Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?

The 58–51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6 °C) up to the Early Eocene Climate Optimum (EECO, 52.9–50.7 Ma), the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric <i>p</i>CO<sub>2</sub...

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Main Authors: G. Hoareau, B. Bomou, D. J. J. van Hinsbergen, N. Carry, D. Marquer, Y. Donnadieu, G. Le Hir, B. Vrielynck, A.-V. Walter-Simonnet
Format: Article
Language:English
Published: Copernicus Publications 2015-12-01
Series:Climate of the Past
Online Access:http://www.clim-past.net/11/1751/2015/cp-11-1751-2015.pdf
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author G. Hoareau
B. Bomou
D. J. J. van Hinsbergen
N. Carry
D. Marquer
Y. Donnadieu
G. Le Hir
B. Vrielynck
A.-V. Walter-Simonnet
author_facet G. Hoareau
B. Bomou
D. J. J. van Hinsbergen
N. Carry
D. Marquer
Y. Donnadieu
G. Le Hir
B. Vrielynck
A.-V. Walter-Simonnet
author_sort G. Hoareau
collection DOAJ
description The 58–51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6 °C) up to the Early Eocene Climate Optimum (EECO, 52.9–50.7 Ma), the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric <i>p</i>CO<sub>2</sub>, controlling warm early Cenozoic climate, may have been released during Neo-Tethys closure through the subduction of large amounts of pelagic carbonates and their recycling as CO<sub>2</sub> at arc volcanoes. To analyze the impact of Neo-Tethys closure on early Cenozoic warming, we have modeled the volume of subducted sediments and the amount of CO<sub>2</sub> emitted along the northern Tethys margin. The impact of calculated CO<sub>2</sub> fluxes on global temperature during the early Cenozoic have then been tested using a climate carbon cycle model (GEOCLIM). We show that CO<sub>2</sub> production may have reached up to 1.55 × 10<sup>18</sup> mol Ma<sup>−1</sup> specifically during the EECO, ~ 4 to 37 % higher that the modern global volcanic CO<sub>2</sub> output, owing to a dramatic India-Asia plate convergence increase. The subduction of thick Greater Indian continental margin carbonate sediments at ~ 55–50 Ma may also have led to additional CO<sub>2</sub> production of 3.35 × 10<sup>18</sup> mol Ma<sup>−1</sup> during the EECO, making a total of 85 % of the global volcanic CO<sub>2</sub> outgassed. However, climate modeling demonstrates that timing of maximum CO<sub>2</sub> release only partially fits with the EECO, and that corresponding maximum <i>p</i>CO<sub>2</sub> values (750 ppm) and surface warming (+2 °C) do not reach values inferred from geochemical proxies, a result consistent with conclusions arising from modeling based on other published CO<sub>2</sub> fluxes. These results demonstrate that CO<sub>2</sub> derived from decarbonation of Neo-Tethyan lithosphere may have possibly contributed to, but certainly cannot account alone for early Cenozoic warming. Other commonly cited sources of excess CO<sub>2</sub> such as enhanced igneous province volcanism also appear to be up to 1 order of magnitude below fluxes required by the model to fit with proxy data of <i>p</i>CO<sub>2</sub> and temperature at that time. An alternate explanation may be that CO<sub>2</sub> consumption, a key parameter of the long-term atmospheric <i>p</i>CO<sub>2</sub> balance, may have been lower than suggested by modeling. These results call for a better calibration of early Cenozoic weathering rates.
