We describe a scenario of climate forcing on sedimentation recorded in the late Paleocene-early Eocene Cicogna marine section from the Belluno Basin (NE Italy). Previously published magneto-biostratigraphic data revealed that the ∼81 m Cicogna section extends from Chron C25r to Chron C23r spanning the NP7/NP8-NP12 nannofossil zones (∼52.2-56.6 Ma). Using previously published rock magnetic data, augmented by data from this study, we describe and thoroughly discuss a pronounced increase of hematite (relative to maghemite or magnetite) between ∼54.9 and 54.6 Ma immediately above the Paleocene-Eocene boundary, followed by a second, long-term increasing trend from ∼54 Ma up to ∼52.2 Ma in the early Eocene. This hematite is essentially of detrital origin, insofar as it is associated with a strong shallow bias of paleomagnetic inclinations, and is interpreted to have formed on land by the weathering of Fe-bearing silicates and other primary minerals. We speculate that the warm and humid climate typical of the Paleocene-Eocene thermal maximum (PETM, ∼54.9 Ma) as well as of the warming trend leading to the early Eocene climatic optimum (EECO; ∼52-50 Ma) enhanced continental weathering of silicate rocks with the consequent production, transport, and sedimentation of detrital hematite grains. This hypothesis is confirmed by a statistical correlation between the rock magnetic properties and global climate as revealed by a standard benthic oxygen isotope record from the literature. Our temporal coupling between oxidation state of sedimentary magnetic phases and global climate is therefore consistent with the existence in the Paleocene-Eocene of the silicate weathering negative feedback mechanism for the long-term stabilization of the Earth's surface temperature. Copyright 2010 by the American Geophysical Union.

Silicate weathering machine at work: Rock magnetic data from the late Paleocene–early Eocene Cicogna section, Italy / E. Dallanave, G. Muttoni, L. Tauxe, D. Rio. - In: GEOCHEMISTRY, GEOPHYSICS, GEOSYSTEMS. - ISSN 1525-2027. - 11:7(2010), pp. Q07008.1-Q07008.14.

Silicate weathering machine at work: Rock magnetic data from the late Paleocene–early Eocene Cicogna section, Italy

G. Muttoni
Secondo
;
2010

Abstract

We describe a scenario of climate forcing on sedimentation recorded in the late Paleocene-early Eocene Cicogna marine section from the Belluno Basin (NE Italy). Previously published magneto-biostratigraphic data revealed that the ∼81 m Cicogna section extends from Chron C25r to Chron C23r spanning the NP7/NP8-NP12 nannofossil zones (∼52.2-56.6 Ma). Using previously published rock magnetic data, augmented by data from this study, we describe and thoroughly discuss a pronounced increase of hematite (relative to maghemite or magnetite) between ∼54.9 and 54.6 Ma immediately above the Paleocene-Eocene boundary, followed by a second, long-term increasing trend from ∼54 Ma up to ∼52.2 Ma in the early Eocene. This hematite is essentially of detrital origin, insofar as it is associated with a strong shallow bias of paleomagnetic inclinations, and is interpreted to have formed on land by the weathering of Fe-bearing silicates and other primary minerals. We speculate that the warm and humid climate typical of the Paleocene-Eocene thermal maximum (PETM, ∼54.9 Ma) as well as of the warming trend leading to the early Eocene climatic optimum (EECO; ∼52-50 Ma) enhanced continental weathering of silicate rocks with the consequent production, transport, and sedimentation of detrital hematite grains. This hypothesis is confirmed by a statistical correlation between the rock magnetic properties and global climate as revealed by a standard benthic oxygen isotope record from the literature. Our temporal coupling between oxidation state of sedimentary magnetic phases and global climate is therefore consistent with the existence in the Paleocene-Eocene of the silicate weathering negative feedback mechanism for the long-term stabilization of the Earth's surface temperature. Copyright 2010 by the American Geophysical Union.
Settore GEO/02 - Geologia Stratigrafica e Sedimentologica
2010
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/165577
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