Evaluation of the effects of microscale chemical and isotopic heterogeneity of coral skeleton on conventional Sr/Ca and 𝛿18O paleothermometers

Journal of Earth system science

Takehiro Mitsuguchi1¹ 

[1] Institute for Carbonate Geochemistry, 5–5 Ninomiya-cho, Chuo-ku, Kobe 651–0093, Japan.$$

关键词: Coral;    Sr/Ca;    𝛿18O;    center of calcification;    paleotemperature;    microscale heterogeneity.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

Recent studies using secondary ion mass spectrometry revealed microscale heterogeneity of Sr/Ca and 𝛿18O in shallow-water coral skeletons, i.e., Sr/Ca and 𝛿18O differ significantly between two basic microfeatures of the skeleton: the center of calcification (COC) and surrounding fibrous skeleton (SFS). The COC, in contrast with the SFS, consists of highly irregular crystals intermingled with significant amount of organic matter; therefore, analyzing the SFS only would probably be favourable for paleotemperature reconstruction. Conventional Sr/Ca and 𝛿18O paleothermometers are, however, based on the analysis of the mixture of the COC and SFS, and thus may be significantly affected by the above-mentioned heterogeneity. In this study, I have evaluated the heterogeneity-induced effects on the conventional paleothermometers of Porites skeletons using published Sr/Ca, 𝛿18O and volume-fraction data of the COC and SFS and published observations of seasonal variability of bulk skeletal density. Results indicate that the effects may yield significant or serious errors in paleotemperature reconstruction.

【 授权许可】

Unknown