1995/01/01 by Rüdiger Hotten, Hotten, R.
Biochemistry, Genetics and Molecular Biology · Earth and Planetary Sciences · #Geological and Geochemical Analysis #Geology and Paleoclimatology Research #Geomagnetism and Paleomagnetism Studies #Science
paper · pdf · doi:10.2312/polarforschung.63.2-3.123
openalex publication_date 1995/01/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/15
Summary: During the Geological Expedition to the Shackleton Range, Antarctica (GEISHA) in 1987/88, samples were taken from twenty-one basaltic dykes for palaeomagnetic investigations. The directions of characteristic remanent magnetization (ChRM) of the dykes were determined by thermal and alternating-field demagnetization of 268 cares drilled from the specimens collected. Moreover, on account of the hydrothermal and sometimes low-grade metarnorphism of the dyke rock and the resulting partial modification of the primary magnetization, not only were comprehensive magnetic studies carried out, but also ore-microscopic examination. Only thus was it possible to achieve a reasonable assessment and interpretation of the remanent magnetization. Jurassie and Silurian-Devonian ages were confirmed for the dykes of the northern and northwestern Shackleton Range by comparison of the paleopole positions calculated on the basis of the ChRM of the dykes with the known pole positions far the eastern Antarctic, as weil as with polar-wandering curves for Gondwana. Radiometrie ages were also determined far some of the dykes. Middle and Late Proterozoic ages are postulated far the dykes in the Read Mountains. Conclusions on the geotectonic relations of the Shackleton Range can also be drawn from the palaeomagnetic data. It has been postulated that the main strike direction, which differs distinctly from that of the Ross orogen, is due to rotation ar displacement of the Shackleton Range crustal block; however, this was not corroborated. The pole positions for the Shackleton Range agree with those of rocks of the same age from other areas of East Antarctica and its positions in the Palaeozoic-Mesozoic polar-wandering path for Gondwana are evidence against the idea of rotation and rather suggest that the position of the Shakleton Range crustal block is autochthonous. Zusammenfassung: Wahrend der Geologischen Expedition in die Shackleton Range, Antarktika (GEISHA) 1987/88 wurden 21 mafische Gange basaltischer Zusammensetzung fur palaomagnetische Untersuchungen beprobt. Durch thermische und Wechselfeld-Entmagnetisierung von insgesamt 268 aus den Handstucken herausgebohrten Kernproben wurden die charakteristischen remanenten Magnetisierungsrichtungen (ChRM) der Gange ermittelt. Daruber hinaus wurden aufgrund der hydrothermalen und z.T. niedrigmetamorphen Umwandlung des Gangmaterials und einer daraus resultierenden teilweisen Uberpragung der primaren Magnetisierung neben erzpetrographischen auch umfangreiche gesteinsmagnetische Untersuchungen durchgefuhrt. Erst dadurch war eine sinnvolle Bewertung und Interpretation der ermittelten Remanenzen moglich.