oa Biofacies Characterisation in the Marginal Marine Environments of the Malay Basin Using Agglutinated Foraminifera

Benthic foraminifera have been widely used to interpret depositional environments within rock sequence. Due to the enclosed and paralic nature of the Malay Basin, it is difficult to define the biofacies zones based on calcareous foraminiferal assemblages alone. On the other hand, the agglutinated foraminifera are more useful in characterising different biofacies in the paralic setting such as the Malay Basin since they are well represented from marginal marine to bathyal environments (Figure 1). Three modern analogs localities were carried out for the biofacies study; Sedili Besar Estuary and its offshore areas, Klang-Langat Delta and Pahang River Delta (Figure 2). In this study, we used major agglutinated foraminiferal assemblages from selected modern environments to characterise different biofacies in the marginal marine paleoenvironments. Only the most common agglutinated foraminifera species with counts of more than ten are used for the groupings. Results of the Recent foraminiferal assemblages recorded from the modern environments are discussed here. Out of the three different localities, Sedili Besar Estuary covers the most detailed and widespread depositional facies within the marginal marine. Several biofacies zones can be differentiated based on the abundance of the main agglutinated foraminifera (Figure 3). The occurrences of agglutinated foraminiferal species such as Ammobaculites exiguus, Textularia sp and Arenoparrella mexicana can be used to differentiate the nearshore, shallow marine and brackish intertidal depositional settings. The distribution patterns of some agglutinated foraminiferal assemblages inferred from this study can also be used to imply water depth, salinity and sand distribution within the marginal marine environment. Thus, it could further improve our current understanding of different depositional environments in the Malay Basin and will lead to a more precise characterisation of the paleoenvironments.