Radiometric time scale for the upper Eocene and Oligocene based on K/Ar and Rb/Sr dating of volcanic biotites from the pelagic sequence of Gubbio, Italy.

Alessandro Montanari, Robert Drake, David Martin Bice, Walter Alvarez, Garniss H. Curtis, Brent D. Turrin, Donald J. DePaolo

Research output: Contribution to journalArticle

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Abstract

Several samples of unaltered volcanic biotite were recovered from 5 biostratigraphically and magnetostratigraphically controlled bentonite horizons in the continuous upper Eocene-Oligocene pelagic carbonate sequence of Gubbio. The combined K-Ar and Rb-Sr dates are here used to calibrate the following 5 stratigraphic levels, from top to bottom: Level 5-upper part of Globorotalia opima opima planktonic foraminiferal zone, upper part of indistinct NP23-NP24 nannoplankton zone and CP18 nonnoplankton zone, bottom of magnetic anomaly 9N: 28.0+ or -0.3Ma. Level 4-Globigerina ampliapertura and Cassigerinella chipolensis zone, lower part of NP23 zone and bottom of CP18 zone, upper part of anomaly 12R:32.0+ or -0.8Ma. Level 3-Pseudohastigerina micra zone, upper part of NP21 and CP16b zones, top of anomaly 13N:35.4+ or -0.4Ma. Level 2-upper part of Globigerinatheka semiinvoluta zone, upper part of NP18 and CP15a zones, top of magnetic anomaly 16N:36.0+ or -0.4Ma. Level 1-lower part of G. semiinvoluta zone, between zones NP18 and NP19, middle part of zone CP15a, upper part of anomaly 17N:36.4+ or -0.3Ma. From these data, the interpolated age for the much-debated Eocene-Oligocene boundary is 35.7Ma with a 2 standard-deviation uncertainty of 0.4Ma.-from Authors

Original languageEnglish (US)
Pages (from-to)596-599
Number of pages4
JournalGeology
Volume13
Issue number9
DOIs
StatePublished - Jan 1 1985

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Oligocene
Eocene
timescale
magnetic anomaly
anomaly
dating
Eocene-Oligocene boundary
nanoplankton
bentonite
biotite
carbonate

All Science Journal Classification (ASJC) codes

  • Geology

Cite this

Montanari, Alessandro ; Drake, Robert ; Bice, David Martin ; Alvarez, Walter ; Curtis, Garniss H. ; Turrin, Brent D. ; DePaolo, Donald J. / Radiometric time scale for the upper Eocene and Oligocene based on K/Ar and Rb/Sr dating of volcanic biotites from the pelagic sequence of Gubbio, Italy. In: Geology. 1985 ; Vol. 13, No. 9. pp. 596-599.
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abstract = "Several samples of unaltered volcanic biotite were recovered from 5 biostratigraphically and magnetostratigraphically controlled bentonite horizons in the continuous upper Eocene-Oligocene pelagic carbonate sequence of Gubbio. The combined K-Ar and Rb-Sr dates are here used to calibrate the following 5 stratigraphic levels, from top to bottom: Level 5-upper part of Globorotalia opima opima planktonic foraminiferal zone, upper part of indistinct NP23-NP24 nannoplankton zone and CP18 nonnoplankton zone, bottom of magnetic anomaly 9N: 28.0+ or -0.3Ma. Level 4-Globigerina ampliapertura and Cassigerinella chipolensis zone, lower part of NP23 zone and bottom of CP18 zone, upper part of anomaly 12R:32.0+ or -0.8Ma. Level 3-Pseudohastigerina micra zone, upper part of NP21 and CP16b zones, top of anomaly 13N:35.4+ or -0.4Ma. Level 2-upper part of Globigerinatheka semiinvoluta zone, upper part of NP18 and CP15a zones, top of magnetic anomaly 16N:36.0+ or -0.4Ma. Level 1-lower part of G. semiinvoluta zone, between zones NP18 and NP19, middle part of zone CP15a, upper part of anomaly 17N:36.4+ or -0.3Ma. From these data, the interpolated age for the much-debated Eocene-Oligocene boundary is 35.7Ma with a 2 standard-deviation uncertainty of 0.4Ma.-from Authors",
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Radiometric time scale for the upper Eocene and Oligocene based on K/Ar and Rb/Sr dating of volcanic biotites from the pelagic sequence of Gubbio, Italy. / Montanari, Alessandro; Drake, Robert; Bice, David Martin; Alvarez, Walter; Curtis, Garniss H.; Turrin, Brent D.; DePaolo, Donald J.

