Magnetostratigraphy

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Magnetostratigraphy

• Wout Krijgsman Cor Langereis
• Paleomagnetic Laboratory
• Fort Hoofddijk
• Department of Earth Sciences
• Utrecht University

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MagnetostratigraphyPossibilities, pitfalls and
applications

• Cor Langereis, Wout Krijgsman
• Paleomagnetic Laboratory Fort Hoofddijk
• Dept. of Earth Sciences, Utrecht University
• Giovanni Muttoni
• Dept. of Earth Sciences, University of Milan
• Manfred Menning
• Geoforschungs Zentrum Potsdam, Germany

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Magnetostratigraphya dipole reversing at
irregular times
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Origin of reversals
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GPTS Geomagnetic Polarity Time Scale
Barcode may give unique solutions - but of an
essentially BINARY nature - and can be distorted
in the rock record
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Magnetostratigraphy ? part of integrated
stratigraphy

• Biostratigraphy first-order chronology
• - taxonomy, reworking, diachrony, ages
• Magnetostratigraphy globally synchonous barcode
• - depends on good paleomagnetic signal
  recording
• Cyclostratigraphy astronomical dating,
  fine-tuning
• - astronomical solutions (gt 20 Ma)
• - interpretation of phase relations

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Integrated stratigraphy

• Biostratigraphy
• - first-order chronology
• Magnetostratigraphy
• - globally synchonous barcode
• Cyclostratigraphy
• - fine-tuning astronomical dating

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Geomagnetic time scales
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K/Ar dating of lavas Cox et al., 1964
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Magneto-bio-stratigraphy
Opdyke et al., 1966
- Advent of deep-sea cores inclination only -
Biostratigraphy (faunal zones) for dating
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Marine magnetic anomalies
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Marine magnetic anomalies
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Marine magnetic anomalies
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Pitman and Heirtzler, 1966
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MarineMagneticAnomalies
DeepSeaCores
vs.
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Continental drift
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Developing the GPTS
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PaleomagnetismDRM vs. CRM- inclination
error- delayed NRM acquisition
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Accuracy of recording reversals
Watkins, 1968
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Geomagnetic Polarity Time Scale(GPTS)or
Polarity zones (subchrons) or excursions
(cryptochrons) ?
Geomagnetic Instability Time Scale(GITS)reve
rsal excursions
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Magnetostratigraphic resolution

• Laj Channell (2007) proposed

Resolution depends on - sampling resolution
(easy just take more samples) - sediments
sedimentation rate suitable recording medium -
diagenesis, lock-in depth, overprints, etc., etc.
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Magnetostratigraphic resolution
Nomenclature OK but for practical (integrated)
stratigraphy and constraints on
chronostratigraphy ?
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Marine magnetic anomalies
World crustal age
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Triassic magnetostratigraph beyond the sea
floor record
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Even oldermagneto-stratigraphy ?
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The times they are a-changin
(Bob Dylan, 1964) Wout Krijgsman
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Time dates 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)GTS2004
Neogene based on astronomical ages
Paleogene based on radio-isotopic ages
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Magnetostratigraphy Cyclostratigraphy
Astronomical TuningClimate cyclesAstronomical
solutions
Hilgen et al., 2004
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Astronomical Polarity Time Scale (APTS) for the
Mediterranean Neogene
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(No Transcript)
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Sicily, 2 weeks ago
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Sampling, 15 years ago
Sicily, 2 weeks ago
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Cyclostratigraphy astronomical tuning ... ATNTS
in GTS2004
Lourens et al., 2004
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Biostratigraphy vs. Magnetostratigraphy

• Problems
• Taxonomy
• Diachrony
• Reworking
• Ages

• Problems
• Correlation
• Primary signal
• vs. overprint
• Ages

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Correlation Requires unique pattern fit
Magneto age 7.6 0.1
K/Ar age 6.16 0.30
Garces et al., 2001
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Ages GPTS not independent of other dating
techniques
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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)

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Messinian evaporites Northern Apennines (Italy)
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Messinian Chronology
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Messinian Salinity Crisis
Evaporites synchronous all over Mediterranean at
5.96 Ma
Krijgsman et al. 1999
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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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Radio-Isotopic dating

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

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Error determination
Ar/Ar ratio 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.
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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)
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Method Garces et al. (2001) Magnetic 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
Morocco / Spain Kuiper et al., 2008
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Intercalibration Inter-laboratory calibration
Kuiper et al., 2008 (Science)
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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
Pontian
Dacian

• Stoica et al., submittted

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Carpathians foredeep
EC
SC

• Vasiliev et al., 2004 2005

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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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The evolution of Paratethys the lost sea of
Central Eurasia
Vici project 2011 3 PhD / 2 Postdoc positions