A Simple Approach to Simulate the Complexity of Planktonic Foraminifer Oxygen Isotope Time Series
Abstract
Oxygen isotopic curves measured on different planktonic foraminifer species at the same site often exhibit a variable offset. This means that the habitats of the involved species may change through time, which affects the interpretation of the paleoclimatic records. Here we propose to investigate the effect of habitat change by comparing measured and mechanistically computed calcite oxygen isotopic ratios (δ18O) for N. pachyderma left and right coiling, G. bulloides, and G. ruber. To this end we developed the module "Foraminifers as Modeled Entities" (FAME) using species and temperature-dependent growth rates to predict the vertical and seasonal habitat of each species. FAME is forced by hydrography and water δ18O taken from observations or models, and predicts sedimentary average δ18O for each planktonic foraminifer species. FAME yields excellent agreement with MARGO Late Holocene and core top planktonic δ18O data when forced with WOA13 temperature and GISS water δ18O data, in contrast to the calculation of calcite equilibrium δ18O without correction for foraminifer habitat. We explore the applicability of the module to the past by forcing it with vertical temperature and water δ18O profiles computed by the isotope-enabled Earth System Model of Intermediate Complexity iLOVECLIM and compare δ18O simulations with fossil data for the LGM time slice and for the last deglaciation.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFMPP31C2290W
- Keywords:
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- 3344 Paleoclimatology;
- ATMOSPHERIC PROCESSESDE: 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHYDE: 4928 Global climate models;
- PALEOCEANOGRAPHYDE: 4944 Micropaleontology;
- PALEOCEANOGRAPHY