Bulk sediment 14C dating in an estuarine environment: How accurate can it be?

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Abstract

Abstract Due to a lack of marine macrofossils in many sediment cores from the estuarine Baltic Sea, researchers are often forced to carry out 14C determinations on bulk sediment samples. However, ambiguity surrounding the carbon source pathways that contribute to bulk sediment formation introduces a large uncertainty into 14C geochronologies based on such samples, and such uncertainty may not have been fully considered in previous Baltic Sea studies. We quantify this uncertainty by analyzing bulk sediment 14C determinations carried out on densely spaced intervals in independently dated late-Holocene sediment sequences from two central Baltic Sea cores. Our results show a difference of ~600?14C?yr in median bulk sediment reservoir age, or R(t)bulk, between the two core locations (~1200?14C?yr for one core, ~620?14C?yr for the other), indicating large spatial variation. Furthermore, we also find large downcore (i.e., temporal) R(t)bulk variation of at least ~200?14C?yr for both cores. We also find a difference of 585?14C?yr between two samples taken from the same core depth. We propose that studies using bulk sediment 14C dating in large brackish water bodies should take such spatiotemporal variation in R(t)bulk into account when assessing uncertainties, thus leading to a larger, but more accurate, calibrated age range.

Detaljer

Författare
  • Bryan C. Lougheed
  • Stephen P. Obrochta
  • Conny Lenz
  • Anette Mellström
  • Brett Metcalfe
  • Raimund Muscheler
  • Maja Reinholdsson
  • Ian Snowball
  • Lovisa Zillén
Enheter & grupper
Externa organisationer
  • Uppsala universitet
  • Vrije Universiteit Amsterdam
  • Akita University
  • Sveriges Geologiska Undersökning, SGU
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Geologi
  • Multidisciplinär geovetenskap
  • Oceanografi, hydrologi, vattenresurser

Nyckelord

Originalspråkengelska
Sidor (från-till)123-131
Antal sidor9
TidskriftPaleoceanography
Volym32
Utgåva nummer2
StatusPublished - 2017 feb 1
PublikationskategoriForskning
Peer review utfördJa