Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum
Data files
Feb 05, 2024 version files 175.21 KB
Abstract
The global ocean’s oxygen (O2) inventory is declining in response to global warming, but the future of the low-oxygen tropics is uncertain. We present new evidence for tropical oxygenation during the Paleocene-Eocene Thermal Maximum (PETM), a warming event that serves as a geologic analogue to anthropogenic warming. Foraminifera-bound nitrogen isotopes indicate that the tropical North Pacific oxygen-deficient zone contracted during the PETM. A concomitant increase in foraminifera size implies that oxygen availability rose in the shallow subsurface throughout the tropical North Pacific. These changes are consistent with ocean model simulations of warming, in which a decline in biological productivity allows tropical subsurface oxygen to rise even as global ocean oxygen declines. The tropical oxygen increase may have helped avoid a mass extinction during the PETM.
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Metadata
Oxygen rise in the tropical upper ocean during the Paleocene-Eocene Thermal Maximum
Authors
Simone Moretti, Alexandra Auderset, Curtis Deutsch, Ronja Schmitz, Lukas Gerber, Ellen Thomas, Valeria Luciani, Maria Rose Petrizzo, Ralf Schiebel, Aradhna Tripati, Philip Sexton, Richard Norris, Roberta DOnofrio, James Zachos, Daniel M. Sigman, Gerald H. Haug, Alfredo Martnez-Garca
File list
Moretti_et_al_2023_DataS1.csv
Moretti_et_al_2023_DataS2.csv
File descriptions
Moretti_et_al_2023_DataS1.csv This file contains all the nitrogen isotope data and nitrogen content of planktic foraminifera presented in this work from ODP Sites 1263, 1210, 1209, 690, 865 and DSDP Site 213. For site 1263, a composite depth scale is provided as the data is based on two individual drilling holes.
Columns of* Moretti_et_al_2023_DataS1.csv:
- Sample ID: The unique identifier of the sample used according to the International Ocean Drilling Program (IODP) terminology. These identifiers are typically created by curators of IODP core repositories at the time of sediment core sampling.
- Depth mbsf (m): mbsf stays for meters below sea floor, and it represent the depth scale that is the basis for any subsequent processing such as the creation of an age model or of a composite depth in case more than one depth scale have to be combined.
- Relative age (kyr): Age (in thousands of years) with respect to the onset of the Paleocene Eocene Thermal Maximum. Negative values represent time before the onset of the PETM and positive values represent times after the onset.
- Foram type: the type of foraminifera that was analyzed for nitrogen isotopes. There are three dominant taxa in the PETM, Morozovella, Acarinina and Subbotina.
- N content (nmol/mg): The amount of foram-bound nitrogen contained in each milligram of cleaned foraminifera calcite.
- FB-15N (): The nitrogen isotopic composition of the foram-bound organic matter in standard permil notation.
- Foraminifera Size (m): The size range in which planktic foraminifera were collected and subsequently analyzed.
- Depth rmcd (m): revised meter of composite depth, this is provided only for site 1263, as our dataset for this Site is based on two individual holes (C, D), and thus two individual depth scales that are combined into a single composite one.
- Moretti_et_al_2023_DataS2.csv This file contains seawater pO2 estimations for the deep ocean-dwelling trochospiral benthic foraminifera and upper ocean-dwelling planktic foraminifera based on the metabolic model presented in this work.
- Columns of* Moretti_et_al_2023_DataS2.csv:
- Sample ID: The unique identifier of the sample used according to the International Ocean Drilling Program (IODP) terminology. These identifiers are typically created by curators of IODP core repositories at the time of sediment core sampling.
- Depth mbsf (m): mbsf stays for meters below sea floor, and it represent the depth scale that is the basis for any subsequent processing such as the creation of an age model or of a composite depth in case more than one depth scale have to be combined.
- Relative age (kyr): Age (in thousands of years) with respect to the onset of the Paleocene Eocene Thermal Maximum. Negative values represent time before the onset of the PETM and positive values represent times after the onset.
- Source benthic foraminifera size data: the source publication where foraminifera size data was used for computation of changes in environmental deep ocean oxygen partial pressure (see Related works).
- Deep ocean relative pO2: reconstructed relative change in oxygen partial pressure in the deep ocean with respect to pre-PETM values.*
- Source planktic foraminifera size data: the source publication where foraminifera size data was used for computation of changes in environmental upper ocean oxygen partial pressure (see Related works).
- M. subbotinae relative pO2, M. pasionensis relative pO2, M. occlusa relative pO2, M. velascoensis relative pO2, S. velascoensis relative pO2, A. soldadoensis relative pO2, S. velascoensis relative pO2, S. triangularis relative pO2, S. inaequispira relative pO2: these columns represent the reconstructed relative change in oxygen partial pressure in the surface ocean with respect to pre-PETM values for each of the listed species.
Methods for dataset collection
- Moretti_et_al_2023_DataS1.csv: Fossil foraminifera were manually separated from the sediment fraction above 150 micrometres. Nitrogen isotope composition of organic linings encased in planktic foraminiferacalcite (FB-15N) was measured with the persulfate-denitrifier method. Acid dissolution of foraminifera shells and potassium persulfate oxydation of organic linings were performed according to the methodology of Ren et al., 2009, with the subsequent modifications outlined in Leichliter et al., 2021. Analysis of FB-15N was performed through the denitrifier methodand measured in a IRMS MAT253 coupled with customized gas-bench (Sigman et al., 2001; Weigand et al., 2016).
- Moretti_et_al_2023_DataS2.csv: Seawater pO2 is reconstructed by applying a trait-based physiological model for the response of foraminifera shell size to changes in temperature and oxygen. For our computations, we used published planktic and benthic foraminifera size records (Petrizzo et al., 2007; Kaiho et al., 2006) and reconstructed sea surface temperatures (Zachos et al., 2003). See Related works.
Related works:
- https://doi.org/10.1016/j.palaeo.2005.12.017
- https://doi.org/10.1016/j.marmicro.2006.11.007
- https://doi.org/10.1126/science.1090110
Additional info:
cells filled with "n/a" contain no data
When importing the .csv files in software like Microsoft Excel, use comma as the delimiter for correct visualization.
Methods
Moretti_et_al_2023_DataS1.csv
Fossil foraminifera were manually separated from the sediment fraction above 150 micrometres. Nitrogen isotope composition of organic linings encased in planktic foraminifera calcite (FB-δ15N) was measured with the persulfate-denitrifier method. Acid dissolution of foraminifera shells and potassium persulfate oxydation of organic linings were performed according to the methodology of Ren et al., 2009, with the subsequent modifications outlined in Leichliter et al., 2021. Analysis of FB-δ15N was performed through the denitrifier method and measured in an IRMS MAT253 coupled with a customized gas-bench (Sigman et al., 2001; Weigand et al., 2016).
Moretti_et_al_2023_DataS2.csv
Seawater pO2 is reconstructed by applying a trait-based physiological model for the response of foraminifera shell size to changes in temperature and oxygen. For our computations, we used published planktic and benthic foraminifera size records (Petrizzo et al., 2007; Kaiho et al., 2006) and reconstructed sea surface temperatures (Zachos et al., 2003). See "Related works".