Open AccessThe exaggerated radiocarbon age of deposit‐feeding molluscs in calcareous environments
Author(s) -
England John,
Dyke Arthur S.,
Coulthard Roy D.,
Mcneely Roger,
Aitken Alec
Publication year - 2013
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/j.1502-3885.2012.00256.x
Subject(s) - calcareous , geology , carbonate , radiocarbon dating , paleontology , oceanography , chemistry , organic chemistry
Throughout northern C anada, 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 P ortlandia arctica , and suspension feeders, mainly H iatella arctica and M ya truncata , collected from both calcareous and non‐calcareous H olocene sediments. Deposit feeders from calcareous sediments are older than their suspension‐feeding counterparts by as much as 2240±130 14 C 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 P recambrian 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 N orth A merican and the E urasian A rctic. This has prompted several researchers to exclude deposit feeders from their late Q uaternary reconstructions. The same chronological problem of deposit‐feeding molluscs now needs to be more widely acknowledged by the marine community.