The times they are achangin

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The times they are a-changin
(Bob Dylan, 1964) Wout Krijgsman Paleomagnetic
laboratory Fort Hoofddijk Utrecht
University
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Time in the geological and Fort Hoofddijk
contextdates and rates
Tools Biostratigraphy Magnetostratigraphy Astroch
ronology Isotopic dating
Aims Marine-continental Paratethys-Mediterranean
Synchrony-diachrony Event stratigraphy
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Geological Time ScaleGradstein et al. (2004)
Neogene based on astronomical ages
Paleogene based on radio-isotopic ages
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Messinian Chronology
Messinian GSSP at Oued Akrech 7.251 Ma (Hilgen
et al. 2000 Episodes)
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Messinian Chronology
Zanclean GSSP at Eraclea Minoa 5.333 Ma (Van
Couvering et al. 2000 Episodes)
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Biostratigraphy

• Problems
• Reworking
• Taxonomy
• Diachrony
• Ages

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Magnetostratigraphy

• Problems
• Correlation
• Primary signal vs overprint
• Ages

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Problem Correlation Only significant
magnetostratigraphic dating if unique pattern
fit!
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Problem Correlation Only significant
magnetostratigraphic dating if unique pattern
fit!
Magneto age 7.6 0.1
K/Ar age 6.16 0.30
Garces et al., 2001
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Problem Ages Geomagnetic Polarity
Time Scale (GPTS) is not independent on other
dating techniques
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Problem The times they are
a-changing Ages change with time!
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Astrochronology

• Problems
• Cycle recognition
• Phase relation
• Correlation
• Astronomical solution

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Astrochronology correlation of cyclic variations
in the geological record to computed astronomical
(age) curves
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Milankovitch cycles
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Sapropel-marl cycles, upper Miocene, Sicily
Eccentricity minimum
Precession minimum
Gibliscemi, Sicily, Italy
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Partial Unit-Stratotype of the Zanclean stage
(Lower Pliocene)
Punta di Maiata, Sicily, Italy
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Lignite-marls cycles, Mio-Pliocene, Greece
Precession minimum
Ptolemais quarry, Greece
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Sand-marls cycles, Mio-Pliocene, Romania
PONTIAN Acc. rate in C3r
137cm/kyr Periodicity cycles 22.7kyr
Putna river section,eastern Carpathians
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Clay-carbonate cycles, Miocene, Spain
Orera section, Spain
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Clay-carbonate cycles, Triassic, USA
Painted desert/Petrified forrest, Arizona
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MioceneAPTS

• Astrochronology for the Late Miocene
• Sections on Crete correlated bed-to-bed to Sicily
• Hilgen et al. (1995)
• EPSL

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Messinian evaporites Northern Apennines (Italy)
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Messinian Chronology
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Chronology
Evaporites synchronous all over Mediterranean at
5.96 Ma
Astrochronology Mediterranean Messinian (Krijgsman
et al. 1999 Nature)
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Chronology evaporites
Cyclostratigraphy Italy Evaporites 16 cycles
(Marabini and Vai, 1988)
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Chronology evaporites
Cyclostratigraphy Spain Evaporites 14-17 cycles
(Dronkert, 1976 M.S.G.l. Fortuin et al., 2000
Sed. Geol.)
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Chronology evaporites
Top of Lower Evaporites 5.60-5.52 Ma (Krijgsman
et al. 2001 Sed. Geol.)
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La93 ltgt La2004
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Isotopic dating

• Problems
• Technique (K/Ar vs Ar/Ar)
• Error determination
• Mineral dating standards

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Problem error determination
this ratio is measured on a mass spectrometer,
precision depends on e.g. measurement protocol,
mass discrimination
decay constant
J is an irradiation parameter and its accuracy
depends on an accurately known age of a mineral
standard. Further, optimizing irradiation
conditions can reduce the influence of
interfering nuclear reactions
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Problem mineral dating standards Fish Canyon
Tuff
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Betic Corridor problem
K/Ar age of 6.16 0.30
Ar/Ar age of 7.71 0.11
Magnetostratigraphy Tortonian Salinity Crisis
Fortuna Basin (Garces et al. 1998 2001 EPSL
Basin Research)
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Problem Technique Garces et al. (2001)
Magnet. age 7.6 0.1 Ma Bellon et al. (1983)
K/Ar age 6.16 0.30 Ma Kuiper et al. (2002)
Ar/Ar age 7.71 0.11 Ma
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Intercalibration Isotopic ages and astronomical
ages
Faneromeni section Messinian, Crete
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40Ar/39Ar vs astronomical ages
6.94 Ma
Fan-a1, Crete Miocene, marine 2? 0.01 Ma N
44 3 different irradiations
6.65
6.75
6.85
6.95
7.05
7.15
Age (Ma)
Kuiper et al., 2003
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40Ar/39Ar vs astronomical ages
Ptolemais SLM3T
Ptolemais SR3M
4.39 Ma
4.31Ma
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4.1
4.2
4.3
4.4
4.5
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4.1
4.2
4.3
4.4
4.5
Age (Ma)
Age (Ma)
Messadit Me-1
Messadit Me-11
6.45 Ma
6.58 Ma
6.2
6.3
6.4
6.5
6.6
6.7
6.2
6.3
6.4
6.5
6.6
6.7
Age (Ma)
Age (Ma)
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Intercalibration Isotopic ages and astronomical
ages
Kuiper et al., 2008 Morocco / Spain Messinian
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Intercalibration Isotopic ages and astronomical
ages
Kuiper et al., 2008 Morocco / Spain Messinian
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Intercalibration Isotopic ages and astronomical
ages
K/T Boundary Zumaia (Spain) new age of 65.96 Ma
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Mediterranean vs Paratethys Late Miocene -Early
Pliocene
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Evolution of the Time Scales from Eastern
Paratethys
10 TIMES longer
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Carpathians foredeep
EC
SC

• Vasiliev et al., 2004 2005

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Carpathians foredeep
Pontian
Dacian

• Stoica et al., submittted

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Putna Valley
PONTIAN Acc. rate in C3r
137cm/kyr Periodicity cycles 22.7kyr
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Southern Carpathians
Eastern Carpathians
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Astronomical Polarity Time Scale (APTS) for the
Mediterranean Neogene