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Evaluation of oxygen isotope and Mg/Ca ratios in high-magnesium calcite from benthic foraminifera as a proxy for water temperature
- Source :
- Journal of Geophysical Research: Biogeosciences. 122:185-199
- Publication Year :
- 2017
- Publisher :
- American Geophysical Union (AGU), 2017.
-
Abstract
- Oxygen isotope ratios (δ18O) and Mg/Ca ratios in organically produced calcium carbonate (calcite and aragonite) by marine species have been used as proxies for paleotemperature. The relationship between the components of large benthic foraminiferal tests (high-magnesium calcite) and seawater temperature has been little investigated yet. We conducted culture experiments using two species of reef-dwelling large benthic foraminifera under six temperature conditions (21–30°C). We selected the perforate species Calcarina gaudichaudii, and the imperforate species Amphisorus kudakajimensis, both of which are host to algal symbionts, for the experiments. The results indicated the significant correlation of Mg/Ca ratios (C. gaudichaudii and A. kudakajimensis) and δ18O (C. gaudichaudii) with temperature. The test weight of both species showed temperature dependency, with maxima at 27°C or 29°C and subsequent decline at 30°C. After correction for the contribution of the initial tests, which can be calculated from the weight ratios of the initial and cultured tests, the relationships of the Mg/Ca ratios and δ18O to temperature were obtained with the least squares best fit method as follows: C. gaudichaudii: T = 18.5–4.52 (δ18Oc–δ18Osw), A. kudakajimensis: T = 25.0–4.96 (δ18Oc–δ18Osw), and C. gaudichaudii and A. kudakajimensis: Mg/Ca = 2.85 T + 81.20. We concluded that species-specific calibration is unnecessary for Mg/Ca-temperature relationship, although it is necessary for δ18O related to the different calcification mechanisms of imperforate (A. kudakajimensis) and perforate (C. gaudichaudii) species.
- Subjects :
- Atmospheric Science
010504 meteorology & atmospheric sciences
δ18O
Soil Science
Aquatic Science
engineering.material
010502 geochemistry & geophysics
01 natural sciences
Isotopes of oxygen
Foraminifera
chemistry.chemical_compound
0105 earth and related environmental sciences
Water Science and Technology
Calcite
Ecology
biology
Aragonite
Paleontology
Forestry
Oxygen isotope ratio cycle
biology.organism_classification
Oceanography
Calcium carbonate
chemistry
Environmental chemistry
engineering
Seawater
Geology
Subjects
Details
- ISSN :
- 21698953
- Volume :
- 122
- Database :
- OpenAIRE
- Journal :
- Journal of Geophysical Research: Biogeosciences
- Accession number :
- edsair.doi...........d4894ee370992d66f84f4a6c6a6b456c