Geology of the South-East Margin of the Takitimu Mountains, Southland, New Zealand.

Kennedy, TJ

Approximately 17,200 ft. of Permian strata, exposed on the south-east margin of the Takitimu Mountains Southland, New Zealand, are chiefly andesitic and basaltic lavas and diorite silts, as well as clastic and sedimentary rocks whose constituent particles were derived from Permian pyroclastic eruptions of augite (and hornblende) andesites. These rocks were steeply tilted and eroded before the deposition of Triassic volcanogenic sediments which now rest unconformably on the Permian strata.
During diagenesis volcanic glass has crystallized to heulandite and analcime, and associated minerals are chlorite, celadonite and prehnite. Plagioclase has altered to albite and one or more hydrous Ca-bearing minerals, including prehnite. Albitization is incomplete on every scale. Laumontite is only found in veins, and stilbite is common in cavities of volcanic rook.
Gravimetric determination of the amount of silica in two of the Permian basalts gave values of 48.87 and 48.16%.Average K2O, Na2O and K2O:Na2O values for Permian Volcanics are respectively 1.091 3.23 and 0.29, which coincide with volcanic belt No.1 of Challis (1968).
The discovery of Mellarium in a partly calcified conglomerate establishes the presence of a new Etalian locality near Wilanda Downs. A new Formation in the Productus Creek Group (Mt. Wilanda Limestone) is defined.

65 Leaves. Photos, map (folded in pocket); 30 cm.

1969Kennedy

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