Geology of an area between Northwest and Southwest Arms, Middle Fiord, Lake Te Anau.

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Ryder-Turner, Alastair George.

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Abstract:

An area covering approximately 25 square kilometres between the N.W. and S.W. Arms of Lake Te Anau is described.
The area is divided into two terranes on the basis of differing styles of tectonic deformation, metamorphism and rock types. The line of demarkation falls on the Howitt Peaks Fault - a major northeast-southwest striking feature. The rocks to the northwest include schists, quartzofeldspathic- and hornblende bearing- orthogneisses, while the rocks to the southeast consist of gneisses, a layered gabbro, hornblende tonalites and diorites, tonalites, granodiorites and granites. A Late Stage granite is intruded on both sides of the fault.
At least three and possibly four tectonic/deformation events are recognized : one producing a pervasive foliation and lineation; the second, activation of large scale faulting; the third, reactivation and uplift.
Two stages of metamorphism are also recognized : Tuhuan (?) amphibolite facies metamorphism and Rangitata prehnite-purnpellyite (?) facies metamorphism. The possibility of formation of the foliation and lineation as a result of pre-Tuhuan deformation as distinct from the development of syn-Tuhuan lineation is postulated.
The tectonic-"stratigraphic" position of the area in Fiordland with respect to the models of Gibson (1979) and Oliver & Coggon (1979) is discussed and it is suggested that it may straddle the lateral equivalent of the Doubtful Sounq and Western Manapouri Provinces.

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128 leaves : ill. (some col.), maps ; 30 cm.

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OU geology Identifier:

1980Ryder-Turner

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Location (WKT, WGS84):

POLYGON ((167.524545568000121 -45.056757791999985,167.567776805000108 -45.057924913999955,167.589182872000038 -45.129208670999958,167.591698727000107 -45.137574876999963,167.500653986000088 -45.148688074999939,167.45255927200003 -45.105911456999934,167.500504435000039 -45.056101594999973,167.524545568000121 -45.056757791999985))

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http://download.otagogeology.org.nz/temp/Abstracts/1980Ryder-Turner.pdf

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Citation

Ryder-Turner, Alastair George., “Geology of an area between Northwest and Southwest Arms, Middle Fiord, Lake Te Anau.,” Otago Geology Theses, accessed February 7, 2025, https://theses.otagogeology.org.nz/items/show/139.

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