Epitaxial calcite cements in Earth history: a cooler-water phenomenon during aragonite-sea times?
Published:January 01, 2006
Andrea C. Knoerich, Maria Mutti, 2006. "Epitaxial calcite cements in Earth history: a cooler-water phenomenon during aragonite-sea times?", Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls, H. M. Pedley, G. Carannante
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Epitaxial calcite overgrowths on echinoderm fragments are important contributors to the rock record during specific time intervals in Earth history (so-called 'calcite-sea' times). Such overgrowths also occur throughout the Phanerozoic in heterozoan carbonate associations, where, these cements often form the volumetrically most important cement type. The origin and environment in which this cement forms are controversially debated, reaching from early marine, meteoric, burial to emergence. The formation of epitaxial overgrowth in calcite sea shallow-water carbonates is reported from early diagenetic environments (marine, marine burial and meteoric), whereas for aragonite sea shallow-water heterozoan carbonates generally a later, burial diagenetic environment of epitaxial cement precipitation is stated. Data from the central Mediterranean area (Maltese Islands and Sicily) show that also in heterozoan shallow-water carbonates the main phase of epitaxial cement precipitation can occur early, in the marine, meteoric and marine burial environment. Cementation was not sourced by pressure solution of calcitic grains, which clearly postdates epitaxial cement growth, but by the early dissolution of aragonitic biota. These findings underline the importance of aragonitic components as an early cement source in aragonite-sea time non-tropical/heterozoan carbonates and emphasize the similarity of the diagenetic evolution of these rocks with calcite-sea time tropical carbonates.
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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.