Environmental change inferred from multiple proxies from an 18 cal ka BP sediment record, Lake Barrine, NE Australia

Abstract

Lake Barrine (17.25°S, 145.64°E), on the Atherton Tablelands in tropical northeast Australia, was formed as a maar lake in the late Pleistocene. The 65 m-deep stratified lake provides a detailed sediment record of climate and environmental change on the Tablelands. We reconstruct hydroclimate and vegetation change over the last ∼18,000 years from a 7.2 m long sediment core at 20-year resolution using multiple paleoenvironmental proxies (μ-XRF elements, δ13CTOC, TOC and C:N ratio). The data series are supported by a chronology based on 22 accelerator mass spectrometer (AMS) radiocarbon dates. The results suggest a distinct period of intense but highly seasonal rainfall coincident with the Antarctic Cold Reversal (14.7–13.0 cal ka BP). This period was followed by a trend into the early Holocene toward wetter, less seasonal conditions that allowed the progressive establishment of tropical forest in the catchment. The catchment was completely covered by closed forest by 7.3 cal ka BP. The inferred precipitation changes at Lake Barrine are consistent with other records on the Tablelands and in phase with the changes in tropical SE Africa, NW Australia and anti-phase with the East Asian summer monsoon region in the Holocene but not before that. This result supports previous conclusions that precipitation variations correlate (in phase or anti-phased) in these regions. This correlation results from a dynamic balance among intertropical convergence zone (ITCZ), the Indian Ocean Dipole (IOD) and El Niño Southern Oscillation (ENSO).