Lithofacies and dynamics of a cool-water carbonate seaway: mid-Tertiary, Te Kuiti Group, New Zealand
Published:January 01, 2006
Alexis S. Anastas, Robert W. Dalrymple, Noel P. James, Campbell S. Nelson, 2006. "Lithofacies and dynamics of a cool-water carbonate seaway: mid-Tertiary, Te Kuiti Group, New Zealand", Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls, H. M. Pedley, G. Carannante
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The Waimai, Orahiri and Otorohanga limestones of the upper Eocene to lowermost Miocene Te Kuiti Group, North Island, New Zealand, provide examples of cool-water carbonate sedimentation within seaways. The limestones are dominated by grainstones and packstones, and contain abundant bryozoans, benthic foraminifers and echinoderm fragments, with only small amounts of siliciclastic material. Horizontally bedded and cross-bedded lithofacies represent sedimentation in wave-dominated and current-dominated settings, respectively; biostrome lithofacies are less abundant and tend to be associated with the current-generated deposits. The migration of dune fields and the associated biostromes generate laterally restricted cyclic alternations of lithofacies. Stratigraphic partitioning of cross-bedded and wave-dominated lithofacies demonstrate that the Te Kuiti seaway alternated between current-dominated, wave-dominated and mixed-energy conditions. Eustatically and/or tectonically produced changes in water depth had the most important influence, with current-dominated conditions prevailing when water depth was optimal to allow flow acceleration through the seaway. Wave-dominated or mixed-energy conditions prevailed when water depth was less or more than this optimum depth. Mixed-energy conditions were most prevalent in widest seaways. The controls on seaway sedimentation inferred have application to other carbonate and siliciclastic seaway successions.
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Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls
During the past decade, work on cool water carbonates has expanded to become a mainstream research area. Studies on modern and Quaternary deposits will continue to be important; however, there is increasing momentum towards unravelling sediment processes, biota-sediment interactions and diagenetic products in Cenozoic and older cool-water carbonates.
Many contributions in this book document Cenozoic and Quaternary carbonates from landlocked (microtidal) water-bodies. These carbonates display important differences in biota and fabric distributions when compared with world ocean examples. Consequently, the scientific community is now better placed to reinterpret pre-Tertiary carbonates where there is a suspicion that they have developed under microtidal conditions. Some papers in the book provide new approaches to interpreting environmental change within macrotidal regimes and others lay firm foundations for future cool-water carbonate diagenetic research
The aim of the book is to illustrate recent international contributions to cool-water carbonates research, with an emphasis on Neogene and Recent case studies. Contributions are divided into three sections: microtidal carbonates from the Mediterranean realm; macrotidal examples from New Zealand, Australia and Mexico; and early diagenetic fabrics.