Palaeomagnetic Studies on Mafic Dykes of the Shackleton Range, Antarctica, and Their Geotectonic Relevance
Palaeomagnetic Studies on Mafic Dykes of the Shackleton Range, Antarctica, and Their Geotectonic Relevance
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南极洲沙克尔顿山脉基性岩脉的古地磁研究及其大地构造相关性
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发表时间：
1995
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通讯作者：
Rüdiger Hotten
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作者：
Rüdiger Hotten
摘要：1987/88 年南极沙克尔顿山脉地质考察 (GEISHA) 期间，从 21 个玄武岩岩脉中采集了样本用于古地磁研究。堤坝的特征剩磁 (ChRM) 方向是通过对从收集的样本中钻出的 268 个槽进行热消磁和交变场退磁来确定的。此外，考虑到脉岩的热液作用和有时的低品位变质作用以及由此产生的初级磁化强度的部分改变，不仅进行了全面的磁学研究，而且还进行了矿石显微镜检查。只有这样，才有可能对剩磁进行合理的评估和解释。通过比较基于堤坝 ChRM 计算的古极位置与远至南极东部的已知极位置以及冈瓦纳极地漂移曲线，确定了沙克尔顿山脉北部和西北部堤坝的侏罗纪和志留纪-泥盆纪年龄。一些堤坝的辐射年龄也被确定。里德山脉的堤坝附近被假定为中元古代和晚元古代。关于沙克尔顿山脉大地构造关系的结论也可以从古地磁数据中得出。据推测，与罗斯造山带明显不同的主要走向是由于沙克尔顿山脉地块的旋转和位移所致；然而，这一说法并未得到证实。沙克尔顿山脉的极位置与东南极洲其他地区同龄岩石的极位置一致，其在冈瓦纳古生代-中生代极地徘徊路径中的位置是反对旋转观点的证据，并且表明沙克尔顿山脉地壳块的位置是自生的。 Zusammenfassung：Wahrend der“地质探险队在南极沙克尔顿山脉”（GEISHA）1987/88 wurden 21 mafische Gange basaltischer Zusamensetzung Fur palaomagnetische Untersuchungen beprobt。在 268 小时内，将热敏和韦克塞尔费尔德磁化过程置于恒磁测试中。 Daruber hinaus wurden aufgrund der 水热和 z.T.刚体材料的变形和最终结果是最初的磁化过程中的重要组成部分。第一次达杜奇战争是一场罪恶的战争，并且对战争的解释和解释。
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.