Distribution of Foraminifera off the Terengganu River Mouth, East Coast Peninsular Malaysia

Abstract

Abstract The distributions of modern foraminiferal species represent an important tool for petroleum geologists to characterize paleoenvironments. This paper documents the distribution of benthic foraminifera on the inner shelf (<40 m water depth) immediately offshore of the Terengganu River mouth, one of the three major drainages on the east coast of peninsular Malaysia. Sediment substrate type primarily controls the distribution of species; temperature, salinity, dissolved oxygen, and pH vary little in the study area and have little influence. Sandy substrates (mostly coarse and very coarse sand) from 20 to 40 m water depth are characterized by abundant specimens of the larger foraminifera Amphistegina spp. Muddy substrates immediately adjacent to the Terengganu River mouth from 12 to 20 m water depth are characterized by higher diversity assemblages dominated by several smaller calcareous taxa and the agglutinated species Ammobaculites exiguus. The latter species has been documented in muddy sediments at other river mouths on the east coast of peninsular Malaysia. Strong, seasonally reversing monsoon-driven currents affect sediment transport along the east coast of peninsular Malaysia and therefore indirectly influence the distributions of foraminiferal species. The results of this study add to the increasingly extensive database on modern foraminiferal distributions that provides a model for paleoenvironmental interpretations of hydrocarbon-bearing Neogene strata off the east coast of Thailand and peninsular Malaysia.