Rough Islands
| Rough Islands | ||
|---|---|---|
| Waters | Prydz Bay | |
| Geographical location | 68 ° 51 ′ S , 77 ° 50 ′ E | |
|
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| Main island | Filla Island | |
The Rauer Islands are a group of rocky islands off the Ingrid Christensen coast of Princess Elisabeth Land in East Antarctica . In the south-eastern part of Prydz Bay they are between the tongue of Sørsdal Glacier and Ranvik Bay . The largest island of the group is Filla Island with a length of 5 km .
The Norwegian captain Klarius Mikkelsen (* 1887) discovered them in February 1935 during his voyage with the whaling ship Thorshavn on behalf of the whaling entrepreneur Lars Christensen . It is named after a group of islands in the Norwegian Oslofjord near the town of Tønsberg .
geology
The rocks of the Rauer Islands contain both archaic and paleoproterozoic crustal components . The magmatic Scherbinina-layer complex (SLC), a polydeformierte and metamorphierte iron-rich tholeiite - intrusion is of a plurality of deformed meta basitischen Dykes penetrated. These show archaic ages. The SLC and three of these dycegenerations were intruded by tonalitic and Trondhjemitic layers representative of archaic Felsic orthogneiss that exist outside the SLC. Using zirconium dating , the magmatic age of the SLC could be determined to be 2,844 mya . A detritic zircon structure indicates protoliths (parent rocks) that are up to 3,470 mya old. In addition to the igneous rocks, a biotite , garnet , quartz and feldspar- containing paragneiss sequence with minor metamorphic mafic rock components also formed . Both together make up about 50 percent of the outcrops . The rocks of the Rauer Islands differ significantly from the nearby Vestfold Mountains , which mainly consist of orthogneiss with an age range between 2,526 and 2,487 mya.
A mesoproterozoic tectono-thermal event was documented between 1,030 and 1,000 mya on the basis of the metamorphosed intrusiva, in which amphibolite facies to granulite facies were generated. At the same time, juvenile (new) felsic crust components developed. From 530 to 510 mya, high-grade deformations and metamorphoses of the paragneiss occurred in the southwestern areas of the Rauer Islands.
It is believed that the Rauer Islands developed as a late Paleoproterozoic orogenic belt. During the formation of East Gondwana , this had tectonic contact with the East Indian Singhbhum Kraton, which is separated from the East Ghats by the Mahanadi Trench .
Web links
- Rauer Islands in the Geographic Names Information System of the United States Geological Survey (English)
- Rough Islands on geographic.org (English)
- Location map of the Rauer Islands in the database of the Australian Antarctic Data Center (English)
- PD Kinny, LP Black and JW Sheraton: Zircon ages and the distribution of Archaean and Proterozoic rocks in the Rauer Islands. In: Antarctic Science, Volume 5, Issue 2 June 1993, pp. 193-206. doi: 10.1017 / S0954102093000252 , alternative
- EV Mikhalsky: The Tectogenesis Stages of the Antarctic Shield: Review of Geochronological Data. In: Moscow University Geology Bulletin, 2007, Vol. 62, No. 3, pp. 143-154. doi: 10.3103 / S0145875207030027 , PDF
- LP Black, JW Sheraton and PD Kinny: Archaean Events in Antarctica. In: Recent Progress in Antarctica Earth Scienence, pp. 1-6. PDF
Individual evidence
- ↑ SL Harley, I. .Snape and LP Black: The evolution of a layered metaigneous complex in the Rough Group, East Antarctica: evidence for a distinct Archaean terrane. In: Precambrian Research, Volume 89, Issues 3-4, June 1998, Pages 175-205. doi: 10.1016 / S0301-9268 (98) 00031-X , alternatively
- ↑ Simon L. Harley, Ian CW Fitzsimons and Yue Zhao: Antarctica and supercontinent evolution: historical perspectives, recent advances and unresolved issues. In: Geological Society, London, Special Publications, 383, 1-34, 9 October 2013. doi: 10.1144 / SP383.9 , alterantiv