TIMING AND WARMTH OF THE LAST INTERGLACIAL PERIOD: NEW U-SERIES EVIDENCE FROM HAWAII AND BERMUDA

The timing and duration of the peak of the last interglacial period (isotope substage 5e) have been controversial, with some studies suggesting a relatively short duration that is orbitally forced and others suggesting a long duration that is only partly related to orbital forcing. Thirty new, high-precison TIMS U-series ages of last interglacial corals from Hawaii and Bermuda test these competing hypotheses. Corals from slowly uplifting Oahu range from ~134 to ~113 ka, with most ages between ~125 and ~115 ka. With recently published U-series ages from nearby Lanai, the data suggest a long last interglacial period that may have occurred from ~136 to at least 115 ka. The results indicate that orbital forcing may not have been the only control on ice sheet growth and decay, because sea level would have been high at times well before (~134-136 ka) and well after (~113-115 ka) the high-latitude (65°N) summer insolation high at ~126 ka. In contrast to Hawaii, fossil corals on Bermuda are derived from patch reefs that likely were "catch-up" responses to sea level rise. Thus, corals on Bermuda should overlap with, but not be as old as the range of corals on Oahu. Corals on Bermuda give a range of ~125 to ~113 ka, which supports this hypothesis. A large number of emergent marine localities worldwide have now been dated to the last interglacial period. We compiled published faunal data from which marine paleotemperatures can be inferred. Both Oahu and Bermuda have a number of extralimital southern species of mollusks, suggesting warmer-than-present waters during the last interglacial period. Warmer waters are also inferred for last-interglacial localities around most of North America, Japan, the Mediterranean basin and Western Australia, indicating a global movement of relatively warm currents to higher latitudes than is the case today.