Geology of Romahapa area, south-east Otago.

Waddell, SJ

A map and description of the geology of 9 square miles of the Romahapa area is presented. The area is underlain by sedimentary rocks of ?upper Palaeozoic and lower Mesozoic age. Fossil evidence fixes the age limits as Permian or post-Permian to pre-Oretian. The oldest rocks of the area are described as two new formations, a lower North Romahapa Conglomerate and an upper Waituti Formation, comprising the North Romahapa Group. A distinctive conglomerate from this group is described in lithologic and petrographic detail. The group is established on lithologic grounds. The other rocks of the area are not so extensively described.
Where applicable all rocks are described and compared using Folk's sandstone classification. The vast majority of the rocks fall in the "volcanic arenite" area of this classification. Alteration effects are considered to be consistent with zeolite facies metamorphism.
A tentative structural interpretation is given, based on the limited field data available. It is not claimed to be the only possible interpretation, nor necessarily the correct one, and is likely to be a gross simplification. On its basis, an episode of deformation of possible late Permian age is tentatively suggested.
Finally a brief section on economic geology is presented.

70 leaves. Photos, map (folded in pocket); 27 cm.

1969Waddell

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