Snapshot of a lower Pliocene Dendropoma reef from Sant Onofre (Baix Ebre Basin, Tarragona, NE Spain)

Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

Contents lists available at ScienceDirect

Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo

Snapshot of a lower Pliocene Dendropoma reef from Sant Onofre (Baix Ebre Basin, Tarragona, NE Spain) Julio Aguirre a,⁎, Zaín Belaústegui b, Rosa Domènech b, Jordi M. de Gibert b,1, Jordi Martinell b a b

Dpt Estratigrafía y Paleontología, Facultad de Ciencias, Universidad de Granada, Fuentenueva s/n, 18002 Granada, Spain IRBio (Biodiversity Research Institute) and Dpt. d'Estratigrafia, Paleontologia i Geociències Marines, Universitat de Barcelona, Martí Franquès s/n, E-08028 Barcelona, Spain

a r t i c l e

i n f o

Article history: Received 5 June 2013 Received in revised form 26 November 2013 Accepted 9 December 2013 Available online 18 December 2013 Keywords: Vermetid reef Dendropoma Rapid burial Baix Ebre Basin Early Pliocene NE Mediterranean

a b s t r a c t We study a vermetid–coralline algal buildup from the lower Pliocene deposits of the Baix Ebre Basin (Sant Onofre, NE Spain). The bioconstruction framework is made up by the intergrowth of Dendropoma and encrusting coralline algae, mostly Spongites fruticulosus with rare Neogoniolithon brassica-florida. Thus, it can be considered a fossil analog of the present-day Mediterranean Dendropoma reefs. The bioconstruction developed on top of a flat palaeotopographic high formed by pre-Pliocene substrate in a sheltered embayment. Submarine cliff sediments, consisting of big blocks and boulders, were deposited along the margin of the palaeohigh. Crusts of coralline algae, intergrowing with serpulids and vermetids, extend from the flat top downwards along the talus. Gray-bluish marl, yellowish silt and fine-grained sand, were deposited in the surrounding low areas. A rich and diverse dweller assemblage occurs in the buildup: bivalves (pectinids, venerids, Lithophaga), gastropods (muricids, nassarids, olivids, cancellarids), ahermatypic coral Cladocora ?, barnacles of the family Pyrgomatidae, Balanus trigonus and regular echinoids. In the talus deposits, clusters of Neopycnodonte cochlear, Hinnites ercolanianus and Balanus sp. dominate the faunal assemblage. Further, the blocks of the talus are densely bored, showing Gastrochaenolites, Entobia, Maeandropolydora and Caulostrepsis. Faunal and boring assemblages indicate that the buildup settled and developed in very shallow conditions (most likely less than 10 m water depth). The whole fossil assemblage, framework and dweller community, are preserved in situ, maintaining their original growth positions. Development in a protected setting, together with rapid burial due to progradation of siliciclastics on top of the palaeotopographic high, accounts for this exceptional preservation in such a shallow environment. The vermetid bioconstruction of Sant Onofre represents the only carbonate deposits found in the lower Pliocene basins of NE Spain. Sequence stratigraphic architecture indicates that these carbonates represent the maximum flooding deposits. Thus, maximum carbonate production took place due to sediment starvation in the palaeohigh while terrigenous deposits were formed in the surrounded low areas. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Vermetids, as a group, inhabit low latitudes, from tropical to warmtemperate sea waters (Keen, 1961; Safriel, 1975; Schiapparelli and Cattaneo-Vietti, 1999; Vescogni et al., 2008). In this latitudinal region all over the world, vermetid bioconstructions are typical coastal geomorphologic features in intertidal and shallow-subtidal marine waters (Safriel, 1975; Vescogni et al., 2008). These gastropods show specific adaptations and an enormous phenotypic plasticity that make them excellent organisms to withstand high hydraulic energy in shallow waters (Schiapparelli and Cattaneo-Vietti, 1999; Schiapparelli et al., 2006). In the present-day Mediterranean, vermetid reefs are one of the most important bioconstructed ecosystems in coastal settings that are ⁎ Corresponding author. Tel.: +34 958 248332; fax: +34 958 348528. E-mail address: [email protected] (J. Aguirre). 1 This paper is dedicated to Jordi M. de Gibert, deceased during the production of the manuscript. 0031-0182/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.palaeo.2013.12.011

highly vulnerable threatened (Bouderesque, 2004; Templado et al., 2004; Calvo et al., 2009; MAP, 2010; Sarà et al., 2011). These bioconstructions are referred to as vermetid or Dendropoma reefs, trottoires or corniche (Bosence, 1985). They occur in intertidal and shallow-subtidal waters, from 0 to 6 m depth, and occupy the warmest southern Mediterranean Sea, below 38°N of latitude, since the geographic distribution of Dendropoma is restricted to winter temperatures higher than 14 °C (Laborel, 1961; Pérès and Picard, 1964; Safriel, 1975; Laborel, 1986, 1987; Antonioli et al., 1999; Templado et al., 2009; Chemello and Silenzi, 2011). However, deeper vermetid buildups can also be found (Schiapparelli et al., 2006; Vescogni et al., 2008). The Mediterranean vermetid bioconstructions are principally made up of the intergrowth of the sessile gastropod Dendropoma petraeum and the coralline red alga Neogoniolithon brassica-florida (see recent summary in Chemello and Silenzi, 2011). Nonetheless, Calvo et al. (2009) have shown the existence of, at least, four cryptic regional species of Dendropoma (monophyletic clades) based on genetic analyses. Other vermetid genera, such as Petaloconchus or Vermetus, are also