In: Geology, Vol. 13, No. 9, 01.01.1985, p. 596-599.

Research output: Contribution to journalArticle

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T1 - Radiometric time scale for the upper Eocene and Oligocene based on K/Ar and Rb/Sr dating of volcanic biotites from the pelagic sequence of Gubbio, Italy.

AU - Montanari, Alessandro

AU - Drake, Robert

AU - Bice, David Martin

AU - Alvarez, Walter

AU - Curtis, Garniss H.

AU - Turrin, Brent D.

AU - DePaolo, Donald J.

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N2 - Several samples of unaltered volcanic biotite were recovered from 5 biostratigraphically and magnetostratigraphically controlled bentonite horizons in the continuous upper Eocene-Oligocene pelagic carbonate sequence of Gubbio. The combined K-Ar and Rb-Sr dates are here used to calibrate the following 5 stratigraphic levels, from top to bottom: Level 5-upper part of Globorotalia opima opima planktonic foraminiferal zone, upper part of indistinct NP23-NP24 nannoplankton zone and CP18 nonnoplankton zone, bottom of magnetic anomaly 9N: 28.0+ or -0.3Ma. Level 4-Globigerina ampliapertura and Cassigerinella chipolensis zone, lower part of NP23 zone and bottom of CP18 zone, upper part of anomaly 12R:32.0+ or -0.8Ma. Level 3-Pseudohastigerina micra zone, upper part of NP21 and CP16b zones, top of anomaly 13N:35.4+ or -0.4Ma. Level 2-upper part of Globigerinatheka semiinvoluta zone, upper part of NP18 and CP15a zones, top of magnetic anomaly 16N:36.0+ or -0.4Ma. Level 1-lower part of G. semiinvoluta zone, between zones NP18 and NP19, middle part of zone CP15a, upper part of anomaly 17N:36.4+ or -0.3Ma. From these data, the interpolated age for the much-debated Eocene-Oligocene boundary is 35.7Ma with a 2 standard-deviation uncertainty of 0.4Ma.-from Authors

AB - Several samples of unaltered volcanic biotite were recovered from 5 biostratigraphically and magnetostratigraphically controlled bentonite horizons in the continuous upper Eocene-Oligocene pelagic carbonate sequence of Gubbio. The combined K-Ar and Rb-Sr dates are here used to calibrate the following 5 stratigraphic levels, from top to bottom: Level 5-upper part of Globorotalia opima opima planktonic foraminiferal zone, upper part of indistinct NP23-NP24 nannoplankton zone and CP18 nonnoplankton zone, bottom of magnetic anomaly 9N: 28.0+ or -0.3Ma. Level 4-Globigerina ampliapertura and Cassigerinella chipolensis zone, lower part of NP23 zone and bottom of CP18 zone, upper part of anomaly 12R:32.0+ or -0.8Ma. Level 3-Pseudohastigerina micra zone, upper part of NP21 and CP16b zones, top of anomaly 13N:35.4+ or -0.4Ma. Level 2-upper part of Globigerinatheka semiinvoluta zone, upper part of NP18 and CP15a zones, top of magnetic anomaly 16N:36.0+ or -0.4Ma. Level 1-lower part of G. semiinvoluta zone, between zones NP18 and NP19, middle part of zone CP15a, upper part of anomaly 17N:36.4+ or -0.3Ma. From these data, the interpolated age for the much-debated Eocene-Oligocene boundary is 35.7Ma with a 2 standard-deviation uncertainty of 0.4Ma.-from Authors

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