Open AccessA 170‐year Sr/Ca and Ba/Ca coral record from the western Pacific warm pool: 1. What can we learn from an unusual coral record?
Author(s) -
Alibert Chantal,
Kinsley Leslie
Publication year - 2008
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006jc003979
Subject(s) - oceanography , upwelling , barium , seawater , coral , geology , porites , coral reef , chemistry , inorganic chemistry
A long‐lived Porites coral from New Ireland (2.5°S, 150.5°E), Papua New Guinea, has been analyzed for Sr/Ca and Ba/Ca by laser ablation inductively coupled plasma mass spectrometry (LA‐ICPMS). The top 50 years of the core are examined here and compared with instrumental sea surface temperatures (SSTs). For the small range of SST in the warm pool, Sr/Ca shows an unusually large response. The best estimate for the slope of a temperature calibration is –0.23 ± 0.03 mmol/mol per°C. This strong slope is partly a result of the high‐resolution sampling, but is also due to additional biological mediation of the Sr/Ca ratios, which appears to be associated with seasonal changes of calcification rate, and limits the prediction skills of this proxy thermometer. High‐density bands synchronous with high Sr/Ca ratios suggest that calcification may be enhanced by beneficial small amounts of nutrients available during El Niño. Transient Ba enrichment, synchronous with colder than average SST, is also observed during El Niño and attributed to the shoaling of the New Ireland Coastal Undercurrent. The high level of enrichment, in particular during upwelling triggered by westerly wind bursts, suggests an origin from both dissolved seawater and marine biological barium.