10

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

able to form these structures (Safriel, 1975; Laborel and LaborelDeguen, 1996; Chemello and Silenzi, 2011). Among the coralline algae, Lithophyllum byssoides (= Lithophyllum lichenoides), Lithophyllum incrustans, Lithophyllum tortuosum, Lithophyllum congestum and Neogoniolithon mamillosum might be also present in lesser abundance (Blanc and Moliner, 1955; Laborel, 1961; Templado et al., 2009; Chemello and Silenzi, 2011). Coralline algae form coatings surrounding the vermetid tubes strengthening the bioconstruction (Laborel and Laborel-Deguen, 1996), thus, playing a major role as stabilizer of the buildups. Due to the development of the vermetid reefs in the intertidal zone, fossil counterparts have been used as proxies for palaeocoastline reconstructions as well as to estimate tectonic uplift of land and sea-level changes (Pérès and Picard, 1964; Safriel, 1975; Pirazzoli et al., 1989; Laborel and Laborel-Deguen, 1996; Antonioli et al., 1999; Betzler et al., 2000; Antonioli et al., 2002; Lambeck et al., 2004; Morhange et al., 2006; Sivan et al., 2010). However, Vescogni et al. (2008) demonstrated that vermetid reefs could also occur in deeper settings. These authors estimated a bathymetry of up to 50 m water depth for vermetid (Petaloconchus) reefs in upper Miocene reef carbonates in southern Italy and Crete. Recent oxygen stable isotopic analyses have proven that vermetids precipitate their shells in isotopic equilibrium with the sea water (Silenzi et al., 2004). Therefore, the characteristic biogeographic distribution, together with the δ18O analyses, has also contributed to use vermetid shells as palaeothermometers and to reconstruct palaeoclimate changes (Silenzi et al., 2004; Sisma-Ventura et al., 2009; Chemello and Silenzi, 2011). In the Pliocene deposits of the Sant Onofre area, Baix Ebre Basin (Tarragona, NE Spain), one example of wonderfully exposed vermetid– coralline algal buildup is found. The Pliocene sediments in the Baix Ebre region are known since the beginning of the 20th century (Gignoux and Fallot, 1922). Later studies dealt with micromammal paleontology (Agustí et al., 1983; Agustí, 1985), marine mollusks (Martinell and Domènech, 1984), stratigraphy and sedimentology (Martinell, 1988; Arasa, 1990), and ichnology (Martinell and Domènech, 1995; de Gibert and Martinell, 1996, 1998; de Gibert et al., 1998). However, no detailed study has been carried out on the vermetid bioconstruction. It developed on top of a flat palaeotopographic high that was surrounded by siliciclastics (de Gibert, 1996; de Gibert and Martinell, 1996; de Gibert et al., 1998). These authors interpreted the Pliocene bioconstruction and associated sediments as formed in a shallow-water rocky-shore setting based on the bioerosion assemblage found affecting the exposed pre-Pliocene substrate, which was assigned to the Entobia ichnofacies. The vermetids and the coralline algae contributed to the carbonate production, whereas silt and clay were deposited in the surrounding areas. The particular palaeotopographic configuration makes the Sant Onofre bioconstruction to be the only marine carbonates recorded all over the NE Iberian Pliocene basins. The main objectives of this paper are: a) to study the taxonomic composition in terms of ecological guilds (framework builders, dwelling populations associated with the buildup and the organisms living in the vicinity of the bioconstruction); b) to assess the distribution of the components within the bioconstruction and in the surroundings; c) to infer the palaeoenvironmental setting in which the vermetid–coralline algal bioconstruction developed; d) to elucidate the sequence stratigraphic context in which the studied carbonates were produced; and e) to compare them with other similar Neogene and recent Mediterranean vermetid buildups. 2. Location and geological context The outcrop is located near Tortosa, SW of the Tarragona province (NE Spain), close to the recent delta of the Ebro River and within the Baix Ebre region (Fig. 1). The Pliocene deposits crop out in a quarry located at Km 4 of road C-42 between Tortosa and L'Aldea villages. The

Fig. 1. Geological map and location of the outcrop studied herein (black star).

outcrop takes the name of Sant Onofre from a former hermitage, which stood there prior to the quarry. The Baix Ebre Basin is the result of the overprinting of Neogene extensional faulting over the tectonic unit known as the Linking Zone, which connects the Catalan Coastal Ranges (to the north) and the Iberian Range (to the west) (Guimerà and Álvaro, 1990). The palaeogeography of the Baix Ebre Basin during the Pliocene was reconstructed by Fleta et al. (1991, fig. 7), who, based on both outcrops and core data, interpreted the basin as a bay with two narrowly-connected areas. The inner part was enclosed and clearly brackish, while the outer was more open to marine conditions. The Sant Onofre outcrop is located in the transitional area between both zones where freshwater influences were very important, as indicated by the mollusk assemblages (Martinell and Domènech, 1984). 3. Stratigraphy and sedimentology of the lower Pliocene succession The lower Pliocene deposits in the Sant Onofre area unconformably overlay conglomerates of the Anguera siliceous conglomerate unit of Arasa (1990) (Fig. 2). The stratigraphy of the lower Pliocene of the Baix Ebre Basin has been reported by Arasa (1990), Fleta et al. (1991) and de Gibert and Martinell (1996). These authors identified three informal lithostratigraphic units, which from base to top are (Figs. 2 and 3): a) The basal detrital marine unit crops out very locally and is constituted by calcareous gravel and massive sandstone. The clasts are bored (Gastrochaenolites, Entobia, Maeandropolydora, Caulostrepsis) and encrusted by bivalves (oysters, Hinnites) and balanid barnacles (Martinell and Domènech, 1995). Lithofacies and fossils are indicative of littoral conditions. b) The Campredó blue clay unit, 65 m thick, consists of mudstone and sandstone, which can be subdivided into three subunits: b1) The lower sandy clay subunit is formed by tabular sandstone beds with horizontal lamination, laminae being from millimeter to centimeter in thickness, that intercalate yellowish silty clay. Microfossils are very scarce (some poorly preserved ostracods and foraminifers), while J-shaped burrows may be very abundant (de Gibert and Martinell, 1996).

