Calcium isotopes in planktonic foraminifera - core tops and sediment trap samples, supplement to: Griffith, Elizabeth M; Paytan, Adina; Kozdon, Reinhard; Eisenhauer, Anton; Ravelo, Ana Christina (2008): Influences on the fractionation of calcium isotopes in planktonic foraminifera. Earth and Planetary Science Letters, 268(1-2), 124-136

• Main Authors: Griffith, Elizabeth M, Paytan, Adina, Kozdon, Reinhard, Eisenhauer, Anton, Ravelo, Ana Christina
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 2016
• Subjects: Ocean Drilling Program ODP; Griffith; Planktonic foraminifera
• Online Access: https://dx.doi.org/10.1594/pangaea.858628; https://doi.pangaea.de/10.1594/PANGAEA.858628

For paleoceanographic studies, it is important to understand the processes that influence the calcium (Ca) isotopic composition of foraminiferal calcite tests preserved in the sediment record. Seven species of planktonic foraminifera from coretop sediments collectively exhibited a Ca temperature dependent fractionation of 0.013 per mil per °C. This is in agreement with previously published estimates for most species of planktonic foraminifera as well as biogenic and inorganic calcite and aragonite. Four species of planktonic foraminifera collected from a sediment trap showed a considerable amount of scatter and no consistent temperature dependent fractionation. Analyzed size fractions of coretop samples show no significant relationship with d44/40Ca. However, preliminary results suggest that the symbiotic and spinose foraminifera G. sacculifer might exhibit a relationship between test size and d44/40Ca. A one-box model in which Ca isotopes are allowed to fractionate by Rayleigh distillation from a biomineralization reservoir (internal pool) was used to constrain the isotopic composition of the original biomineralization Ca reservoir, assuming around 85% of the Ca reservoir is precipitated and the fractionation factor during precipitation is 0.9985 + 0.00002(T ºC). To explain the foraminiferal Ca isotope data, this model indicates that the Ca isotopic composition of the biomineralization reservoir is offset from seawater (approximately -0.8per mil).