Abstract
Further understanding of past climate requires a robust estimate of global ice volume fluctuations that in turn rely on accurate global sea-level reconstructions. An advantage of Marine Isotope Stage 2 (MIS 2) is the availability of suitable material for radiocarbon dating to allow comparison of sea-level data with other paleoclimatic proxies. However, the number and accuracy of sea-level records during MIS 2 is currently lacking. Here we present the history of MIS 2 eustatic sea-level change as recorded in the Bonaparte Gulf, northwestern Australia by reconstructing relative sea level and then modeling glacial isostatic adjustment. The isostatically-corrected global sea-level history indicates that sea-level plateaued from 25.9 to 20.4 cal kyr BP (modeled median probability) prior reaching its minimum (19.7 to 19.1 cal kyr BP). Following the plateau, we detect a 10-m global sea-level fall over ~1,000 years and a short duration of the Last Glacial Maximum (global sea-level minimum; 19.7 to 19.1 cal kyr BP). These large changes in ice volume over such a short time indicates that the continental ice sheets never reached their isostatic equilibrium during the Last Glacial Maximum.
Highlights
Global sea-level change during the Pleistocene glacial-interglacial cycles reflects fluctuating continental ice volume that is primarily related to the variable planetary distribution of incoming solar radiation caused by changes in the Earth’s orbit[1,2]
We present comprehensive global sea-level history from the full duration of Marine Isotope Stage 2 (MIS 2) from the Bonaparte Gulf (Fig. 1) through the application of glacial isostatic adjustment (GIA) modeling to a multi-proxy relative sea-level (RSL) record constructed from a transect of ten gravity cores
The transect of cores were recovered from the Bonaparte Gulf, between a water depth of −120 and −67 m during cruise of KH-11-1 in 2011 (Figs 1, 2, and Supplementary Table S1)
Summary
Global sea-level change during the Pleistocene glacial-interglacial cycles reflects fluctuating continental ice volume that is primarily related to the variable planetary distribution of incoming solar radiation caused by changes in the Earth’s orbit[1,2]. The Bonaparte Gulf (Fig. 1), northwestern Australia, is a broad and shallow continental shelf with a centered depression surrounded by carbonate platforms and terraces. These platforms and terraces are presently submerged but were exposed when sea level fell 70 m below present levels. The Bonaparte Gulf is a far-field site and one of the few sites with high-resolution relative sea-level (RSL) records spanning MIS 213–15. We present comprehensive global sea-level history from the full duration of MIS 2 from the Bonaparte Gulf (Fig. 1) through the application of glacial isostatic adjustment (GIA) modeling to a multi-proxy RSL record constructed from a transect of ten gravity cores. The results document the evolution of large-glacial sea level with previously-unattained resolution, precision, and accuracy during MIS 2
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