Late tertiary terrestrial strata of North Otago and South Canterbury, and their genetic relationships

Black, Brett V. N. (Brett Victor Nicol), 1973-

The stratigraphic succession in North Otago and South Canterbury consists of early Tertiary fluvial sediments and middle Tertiary marine strata (Onekakara Group; absent west of Lake Aviemore), (?)middle Miocene-Pliocene clay- and quartz-rich (± schist/semi-schist), fluvial and lacustrine strata (Waitangi Coal Measures), (?)late Miocene-Recent immature sandstones and conglomerates, and Quaternary fan gravels. Published and unpublished literature contains at least 18 different approaches for subdivision of this succession. The clayand quartz-rich Waitangi Coal Measures initially formed while there was little topographic relief in the region. These initial deposits probably had at least one source in Central Otago that provided schistose material. The W aitangi Coal Measures continued to be deposited intermittently as uplift of the Southern Alps resulted in the formation of early immature conglomerates and sandstones. The coal measures are interfingered with the overlying greywacke-bearing conglomerates and sandstones. Manuherikia Group, of Central Otago, is extended to include the Waitangi Coal Measures because there are similarities between the coal measures and Manuherikia Group strata. The late Miocene to Recent conglomerates have formed during the rise of faultbounded greywacke and semischist mountain ranges. I propose the name Clay Cliffs Formation for the oldest tectonically generated, greywacke-bearing, quartz-rich, immature conglomerates. The name Kurow Conglomerate is used for coarse, greywacke-bearing conglomerates that succeed the Clay Cliffs formation. Usage of Kurow Group is discontinued because the name Kurow Conglomerate has priority, and because genetically unrelated strata have previously been placed in Kurow Group. Likewise, usage of Benmore, Glentanner, and BalmoralIrishman's Creek Beds is discontinued because Kurow Conglomerate has priority, and because Benmore and Balmoral-Irishman's Creek Beds include genetically unrelated strata. Hawkdun Group, of Central Otago, is extended to include Clay Cliffs Formation and Kurow Conglomerate because they are similar to W edderburn Formation and Maniototo Conglomerate which have previously been included in the Hawkdun Group in Central Otago. Clay Cliffs Formation and Kurow Conglomerate are provisionally correlated with Wedderburn Formation and Maniototo Conglomerate respectively. Kurow Conglomerate is, commonly, overlain with angular unconformity by younger glacio-fluvial and fan gravels. Locally, however, Kurow Conglomerate appears to be conformably overlain by younger tectonically generated strata. This continuous succession of tectonically generated sediments represents uplift associated with the Kaikoura Orogeny. All Hawkdun Group strata, and all overlying, tectonically generated, terrestrial (non-marine) sediments in the study area are placed in the Aoraki Supergroup (new). All immature, late Miocene to Recent tectonically generated terrestrial strata in South Island are provisionally correlated with the Aoraki Supergroup.

1 v. (various pagings) : ill., col. maps (some folded) ; 30 cm.

2000Black_BVN

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