Preprints
https://doi.org/10.5194/egusphere-2023-2906
https://doi.org/10.5194/egusphere-2023-2906
19 Dec 2023
 | 19 Dec 2023

Evaluating manual versus automated benthic foraminiferal δ18O alignment techniques for developing chronostratigraphies in marine sediment records

Jennifer L. Middleton, Julia Gottschalk, Gisela Winckler, Jean Hanley, Carol Knudson, Jesse R. Farmer, Frank Lamy, Lorraine E. Lisiecki, and the Expedition 383 Scientists

Abstract. Paleoceanographic interpretations of Plio-Pleistocene climate variability over the past 5 million years rely on the evaluation of event timing of proxy changes in sparse records across multiple ocean basins. In turn, orbital-scale chronostratigraphic controls for these records are often built from stratigraphic alignment of benthic foraminiferal stable oxygen isotope (δ18O) records to a preferred dated target stack or composite. This chronostratigraphic age model approach yields age model uncertainties associated with alignment method, target selection, the assumption that the undated record and target experienced synchronous changes in benthic foraminiferal δ18O values, and the assumption that any possible stratigraphic discontinuities within the undated record have been appropriately identified. However, these age model uncertainties and their impact on paleoceanographic interpretations are seldom reported or discussed. Here, we investigate and discuss these uncertainties for conventional manual and automated tuning techniques based on benthic foraminiferal δ18O records and evaluate their impact on sedimentary age models over the past 3.5 Myr using three sedimentary benthic foraminiferal δ18O records as case studies. In one case study, we present a new benthic foraminiferal δ18O record for International Ocean Discovery Program (IODP) Site U1541 (54°13’S, 125°25’W), recently recovered from the South Pacific on IODP Expedition 383. The other two case studies examine published benthic foraminiferal δ18O records of Ocean Drilling Program (ODP) Site 1090 and the ODP Site 980/981 composite. Our analysis suggests average age uncertainties of 3 to 5 kyr, 1 to 3 kyr, and 2 to 6 kyr associated with the use of manual over automated alignment methods, automated probabilistic alignment itself, and the choice of tuning target, respectively. Age uncertainties are higher near stratigraphic segment ends and where local benthic foraminiferal δ18O stratigraphy differs from the tuning target. We conclude with recommendations for community best practices for the development and characterization of age uncertainty of sediment core chronostratigraphies based on benthic foraminiferal δ18O records.

Jennifer L. Middleton, Julia Gottschalk, Gisela Winckler, Jean Hanley, Carol Knudson, Jesse R. Farmer, Frank Lamy, Lorraine E. Lisiecki, and the Expedition 383 Scientists

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2906', Anonymous Referee #1, 16 Jan 2024
    • AC1: 'Reply on RC1', Jennifer Middleton, 15 Feb 2024
  • RC2: 'Comment on egusphere-2023-2906', Anonymous Referee #2, 29 Jan 2024
    • AC2: 'Reply on RC2', Jennifer Middleton, 15 Feb 2024

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2906', Anonymous Referee #1, 16 Jan 2024
    • AC1: 'Reply on RC1', Jennifer Middleton, 15 Feb 2024
  • RC2: 'Comment on egusphere-2023-2906', Anonymous Referee #2, 29 Jan 2024
    • AC2: 'Reply on RC2', Jennifer Middleton, 15 Feb 2024
Jennifer L. Middleton, Julia Gottschalk, Gisela Winckler, Jean Hanley, Carol Knudson, Jesse R. Farmer, Frank Lamy, Lorraine E. Lisiecki, and the Expedition 383 Scientists
Jennifer L. Middleton, Julia Gottschalk, Gisela Winckler, Jean Hanley, Carol Knudson, Jesse R. Farmer, Frank Lamy, Lorraine E. Lisiecki, and the Expedition 383 Scientists

Viewed

Total article views: 378 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
259 94 25 378 27 12 16
  • HTML: 259
  • PDF: 94
  • XML: 25
  • Total: 378
  • Supplement: 27
  • BibTeX: 12
  • EndNote: 16
Views and downloads (calculated since 19 Dec 2023)
Cumulative views and downloads (calculated since 19 Dec 2023)

Viewed (geographical distribution)

Total article views: 374 (including HTML, PDF, and XML) Thereof 374 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 

Cited

Latest update: 12 Apr 2024
Download
Short summary
We present oxygen isotope data for a new sediment core from the South Pacific and assign ages to our record by aligning distinct patterns in observed oxygen isotope changes to independently dated target records with the same patterns. We examine the age uncertainties associated with this approach caused by human vs. automated alignment, and the sensitivity of outcomes to the choice of alignment target. These efforts help us understand the timing of past climate changes.