Short reversals of the earth’s magnetic field and its relative paleointensity variations as chronostratigraphic tools - perspectives and limitations

• Autorzy: Nowaczyk Norbert R.
• Konferencja: The Dating of Quaternary Marine and Land sediments (21-25.06.1999 ; Poznań, Poland)
• Języki publikacji: EN

Abstrakty

EN

Geomagnetic variations in direction as well as in intensity throughout the geologic history as documented in the remanent magnetization of sediment successions generally offer a potential (the investigations are performed in correlation) for dating of these sediments. Therefore, magnetostratigraphic investigations are performed in order to monitor geomagnetic fluctuations and to correlate them to established reference datasets such as the geomagnetic polarity time scale. The last major reversal of the earth’s magnetic field occured at about 780 ka. Since then, a quite large number of so-called reversal excursions with a duration of a few thousand years interrupted the normal polarity phase of the geomagnetic field, known as the ’Brunhes Chron’, about each 50 to 100 kyr. According to absolute as well as relative paleointensity determinations the field intensity throughout the Brunhes Chron was not constant but variable at least within the range of one order of magnitude. Especially reversal excursions, as expressed by magnetization directions differing largely from the expected dipole direction for a certain site, are associated with pronounced lows in the field intensity. So, in principle, determination of the sediment’s magnetization in terms of direction and intensity of time-calibrated curves can provide a detailed age model of (late) Quaternary sediments.

Słowa kluczowe

EN

paleomagnetism; geomagnetic excursions; paleointensity fluctuations; time scales

PL

paleomagnetyzm; wycieczki geomagnetyczne; wahania paleointensity; skala czasowa

• Wydawca: Uniwersytet im. Adama Mickiewicza. Instytut Geologii
• Czasopismo: Geologos
• Rocznik: 2000
• Tom: Vol. 5
• Strony: 5--12
• Opis fizyczny: Bibliogr. 16 poz.

Twórcy

autor

Nowaczyk Norbert R.

• GeoForschungsZentrum Potsdam, Projektbereich 3.3 “Sedimente und Beckenbildung” - Laboratory for Paleo- and Rock Magnetism, Telegrafenberg Haus C, 14473 Potsdam, Germany

Bibliografia

• Cande S. C. & Kent D. V., 1995: Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic. J. Geophys. Res., 100B: 6093-6095.
• Channell J. E. T., Hodell D. A. & Lehman B., 1997: Relative geomagnetic paleointensity and δ18O at ODP Site 983 (Gardar Rift, North Atlantic) since 350 ka. Earth Planet. Sci. Lett., 153: 103-118.
• Channell J. E. T., Stoner J. S., Hodell D. A. & Charles C. D., 2000: Geomagnetic paleointensity for the last 100 kyr from the subantartic South Atlantic: a tool for inter-hemispheric correlation. Earth, planet. Sci. Lett., 175: 145-160.
• Gubbins D., 1999: The distinction between geomagnetic excursions and reversals. Geophys. J. Int., 137: F1-F3.
• Guyodo Y. & Valet J.-P., 1999: Global changes in intensity of the Earth’s magnetic field during the past 800 kyr. Nature, 399: 249-252.
• Kirschvink J. L., 1980: The least-squares line and plane and the analysis of palaeomagnetic data. Geophys. J. R. Astr. Soc., 62: 699-718.
• Laj C., Kissel C., Mazaud A., Channell J. E. T. & Beer J., 2000: North Atlantic paleointensity stack since 75 ka (NAPIS-75) and the duration of the Laschamp event. Phil. Trans. R. Soc. Lond. A, 258: 1009-1025.
• Langereis C., Dekkers M. J., de Lange G. J., Paterne M. & van Santvoort P. J. M., 1997: Magnetostratigraphy and astronomical calibration of the last 1.1 Myr from an eastern Mediterranean piston core and dating of short events in the Brunhes. Geophys. J. Int., 129: 75-94.
• LOVLIE R., 1989a: Palaeomagnetic stratigraphy: a correlation method. Quat. Int., 1: 129-149.
• LOVLIE R., 1989b: Palaeomagnetic excursions during the last interglacial/glacial cycle: a synthesis. Quat. Int., 3/4: 5-11.
• Lund S. P., Acton G., Hastedt M. & Wlliams T., 1998: Geomagnetic field excursions occurred often during the last million years. EOS, 79(14): 178-179.
• Nowaczyk N. R., 1997: High-resolution magnetostratigraphy of four sediment cores from the Greenland Sea II - Rock magnetic and palaeointensity data. Geophys. J. Int., 131: 325-334.
• Nowaczyk N. R. & Frederichs T. W., 1999: Geomagnetic events and relative palaeointensity variations during the past 300 ka as recorded in Kolbeinsey Ridge sediments, Iceland Sea: indications for a strongly variable geomagnetic field. Int. J. Earth. Sci., 88: 116-131.
• Nowaczyk N. R., Frederichs T. W., Eisenhauer A. & Gard G., 1994: Magnetostratigraphic data from late Quaternary sediments from the Yermak Plateau, Arctic Ocean: Evidence for four geomagnetic polarity events within the last 170 ka of the Brunhes Chron. Geophys. J. Int., 117: 453-471.
• Nowaczyk N. R. & Knies J., 2000: Magnetostratigraphic results from Eastern Arctic Ocean - AMS14C ages and relative palaeointensity data of the Mono Lake and Laschamp geomagnetic reversal excursions. Geophys. J. Int., 140: 185-197.
• TAUXE L., 1993: Sedimentary records of relative paleointensity of the geomagnetic field: theory and practice. Rev. Geophys., 31 (3): 319-354.

Uwagi

Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2019).