Paleonestrain and paleodirection of the geomagnetic field during the Cretaceous superchron and in the Paleocene by rocks of West Antarctica
- Antarctida,
- Crataceous superchron,
- paleointensity,
- paleodirections,
- Thellier-method
Abstract
The complex palaeomagnetic research of a representative collection of Andean Intrusive Suite from the western part of Antarctic Peninsula (near Ukrainian Antarctic base Academik Vernadsky) were carried out. The collection of samples is various on a chemical compound and includes gabbrous, diorites and quartz diorites, tonalities, granodiorites and granites. The age of igneous complex varies from 58 to 106 Ma, most of the rocks to date from Upper Cretaceous (Cretaceous magnetic polarity subchron). The magnetic and petromagnetic parameters of samples have been studied in two laboratories. The palaeomagnetic directions have been calculated after whole temperature demagnetization. For palaeointensity determination the significant part of a collection using Thellier-Coe method with “checkpoints” procedure have been studied. For six points authentic definitions of palaeointensity are received. Seven from 8 VDM values are twice or more times below its present day value. Average value VDM in Cretaceous is 5.7х1022 Am2, at high scope of secular variations VDM changes from 1.1x1022 Am2 to 14x1022 Am2. By comparison of average values VDM in Cretaceous subchron and Paleocene show the close values which confirm the hypothesis about absence of correlation between VDM values and inversions frequency.
References
- Bakhmutov, V.G. (2002). Geologicheskie i paleomagnitny`e issledovaniya v Zapadnoj Antarktike (rajon Argentinskix ostrovov) i ix znachenie dlya paleotektonicheskix rekonstrukcij Antarkticheskogo poluostrova [The geologic and paleomagnetic research in the Western Antarctica (Argentine Islands region) and their meaning for paleotectonic reconstructions]. Byulleten` UAC, 4, 11-24.
- Burakov, K.S. (1973). Metod opredeleniya napryazhennosti geomagnitnogo polya po krivy`m termorazmagnichivaniya In i Irt [Method for identification of the strain of the geomagnetic field by the curves of thermodemagnetization In and Irt]. Materialy` ІX konferencii po voprosam postoyannogo geomagnitnogo polya, magnetizmu gorny`x porod i paleomagnetizmu. Baku, 1973. Ch.2, 56-57.
- Vodovozov, V.Yu., Gladkochub, D.P., & Bakhmutov, V.G. (2006). Antarktandy`. Predvaritel`ny`e rezul`taty` paleomagnitnogo izucheniya. Oblasti aktivnogo tektogeneza v sovremennoj i drevnej istorii Zemli [Antarctandes. Preliminary results of the paleomagnetic study. Areas of the active tectogenesis in the current and ancient history of the Earth]. Materialy` XXXIX Tektonicheskogo soveshhaniya. Moskva. T. 1, 93-96.
- Grikurov, G.E`. (1973). Geologiya Antarkticheskogo poluostrova [Geology of the Antarctic Peninsula]. Moscow, Nauka.
- Gladkochub, D.P., Bakhmutov, V.G., Vodovozov, V.Yu., & Vashhenko, V.N. (2009). Andijskij kompleks Zapadnoj Antarktiki: vozrast, sostav, geodinamicheskaya poziciya. Geologiya polyarny`x oblastej Zemli [The Andean complex of the West Antarctica: age, composition, geodynamic position]. Materialy` XLII Tektonicheskogo soveshhaniya, 1, 132-134.
- Shherbakov, V.P., & Sy`cheva, N.K. (2006). Ob izmenenii velichiny` geomagnitnogo dipolya za geologicheskuyu istoriyu Zemli [On the changes in the modulus of the geomagnetic dipole over the geologic history of the Earth]. Fizika Zemli, 3, 201-206.
- Shherbakova, V.A., Asanidze, B.Z., Shherbakov, V.P., & Zhidkov, G.V. (2008). O povtornom opredelenii paleonapryazhennosti v melu po kollekcii A.S. Bol`shakova i G.M. Solodovnikova [On the re-identification of paleostrain in the Cretaceous period using A.S. Bolshakov’s collection]. Fizika Zemli, 11, 69-74.
- Shherbakova, V.V., Shherbakov, V.P., Bretshtejn, Yu.S., & Zhidkov, G.V. (2010). Paleonapryazhennost` i paleonapravlenie geomagnitnogo polya v srednem miocene po pozdnekajnozojskim vulkanitam Primor`ya [Paleostrain and paleodirection of the magnetic field in the middle miocene by the late Cenosoic vulcanites of Primor’ye]. Fizika Zemli (in print).
- Cande, S.C., & Kent, D.V. (1995). Revised calibration of the geomagnetic polarity timescale for the Late Cretaceous and Cenozoic, Journal of Geophysical Research, 100, 6093–6095.
- Chadima, M., & Hrouda, F. (2006). Remasoft 3.0, a user-friendly paleomagnetic data browser and analyzer. Travaux Geophysiques, XXVII, 20–21.
- Coe, R.S., Gromme, C.S., & Mankinen, E.A. (1978). Geomagnetic paleointensities from radiocarbon-dated lava flows on Hawaii and the question of the Pacific nondipole low. J. Geophys. Res., 83, 1740–1756.
- Enkin, R.J. (1994). A computer program package for analysis and presentation of paleomagnetic data. Pacific Geoscience Centre. Geological Survey of Canada. p. 16.
- Geological map of Southern Graham Land (scale 1:500000). British Antarctic Survey. 1979.
- Grunow, A.M. (1993). New paleomagnetic data from Antarctic Peninsula and their tectonic implication. J. Geophys.Res., 98(B8), 13815–13833.
- Lewandowski, M., Werner, T., & Nowozynski, K. (1997). PDA-pack of Fortran programs for palaeomagnetic data analysis. Inst. Geophys. Pol. Acad. Sci. Manuscript., 1–17.
- Shcherbakova, V.V., Perrin, M., Shcherbakov, V.P., Pavlov, V.E., Ayvaziyan, A., & Zhidkov, G.V. (2009). Rock magnetic and paleointensity results from Mesozoic baked contacts of Armenia. Earth Planet. Space, 61, 23–39.
- Thellier, E., & Thellier, O. (1959). Sur l'intensite du champ magnetique terrestre dans le passe historique et geologique. Ann. Geophys., 15, 285–376.
- Wilson, R.L. (1966). Palaeomagnetism and Rock Magnetism. Earth. Sci. Rev., 1, 175.
- Zijderveld, J.D.A. A.C. demagnetization of rocks: analysis of results. In: D. W. Collinson, K. M. Kreer (Eds.), Methods in palaeomagnetism. Amsterdam, Elsevier Publ. Co. 1967. pp. 254–286.