The Subis Platform is considered one of the very few outcrops in Malaysia which records remarkable changes in the growth history of a carbonate system. The Subis Platform is located near Batu Niah, Sarawak. Stratigraphically, the Subis Platform is named the Subis Limestone, a member of the Tangap Formation. This article discusses the older succession of the Subis Limestone at the Subis-2 well and the Hollystone Quarry. Both well and outcrop indicate a slightly older succession based on the occurrence of larger benthic foraminifera and calcareous nannofossils. The age of the Subis Limestone ranges from Oligocene to Miocene, based on the occurrence of the larger benthic foraminifera Miogypsinoides sp. (late Oligocene, Te4) and Miogypsina sp. (early Miocene, Te5), as well as on the calcareous nannofossils Sphenolithus capricornutus and Sphenolithus conicus (Te4). The boundary between the late Oligocene and the early Miocene coincides with a sharp change from foraminifera-dominated facies to coral-dominated facies, shown at the Hollystone Quarry. The Subis Limestone records a transgression event from mixed siliciclastic–carbonate (Subis-2 well) to clean biohermal carbonates as shown in the outcrops of the Subis quarries. Our findings on the Oligo–Miocene boundary were then compared with those from other carbonates around Southeast Asia. It is clear that coral reefs existed in Southeast Asia earlier than was first thought, by Oligocene times. The role of localized tectonic events, siliciclastic influx, oceanic mineralization, and Indonesian Throughflow are the main controls to determine the biota changes from foraminifera to coral-dominated facies.

Abstract The Iberian Peninsula has some of the most extensive Cambrian outcrops in Europe ( Lotze 1961 c ), including a diverse, continuous record of fossils and facies, and is thus a fundamental source of biostratigraphic information for the Cambrian System and its intercontinental correlations. Most exposures of Iberian Cambrian rocks occur in the Iberian Massif, but they are also known from the Pyrenees, the Catalonian Coastal Ranges and the Iberian Ranges (Fig. 3.1 ). Many exposures are geographically isolated and/or show tectonic boundaries, and facies changes are common, and these characteristics have led to a profuse stratigraphic nomenclature (see Fig. 3.2 ; Zamarreño 1983; Liñán et al . 1993 a ). Following Lotze (1961 c ), however, the Cambrian sequence can be overviewed as a diachronous Lower to Middle Cambrian carbonate sequence sandwiched by silici-clastic successions (Fig. 3.2 ). The lower of the siliciclastic units is entirely Lower Cambrian, whereas the upper unit ranges from upper Lower or Middle Cambrian to Upper Cambrian (Fig. 3.2 ). The Lower Cambrian series has been subdivided into the Corduban, Ovetian, Marianian and Bilbilian stages, and the Middle Cambrian series subdivided into the Leonian, Caesaraugustan and Languedocian stages (Fig. 3.2 ). The Precambrian/Cambrian boundary stratotype was erected by the International Subcommission on Cambrian Stratigraphy (ISCS) at the Fortune Head section in eastern Newfoundland (Canada) with the first appearance datum (FAD) of Phycodes (= Trichophycus) pedum ( Landing 1994 ). This FAD coincides with behavioural changes, increased