Evidence fora change in Milankovitch forcing caused by extraterrestrial events at Massignano, Italy, Eocene-Oligocene boundary GSSP

Rachel E. Brown, Christian Koeberl, Alessandro Montanari, David Martin Bice

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

High-resolution spectral analyses of fourclimate proxies from Massignano, Italy (Eocene-Oligocene boundary global stratotype section and point [GSSP]), indicate that the deposition of this rhythmically bedded sedimentary sequence was controlled by Milankovitch orbital cycles. An inverse relationship between the magnetic susceptibility record and the co-varied calcium carbonate, d18O, and d13C records is indicative of a climate model in which limestones represent dry/cold periods, while marly limestones represent warm/wet periods. Through pattern matching of band-pass filtered signals with the La2004 eccentricity curve, we propose an astrochronological calibration forthis important time period. Constrained by three radioisotopically dated volcanic ashes and based on a band-pass version of eccentricity that exhibits expected amplitude modulations, ourastrochronology yields a refined age for the Eocene-Oligocene boundary of 33.91 ± 0.05 Ma. Orbital forcing is less pronounced in the lowerportion of the Massignano section (meterlevels 0-15), which contains evidence of several impact events and a 2.2-m.y.-long comet/asteroid shower. We propose that substantial, nonperiodic climate alterations caused by this period of enhanced extraterrestrial activity mask the Milankovitch climate cycles. Possible mechanisms for the exaggeration of impact-related climatic changes include the ice-albedo feedback or the combined effect of impact-related atmospheric alterations with ongoing dust-particle loading associated with the comet/asteroid shower.

Original languageEnglish (US)
Pages (from-to)119-137
Number of pages19
JournalSpecial Paper of the Geological Society of America
Volume452
DOIs
StatePublished - Jan 1 2009

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Eocene-Oligocene boundary
stratotype
eccentricity
asteroid
comet
limestone
climate cycle
orbital forcing
volcanic ash
magnetic susceptibility
spectral resolution
sedimentary sequence
calcium carbonate
albedo
climate modeling
dust
calibration
ice
climate change
climate

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

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title = "Evidence fora change in Milankovitch forcing caused by extraterrestrial events at Massignano, Italy, Eocene-Oligocene boundary GSSP",
abstract = "High-resolution spectral analyses of fourclimate proxies from Massignano, Italy (Eocene-Oligocene boundary global stratotype section and point [GSSP]), indicate that the deposition of this rhythmically bedded sedimentary sequence was controlled by Milankovitch orbital cycles. An inverse relationship between the magnetic susceptibility record and the co-varied calcium carbonate, d18O, and d13C records is indicative of a climate model in which limestones represent dry/cold periods, while marly limestones represent warm/wet periods. Through pattern matching of band-pass filtered signals with the La2004 eccentricity curve, we propose an astrochronological calibration forthis important time period. Constrained by three radioisotopically dated volcanic ashes and based on a band-pass version of eccentricity that exhibits expected amplitude modulations, ourastrochronology yields a refined age for the Eocene-Oligocene boundary of 33.91 ± 0.05 Ma. Orbital forcing is less pronounced in the lowerportion of the Massignano section (meterlevels 0-15), which contains evidence of several impact events and a 2.2-m.y.-long comet/asteroid shower. We propose that substantial, nonperiodic climate alterations caused by this period of enhanced extraterrestrial activity mask the Milankovitch climate cycles. Possible mechanisms for the exaggeration of impact-related climatic changes include the ice-albedo feedback or the combined effect of impact-related atmospheric alterations with ongoing dust-particle loading associated with the comet/asteroid shower.",
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Evidence fora change in Milankovitch forcing caused by extraterrestrial events at Massignano, Italy, Eocene-Oligocene boundary GSSP. / Brown, Rachel E.; Koeberl, Christian; Montanari, Alessandro; Bice, David Martin.

In: Special Paper of the Geological Society of America, Vol. 452, 01.01.2009, p. 119-137.

Research output: Contribution to journalArticle

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