Neogene coralline-algal growth-forms and their palaeoenvironments in the Almanzora river valley (Almeria, S.E. Spain)

Romano

2007

Facies analysis of Bartonian–Priabonian shallow-water carbonate successions and the integration with palaeoecological analysis are used to produce a detailed palaeoenvironmental model. In the proximal middle ramp, porcelaneous foraminiferal packstone facies is characterised by larger foraminifera such as Praturlonella and Spirolina. These forms thrived in a shallow-water setting with low turbidity, high-light intensity and lowsubstrate stability. The foraminiferal packstone facies, the thin coralline wacke–packstone facies and the rhodolith packstone facies deposited approximately in the same depth range adjacent to one another in the middle-ramp. Nummulitids (Nummulites, Assilina, Pellatispira, Heterostegina and Spiroclypeus) increase in abundance in the middle to distal mid-ramp together with the orthophragminids. Coralline algae, represented by six genera, are present in all facies. Rhodoliths occur in all facies but they show different shapes and growth forms. They develop laminar sub-ellipsoidal shapes in higher turbulence conditions on mobile sand substrates (foraminiferal packstones and rhodolith rudstones), whilst sub-discoidal shapes often bound by thin encrusting coralline plants in lower hydrodynamic settings. The distinctive characteristics of the palaeoecological middle-ramp gradient are an increase in dominance of melobesioids, a thinning of the encrusting coralline plants and a flattening of the larger benthic foraminiferal shells

Section: Facies Interpretationmentioning

confidence: 85%

Upper Eocene larger foraminiferal–coralline algal facies from the Klokova Mountain (southern continental Greece)

Barattolo

Romano

2007

“…The rhodoliths of deeper water or low hydrodynamicenergy environments show large constructional void spaces, may lack an identifiable nucleus, and are composed of thin, irregular, encrusting thalli (e.g., Braga and Martín 1988;Barattolo et al 2007;Bassi 1998Bassi , 2005Nalin et al 2008;Bassi et al 2006Bassi et al , 2009. The predominantly asymmetrical and loosely packed inner structure of the studied rhodoliths in the present case indicates occasional overturning in an environment with moderate water turbulence.…”

Section: Paleoecology Of Rhodolithsmentioning

confidence: 55%

Origin and resedimentation of rhodoliths in the Late Paleocene flysch of the Polish Outer Carpathians

Leszczyński

Kołodziej

et al. 2012

This study analyses the rhodolith-bearing deposits in the largest and most rhodolith-rich outcrop of the Polish Outer Carpathian flysch, located in the Silesian Nappe, at the village of Melsztyn. The rhodoliths and sparse associated biota occur as resedimented components in a deep-marine succession of siliciclastic conglomerates and coarse-grained sandstones, deposited by high-density turbidity currents and debris flows. The sediment was derived from a fan-delta system located at the southern margin of the Silesian flysch basin. Stratigraphic data indicate that the succession represents the Upper Istebna Sandstone deposited during the Late Paleocene. The rhodoliths are composed mostly of coralline red algae with seven genera and eight species representing the family Sporolithaceae and the subfamilies Mastophoroideae and Melobesioideae. Rhodoliths show sub-spheroidal and subellipsoidal shapes with encrusting, warty and lumpy growth forms. Lumpy growth forms show massive inner arrangements, whereas the encrusting growth forms are usually made of thin thalli and show more loosely packed inner arrangements. The rhodoliths grew on a moderately mobile siliciclastic substrate in a shallow-marine environment with a low net sedimentation rate. It is inferred that the growth of rhodoliths was favored during a relative sea-level rise. During the subsequent sea-level fall, the rhodoliths and associated siliciclastic deposits were resedimented by gravity flows into the deep-sea setting. The analyzed deposits, like other Paleocene-Eocene deposits of the Polish Outer Carpathians, provide no evidence of coeval widespread shallow-marine carbonate sedimentation along the margins of the Outer Carpathian flysch basins.

“…The rhodolith rudstone/ floatstone facies increases in thickness seaward, from the Caria section to the Tropea section. Rhodoliths in this facies are well preserved and exhibit shapes and growthmorphologies characteristic of low-energy environments (e.g., Braga and Martin 1988;Bassi et al 2006Bassi et al , 2009b. These calm-water conditions are supported by depth Facies (2012) 58:191-215 209 estimates inferred from the depth distribution of similar modern Mediterranean coralline algal assemblages (Lithophyllum cf.…”

Section: Discussionmentioning

confidence: 98%

An Upper Miocene siliciclastic-carbonate ramp: depositional architecture, facies distribution, and diagenetic history (Capo Vaticano area, southern Italy)

Gramigna

Russo

2011

During the Late Miocene, the marginal areas of the Mediterranean Basin were characterized by the development of mixed siliciclastic-carbonate ramps. This paper deals with a temperate siliciclastic-carbonate ramp (late Tortonian-early Messinian in age) which crops out in the Capo Vaticano area, Southern Apennines (Italy). Carbonate components are mainly represented by calcitic skeletal fragments of coralline red algae, bryozoans, bivalves, and larger foraminifera, whereas corals, brachiopods, echinoderms, and planktonic foraminifera are subordinate. In the studied ramp, the depositional geometries of the main unit, the 'Sabbie gialle ad Heterostegina', show a gradual steepening from low/middle (dip about 2-5°) to steep slope settings (up to 25°). The microfacies observations, the quantitative analyses of the main biogenic components as well as the rhodolith shapes and growth forms allowed the differentiation between the middle and the outer ramp depositional setting and the refining of the stratigraphic framework. The middle ramp is characterized by coralline red algal debris packstone facies often associated with larger foraminiferal floatstone/packstone facies, while the outer ramp is characterized by rhodolith floatstone/rudstone facies. These facies pass basinward into typical openmarine deposits (planktonic foraminiferal facies). The taxonomic composition of the coralline red algal assemblage points to a temperate paleoclimate and emphasizes the Miocene Mediterranean phytogeographic patterns. The absence of non-skeletal grains (ooids and green algae), the paucity of Porites patch reefs, the rare occurrence of primary marine cementation, all confirm that the studied ramp was poorly lithified within a warm-temperate setting. The flat depositional profile of the ramp can be related to the absence or paucity of primary marine carbonate cements.