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

11

Fig. 2. Stratigraphical log and lithostratigraphic units. A. Geological map of the studied area (ASC, LSC, BC, USC, SOC and VCA are the acronyms of the differentiated units as indicated in B). B. Stratigraphic log of the lower Pliocene succession at Sant Onofre.

b2) The intermediate blue clay subunit is made up of gray-blue marl containing a rich mollusk assemblage (Martinell and Domènech, 1984). Gastropods and bivalves are accompanied by spatangoid echinoids and decapod remains. Micropalaeontological assemblages yield abundant ostracods and foraminifers, mainly Nonion and Ammonia. The presence of melanopsid and potamid gastropods suggests the proximity of the continent. b3) The upper sandy clay subunit consists of sandstone layers interbedded with yellowish clay. Sandstone beds show horizontal lamination and small-scale trough cross-lamination. Mollusks and spatangoid echinoids are present, although poorly preserved, together with common vegetal remains and abundant foraminifers. Benthic foraminiferal assemblages, as in the intermediate blue clay subunit, are dominated by Nonion and Ammonia although these assemblages are less diverse. Bioturbation is common and diverse with Sinusichnus sinuosus, Teichichnus rectus, Scolicia isp., Nereites missouriensis, Skolithos linearis and escape traces (de Gibert and Martinell, 1996). The subunit ends with a 3 m thick sandstone bed with large-scale planar cross-bedding. The Campredó blue clay unit as a whole records sedimentation in a shallow marginal bay. The lower and upper subunits correspond to more proximal settings, while the intermediate subunit was formed in more central areas of the bay.

c) The Sant Onofre carbonate unit ends the lower Pliocene succession in this area. This unit is formed by palustrine and lacustrine mudstone and carbonates with common root traces and charophyte oogonies, as well as fossil micromammals that allow assigning these deposits to the Ruscinian (Agustí et al., 1983; Agustí, 1985). de Gibert (1996) described an additional very distinctive unit in the lower Pliocene deposits, the rhodophyte unit. This is herein referred to as the vermetid–coralline algal unit. This unit develops on top of an existing rocky palaeorelief and it is buried by the Campredó blue clay unit, which onlaps the pre-Pliocene substrate (Figs. 2 and 3). This unit is the object of the present paper and is fully described below. Red continental conglomerates, the Roca Corba conglomerate unit, overlay on top of the lower Pliocene lacustrine deposits (Arasa, 1990). This author attributed these terrigenous sediments to the upper Pliocene (Villafranchian ?). 4. General features of the vermetid–coralline algal unit This unit crops out in a very limited area associated to a pre-existing palaeohigh made up of Miocene conglomerates (Figs. 2 and 3). This palaeorelief is constituted by a flat, horizontal platform and a steeply dipping slope. The carbonate unit, consisting of a crust several decimeters in thickness on top of the flat platform, is made up of vermetid– coralline algal bindstones and associated packstones. They are

12

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

Fig. 3. General view of the Sant Onofre outcrop and its explanatory diagram.

exposed discontinuously on an area of about 150 m2. Nevertheless, they are seen only in slightly higher areas, as the substrate in between is covered by burrowed sandstones of the upper sandy clay subunit. Up to 8 m of the slope of the palaeorelief is exposed below the platform. This palaeocliff bears abundant bioerosion trace fossils (mostly Gastrochaenolites and Entobia) and encrusting oysters, pectinids and barnacles (de Gibert et al., 1998). The slope is made up of areas of the pre-Pliocene substrate but also by sectors where boulders and breccias of smaller clasts cover the substrate. The carbonate facies found on the flat top extend into the slope occupying

small gutters between boulders. Here, the carbonates are made up of coralline algal patches encrusting serpulids and vermetids. 5. Taxonomic and taphonomic description of the fossil assemblages 5.1. The framework builders The bioconstruction is mostly formed by the intergrowth of vermetids and coralline algae, locally accompanied by serpulid worms (Fig. 4). However, the proportion of the two major builders varies

Fig. 4. A. Close-up view of the vermetid–coralline algal framework at the top of the palaeotopographic high. Note the fine-grained nature (packstone, sometimes mudstone) of the matrix (the yellowish sediment). B. Close-up view of the bioconstruction showing the vermetids encrusted by the coralline algae.

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

depending on the position in the palaeohigh. The buildup in the flat top of the palaeorelief is mostly dominated by vermetids, while coralline algae are the most important framework builders in the patches colonizing the boulders and breccias deposited in the talus surrounding the high. In the top of the palaeotopographic high, the bioconstruction framework is produced by the vertical growth of the gastropods. Vermetids have been identified as Dendropoma sp., which built tubular, wormlike aragonitic skeletons with diameters of up to 5 mm. Coralline algae coated and intergrew among the vermetid shells. The combined growth of vermetids and coralline algae produced a rigid framework but with numerous voids in between. These open spaces were filled up with micrite carbonate (wackestone, rarely mudstone) (Fig. 4). The most abundant coralline algal species encrusting the vermetids is the mastophoroid Spongites fruticulosus (85% of the total algal assemblage) (Fig. 5A–C), followed in lesser abundance by Neogoniolithon brassica-florida (15% of the assemblage) (Fig. 5D). Spongites forms both massive crusts (up to 1.5 mm thick) and fruticose thalli (up to 1.5 cm long), while Neogoniolithon shows an encrusting growth habit (up to 1 mm in thickness). When the two species are present, Neogoniolithon always attaches directly on the vermetid shells, while Spongites normally grows on top of the previous algal colonization. Very often, encrusting benthic foraminifers, such as planorbulinids and rarely Haddonia and Miniacina, occur attached to the coralline algae (de Gibert, 1996). The organisms erecting the bioconstruction are preserved in their original growth position. This is inferred since the maximum development of coralline algal upward growths is consistent with geopetal filling-up fabrics pointing to an upright orientation. In the talus surrounding the palaeohigh, heterogeneous breccias consisting of blocks of conglomerates derived from the pre-Pliocene basement were deposited. Coralline algal–serpulid–vermetid patches formed in the talus. They extend continuously down slope colonizing groove-like structures joining together blocks (Fig. 6). The patches are mostly formed by coralline algae intergrowing mainly with wormtube serpulids and, in lesser abundance, Dendropoma. As in the upper flat platform, Spongites fruticulosus is the most abundant coralline algal

