Fréquence des datations Au 14C de faunes marines post-glaciaires de l'est du Canada et variations paléoclimatiques
Abstract A statistical analysis of radiocarbon dates for 365 samples associated with postglacial marine deposits of Eastern Canada and New England, U.S.A., yield a non-random statistical distribution. This distribution pattern is explained by two principal controls (that are partly interdependent): (1) secondary eustatic fluctuations, creating relative stabilizations of the sea level with an uplifting land; and (2) more generally the climatic variations. Other factors involved may include: (1) limitations of 14C dating method; (2) non-statistical sampling methodology adopted by the Quaternary geologists; (3) lack of intensive study of some of the marine basins; and (4) incidence of rapidly changing paleogeographic events (opening and shoaling of marine basins, glacial re-advances and changes in the ice flow). The statistical appraisal of errors in published 14C dates and the standard deviation, calculated with sliding means, enable us to screen out the influence of most of the non-climatic factors. With this technique, we are also able to draw a curve based on a general synthesis of all variations in 14C dates distribution. In this way, the irregularities observed in the synthesis curve are now correlated with paleoclimatic and paleogeographic events that took place in Eastern Canada between 15,000 years B.P. to present. That curve shows a close correlation during the Holocene with other climatic indicators and gives some original informations concerning the period 15,000–10,000 B.P. No attempt has been made to adjust radiocarbon years to calendar years for two reasons: (1) lack of agreement between comparative curves prior to 7,000 B.P.; and (2) lack of information concerning the effect of “old waters” on shell dates.