Revisions and Extension of the Hohenheim Oak and Pine Chronologies: New Evidence About the Timing of the Younger Dryas/Preboreal Transition

Abstract

Oak and pine samples housed at the Institute of Botany, University of Hohenheim, are the backbone of the early Holocene part of the radiocarbon calibration curve, published in 1993 (Becker 1993; Kromer and Becker 1993; Stuiver and Becker 1993; Vogel et al. 1993). Since then the chronologies have been revised. The revisions include 1) the discovery of 41 missing years in the oak chronology and 2) a shift of 54 yr for the oldest part back into the past. The oak chronology was also extended with new samples as far back as 10,429 BP (8480 BC). In addition, the formerly tentatively dated pine chronology (Becker 1993) has been rebuilt and shifted to an earlier date. It is now positioned by 14C matching at 11,871-9900 BP (9922–7951 BC) with an uncertainty of ±20 yr (Kromer and Spurk 1998). With these new chronologies the 14C calibration curve can now be corrected, eliminating the discrepancy in the dating of the Younger Dryas/Preboreal transition between the proxy data of the GRIP and GISP ice cores (Johnsen et al. 1992; Taylor et al. 1993), the varve chronology of Lake Gościąż (Goslar et al. 1995) and the pine chronology (Becker, Kromer and Trimborn 1991).

Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/234U/238U and 14C dates on pristine corals

“…Paired 230 Th/ 234 U/ 238 U and 14 C age dating of corals Radiocarbon ages must be converted to calendar ages via an independent chronometer for accurate dating applications. Radiocarbon ages spanning the last 11,900 years are calibrated by making radiocarbon age determinations on tree rings of known age (Damon and Long, 1962;Damon et al, 1963;Stuiver et al, 1998a, b;Spurk et al, 1998;Friedrich et al, 1999;Reimer et al, 2002Reimer et al, , 2004. For the age interval between 12,000 years and 50,000 years before present, radiocarbon ages are calibrated by less precise and less accurate methods, such as varved sediments (Hughen et al, 1998(Hughen et al, , 2000(Hughen et al, , 2004bSchramm et al, 2000;Goslar et al, 2000a, c;Kitagawa and van der Plicht, 2000;Hughen et al, 2004b;van der Plicht et al, 2004), correlation of distinct fluctuations in ocean/climate proxies dated by radiocarbon with similar features in the Greenland ice cores dated by layer counting and flow models (Hughen et al, 2000(Hughen et al, , 2004aVoelker et al, 2000), 230 Th/ 234 U/ 238 U dating of speleothems (Vogel and Kronfeld, 1997;Goslar et al, 2000b;Beck et al, 2001) and corals (Fairbanks, 1990;Edwards et al, 1993;Bard et al, 1990Bard et al, , 1998aBurr et al, 1998;Yokoyama et al, 2000;Cutler et al, 2004;Paterne et al, 2004;van der Plicht et al, 2004).…”

A late-glacial high-resolution site and source temperature record derived from the EPICA Dome C isotope records (East Antarctica)

“…One tie point corresponds to the end of the Younger Dryas, 11.5 kyr BP [39], as inferred from a comparison with the Byrd records, and the other to the 10 Be peak for which an age of 41 þ 2 kyr BP is assigned derived from the dating of the coeval Laschamp magnetic event [40]. Because the ND record for the section deeper than 580 m was not previously available to estimate snow accumulation rates, which are required for establishing a chronology, Schwander et al [38] inferred this EDC1 ND record from the old Dome C record.…”

Preliminary Report of the First Workshop of the Intcal04 Radiocarbon Calibration/Comparison Working Group

“…Using ample new finds, this part of the chronology is now securely cross-dated and sufficiently replicated. The tentative dendro-link as documented in Spurk et al (1998) in the interval 11,200 to 11,370 cal BP is replaced by a statistically reliable match. The older part of the chronology therefore was shifted 70 yr to older ages.…”