Evolutionary history of the Malacca Strait driven by sea level changes over the last 16 ka

Abstract

The Malacca Strait connects the Sunda Shelf and Andaman Sea, which is a chokepoint for the exchange of both material and energy between two larger bodies of water. However, the evolutionary history of the Malacca Strait is poorly understood, although its development can be closely linked to regional paleoenvironmental changes. In this study, we present multiple new analytical results on the basis of a high-resolution chronology, including grain size, geochemical composition, and SrNd isotopic compositions in both labile and detrital fractions of sediments from surface samples as well as core samples. We aim to reveal the evolutionary history of the Malacca Strait by tracing records of the geochemical compositions and SrNd isotopic compositions of both labile and detrital fractions of sediments. A provenance transition between ∼10 and ∼7 ka has been identified, with the occurrence of a Sunda Shelf sediment signal at approximately 10 ka. Combining the shifting provenance and varying depositional environment since 16.28 ka allows us to distinguish three distinct evolutionary stages of the Malacca Strait: 1) Stage I, during 10–15 ka, a general estuary and embayment environment with provenances from the Malaysian Peninsula, Sumatra and the eastern shelf of the Andaman Sea; 2) Stage II, during the early Holocene at 10–7 ka, a period of an initial strait configuration with a narrow and shallow channel, which only allowed restricted sediment and water mass influx into the strait; and 3) Stage III, a highstand of sea level since ∼7 ka, a phase of a fully opened strait with a high-energy hydrodynamic environment dominated by tidal and northwestward currents. It suggested that the initial opening of the strait may have been incapable of providing higher-energy depositional environments, such as those present today, whereas the optimal sea level since 7.26 ka promoted throughflow in the Malacca Strait. Our results demonstrate that sea level was the first-order control of sedimentary evolution in the strait, whereas the monsoon climate only played a secondary role.