EPICA Dome C Ice Core Timescales EDC3

The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new EDC3 chronology, which is based on the use of 1) a snow accumulation and mechanical flow model, and 2) a set of independent age markers along the core. These are obtained by pattern matching of recorded parameters to either absolutely dated paleoclimatic records, or to insolation variations. We show that this new time scale is in excellent agreement with the Dome Fuji and Vostok ice core time scales back to 100 kyr within 1 kyr. Discrepancies larger than 3 kyr arise during MIS 5.4, 5.5 and 6, which points to anomalies in either snow accumulation or mechanical flow during these time periods. We estimate that EDC3 gives accurate event durations within 20% (2 sigma) back to MIS11 and accurate absolute ages with a maximum uncertainty of 6 kyr back to 800 kyr.

Age determination and stable oxygen isotope record of ODP Hole 167-1017E

Oxygen isotopic (d18O) climatic stratigraphy and radiocarbon chronology, at high resolution, have been used to establish an age model for Ocean Drilling Program Hole 1017E, a continuous 25-m sequence of hemipelagic sediments from the continental slope (956 m water depth), east of Point Arguella, Southern California. The upper part of Hole 1017E from ~33 ka (7.445 mbsf) was dated using 13 calendar-corrected radiocarbon ages of mixed planktonic foraminiferal assemblages. Benthic oxygen isotopic stratigraphy records a continuous 130-k.y. sequence ranging from marine isotope Stage 6 to the present day. The benthic d18O curve, representing the last two interglacial and glacial cycles, closely resembles the well-dated, deep-sea reference sequence, providing a detailed chronologic framework. Sedimentation rates remained relatively constant throughout the sequence at ~18 cm/k.y. and were sufficiently rapid to provide considerable potential for high-resolution paleoceanographic/paleoclimatic investigations. Planktonic foraminiferal oxygen isotopic stratigraphy based on the surface-dwelling form Globigerina bulloides defines an almost complete sequence of interstadial/stadial oscillations (Dansgaard/Oeschger cycles [D/O]). Combined use of radiocarbon chronology, deep-sea oxygen isotopic datums, and visual pattern matching has enabled us to identify the sequence of D/O cycles as described for the Greenland (GRIP2) ice core. This has strengthened the stratigraphic framework for the last 60 k.y. in the sequence as a basis for further paleoenvironmental investigations.