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The first radiolarian fauna obtained from Permian carbonates in Thailand is of late Kungurian age and is present in the basal beds of the carbonate–mudstone–chert Phap Pha Formation, Ratburi Group. This succession contains several species of the radiolarian Pseudoalbaillella, and some sponge spicules. The radiolarian fauna consists of abundant Pseudoalbaillella aidensis and P. elegans together with P. fusiformis, P. longtanensis, P. m. rhombothoracata and P. sp. A. Other species include P. cf. aidensis, P. cf. elongata, P. cf. fusiformis, P. cf. ishigai, P. cf. lomentaria, P. cf. longicornis, P. cf. longtanensis, P. cf. ornata, P. cf. simplex, P. cf. m. scalprata, P. cf. m. postscalprata, P. cf. u–forma m. I, P. cf. u–forma m. II, and P. spp. The radiolarian assemblage suggests its correlation to the P. longtanensis Zone which, in turn, is correlated to the P. ishigai Zone of late Kungurian age. The occurrence of an abundant but generically low–diversity radiolarian fauna suggests restricted physical conditions and, with other evidence, suggests deposition along a cool deglaciating or deglaciated continental margin with an abundance of silica possibly provided by glacial meltwaters. The abundant chert in the Phap Pha Formation is part of the widespread Permian Chert Event.

Lower Palaeozoic rocks have been mapped in Kayin State in an area previously shown on published maps as either metamorphic or possibly Lower or Upper Palaeozoic rocks. Three new formations, with a total thickness of over 900 m, apparently overlain by an, at least, 100 m thick Upper Palaeozoic formation are mapped along the Salween River and along the road from Yinbaing, in Myanmar, to Tha Song Yang, in Thailand. The Lower Palaeozoic succession consists of the predominantly siliciclastic Kyaukpulu and Kushwe–e–we formations and an overlying, predominantly carbonate Meseik Ashe Formation which contains Middle Ordovician (Darriwilian) conodonts. The older two formations are probable correlates of the Ngwetaung and Lokeypin formations of the southern Shan State of Myanmar and the Lower Ordovician siliciclastics of western Thailand. The overlying, peritidal to shallow subtidal carbonates of the Meseik–Ashe Formation are correlates of the Wunbye and Sitha formations of Shan State, Myanmar. The thick–bedded, quartz arenites of the Nyaungwiang Formation are faulted against the Ordovician carbonates and are probable lithological correlates of the Carboniferous Taungnyo Formation. The folds in the Lower Palaeozoic rocks are overturned to the northeast and deformation was in one major phase between the Tournaisian and the Early Permian. The Lower Palaeozoic strata may probably be followed as a ridge for at least 100 km towards the NNW, close to the western border of the Sibuma Block which is separated by a postulated cryptic suture from the Irrawaddy Block to the west.

A Middle Permian carbonate sequence at Khao Somphot in the south of the Khao Khwang Platform has been measured and analyzed. This sequence is characterized by prolific fossil content and large, bizarre alatoconchid bivalves. Nine major microfacies types are differentiated and consist of: algal-foram facies, fusuline facies, alatoconchid facies, lime mudstone/wackestone facies, laminated bindstone facies, fine-grained cortoid grainstone facies, coral biostrome facies, crinoidal packstone facies and carbonate breccia/conglomerate facies. Laminated bindstone, lime mudstone with fenestral fabric and algal foram facies represent loferites deposited in a restricted intertidal zone of an inner ramp. Fusuline grainstone and cortoid grainstone facies indicate sand shoals of an inner ramp. The fusuline wackestone/packstone and alatoconchid facies were deposited in a subtidal, below fair-weather wave base environment in the mid-ramp. The crinoidal facies, which overlies collapse breccia, possibly accumulated during transgression in the deeper part of the mid-ramp. Storm deposits are prevalent throughout as thin accumulates and as alatoconchid floatstone/rudstone (coquinite) layers and are common in mid-ramp setting. The Khao Khwang Platform probably evolved from a rimmed platform in the Early Permian to a ramp in the Middle Permian. The general trend of δ 13C composition from both brachiopod shell and rock matrix from the lower part of the study section (Wordian) is significantly high. Moreover, the δ 13C signature from this interval is up to 8 VPDB‰, which suggests high productivity on the tropical Tethyan shelf of the Indochina Terrane. An abrupt negative shift in δ 13C in the late Wordian and late Capitanian indicating significant changes in paleoenvironment, productivity and the carbon cycle is probably contemporaneous with the Kamura event recorded from sediments of the mid-Panthalassa Ocean in Japan and elsewhere related to global cooling and a sea-level lowstand.

A 4. m thick section of silicified shales from Ban Phonxai in central Laos contains the radiolarians Trilonche davidi , T. hindea , T. minax , T. palimbola , Stigmosphaerostylus spp. and Ceratoikiscum ? sp. and the tentaculitids Homoctenus ultimus and Costulatostylionina vesca which together indicate a Frasnian age. This pelagic, deep shelf fauna from the Indochina Terrane is similar to that from South China and shows that tentaculitids may be common and biostratigraphically useful in radiolarian cherts and shales in South East Asia. This discovery probably necessitates mapping of the Late Devonian Phon Tiou Fm in this area which is currently mapped as the Early Carboniferous Boulapha Formation.

Middle Triassic radiolarians were obtained from a bedded chert sequence in Chiang Dao, northern Thailand. Sixty-four species were identified into two assemblages, which indicate two stratigraphic levels including lower Illyrian (lowermost upper Anisian) and upper Illyrian (uppermost Anisian). The occurrence of upper Anisian radiolarians in our study indicates the former existence of a relatively deep marine environment in northern Thailand with a seaway between eastern and western Palaeotethys. The stratigraphic units containing bedded chert in this area were formerly dated on the basis of fossil evidence and petrological similarities. However, the strata in the study area are possibly not part of a continuous stratigraphic sequence, but consist of tectonic slices. The fossil age from any slice indicates only the geological age of the given slice, and adjacent slices are often of different ages. Parts of the sequence formerly mapped as Carboniferous and Permian are Middle Triassic in the study area. The sequence covers the Carboniferous to Middle Triassic and can be correlated with the eastern zone of the Changning-Menglian Belt in southwestern Yunnan, China.