13

Fig. 6. A. Coralline algal patches growing in the talus of the palaeohigh. B. The coralline algae are joining together blocks of the talus deposits Inset represents a detailed view of the coralline algal crusts. Cap of photo camera = 60 mm.

species, followed by Neogoniolithon brassica-florida in lesser abundance. These two algal species show the same growth habits and disposition as described above. In one sample, collected in the lowermost part of the talus deposits, a fruticose thallus of Lithothamnion sp. occurs. The matrix

Fig. 5. Microphotographs of the framework assemblage. A. General view of the vermetids (V) encrusted by the coralline algae (CA). S = serpulid B. Overgrowth of S. fruticulosus. C. Detail of S. fruticulosus showing the thallus anatomy and uniporate sporangial conceptacles. D. Encrusting thallus of N. brassica-florida. C = uniporate sporangial conceptacles.

14

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

enveloping the builders is a bioclastic packstone, occasionally grainstone. Identifiable bioclasts are foraminifers, barnacle plates, bivalves, gastropods and fragments of regular echinoids. 5.2. The dwelling populations associated with the bioconstruction Organisms associated with the builders correspond to two separate guilds: those dwelling directly related to it (the bioconstruction dwelling guild) (Fig. 7), and those who inhabited the cliff below (the cliff dwelling/destroying guilds) (Figs. 8 and 9). The bioconstruction dwelling guild was formed by a plethora of different taxa, mainly invertebrates. Molluscs are the most diversified and are recorded as shells of epibenthic pectinids (Chlamys multistriata, Mimachlamys varia) or casts and internal molds of epi- or endobenthic gastropods (muricids, nassarids, olivids, cancellarids, etc.), and endobenthic bivalves (mainly veneraceans), mostly with complete valves and closed shells (Fig. 7D and E). Moreover, some scarce ahermatypic colonies of the coral Cladocora? have been tentatively identified, as the skeleton is dissolved (Fig. 7B and F). Inside the corals, there are concentrations of barnacle cirripeds attributed to the family Pyrgomatidae, probably belonging to the genus Savignium, formerly Pyrgoma according to Mokady et al. (1999) and Brickner and Høeg (2010). These barnacles may also occur as isolated complete and

articulated skeletons and forming chaotic concentrations of several decimeters in the largest dimension (Fig. 7A and C). In all these cases, cirriped skeletons come out complete, sometimes slightly crushed due to sediment overload. Other barnacles (Balanus trigonus) under 1 cm high also appear attached to molluscan shells or pebbles. Echidoids also inhabited the bioconstruction (Fig. 7H). They are mainly represented by cidaroids, occurring as fragments or collapsed tests or isolated spines, and other regular echinoids. The bioconstruction gave rise to a hard substrate on which lithophagous mytilids bored. Although Gastrochaenolites are more conspicuous in cobbles and rocky surfaces, several quite big molds of the borer mytilid Lithophaga sp. (with an antero-posterior diameter up to 7 cm) have been found associated to the buildup (Fig. 7G). The blocks of the palaeocliff talus are extensively bored and encrusted. The main borings are large subhorizontal Gastrochaenolites torpedo, locally in high densities, and Entobia ispp., which occupies the areas between the bivalve borings (Fig. 8A–B). Gastrochaenolites torpedo appears in the lower half of the outcrop, being smaller in the base and larger upwards. Boring assemblages constitute the destroying guild. Attached to the pre-Pliocene conglomeratic wall and to the boulders of the talus, there are numerous encruster bivalves that represent the cliff dwelling guild. They are mainly Neopycnodonte cochlear and the pectinid Hinnites ercolanianus (Fig. 9). Neopycnodontids, especially

Fig. 7. Dwelling community associated to the vermetid–coralline algal framework: A. Pyrgomatid cluster. B. Cladocora? colony. C. Detail of an isolated pyrgomatid. D. Section of an articulated lithophagous bivalve. E. Mold of a muricid gastropod. F. Detail of a Cladocora? colony. G. Mold of an articulated Lithophaga lithophaga. H. Complete cidaroid test.

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

15

Fig. 8. Destroying guild in the palaeocliff talus: A. Gastrochaenolites torpedo. B. G. torpedo (large borings) and Entobia isp. (small borings).

visible over the bored surface, form dense metric concentrations of some hundreds of shells leaned against the palaeorelief and overhanging the lower surface of big blocks in the talus (Fig. 9B). Hinnites ercolanianus are directly attached to the pre-Pliocene conglomerates and share the surface with the bivalve borings (Fig. 9A). These pectinids occur isolated or in clusters of several individuals and only left valves are preserved (Fig. 9A). Moreover, rather isolated Balanus less than 1 cm in high appear directly attached to the conglomerate, or to the other bioclasts. The encrusted valves often also host borings (Entobia ispp., Iramena isp.) and are encrusted in turn by scarce foraminifers, serpulids and bryozoans. 6. Discussion 6.1. Palaeoenvironmental interpretation Previous studies in the Sant Onofre area have shown that the studied lower Pliocene sediments represent rocky-shore deposits formed in very shallow waters based on the boring ichnoassemblage, assignable to the Entobia ichnofacies (Martinell and Domènech, 1995; de Gibert and Martinell, 1996; de Gibert et al., 1998). de Gibert et al. (1998) estimated a water depth from 0 to about 10 m. Furthermore, the abundance of Entobia borings, together with the presence of other ichnogenera (such as Caulostrepsis, Meandropolydora, and Trypanites) in the basal detrital marine unit cropping out in the vicinity of the Sant Onofre high, suggests also very clear waters (Martinell and Domènech, 1995). The mollusk assemblages found in the coetaneous fine-grained siliciclastics

Fig. 9. Dwelling guild inhabiting the palaeocliff talus: A. Hinnites ercolanianus. B. Cluster of Neopycnodonte cochlear.

