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 language | English (US) |
|---|---|
| Pages (from-to) | 119-137 |
| Number of pages | 19 |
| Journal | Special Paper of the Geological Society of America |
| Volume | 452 |
| DOIs | |
| State | Published - Jan 1 2009 |
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All Science Journal Classification (ASJC) codes
- Geology
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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 journal › Article
TY - JOUR
T1 - Evidence fora change in Milankovitch forcing caused by extraterrestrial events at Massignano, Italy, Eocene-Oligocene boundary GSSP
AU - Brown, Rachel E.
AU - Koeberl, Christian
AU - Montanari, Alessandro
AU - Bice, David Martin
PY - 2009/1/1
Y1 - 2009/1/1
N2 - 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.
AB - 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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U2 - 10.1130/2009.2452(08)
DO - 10.1130/2009.2452(08)
M3 - Article
AN - SCOPUS:74949101843
VL - 452
SP - 119
EP - 137
JO - Special Paper of the Geological Society of America
JF - Special Paper of the Geological Society of America
SN - 0072-1077
ER -