Bulletin of the Geological Society of Malaysia, Volume 20, August 1986, pp. 243 – 247
6E, Lorong 16/10C, Petaling Jaya, Malaysia
Abstract: One hundred and seventy-five samples of suspected Late Palaeozoic and Triassic limestones from more than thirty localities in Sumatra (mainly north of the equator) have been collected for conodont studies. Of the forty-five samples so far processed, eighteen contained conodants, fifteen of these being dateable to varying degrees of precision.
Lower Carboniferous (Visean) conodonts are recorded from the Alas Formation of the Alas Valley and near Bukit tinggi. Middle and Upper Triassic conodonts are recorded from limestones in the Prapat, Balige, Dk Pusakbukit Peninsula, Sungei Wampu and Sungei Kalue areas. Some of these limestones (Balige, Sungei Wampu and Sungei Kalue) were previously considered to be of Carbo-Permian age but are here shown to be Triassic or possibly younger (Sungei Kalue limestones).