(blue marl and silt of the Campredó blue clay unit) surrounding the palaeotopographic high points also to a deposition in a very shallow enclosed palaeobay with continental influences (Martinell and Domènech, 1984). The most abundant coralline algal species involved in the vermetid bioconstruction is Spongites fruticulosus, followed by Neogoniolithon brassica-florida in lesser abundance. S. fruticulosus and N. brassica-florida are species typically inhabiting shallow waters, both in the present-day marine waters (Adey and Macintyre, 1973; Adey, 1979; Adey et al., 1982; Minnery et al., 1985; Adey, 1986; Minnery, 1990; Bressan and Babbini, 2003; Braga and Aguirre, 2009) and in other Cenozoic basins (Braga and Martín, 1988; Braga and Aguirre, 2001, 2004; Brandano et al., 2005; Bassi et al., 2006; Braga et al., 2009, 2010; Braga and Bassi, 2011; Langar et al., 2011; Aguirre et al., 2012). When palaeobathymetry can be confidently inferred, S. fruticulosus dominates in waters no deeper than 30 m, as in different upper Miocene reef deposits from west and central Mediterranean (Braga et al., 2009). Therefore, the presence of these two coralline algal species is consistent with the proposed palaeoenvironmental interpretation. Nonetheless, it is worth mentioning that S. fruticulosus has been found up to 75 m water depth in the present-day Mediterranean (Basso and Rodondi, 2006). Algal assemblages in the buildups formed in the talus slope are also dominated by Spongites fruticulosus and Neogoniolithon brassica-florida. It is worth mentioning, however, that we have found Lithothamnion sp.

16

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

in the algal assemblage occurring in the lowermost part of the talus deposits. At present, representatives of the subfamily Melobesioideae occur in deeper waters, several tens of meters, both in present-day Mediterranean (Basso, 1998; Bressan and Babbini, 2003; Braga and Aguirre, 2009) and in other Cenozoic basins (Braga and Aguirre, 2001, 2004; Bassi et al., 2006; Braga et al., 2009, 2010; Aguirre et al., 2012). The empty spaces in the vermetid bioconstruction are filled up by carbonate muddy sediment (wakestone, rarely mudstone). Both in recent and Pleistocene vermetid reefs, the sediment occupying the voids is coarse-grained particles (i.e. Safriel, 1975) since the fine-grained sediments are washed out due to the high hydraulic energy affecting these ecosystems. According to Fleta et al. (1991), the lower Pliocene deposits of the Sant Onofre area were formed in a sheltered bay with a topographic high in the connection of the bay with the open Mediterranean (Fig. 10). This palaeogeographic configuration favored restriction in the inner part of the bay and the consequent deposition of very fine grained sediments in a very low energy context. A low-energy setting is also consistent with the profuse development of coralline algae producing fruticose growth forms (i.e. Adey and Macintyre, 1973; Bosence, 1983; Steneck, 1986). The vertical growth of the vermetid–coralline algal framework might trap the finegrained sediment. Further, low hydraulic energy warranted a stable substrate for the effective attachment of gastropod larvae and algal propagules as well as the subsequent development of the buildup. The studied deposits also suggest a low-sedimentation setting. The present-day Dendropoma reefs grow slowly in areas of low siliciclastic inputs (MAP, 2010). Further, in the case of the coralline algae, they are very sensitive to high sedimentation rates (Adey and Macintyre, 1973; Milliman, 1977; Bosence, 1983; Steller et al., 2009; Aguirre et al., 2012). Experimental studies have shown that coralline algae become killed off after some weeks permanently buried (Figueiredo et al., 2009). Coralline algal–serpulid–vermetid patches occurring in the talus of the palaeotopographic high are made up of fruticose and encrusting coralline algae coating mostly serpulid worm-tubes. These patches stabilized the talus deposits since they occur attached on boulders and clasts joining together the siliciclastic particles. Here, the voids were filled up by coarser sediment (grainstone) than in the top of the palaeohigh. The finer sediment reworked downslope along the talus was washed out and the sediment trapped in the voids was sand particles. The proposed very shallow-water setting for the formation of the Sant Onofre vermetid–coralline algal bioconstruction is consistent with the interpretation proposed for other vermetid reefs found in the

Fig. 10. Palaeogeographic reconstruction of the Sant Onofre area during the lower Pliocene. After Fleta et al. (1991).

