Comment on “A synchronized dating of three Greenland ice cores throughout the Holocene” by B. M. Vinther et al.: No Minoan tephra in the 1642 B.C. layer of the GRIP ice core

摘要

There has been much debate in recent years among archaeologists and Earth scientists about the date of the Minoan eruption of Santorini (Thera). This debate has centered upon archaeological finds, radiocarbon dating and proxy sources including dendrochronology and acid spikes in the Greenlandic ice cores. Defining the exact date of the Minoan eruption is vital in synchronizing differing chronologies for civilizations around the Mediterranean, where many 2nd millennium B.C. cultures record this cataclysmic event. Current studies of these records have led to suggested dates for the eruption between about 1650 and 1500 B.C., and reconciling these differing dates is clearly vital in archaeology (see Friedrich [2000], Manning [1999] (see further information at http://www.informath.org/BiOr04i.pdf), Manning et al. [2006] and Bietak and Czerny [2007] for further discussion). Recently Vinther et al. [2006], in providing a chronology for the Holocene from Greenlandic ice cores, state that the date for the Minoan eruption (GICC05) is 3641 ± 5 b2k (or 1642 ± 5 B.C.) and that an acid spike from this eruption is present in all three cores (namely, DYE-3, GRIP and NGRIP). Vinther et al. [2006] acknowledge that another source for the glass shards at this level in the ice cores has been proposed as the Alaskan volcano Aniakchak [Pearce et al., 2004]. However, they dismiss this noting [Vinther et al., 2006, p. 9] “analysis of the GRIP ice core has established that the tephra from the eruption arrived in Greenland several months before the arrival of the sulphate aerosols” citing a description by Hammer et al. [2003] of the sulphate/particle distribution. Vinther et al. [2006] suggest that material from an Alaskan volcano would be expected to arrive simultaneously via the tropospheric flow, and note that the delay in the arrival of the sulphate aerosols could only occur if transport were through the stratosphere which they conclude indicates a low-latitude eruption. The presence of an acid spike in the DYE-3 ice core at this time is also argued to indicate a midlatitude eruption as Alaskan and northern latitude volcanic eruptions tend not to be recorded in this more southerly core.