δ 18 O and δ 13 C of planktonic foraminifer Globigerinoides ruber: Effects of test size sampling and laboratory treatment

• Published in: Palaeoworld
• Main Authors: Xu, Ye, Li, Bao-Hua
• Format: Report
• Language: English
• Published: ELSEVIER 2024
• Subjects: Cleaning method; test size; stable isotope; planktonic foraminifera; Globigerinoides ruber; ISOTOPIC COMPOSITION; STABLE-ISOTOPES; DIFFERENTIAL DISSOLUTION; CORE-TOPS; SURFACE; CARBON; TEMPERATURE; OXYGEN; FRACTIONATION; CYCLES; Paleontology; Planktonic foraminifera
• Online Access: http://ir.nigpas.ac.cn/handle/332004/43543; https://doi.org/10.1016/j.palwor.2023.01.012

The effects of test size sampling and ultrasonic cleaning on stable oxygen (delta O-18) and carbon (delta C-13) isotopes of planktonic foraminifera (Globigerinoides ruber) were evaluated in this study. The G. ruber tests observed under the scanning electron microscope show that shells can be completely cleaned only through cracking and ultrasonic cleaning. We found that there is no statistically significant effect of cleaning on obtaining more stable and reliable delta O-18 values of G. ruber, suggesting cracking and ultrasonic cleaning may be unnecessary before isotope analysis. Five size ranges were chosen to investigate the delta O-18 and delta C-13 differences in test size. The results show that there is a positive correlation between the delta C-13 value and test size. No obvious delta O-18 difference is observed for the size range from 150 mu m to 355 mu m, though a stronger delta O-18 depletion exists for the coarser fraction (> 355 mu m). To obtain more consistent and accurate stable isotopes, and considering the size-linked delta C-13, it is recommended to select the 200-355 mu m size fraction of G. ruber with the size range as narrow as possible. (c) 2023 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights reserved.