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spelling doaj.art-2e03d08802c841dca0e62f2ccc46bf172022-12-22T02:53:21ZengCopernicus PublicationsClimate of the Past1814-93241814-93322015-12-0111121751176710.5194/cp-11-1751-2015Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?G. Hoareau0B. Bomou1D. J. J. van Hinsbergen2N. Carry3D. Marquer4Y. Donnadieu5G. Le Hir6B. Vrielynck7A.-V. Walter-Simonnet8UMR 6249 Chrono-environnement (CNRS-Université de Franche-Comté), 25030 Besançon CEDEX, FranceUMR 6249 Chrono-environnement (CNRS-Université de Franche-Comté), 25030 Besançon CEDEX, FranceDepartment of Earth Sciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, the NetherlandsUMR 6249 Chrono-environnement (CNRS-Université de Franche-Comté), 25030 Besançon CEDEX, FranceUMR 6249 Chrono-environnement (CNRS-Université de Franche-Comté), 25030 Besançon CEDEX, FranceLSCE/UVSQ/IPSL CEA Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, FranceInstitut de Physique du Globe de Paris, 4 place Jussieu, 75005 Paris, FranceUMR 7193 – ISTEP (CNRS-UPMC), 4 place Jussieu, 75252 Paris CEDEX 05, FranceUMR 6249 Chrono-environnement (CNRS-Université de Franche-Comté), 25030 Besançon CEDEX, FranceThe 58–51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6 °C) up to the Early Eocene Climate Optimum (EECO, 52.9–50.7 Ma), the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric <i>p</i>CO<sub>2</sub>, controlling warm early Cenozoic climate, may have been released during Neo-Tethys closure through the subduction of large amounts of pelagic carbonates and their recycling as CO<sub>2</sub> at arc volcanoes. To analyze the impact of Neo-Tethys closure on early Cenozoic warming, we have modeled the volume of subducted sediments and the amount of CO<sub>2</sub> emitted along the northern Tethys margin. The impact of calculated CO<sub>2</sub> fluxes on global temperature during the early Cenozoic have then been tested using a climate carbon cycle model (GEOCLIM). We show that CO<sub>2</sub> production may have reached up to 1.55 × 10<sup>18</sup> mol Ma<sup>−1</sup> specifically during the EECO, ~ 4 to 37 % higher that the modern global volcanic CO<sub>2</sub> output, owing to a dramatic India-Asia plate convergence increase. The subduction of thick Greater Indian continental margin carbonate sediments at ~ 55–50 Ma may also have led to additional CO<sub>2</sub> production of 3.35 × 10<sup>18</sup> mol Ma<sup>−1</sup> during the EECO, making a total of 85 % of the global volcanic CO<sub>2</sub> outgassed. However, climate modeling demonstrates that timing of maximum CO<sub>2</sub> release only partially fits with the EECO, and that corresponding maximum <i>p</i>CO<sub>2</sub> values (750 ppm) and surface warming (+2 °C) do not reach values inferred from geochemical proxies, a result consistent with conclusions arising from modeling based on other published CO<sub>2</sub> fluxes. These results demonstrate that CO<sub>2</sub> derived from decarbonation of Neo-Tethyan lithosphere may have possibly contributed to, but certainly cannot account alone for early Cenozoic warming. Other commonly cited sources of excess CO<sub>2</sub> such as enhanced igneous province volcanism also appear to be up to 1 order of magnitude below fluxes required by the model to fit with proxy data of <i>p</i>CO<sub>2</sub> and temperature at that time. An alternate explanation may be that CO<sub>2</sub> consumption, a key parameter of the long-term atmospheric <i>p</i>CO<sub>2</sub> balance, may have been lower than suggested by modeling. These results call for a better calibration of early Cenozoic weathering rates.http://www.clim-past.net/11/1751/2015/cp-11-1751-2015.pdf
spellingShingle G. Hoareau
B. Bomou
D. J. J. van Hinsbergen
N. Carry
D. Marquer
Y. Donnadieu
G. Le Hir
B. Vrielynck
A.-V. Walter-Simonnet
Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
Climate of the Past
title Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
title_full Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
title_fullStr Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
title_full_unstemmed Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
title_short Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?
title_sort did high neo tethys subduction rates contribute to early cenozoic warming
url http://www.clim-past.net/11/1751/2015/cp-11-1751-2015.pdf
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