New Zealand Journal of Geology and Geophysics abstracts
Late Miocene to early Pliocene biofacies of Wanganui and Taranaki
Basins, New Zealand: applications to paleoenvironmental and sequence
stratigraphic analysis
Austin J. W. Hendy*
Peter J. J. Kamp
Department of Earth Sciences
The University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: hendya@email.uc.edu
*Present address: Department of Geology, University
of Cincinnati, Cincinnati, OH 45221-0013, USA.
Abstract The Matemateaonga Formation is late
Miocene to early Pliocene (upper Tongaporutuan to lower Opoitian New
Zealand Stages) in age. The formation comprises chiefly shellbeds,
siliciclastic sandstone, and siltstone units and to a lesser extent
non-marine and shallow marine conglomerate and rare paralic facies. The
Matemateaonga Formation accumulated chiefly in shelf paleoenvironments
during basement onlap and progradation of a late Miocene to early
Pliocene continental margin wedge in the Wanganui and Taranaki Basins.
The formation is strongly cyclothemic, being characterised by recurrent
vertically stacked facies successions, bounded by sequence boundaries.
These facies accumulated in a range of shoreface to mid-outer shelf
paleoenvironments during conditions of successively oscillating sea
level. This sequential repetition of facies and the biofacies they
enclose are the result of sixth-order glacio-eustatic cyclicity.
Macrofaunal associations have been identified from statistical analysis
of macrofossil occurrences collected from multiple sequences. Each
association is restricted to particular lithofacies and stratal
positions and shows a consistent order and/or position within the
sequences. This pattern of temporal paleoecologic change appears to be
the result of lateral, facies-related shifting of broad biofacies
belts, or habitat-tracking, in response to fluctuations of relative sea
level, sediment flux, and other associated paleoenvironmental
variables. The associations also show strong similarity in terms of
their generic composition to biofacies identified in younger
sedimentary strata and the modern marine benthic environment in New
Zealand.
Keywords Wanganui Basin; Taranaki Basin; Miocene;
Pliocene; Tongaporutuan; Kapitean; Opoitian; Matemateaonga Formation;
biofacies; paleoecology; paleoenvironments; sequence stratigraphy
G03048; Received 19 May 2003; accepted 26 January 2004; Online
publication date 1 December 2004
New Zealand Journal of Geology & Geophysics, 2004, Vol. 47:
769-785
0028-8306/04/4704-0769© The Royal Society of New Zealand 2004
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