Rhodolith facies evolution and burial as a response to Holocene transgression at the Pontian Islands shelf break
Published:January 01, 2006
Daniela Basso, Claudia Morbioli, Cesare Corselli, 2006. "Rhodolith facies evolution and burial as a response to Holocene transgression at the Pontian Islands shelf break", Cool-Water Carbonates: Depositional Systems and Palaeoenvironmental Controls, H. M. Pedley, G. Carannante
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Cool to periglacial conditions, accompanied by a sea-level drop, are thought to result in an unchanged composition and ecological meaning of the rhodalgal carbonates, which occur frequently in the present-day, current-swept areas of the Mediterranean upper shelf. Form, internal structure and species composition of rhodoliths are believed to reflect the environmental conditions present in their biotope. To test these hypotheses, the relationship between rhodolith facies and sea-level rise was investigated in four cores recovered at the Pontian Islands (Tyrrhenian Sea) shelf break. The core basal intervals have been AMS radiocarbon dated providing uncalibrated ages ranging from 10 040 ± 50 years bp to 10 380 ± 50 years bp. All four cores show a transition from basal rhodolith-rich, biodetritic, muddy-gravelly sand to rhodolith-barren, silty sand or sandy mud, along a deepening-upward succession. A facies of coralline-coated fragments of bryozoan colonies has been identified above the rhodolith facies as the deepest coralline growth form in all cores, before the final burial. Molluscan associations and rhodolith abundance, morphology and composition are ecologically compatible with the embedding sediment and testify the transition from the late Pleistocene circalittoral coastal detritic or shelf-edge detritic assemblages at the base of cores, up to the present-day bathyal muds. In the late Pleistocene and Holocene, as at present, the Pantine shelf was characterized by a low sedimentary input under moderate current action, fostering deep coralline growth.
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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.