New Zealand Journal of Geology and Geophysics abstracts

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Te Akatarawa Formation--an exotic oceanic-continental margin terrane within the Torlesse-Haast Schist transition zone

S. HADA*

Department of Geology
Kochi University
Kochi 780, Japan

C. A. LANDIS

Geology Department
University of Otago
P.O. Box 56
Dunedin, New Zealand

*Present address: Research Institute for Higher Education, Kobe University, Tsurukabuto, Nada-ku, Kobe 657, Japan.

Abstract  A volcanic-limestone-mudstone melange lies within an upward-coarsening sequence of quartz-rich flysch and conglomerate at Te Akatarawa, South Canterbury, New Zealand. The entire suite comprises the newly proposed Te Akatarawa Formation. Limestone blocks within the melange contain a varied and distinctive fossil assemblage including fusulinids identified as Parafusulina cf. japonica (Gumbel), of Middle Permian age. The Akatarawa Melange originated as an olistostrome adjacent to a low-latitude seamount; overlying clastics accumulated along a continental margin. The entire sequence has been synclinally folded and metamorphosed to pumpellyite-actinolite facies.

Te Akatarawa Formation comprises a small tectonostratigraphic terrane allochthonous with respect to the adjoining Torlesse as well as other terranes of New Zealand. In terms of fusuline paleogeography, Parafusulina japonica occurs within the "Yabeina territory". In contrast, faunas from the North Island Waipapa Terrane belong to the "Colania (Lepidolina) territory". Similar Permian limestones belonging to each of these paleogeographic territories also occur in Japan, but the history of accretion and deformation in New Zealand and Japan differ, with Te Akatarawa being accreted significantly earlier than its Japanese counterparts. These relationships may provide clues to the original positions of Permian faunal realms within Paleotethys-Panthalassa.

Keywords  Torlesse; Te Akatarawa Formation; melange; olistostrome; fusuline; paleobiogeography; Tethys; Permian; tectonostratigraphic terranes; illite; new stratigraphic names

New Zealand Journal of Geology and Geophysics, 1995, Vol. 38: 349-359

0028-8306/95/3803-0349 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (4786K); (scanned from paper original: notes about this process)

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