fossil record (Pirazzoli et al., 1989; Laborel and Laborel-Deguen, 1996; Antonioli et al., 1999; Betzler et al., 2000; Antonioli et al., 2002; Lambeck et al., 2004; Morhange et al., 2006; Sivan et al., 2010). However, Vescogni et al. (2008) paid attention on the possibility of finding these reefs in deeper settings. Thus, they described vermetid reefs, built up by the gastropod Petaloconchus, in shelf edge and in reef talus, up to 50 m water depths, in late Miocene coral reefs from southern Italy and Crete. Similarly, in the early Pliocene temperate carbonate deposits of the Carboneras Basin (SE Spain), vermetids can be important framework builders in coralline–bryozoan–bivalve bioconstructions formed in outer shelf (Aguirre et al., 2012). Regarding the associated dwelling fauna, vagrant organisms, such as regular echinoids and gastropods, inhabited the buildup. Regular echinoids fed on the algae of the bioconstruction. Vagrant gastropods identified correspond to a variety of feeding habits (herbivorous, scavengers, and carnivorous). Some infaunal bivalves colonized the muddy sediment trapped by the builders. Pectinids, mostly Chlamys multistriata and Mimachlamys varia, were also able to settle on the hard substrate provided by the bioconstruction, especially in relatively low depressions within the bioconstruction. Neopycnodonte cochlear forms dense clusters of many individuals growing cemented one on top of the others. These clusters show a patchy distribution occupying steep cliffs of the substrate, or attached underneath overhangs on blocks of the talus. In present-day oceanic waters, N. cochlear preferentially inhabits deep-water settings from 90 to several hundreds of meters (Wisshak et al., 2009; MAP, 2010; Van Rooij et al., 2010). However, occasionally it is also able to colonize shallow waters, mostly in caves and crevices (Arko-Pijevac et al., 2001; HrsBrenko and Legac, 2006). These authors mentioned the presence of clumps of N. cochlear in submarine caves at 10 to 19 m depth in the Adriatic Sea. Massari et al. (2011) also described N. cochlear concentrations in Pleistocene inner-shelf deposits of Calabria, southern Italy, and interpreted the formation of these aggregations with periods of absence or low terrigenous inputs. In the study case, the relative position of the Neopycnodonte clumps with respect to the flat top of the palaeotopographic high indicates that these aggregations formed in waters no deeper than 10 m. 6.2. Taphonomy Very shallow settings are usually represented by high taphonomic destruction due to a combination of high hydrodynamic energy and long-term exposure of the remains in the taphonomic active zone (Powell et al., 1989; Kidwell and Bosence, 1991). In the case study, however, many pieces of evidences suggest absence of transport or reworking as well as in situ preservation of both the builder and the dwelling populations. As commented above, the organisms building the bioconstruction maintain their original growth position. This is shown by the upright growth position of the vermetid and the branching coralline algae that coincide with the normal geopetal textures filling the voids. The algal–serpulid–vermetid patches along the talus breccias and boulders settled and bounded clasts, thus they remain preserved undisturbed from their original growth position (Fig. 6). Regarding the dwelling guilds, the different accompanying fauna are not randomly distributed in the site, but populations show a patchy occurrence. This suggests that they were preserved maintaining their original distribution within the Sant Onofre palaeohigh. Similarly, Surlyk and Christense (1974) described an example of Campanian rocky shore deposits in which fossil assemblages show a characteristic distribution occupying different parts of the coastal boulders. In our study case, the occurrence of small concentrations of pyrgomatid cirripeds as indication of in situ preservation is of particular interest. Pyrgomatids are obligatory inhabitants of porifers and cnidarians (scleractinians and hydrozoans) that are often coral-specific symbionts (i.e. Brickner and Høeg, 2010; Brickner et al., 2010), at least since the Miocene (Ross and Newman, 2000; Santos et al., 2012). In the study case, clusters of

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

these barnacles are found directly associated with coral colonies (the scleractinian Cladocora ?). Thus, scleractinians were colonized by the barnacles and they remained preserved in direct connection with the coral keeping their original life position. Small clusters of pyrgomatids also occur dispersed in the sediment trapped by the vermetid–coralline algal bioconstruction (Fig. 7A). In this second case, barnacles most likely settled on soft-body organisms (either cnidarians or porifers) and, after the death and decay of the soft-bodied host, the pyrgomatids became concentrated in the attachment place of the host animal. In short, the fossilization process, keeping the original patchy distribution of the different populations as well as the original growth position of the organisms, led to an almost snapshot of the original community. It was only biased due to the destruction of the nonskeletonized organisms and the dissolution of originally aragonitic skeletons. The protected and low energy setting in which the deposits took place account for this particular exceptional preservation in very shallow waters. A similar study case was described by Aguirre and Jiménez (1997, 1998) in upper Pliocene deposits of the Almería–Níjar Basin (SE Spain). 6.3. Sequence stratigraphic significance of the vermetid–coralline algal buildup In the NE Iberian Peninsula basins, Pliocene deposits consist of siliciclastics (Martinell, 1988). The bioconstruction of the Sant Onofre is therefore the only record of carbonates. They were formed in a palaeotopographic high starved of terrigenous material. Coeval terrigenous sediments, clay, silt and sand, were deposited in the surrounding low areas. Sequence stratigraphic framework in which the carbonates were formed can be inferred based on the stratigraphic relationship between the siliciclastics and the carbonates, together with facies and palaeoenvironmental interpretations of the former sediments (Martinell and Domènech, 1984; Arasa, 1990; Martinell and Domènech, 1995; de Gibert and Martinell, 1996; de Gibert et al., 1998) (Figs. 11 and 12). The conglomerates of the basal detrital marine unit, interpreted as littoral deposits (Arasa, 1990), represent the lowstand systems tract sediments. The conglomerate onlaps the pre-Pliocene basement and filled up an erosional surface originated during the sea-level drop of the Messinian salinity crisis (Fleta et al., 1991) (Fig. 12A and B). Thus, the beginning of the lower Pliocene marine deposition in the Baix Ebre Basin has been related with the Pliocene global sea-level rise (Arasa, 1990). At this initial stage of the marine deposition, the prePliocene basement that formed the palaeohigh subsequently colonized by the vermetid–coralline algal bioconstruction was probably emerged (Fig. 12B). The conglomerate unit thins and fines upwards passing gradually to the Campredó blue clay unit (Fig. 2). The lower sandy clay subunit has

