2016, Metcalfe, Ian

Limestones exposed north of Raub, Pahang, Malaysia, and sandwiched between the Bentong-Raub Suture Zone and the westernmost margin of the Sukhothai Arc terrane, yield a late Dienerian (late Induan) conodont fauna. The co-occurrence of 'Neospathodus dieneri' Sweet (morphotypes 1, 2 and 3) and 'Neospathodus pakistanensis' Sweet represents the 'Neospathodus dieneri' morphotype 3 sub-zone of the 'Neospathodus dieneri' Zone. The sampled limestones are interpreted as the northwards extension of the Jerus Limestone which crops out near Cheroh and Jerus villages, significantly extending the known outcrop of the Jerus Limestone northwards. The Jerus Limestone is interpreted as hemipelagic and formed in a foredeep or forearc setting on top of the accretionary complex formed by eastwards subduction of the Palaeo-Tethys during the Lower to Middle Triassic.

2017, Metcalfe, Ian

Improved biostratigraphic dating and enhanced understanding of the stratigraphy and depositional and tectonic environments of Devonian and Carboniferous sequences in Malaysia have resolved ambiguities in previous published work and better constrain the nature and timing of the stages of tectonic evolution of the region. The Devonian and Carboniferous stratigraphy of the Malay Peninsula is discussed within a tectonic framework that includes a western Sibumasu Terrane and an eastern Sukhothai Arc (Indochina) block separated by the Bentong-Raub Suture Zone that represents the former Devonian-Triassic Palaeo-Tethys Ocean. The stratigraphy and depositional environments of the Devonian and Carboniferous of Peninsular Malaysia provide important insights into the switch from deposition in shallow shelf to deeper-water margin-slope environments on the passive margin of Gondwana during the early development of the Palaeo-Tethys Ocean. In addition, the Devonian and Carboniferous sediments and faunas of the Western Belt of the Malay Peninsula support and are consistent with placement of the Sibumasu Terrane on the Palaeozoic margin of Australian Gondwana until the early Permian (Sakmarian). Carboniferous sedimentary rocks of the Eastern Belt of the Malay Peninsula were deposited on the margin of the equatorial Indochina Block onwhich the Sukhothai Arc was constructed. Previously erected stratigraphical units, such as the 'Karak Formation', 'Bentong Group', 'Raub Group', and 'Pelong Beds' for Bentong-Raub Suture Zone complex rocks, are meaningless as stratigraphic units, and their use should be discontinued. Devonian and Carboniferous conodont biostratigraphy in the Malay Peninsula is relatively poorly known. The Lower Devonian Pterospathodus amorphognathoides Zone, Ozarkodina eosteinhornensis Zone, and Icriodus woschmidti Zone faunas are known from the Mempelam Limestone of Langkawi and Perlis, and the Upper Devonian (Frasnian) Palmatolepis linguiformis Zone faunas occur in the Sanai Limestone of Perlis. Conodont faunas of the Kanthan Limestone in Perak represent Lower-Middle Devonian (Emsian-Giventian) Eocostapolygnathus gronbergi Zone-Polygnathus asymmetricus Zone faunas, and Mississippian upper Tournaisian Scaliognathus anchoralis Zone, Visean Lochriea commutatus Zone, and Gnathodus bilineatus Zone faunas. Basal Pennsylvanian Declinognathodus noduliferus Zone faunas are also present. Significant reworking of conodonts into the Tournaisian and Visean limestones is recorded. Conodont faunas of the Panching Limestone in the eastern Belt of the Malay Peninsula represent the earliest Pennsylvanian D. noduliferus s.l.-Rhachistognathus primus Zone.

2017, Metcalfe, Ian, Henderson, C M, Wakita, K

Lower Permian (lower Sakmarian) conodonts are reported from a coherent section of Ocean Plate Stratigraphy, and from a limestone block in the Palaeo-Tethys suture zone between Lamphun and Lampang, south of Chiang Mai, northern Thailand. Conodont species from both the pelagic limestones of the OPS section and the limestone block are deep-water forms with distinctive biogeographic affinities comparable to faunas of the Urals and North American Mid-Continent. A new name, Chiang Mai-Chiang Rai Suture Zone, is here proposed for the Palaeo-Tethys suture in northern Thailand that forms the boundary between the Sibumasu Terrane and the Sukhothai Arc terrane. The Inthanon Zone of northern Thailand is interpreted as representing a fold and thrust belt west of the Chiang Mai-Chiang Rai Suture Zone, which comprises Sibumasu Terrane continental margin rocks and remnant klippen of Chiang Mai-Chiang Rai Suture Zone rocks thrust as a nappe westward during the Triassic collision between Sibumasu and the Sukhothai Arc/Indochina Terrane.