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Magnetostratigraphy. Stratigraphy, from the Latin stratum (= layer) and the Greek graphere (= to describe) Literally means the description and study of.

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Presentation on theme: "Magnetostratigraphy. Stratigraphy, from the Latin stratum (= layer) and the Greek graphere (= to describe) Literally means the description and study of."— Presentation transcript:

1 Magnetostratigraphy

2 Stratigraphy, from the Latin stratum (= layer) and the Greek graphere (= to describe) Literally means the description and study of - the succession of - layered rocks Stratigraphy is the science of rock strata Stratigraphy

3 Leonardo da Vinci (1452-1519) fossils are not “jollies of Nature” but are remnants of once-living creatures are not the result of the deluge possibility of mountain uplift

4 Nicolaus Steno (1638-1686) Niels Stensen Laws of Steno (1669) Modern paleontologic ideas

5 Steno’s Laws Law of Superposition: younger strata lie above older strata Law of Horizontality: sedimentary strata were originally deposited horizontally Law of Lateral Continuity: sedimentary strata originally extended in all directions

6 James Hutton (1726-1797) Salisbury Craigs (veins, baked contacts) Heat source deep within the Earth

7 James Hutton (1726-1797) Siccar’s point Angular unconformity Rock cycle Subsidence Deposition Uplift and Deformation Weathering Erosion

8 Law of Faunal Succession 1841 Alcide d´Orbigny Concept of Stage 1856 Carl Albert Oppel - Concept of Biozone

9 Principle of Faunal Succession and Steno’s Laws

10 Charles Lyell (1797-1875) Principles of Geology wwwwww.esp.org/books/lyell/principles/facsmile/contents.htm

11 Charles Lyell (1797-1875) First relative geological time scale (1839) Fossil succession Laws of Steno

12 Geological Time Scale Gradstein et al. (2004) GTS2004 Neogene: based on astronomical ages Paleogene: based on radio-isotopic ages

13 Geological Time: dates and rates Tools: Biostratigraphy Lithostratigraphy Magnetostratigraphy Astrochronology Isotopic dating Aims: Global events Synchrony-diachrony Marine-continental Event stratigraphy

14 Stratigraphic correlations LithostratigraphicChronostratigraphicBiostratigraphic

15 Chronostratigraphy Biostratigraphy Lithostratigraphy

16 Magnetostratigraphy

17 Magnetostratigraphy a dipole reversing at irregular times

18 Geomagnetic time scales

19 K/Ar dating of lavas Cox et al., 1964

20 Magneto-bio-stratigraphy Opdyke et al., 1966 - Advent of deep-sea cores: inclination only - Biostratigraphy (faunal zones) for dating

21 Marine magnetic anomalies

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24 Pitman and Heirtzler, 1966

25 Marine Magnetic Anomalies Deep Sea Cores vs.

26 Developing the GPTS

27 World crustal age Marine magnetic anomalies

28 Pre-Jurassic magnetostratigraphy Pangea From http://www.ldeo.columbia.edu/~pol sen/nbcp/projectdescription.html

29 Pre-Jurassic magnetostratigraphy Position Newark Basin on Pangea From http://www.ldeo.columbia.edu/~pol sen/nbcp/projectdescription.html

30 Pre-Jurassic magnetostratigraphy

31 Triassic-Jurassic geochronology: Magnetostratigraphy and Cyclostratigraphy Astronomical time scale for the Late Triassic based on Newark Basin Pre-Jurassic magnetostratigraphy

32 Triassic magnetostratigraphy … beyond the sea floor record

33 Even older: magneto- stratigraphy ?

34 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 (> 20 Ma) - interpretation of phase relations

35 Integrated stratigraphy Biostratigraphy - first-order chronology Magnetostratigraphy - globally synchonous barcode Cyclostratigraphy - fine-tuning & astronomical dating

36 Biostratigraphy vs. Magnetostratigraphy Problems: Taxonomy Diachrony Reworking Ages Problems: Correlation Primary signal vs. overprint Ages

37 Magnetostratigraphy Pitfalls and problems Only significant magnetostratigraphic dating if: unique pattern fit!

38 Ages GPTS not independent of other dating techniques

39 The times they are a-changing’ Bob Dylan 1964 Ages change with time …

40 Correlation Requires unique pattern fit Garces et al., 2001 K/Ar age 6.16 ± 0.30 Magneto age 7.6 ± 0.1

41 Hilgen et al., 2004 Magnetostratigraphy & Cyclostratigraphy Astronomical Tuning Climate cycles Astronomical solutions

42 Astronomical Polarity Time Scale (APTS) for the Mediterranean Neogene

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44 Astronomical Time Scales

45 Lourens et al., 2004 Cyclostratigraphy & astronomical tuning Accurate definition of GSSP (Oued Akrech, Hilgen et al., 2000)

46 Milankovitch cycles

47 Sapropel-marl cycles, upper Miocene, Sicily Precession minimum Eccentricity minimum Gibliscemi, Sicily, Italy

48 Partial Unit-Stratotype of the Zanclean stage (Lower Pliocene) Punta di Maiata, Sicily, Italy

49 GTS2012

50 Precession minimum Lignite-marls cycles, Mio-Pliocene, Greece Ptolemais quarry, Greece

51 PONTIAN Acc. rate in C3r = 137cm/kyr Periodicity cycles = 22.7kyr Sand-marls cycles, Mio-Pliocene, Romania Putna river section, eastern Carpathians

52 Clay-carbonate cycles, Miocene, Spain Orera section, Spain

53 Clay-carbonate cycles, Triassic, USA Painted desert/Petrified forrest, Arizona

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

55 ATNTS2012 in GTS2012 the successor of ATNTS2004

56 Independent dating methods Radio-isotope dating based on Radio-active decay Astronomical dating based on Orbital parameters ?=?=

57 Intercalibration: Isotopic ages and astronomical ages Faneromeni section: Messinian, Crete

58 40 Ar/ 39 Ar vs. astronomical ages Fan-a1, Crete Miocene, marine 2  : 0.01 Ma; N = 44 3 different irradiations 6.656.756.856.957.057.15 Age (Ma) 6.94 Ma Kuiper et al., 2003

59 Problem Offset ~1% Kuiper et al., 2008

60 Astrochronology Problems: Cycle recognition Phase relation Correlation Astronomical solution

61 La93 <> La2004

62 Radio-Isotopic dating Problems: Technique (K/Ar vs. Ar/Ar) Error determination Mineral dating standards

63 Ar/Ar ratio: mass spectrometer precision depends on e.g. measurement protocol, mass discrimination J is an irradiation parameter and its accuracy depends on an accurately known age of a mineral standard. Decay constant Error determination

64 Mineral dating standards: Fish Canyon Tuff

65 Intercalibration Isotopic ages and astronomical ages Morocco / Spain Kuiper et al., 2008

66 Intercalibration Inter-laboratory calibration Kuiper et al., 2008 (Science)

67 Intercalibration Isotopic ages and astronomical ages K/T Boundary Zumaia (Spain): new age of 65.96 Ma

68 Age and uncertainty for FCT FCs = 28.201 ± 0.046 Ma

69 What about U/Pb FC? Wotzlaw et al.,2014

70 Magnetostratigraphy Possibilities, pitfalls and applications


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