New Zealand Journal of Geology and Geophysics abstracts
Contrasting carbonate depositional systems for Pliocene cool-water
limestones cropping out in central Hawke’s Bay, New Zealand
Vincent Caron
Campbell S. Nelson
Peter J. J. Kamp
Department of Earth Sciences
University of Waikato
Private Bag 3105
Hamilton, New Zealand
email: c.nelson@waikato.ac.nz
Abstract Pliocene limestone formations in central
Hawke’s Bay (eastern North Island, New Zealand) accumulated on and near
the margins of a narrow forearc basin seaway within the convergent
Australia/Pacific plate boundary zone. The active tectonic setting and
varied paleogeographic features of the limestone units investigated, in
association with probable glacioeustatic sea-level fluctuations,
resulted in complex stratigraphic architectures and contrasting types
of carbonate accumulation on either side of the seaway. Here, we
recognise recurring patterns of sedimentary facies, and sequences and
systems tracts bounded by key physical surfaces within the limestone
sheets. The facies types range from Bioclastic (B) to Siliciclastic (S)
end-members via Mixed (M) carbonate-siliciclastic deposits. Skeletal
components are typical cool-water associations dominated by epifaunal
calcitic bivalves, bryozoans, and especially barnacles. Siliciclastic
contents vary from one formation to another, and highlight
siliciclastic-rich limestone units in the western ranges versus
siliciclastic-poor limestone units in the eastern coastal hills.
Heterogeneities in facies types, stratal patterns, and also in
diagenetic pathways between eastern and western limestone units are
considered to originate in the coeval occurrence in different parts of
the forearc basin of two main morphodynamic carbonate systems over
time.
Keywords cool-water limestones; carbonate
platforms; attached platforms; detached platforms; depositional facies;
stratigraphic architecture; Pliocene; Hawke’s Bay
G03040; Received 16 April 2003; accepted 16 September 2003; Online
publication date 1 December 2004
New Zealand Journal of Geology & Geophysics, 2004, Vol. 47:
697-717
0028-8306/04/4704-0697 © The Royal Society of New Zealand 2004
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