17

been interpreted as shallow deposits formed in a restricted palaeobay and the intermediate blue clay subunit represents the deepest deposits of the palaeobay (Martinell and Domènech, 1984; Arasa, 1990). Thus, this part of the unit can be attributed to the transgressive systems tract deposits. During the sea-level rise, the palaeohigh started to be affected by the endolithic communities (Fig. 12C), giving rise to the Entobia ichnofacies in very shallow and clean normal marine waters (Martinell and Domènech, 1995; de Gibert and Martinell, 1996; de Gibert et al., 1998). As the sea-level rose, the palaeohigh was progressively submerged up to the development of the vermetid–coralline algal buildup. Therefore, these carbonate deposits (= the rhodophyte unit of de Gibert, 1996), formed in the top of the palaeohigh during the maximum flooding stage (Fig. 12D). Whether the whole palaeohigh was completely submerged is difficult to state since quarrying activity in the Sant Onofre area might have destroyed part of the outcrops. In any event, marine inundation of the pre-Pliocene substrate in the palaeohigh produced very shallow conditions that favored the profuse development of the vermetid–coralline algal bioconstruction. During the maximum flooding conditions, the finest-grained siliciclastic sediments of the study area, the intermediated blue clay unit, were trapped in the low areas surrounding the palaeohigh, thus triggering the carbonate production on top of the palaeohigh (Fig. 12D). Coarsening-upward trend in the Campredó clay unit, the upper sandy clay subunit, and presence of large scale planar cross-bedding is interpreted as a shallowing trend that ended with the continental lake deposits (the Sant Onofre carbonate unit). Therefore, both the upper part of the Campredó clay and the Sant Onofre carbonate units correspond with the highstand systems tract deposits. These sediments prograded into the basin and covered the vermetid–coralline algal unit (Fig. 12E). The in situ preservation of the whole buildup community was favored due to the rapid advance of the terrigenous deposits that ended the carbonate production and buried the buildup (Fig. 12E). 6.4. Dendropoma reefs as recent analogs From an actualistic point of view, the vermetid–coralline algal buildup of the Sant Onofre is equivalent to the present-day Mediterranean Dendropoma reefs that develop in intertidal or shallow-subtidal settings (i.e. Pérès and Picard, 1964; Safriel, 1975; Templado et al., 2009; MAP, 2010; Chemello and Silenzi, 2011). The most common coralline algal species associated with Dendropoma as major reef builder is Neogoniolithon brassica-florida. This alga inhabits very shallow waters in the present-day Mediterranean (Bressan and Babbini, 2003; Braga and Aguirre, 2009; Langar et al., 2011). However, the Sant Onofre buildup is made up of the intergrowth of Dendropoma and the alga Spongites fruticulosus. This coralline species has never been described so far as major builder of the vermetid

Fig. 11. Summary chart encompassing data on facies, fossil content and sequence stratigraphy of the Sant Onofre outcrop.

18

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

florida, thus the vermetid–algal bioconstruction developed in slightly deeper subtidal waters. 5) Spongites might be common in the recent Dendropoma reefs but it has been misidentified or not yet precisely studied. According to the compilation made by Vescogni et al. (2008), Dendropoma became the most abundant vermetid reef-builder during the Holocene in the Mediterranean. In older deposits, since Middle Miocene to late Pliocene, the major vermetid builder was Petaloconchus instead of Dendropoma (Vescogni et al., 2008). Several hypotheses have been proposed to interpret this change in the composition of the Mediterranean vermetid reefs (Laborel, 1977; Jones and Hunter, 1995), but none of them seem to be satisfactory (Vescogni et al., 2008). To disentangle the mechanisms accounting for this taxonomic replacement is beyond the scope of this paper. Nonetheless, the only vermetid gastropod identified in the Sant Onofre deposits is Dendropoma. This indicates that the evolutionary replacement of the major builders in the Mediterranean vermetid reefs, if true, might start at the end of the Neogene but not during the Holocene. 7. Conclusions

Fig. 12. Interpretative diagrams showing the temporal sequence of events that led to the preservation of the Sant Onofre outcrop.

bioconstructions. Thus, its presence as a major builder in the Sant Onofre bioconstruction is an unusual and new occurrence. Why Spongites fruticulosus is the major builder in the study case is an open question. Several hypotheses can be envisaged: 1) Neogoniolithon brassica-florida might evolve as major builder in the Quaternary, thus, this ecological role in older rocks was addressed by S. fruticulosus. 2) Subtle ecological factors might inhibit the development of one species and favor the growth of the other. For example, N. brassica-florida thrives in high hydrodynamic environments (i.e. Langar et al., 2011). Nonetheless, the inferred palaeoenvironmental conditions suggest deposition in a sheltered, semi-enclosed embayment. Thus, S. fruticulosus could resist better in calmer settings. 3) Alternatively, a certain differential resistance to relatively low salinity waters might also account for the profuse development of S. fruticulosus instead of N. brassica-florida. 4) Additionally, S. fruticulosus is found in deeper waters than N. brassica-

