentong-Raub suture zone (sensu stricto), the Semanggol Formation and other localities in Peninsular Malaysia have produced 97 species of Radiolaria representing 32 genera. Data from 12 localities in fault-bounded blocks of siliceous sedimentary rocks from the Bentong-Raub suture zone indicate Late Devonian (Famennian), Early Carboniferous (Tournaisian and Viséan), and Early Permian (Wolfcampian and Leonardian); these ages represent 8 radiolarian zones. In stratigraphic order these are the Holoeciscus 2-3, Albaillella deflandrei, A. cartalla, Pseudoalbaillella u-forma m. II, Ps. lomentaria, Ps. scalprata m. rhombothoracata, Albaillella sinuata and Pseudoalbaillella longtanensis zones. The "Lower Chert Member" of the Semanggol Formation of northwest Peninsular Malaysia produced latest Early Permian (upper Leonardian), Late Permian (Guadalupian) and Middle Triassic (Anisian and Ladinian) radiolarian assemblages representative of the ?Pseudoalbaillella longtanensis, Follicucullus porrectus, N. ornithoformis, Triassocampe coronata and T. deweveri zones. Two new species of the Late Permian genus Follicucullus ORMISTON & BABCOCK, F. crenulatus n. sp. and F. elongatus n. sp. are described from rocks previously assigned to the Lower Chert Member of the Semanggol Formation of northwest Peninsular Malaysia. The Late Permian Follicucullus japonicus Zone of ISHIGA (1991) is renamed the F. porrectus Zone. The age-spectrum of radiolarians recovered from the Bentong-Raub suture zone (sensu stricto) suggests that an ocean existed between the Sibumasu and Indochina/East Malaya terranes from at least Late Devonian to latest Early Permian time. The presence of latest Early Permian, Late Permian and Middle Triassic (Anisian and lower Ladinian) radiolarians from the "Lower Chert Member" of the Semanggol Formation, and ?Early Carboniferous radiolarians from tuffaceous chert near Kuala Kangsar in the west of the Peninsula, suggests that the accretionary complex of the Palaeo-Tethyan Bentong-Raub suture zone, may extend farther west than previously thought. The "Lower Chert Member" may not be part of the Semanggol Formation, but may be part of the underlying Palaeo-Tethyan accretionary complex. The presence of Late Permian radiolarian-bearing, ribbon-bedded chert from a single locality near Jengka, in the Central Belt, suggests that the Palaeo-Tethyan accretionary complex may also extend east beneath the Triassic Semantan Formation of the Central Belt. Representation of the Palaeo-Tethyan suture zone of Peninsular Malaysia as a narrow zone (13-18 km wide) is not favoured. The Gondwanan-affinity Sibumasu terrane is narrower than presently defined and includes only passive margin continental sequences. All radiolarian-bearing chert and argillite, belts of mélange and imbricate thrust slices of marine sedimentary rocks characteristic of accretionary complexes are not part of the Sibumasu or Indochina/East Malaya terranes, but are of Palaeo-Tethyan origin, forming a distinct accretionary complex terrane thrust westwards over the eastwards-dipping Sibumasu terrane. The Bentong-Raub suture zone of Peninsular Malaysia, the Uttaradit-Nan/Sra Kaeo suture zone of Thailand and the Changning-Menglian suture zone of South China have produced radiolarian faunas of similar biostratigraphic ages, ranging from Late Devonian (Famennian) to Middle Triassic (Ladinian). These ages suggest that Palaeo-Tethys existed between the Sibumasu and Indochina terranes from at least the Late Devonian, persisting through to Middle Triassic (Ladinian) times. © 2002 E. Schweizerbart'sche Verlagsbuchhandlung.