Holocene sea-level change and coastal landscape evolution in the southern Gulf of Carpentaria, Australia

Abstract

A Holocene sea-level history for the southern Gulf of Carpentaria has been constructed based on a review of previously published data, combined with data collected for this study from a variety of sea-level proxies. These sea-level proxies include beach ridges, claypans, mangrove swamps, fossilized in situcoral reefs, beachrock and aeolinite deposits. Results confirm that rising sea-levels during the last Post-Glacial Marine transgression beached the Arafura Sill ca. 11,700 years ago (-53 m), resulting in a change from lacustrine to a marine environment. Sea levels continued to rise to ca. -30 m by 10,000 years ago. By 7,700 cal. yr BP sea-level reached PMSL and continued to rise an elevation of between 1.5 and 2 m above present mean sea-level by 7,000 years ago. Elevated sea levels resulted in the development of raised coral reefs, beach-rock and aeolinite deposits, and the initiation of chenier plains and beach ridges. Sea-level remained ca. +1.5 m above PMSL during the Holocene highstand, accompanied by distinct phases of beach-ridge and chenier plain development. The highstand was followed by arapid regression to within ±0.5 m of PMSL by ca. 3,500 cal. yr BP. When placed into a wider regional context results from this study show thatcoastal landscape evolution in the tropical north of Australia was not only dependenton sea-level change but also show a direct correlation with Holocene climatevariability. Specifically, the formation and preservation of beach-rock deposits,intertidal successions, beach and chenier ridge systems hold valuable sea-level and Holoceneclimate proxies that can contribute to the growing research into lowerlatitude Holocene sea-level and climate histories. ©2019 The Authors.