A continuous multi-millennial record of surficial bivalve mollusk shells from the São Paulo Bight, Brazilian shelf

Troy A. Dexter, Darrell S. Kaufman, Richard A. Krause, Susan L. Barbour Wood, Marcello G. Simões, John Warren Huntley, Yurena Yanes, Christopher S. Romanek, Michał Kowalewski

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


To evaluate the potential of using surficial shell accumulations for paleoenvironmental studies, an extensive time series of individually dated specimens of the marine infaunal bivalve mollusk Semele casali was assembled using amino acid racemization (AAR) ratios (n=270) calibrated against radiocarbon ages (n=32). The shells were collected from surface sediments at multiple sites across a sediment-starved shelf in the shallow sub-tropical São Paulo Bight (São Paulo State, Brazil). The resulting 14C-calibrated AAR time series, one of the largest AAR datasets compiled to date, ranges from modern to 10,307calyr BP, is right skewed, and represents a remarkably complete time series: the completeness of the Holocene record is 66% at 250-yr binning resolution and 81% at 500-yr binning resolution. Extensive time-averaging is observed for all sites across the sampled bathymetric range indicating long water depth-invariant survival of carbonate shells at the sediment surface with low net sedimentation rates. Benthic organisms collected from active depositional surfaces can provide multi-millennial time series of biomineral records and serve as a source of geochemical proxy data for reconstructing environmental and climatic trends throughout the Holocene at centennial resolution. Surface sediments can contain time-rich shell accumulations that record the entire Holocene, not just the present.

Original languageEnglish (US)
Pages (from-to)274-283
Number of pages10
JournalQuaternary Research (United States)
Issue number2
StatePublished - Mar 2014


  • Age distributions
  • Amino acid racemization
  • Holocene
  • Marine bivalves
  • Time-averaging

ASJC Scopus subject areas

  • Arts and Humanities (miscellaneous)
  • Earth-Surface Processes
  • General Earth and Planetary Sciences


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