TY - JOUR
T1 - A Bayesian approach to integrating radiometric dating and varve measurements in intermittently indistinct sediment
AU - Arcusa, Stephanie H.
AU - McKay, Nicholas P.
AU - Wiman, Charlotte
AU - Patterson, Sela
AU - Munoz, Samuel E.
AU - Aquino-López, Marco A.
N1 - Funding Information:
Acknowledgements. This research was funded by Bob and Judi Braudy, and we are grateful for their support. Marco Aquino-López was partially founded by CONACYT CB-2016-01-284451 and COVID19 312772 grants as well as an RDCOMM grant. We thank Dan Buscombe for letting us use the bathymetric equipment, R. Scott Anderson for the identification of macrofossils for 14C dating, Katherine Whitacre for lab assistance, Rosalind Wu from the San Juan National Forest Service for working with us to obtain permits for sampling Columbine Lake, Cody Routson and Darrell Kaufman for helpful feedback on the paper, Quality Thin Sections for producing the thin sections, and Chris Ebert for conducting 14C dating at IonPlus in Zurich. We thank Ethan Yackulic, Charles Mogen, Chip Wiman, Cody Routson, Annie Wong, Andrew Platt, Jenna Chaffeur, Ellie Broadman, and Myriam Caron for the help in the field.
Funding Information:
Financial support. This research has been supported by Bob and Judi Braudy, CONACYT CB-2016-01-284451 and COVID19 312772 grants, and an RDCOMM grant.
Publisher Copyright:
© 2022 Stephanie H. Arcusa et al.
PY - 2022/6/23
Y1 - 2022/6/23
N2 - Annually laminated lake sediment can track paleoenvironmental change at high resolution where alternative archives are often not available. However, information about the chronology is often affected by indistinct and intermittent laminations. Traditional chronology building struggles with these kinds of laminations, typically failing to adequately estimate uncertainty or discarding the information recorded in the laminations entirely, despite their potential to improve chronologies. We present an approach that overcomes the challenge of indistinct or intermediate laminations and other obstacles by using a quantitative lamination quality index combined with a multi-core, multi-observer Bayesian lamination sedimentation model that quantifies realistic under-and over-counting uncertainties while integrating information from radiometric measurements (210Pb, 137Cs, and C) into the chronology. We demonstrate this approach on sediment of indistinct and intermittently laminated sequences from alpine Columbine Lake, Colorado. The integrated model indicates 3137 (95g% highest probability density range: 2753-3375) varve years with a cumulative posterior distribution of counting uncertainties of-13g% to +7g%, indicative of systematic observer under-counting. Our novel approach provides a realistic constraint on sedimentation rates and quantifies uncertainty in the varve chronology by quantifying over-and under-counting uncertainties related to observer bias as well as the quality and variability of the sediment appearance. The approach permits the construction of a chronology and sedimentation rates for sites with intermittent or indistinct laminations, which are likely more prevalent than sequences with distinct laminations, especially when considering non-lacustrine sequences, and thus expands the possibilities of reconstructing past environmental change with high resolution.
AB - Annually laminated lake sediment can track paleoenvironmental change at high resolution where alternative archives are often not available. However, information about the chronology is often affected by indistinct and intermittent laminations. Traditional chronology building struggles with these kinds of laminations, typically failing to adequately estimate uncertainty or discarding the information recorded in the laminations entirely, despite their potential to improve chronologies. We present an approach that overcomes the challenge of indistinct or intermediate laminations and other obstacles by using a quantitative lamination quality index combined with a multi-core, multi-observer Bayesian lamination sedimentation model that quantifies realistic under-and over-counting uncertainties while integrating information from radiometric measurements (210Pb, 137Cs, and C) into the chronology. We demonstrate this approach on sediment of indistinct and intermittently laminated sequences from alpine Columbine Lake, Colorado. The integrated model indicates 3137 (95g% highest probability density range: 2753-3375) varve years with a cumulative posterior distribution of counting uncertainties of-13g% to +7g%, indicative of systematic observer under-counting. Our novel approach provides a realistic constraint on sedimentation rates and quantifies uncertainty in the varve chronology by quantifying over-and under-counting uncertainties related to observer bias as well as the quality and variability of the sediment appearance. The approach permits the construction of a chronology and sedimentation rates for sites with intermittent or indistinct laminations, which are likely more prevalent than sequences with distinct laminations, especially when considering non-lacustrine sequences, and thus expands the possibilities of reconstructing past environmental change with high resolution.
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U2 - 10.5194/gchron-4-409-2022
DO - 10.5194/gchron-4-409-2022
M3 - Article
AN - SCOPUS:85133261100
SN - 2628-3697
VL - 4
SP - 409
EP - 433
JO - Geochronology
JF - Geochronology
IS - 1
ER -