Ages and inferred causes of late Pleistocene glaciations on Mauna Kea, Hawai'i

Jeffrey S. Pigati, Marek Zreda, Chris Zweck, Peter F. Almasi, David Elmore, Warren D. Sharp

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Glacial landforms on Mauna Kea, Hawai'i, show that the summit area of the volcano was covered intermittently by ice caps during the Late Pleistocene. Cosmogen 36Cl dating of terminal moraines and other glacial landforms indicates that the last two ice caps, called Older Makanaka and Younger Makanaka, retreated from their maximum positions approximately 23ka and 13ka, respectively. The margins and equilibrium line altitudes of these ice caps on the remote, tropical Pacific island were nearly identical, which would seem to imply the same mechanism for ice growth. But modelling of glacier mass balance, combined with palaeotemperature proxy data from the subtropical North Pacific, suggests that the causes of the two glacial expansions may have been different. Older Makanaka airatop Mauna Kea was likely wetter than today and cold, whereas Younger Makanaka times were slightly warmer but significantly wetter than the previous glaciation. The modelled increase in precipitation rates atop Mauna Kea during the Late Pleistocene is consistent with that near sea level inferred from pollen data, which suggests that the additional precipitation was due to more frequent and/ or intense tropical storms associated with eastward-moving cold fronts. These conditions were similar to modern La Niña (weak ENSO) conditions, but persisted for millennia rather than years. Increased precipitation rates and the resulting steeper temperature lapse rates created glacial conditions atop Mauna Kea in the absence of sufficient cooling at sea level, suggesting that if similar correlations existed elsewhere in the tropics, the precipitation-dependent lapse rates could reconcile the apparent difference between glacial-time cooling of the tropics at low and high altitudes.

Original languageEnglish (US)
Pages (from-to)683-702
Number of pages20
JournalJournal of Quaternary Science
Volume23
Issue number6-7
DOIs
StatePublished - Sep 2008

Keywords

  • Central Pacific
  • Cosmogenic CI
  • Positive degree day model (PDD)
  • Temperature lapse rate
  • Tropical glaciation

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Earth and Planetary Sciences (miscellaneous)
  • Palaeontology

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