GEOSCAN, résultats de la recherche


TitreThe exaggerated radiocarbon age of deposit-feeding molluscs in calcareous environments
AuteurEngland, J; Dyke, A S; Coulthard, R D; McNeely, R; Aitken, A
SourceBoreas vol. 42, no. 2, 2013 p. 362-373,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20130497
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceNunavut; Territoires du Nord-Ouest
SNRC27; 56; 87; 88; 39; 49; 59; 69; 78; 88; 79; 89; 120; 340; 560
Lat/Long OENS-120.0000 -64.0000 84.0000 66.0000
Sujetsdatations au radiocarbone; datation au radiocarbone; roches sédimentaires; datations au C-14; milieux marins; sédiments marins; carbonates; roches carbonatées; paléontologie; géochronologie; géologie marine; Cénozoïque; Quaternaire
Illustrationslocation maps; tables; plots
Diffusé2012 04 27
Résumé(disponible en anglais seulement)
Throughout northern Canada, live-collected, pre-bomb, deposit-feeding marine molluscs from calcareous sediments yield greater apparent radiocarbon ages than do suspension feeders. We explore the size of this effect in a set of 57 paired datings of deposit feeders, mainly Portlandia arctica, and suspension feeders, mainly Hiatella arctica and Mya truncata, collected from both calcareous and non-calcareous Holocene sediments. Deposit feeders from calcareous sediments are older than their suspension-feeding counterparts by as much as 2240±130 14C years. This is attributed to the uptake of ‘old’ bicarbonate derived from calcareous bedrock. The age discrepancy between suspension and deposit feeders in calcareous terrain is non-systematic in space and time, thereby invalidating the application of a correction. In contrast, the age comparisons are concordant at sites located on the Precambrian Shield. In terrestrial environments underlain by carbonate, previous acceptance of dates on deposit feeders led to erroneous interpretations of deglaciation and relative sea-level history, in both the North American and the Eurasian Arctic. This has prompted several researchers to exclude deposit feeders from their late Quaternary reconstructions. The same chronological problem of deposit-feeding molluscs now needs to be more widely acknowledged by the marine community.