The Oligocene represents a key interval during which coralline algae became dominant on carbonate ramps and luxuriant coral reefs emerged on a global scale. So far, few studies have considered the impact that these early reefs had on ramp development. Consequently, this study aimed at presenting a highresolution analysis of the Attard Member of the Lower Coralline Limestone Formation (Late Oligocene, Malta) in order to decipher the internal and external factors controlling the architecture of a typical Late Oligocene platform. Excellent exposures of the Lower Coralline Limestone Formation occurring along continuous outcrops adjacent to the Victoria Lines Fault reveal in detail the three-dimensional distribution of the reef-associated facies. A total of four sedimentary facies have been recognized and are grouped into two depositional environments that correspond to the inner and middle carbonate ramp. The inner ramp was characterized by a very high-energy, shallow-water setting, influenced by tide and wave processes. This setting passed downslope into an inner-ramp depositional environment which was colonized by seagrass and interfingered with adjacent areas containing scattered corals. The middle ramp lithofacies were deposited in the oligophotic zone, the sediments being generated from combined in situ production and sediments swept from the shallower inner ramp by currents. Compositional characteristics and facies distributions of the Attard ramp are more similar to the Miocene ramps than to those of the Eocene. An important factor controlling this similarity may be the expansion of the seagrass colonization within the euphotic zone. This expansion may have commenced in the Late Oligocene and was associated with a concomitant reduction in the aerial extent of the larger benthonic foraminifera facies. Stackingpattern analysis shows that the depositional units (parasequences) at the study section are arranged into transgressive-regressive facies cycles. This cyclicity is superimposed on the overall regressive phase recorded by the Attard succession. Furthermore, a minor highstand (correlated with the Ru4/Ch1 sequence) and subsequent minor lowstand (Ch2 sequence) have been recognized. The biota assemblages of the Attard Member suggest that carbonate sedimentation took place in subtropical waters and oligotrophic to slightly mesotrophic conditions. The apparent low capacity of corals to form wave-resistant reef structures is considered to have been a significant factor affecting substrate stability at this time. The resulting lack of resistant mid-ramp reef frameworks left this zone exposed to wave and storm activity, thereby encouraging the widespread development of coralline algal associations dominated by rhodoliths.
Recent foraminiferal assemblages are identified in 70 grab samples from 20-380 m depth in the Pontine Archipelago (Tyrrhenian Sea, Italy). All broken and relict tests of benthic foraminifera and other bioclastic sediments were counted for each sample, in order to provide a more complete description of the benthic community. Hierarchical cluster analysis (HCA) was performed on the relative abundances (live + dead) of 53 taxa of benthic foraminifera that were common in the samples. Q-mode HCA recognizes three distinct foraminiferal biofacies, each associated with a particular bioclastic lithofacies: 1) the Asterigerinata-Lobatula-Rosalina biofacies occurs at 20-150 m and is dominated by benthic foraminifera, most notably epiphytic species such as Asterigerinata mantilla, Lobatula lobatula, and Rosalina brad vi; other bioclasts include rhodoliths, bryozoans, and echinoid spines, which constitute the rhodalgal lithofacies; 2) the Cassidulina carinata biofacies at intermediate depths of 100-250 m includes benthic and planktonic foraminifera among branches of bryozoans that constitute the bryomol lithofacies; also present are high percentages of reworked glauconitic tests of shallow-water taxa (e.g., Elphidium, Lobatula, and Asterigerinata), possibly related to Late Quaternary sea-level stillstands; 3) the Uvigerina-Bulimina biofacies at 200-380 m, that is characterized by Uvigerina mediterranea and Bulimina marginata; in addition to benthic and planktonic foraminifera, it has a molechfor lithofacies of bivalves and gastropods
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