Basir Jasin

Permo-Triassic radiolaria from the Semanggol formation, northwest Peninsular Malaysia

Abstract A total of 32 species of radiolaria were identified from 20 chert samples at eight localities of the Semanggol Formation in north and south Kedah. Three assemblages of Radiolaria were recognised representing the Early Permian Pseudoalbaillella scalprata m. rhombothoracata. Late Permian Albaillella levis, and Middle Triassic Triassocampe deweveri Assemblage-Zone. The Pseudoalbaillella scalprata m. rhombothoracata Assemblage-Zone is discovered from Bukit Kampung Yoi and Bukit Larek, north Kedah. The Albaillella levis Assemblage-Zone is recorded from Bukit Tok Bertanduk, north Kedah and Merbau Palas, south Kedah. The Triassocampe deweveri Assemblage-Zone is found from the Lanjut Malau area, north Kedah. The radiolarian assemblages indicate that the age of the chert sequence in the Semanggol Formation ranges from Early permian to Middle Triassic.

Lower permian radiolaria from the Pos Blau area, Ulu Kelantan, Malaysia

Abstract Twenty two species of Radiolaria were identified from a 30 mthick chert sequence exposed at a roadcut near Pos Blau, Ulu Kelantan. The radiolarian assemblage represents the top part of the Pseudoalbaillella lomentaria Zone, upper Wolfcampian which is equivalent to the Sakmarian, Lower Permian. These radiolarian faunas contain elements present in both Southern Urals and Japanese faunas.

Uppermost Jurassic-lower cretaceous radiolarian chert from the Tanimbar Islands (Banda Arc), Indonesia

Abstract This paper describes and figures Mesozoic Radiolaria from cherts in Pulau Ungar, Tanimbar Islands, eastern Indonesia. Two assemblages of Radiolaria are recognised. The lower assemblage is indicative of upper Tithonian (uppermost Jurassic) to Berriasian (lowermost Cretaceous) and the upper assemblage is of upper Valanginian to Barremian age. These are the first precise ages obtained from the Ungar Formation, a unit including sandstones with apparently good petroleum reservoir characteristics.

Late Middle Permian Radiolaria from the Jengka area, central Pahang, Malaysia

Abstract Nine species of well-preserved late Middle Permian radiolarians were retrieved from bedded chert in the Jengka area, central Pahang. The radiolarian assemblage of Entactinia itsukaichiensis, Entactinia sp., Hegleria mammilla, Hegleria sp., Copicyntra sp., Copiellintra sp., Follicucullus monacanthus, Follicucullus japonicus and Pseudobaillella cf. globosa indicative of the Follicucullus japonicus Zone of the late Middle Permian age.

Middle Jurassic radiolarian chert, Indarung, Padang District, and its implications for the tectonic evolution of western Sumatra, Indonesia

Abstract Radiolaria from chert in the Indarung Area belong to the Transhsuum hisuikyoense Zone, indicating an Aalenian, lower Middle Jurassic, age. Carbonate in the area has been dated as Upper Jurassic to Lower Cretaceous from the occurrence of Lovcenipora , and overlying tuff has given a radiometric K/Ar age of 105±3 (Albian, uppermost Lower Cretaceous). The chert and carbonate are probably in tectonic contact, with the chert faulted into the limestone during ENE-directed compression. This comprises one of the best dated occurrences of allochthonous material in Sumatra and confirms the accretion of oceanic material along the Sunda margin during Mid- to Late-Cretaceous times.

Late Jurassic to Early Cretaceous Radiolaria from chert blocks in the Lubok Antu melange, Sarawak, Malaysia

The Lubok Antu melange is composed of blocks of mudstone, shale, sandstone, chert, limestone, hornfels, basalt, gabbro and serpentinite embedded in a strongly cleaved, pervasively sheared, chloritised mudstone matrix. Chert blocks are common and widespread in the melange. Fifty-three species of Radiolaria were identified from 14 samples collected from these chert blocks. The Radiolaria can be grouped into three assemblages. Assemblage I is composed of 17 species. The presence of Ristola altissima (Rust) and Parvicingula excelsa Pessagno and Blome is indicative of late Tithonian (Late Jurassic). Assemblage II consists of 21 species. The occurrence of an index form Staurosphaera septemporata (Parona) indicates middle Valanginian to Barremian age. The presence of Squinabollum fossilis (Squinabol), Archaeodictyomitra vulgaris Pessagno, Obesacapsula somphedia (Foreman), Thanarla praeveneta Pessagno, Pseudodictyomitra pseudomacrocephala (Squinabol), Rhopalosyringium majuroensis Schaaf, Stichomitra communis Squinabol and Holocryptocanium tuberculatum Dumitrica in Assemblage III suggests that the age of this assemblage is late Albian to Cenomanian. All the results show that there are three different ages of the chert blocks present in the Lubok Antu melange.

Late Triassic Radiolaria from the Kodiang Limestone, northwest Peninsular Malaysia

Abstract Two different cherty packstone-wackestone facies are exposed at an abandoned limestone quarry at Bukit Kodiang, Kedah. Chert occurs as discontinuous layers and nodules in the cherty packstone-wackestone. The thickness of individual chert layers varies from 2 to 10 cm. The facies exhibit slump folds. Eighteen species of Radiolaria were identified—Capnuchosphaera triassica De Wever, Triassocampe sulovensis Kozur and Mock, Tetraporobrachia asymmetrica Kozur and Mostler, Xenorum flexum Blome, Canoptum laxum Blome, Palaeosaturnalis triassicus Kozur and Mostler, Canoptum cf. farawayensis Blome, Pseudostylosphaera cf. spinulosa Nakaseko and Nishimura, Hagiastrum cf. augustum Pessagno, Perispongidium sp., Capnuchosphaera sp., Sarla sp., Kahlerosphaera sp., Canoptum sp., Latium sp., Paronaella sp., Sontonaella sp., and Spongostylus sp. The assemblage indicates that the age of the chert bearing strata ranges from late Carnian to middle Norian, Late Traissic.