The Geology of a section through the Central Takitimu Mountains, Southland, New Zealand.
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INTRODUCTION AND SCOPE OF WORK
An investigation of a section through the central Takitimu Mountains is presented in partial fulfilment of the requirements for the B.Sc. (Hons.) Degree to the Geology Dept., University of Otago, New Zealand.
The Takitimu Mountains lie to the S.E. of Lake Manapouri in the South Island, (map 2 ) and consist of a chain of peaks approximately 24 miles long and rising to a maximum height of 5,582 ft. (Spence Peak). The mountains are free of ice and snow in the summer, but there is evidence of past glaciation (plate 1).
Three weeks were spent in the field, from the end of January to mid-February, 1961. Mapping was restricted almost entirely to the upper reaches of the Aparima River, from the Braxton Ridge to the Aparima Peaks (frontispiece) A sketch map based on aerial photographs is included with this report (map 1).
The section investigated includes Lower Permian rocks of the Takitimu Group, constituting the bulk of the mountains, together with the Lower and Middle Triassic sediments. In the Middle Triassic, the Etalian and part of the Kaihikuan stages of the Gore Series have been mapped. All the rocks clip in a general easterly direction and constitute part of the western limb of the Southland Syncline. There is, however, evidence to suggest that the rocks of the Takatimu Group are strongly folded.
A few miles south of the section investigated, the Productus Creek Group outcrops, but the only indication of this group in the Aparima area was the discovery of two boulders of Productus Creek limestone in the Aparima River.
Several new fossil localities in the Kaihikuan and Etlian stages, and one from the Permian (Takatimu Group) are recorded. Several thousand feet of greywacke and siltstone underlying the base of the Etalian are placed tentatively in the Lower Triassic. They would appear to constitute a new Pre-Etalian stage yet to be defined. Fossil localities from these Lower Triassic sediments are also described.
The validity of four species of the ammonoid genus Parapopanoceras set up by Browne ( 1952) is discussed and a genus of brachiopod new to New Zealand is recognised and recorded.
A brief petrological study of the rocks of the Takatimu Group,and the Triassic greywackes and siltstones has been made. The rocks of the Takitimu Group belong to the prehnite-pumpellyite metamorphic facies, while the Triassic sediments belong to the heulandite zone of the zeolite facies.
Some aspects of the clay mineralogy of the Triassic siltstones are included in an appendix.
An investigation of a section through the central Takitimu Mountains is presented in partial fulfilment of the requirements for the B.Sc. (Hons.) Degree to the Geology Dept., University of Otago, New Zealand.
The Takitimu Mountains lie to the S.E. of Lake Manapouri in the South Island, (map 2 ) and consist of a chain of peaks approximately 24 miles long and rising to a maximum height of 5,582 ft. (Spence Peak). The mountains are free of ice and snow in the summer, but there is evidence of past glaciation (plate 1).
Three weeks were spent in the field, from the end of January to mid-February, 1961. Mapping was restricted almost entirely to the upper reaches of the Aparima River, from the Braxton Ridge to the Aparima Peaks (frontispiece) A sketch map based on aerial photographs is included with this report (map 1).
The section investigated includes Lower Permian rocks of the Takitimu Group, constituting the bulk of the mountains, together with the Lower and Middle Triassic sediments. In the Middle Triassic, the Etalian and part of the Kaihikuan stages of the Gore Series have been mapped. All the rocks clip in a general easterly direction and constitute part of the western limb of the Southland Syncline. There is, however, evidence to suggest that the rocks of the Takatimu Group are strongly folded.
A few miles south of the section investigated, the Productus Creek Group outcrops, but the only indication of this group in the Aparima area was the discovery of two boulders of Productus Creek limestone in the Aparima River.
Several new fossil localities in the Kaihikuan and Etlian stages, and one from the Permian (Takatimu Group) are recorded. Several thousand feet of greywacke and siltstone underlying the base of the Etalian are placed tentatively in the Lower Triassic. They would appear to constitute a new Pre-Etalian stage yet to be defined. Fossil localities from these Lower Triassic sediments are also described.
The validity of four species of the ammonoid genus Parapopanoceras set up by Browne ( 1952) is discussed and a genus of brachiopod new to New Zealand is recognised and recorded.
A brief petrological study of the rocks of the Takatimu Group,and the Triassic greywackes and siltstones has been made. The rocks of the Takitimu Group belong to the prehnite-pumpellyite metamorphic facies, while the Triassic sediments belong to the heulandite zone of the zeolite facies.
Some aspects of the clay mineralogy of the Triassic siltstones are included in an appendix.
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29 leaves. Ill. Photos. 27 cm.
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1961Harper
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Harper, CT`, “The Geology of a section through the Central Takitimu Mountains, Southland, New Zealand.,” Otago Geology Theses, accessed December 7, 2024, https://theses.otagogeology.org.nz/items/show/9.