Late Pleistocene and Holocene development of the interior peat-accumulating basin of tropical Tasek Bera, Peninsular Malaysia

Abstract

The stratigraphy of Holocene peat deposits from an interior lowland basin of tropical Peninsular Malaysia provides insight into the hydrological, ecological, and climatic controls on tropical peatland development. Interpretations about vegetation and climate dynamics (including storm intensity) over the past 5000 years are integrated with regional and global climatic and eustatic changes to serve as a proxy for past ecology and climate. Tasek Bera Basin (TBB) is a lowland dendritic basin in tropical Peninsular Malaysia. Accumulation of organic matter occurred in local lakes during the last glacial maximum (LGM), but widespread peat deposition did not start until 5300 BP when climatic changes led to the evolution of a wetland system. Peat accumulation progressively expanded with terrestrialisation of channels and subbasins to paludification of the riparian part of the lowland forest zone. Lithofacies can be distinguished despite the highly diverse peat and organic-rich sediment composition as a result of the climatic and hydrologic changes over the past 5300 years. Peat accumulation rates, ranging from 0.7 to 2.5 mm/year, are highest in Pandanaceae environments and lowest in high-ash swamp forests and environments dominated by Cyperaceae. Transects of peat cores across the mire system show the stratigraphic complexities of the peat is the result of hydrological variations and, thus, plant successional changes. Ash-yield shows that periods of high mineral matter input into the drainage system occurred since the mid-Holocene, indicating rapid and cyclic changes in frequency and magnitude of runoff events and, by inference, storms. Stratigraphic analysis of peat and ash-yield are tools that provide a proxy for development of Holocene hydrologic events in topogenous peat deposits.