In NE Spain, the only lower Pliocene carbonates are represented by the vermetid–coralline algal bioconstruction from Sant Onofre (Baix Ebre Basin, Tarragona). The framework is made up of the intergrowth of the gastropod Dendropoma and coralline red algae, mostly Spongites fruticulosus with rare Neogoniolithon brassica-florida. The vermetid– coralline algal buildup developed in the flat top of a palaeotopographic high made up of pre-Pliocene sediments cropping out in a sheltered embayment. Blocks and boulders were deposited along the margin of the palaeorelief, representing palaeocliff deposits. Fine-grained siliciclastic sediments were deposited in low areas surrounding the palaeotopographic high and in between the blocks of the talus. Crusts formed by coralline algae intergrowing with serpulids and, in lesser abundance, vermetids extend downwards of the palaeocliff along gully-like structures among talus boulders. The vermetid–coralline algal framework was colonized by a rich and diversified faunal assemblage, including bivalves, vagile gastropods, barnacles (most notably coral and sponge-inhabitants of the family Pyrgomatidae), ahermatypic corals and regular echinoids. Further, blocks of the talus were colonized by patches of Neopycnodonte cochlear and Hinnites ercolanianus. These deposits show also a very rich boring ichnoassemblage, including Gastrochaenolites, Entobia, Maeandropolydora, and Caulostrepsis. Fossil and boring assemblages suggests that the bioconstruction developed in very shallow waters, most likely not deeper than 10 m water depth. Thus, it can be considered as a fossil analog of the Dendropoma reefs occurring in the present-day Mediterranean. In situ preservation of the fossil assemblages, both in the bioconstruction and in the talus deposits, suggests that they represent an almost snapshot of the original community. Burial due to progradation of siliciclastics in a sheltered setting accounts for this exceptional preservation in such a shallow conditions. The sequence stratigraphic framework interpretation indicates that the Sant Onofre Dendropoma reef developed during maximum flooding conditions. Carbonate production took place due to siliciclastic starvation in the top of the palaeotopographic high. Finally, it has been considered that Dendropoma does not become the most abundant vermetid reef-builder until the Holocene in the Mediterranean. Nevertheless, this genus is the sole vermetid gastropod in the Sant Onofre outcrop. This could mean that the evolutionary replacement of Petaloconchus for Dendropoma in the composition of Mediterranean vermetid reefs, if true, already started at the end of the Neogene. Acknowledgments We acknowledge the comments and suggestions made by two anonymous reviewers and by the editor of the journal Prof. Surlyk

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

since they have contributed to improve the quality of the text. This study has been developed in the scope of the Research Projects CGL2010-20857 (JA) and CGL 2010-15047 (ZB, RD, JM), from the Secretaría de Estado de I + D + I, Spain. The work by JA is also supported by the Research Group RNM-190 (Junta de Andalucía).

References Adey, W.H., 1979. Crustose coralline algae as microenvironmental indicators in the Tertiary. In: Gray, J., Boucot, A.J. (Eds.), Historical Biogeography, Plate Tectonics and the Changing Environment. Oregon State Univ. Press, Corvallis, pp. 459–464. Adey, W.H., 1986. Coralline algae as indicators of sea-level. In: van de Plassche, O. (Ed.), Sea-level Research: A Manual for the Collection and Evaluation of Data. Free Univ. Amsterdam, Amsterdam, pp. 229–279. Adey, W.H., Macintyre, I.G., 1973. Crustose coralline algae: a re-evaluation in the geological sciences. Geol. Soc. Am. Bull. 84, 883–904. Adey, W.H., Townsend, R.A., Boykins, W.T., 1982. The crustose coralline algae (Rhodophyta: Corallinaceae) of the Hawaiian Islands. Smithson. Contrib. Mar. Sci. 15, 1–74. Aguirre, J., Jiménez, A.P., 1997. Census assemblages in hard-bottom coastal communities: a case study from the Plio-Pleistocene Mediterranean. Palaios 12, 598–608. Aguirre, J., Jiménez, A.P., 1998. Fossil analogues of present-day Cladocora caespitosa coral banks: sedimentary setting, dwelling community, and taphonomy (Late Pliocene, W Mediterranean). Coral Reefs 17, 203–213. Aguirre, J., Braga, J.C., Martín, J.M., Betzler, C., 2012. Palaeoenvironmental and stratigraphic significance of Pliocene rhodolith beds and coralline algal bioconstructions from the Carboneras Basin (SE Spain). Geodiversitas 34, 115–136. Agustí, J., 1985. Roedores y lagomorfos (Mammalia) del Plioceno de San Onofre (Baix Ebre, NE de Espana). Paleontologia i Evolució 19, 57–60. Agustí, J., Anadón, P., Julià, R., 1983. Nuevos datos sobre el Plioceno del Baix Ebre. Aportación a la correlación entre las escalas marina y continental. Acta Geol. Hisp. 18, 123–130. Antonioli, F., Chemello, R., Improta, S., Riggio, S., 1999. Dendropoma lower intertidal reef formations and their palaeoclimatological significance, NW Sicily. Mar. Ecol. 161, 155–170. Antonioli, F., Cremona, G., Immordino, F., Puglisi, C., Romagnoli, C., Silenzi, S., Valpreda, E., Verrubbi, V., 2002. New data on the Holocenic sea-level rise in NW Sicily (Central Mediterranean Sea). Glob. Planet. Chang. 34, 121–140. Arasa, A., 1990. El Terciario del Baix Ebre: aportaciones estratigráficas y sedimentológicas. Acta Geol. Hisp. 25, 271–288. Arko-Pijevac, M., Benac, C., Kovacic, M., Kirincic, M. & M., 2001. A submarine cave at the Island Krk (North Adriatic Sea). Natura Croatica 10, 163–184. Bassi, D., Carannante, G., Murru, M., Simone, L., Toscano, F., 2006. Rhodalgal/bryomol assemblages in temperate-type carbonate, channelized depositional systems: the Early Miocene of the Sarcidano area (Sardinia, Italy). In: Pedley, H.M., Carannante, G. (Eds.), Cool-water Carbonates: Depositional Systems and Palaeoenvironmental Control. Geological Society of London, Special Publications, 255, pp. 35–52. Basso, D., 1998. Deep rhodolith distribution in the Pontian Islands, Italy: a model for the paleoecology of a temperate sea. Palaeogeogr. Palaeoclimatol. Palaeoecol. 137, 173–187. Basso, D., Rodondi, G., 2006. A Mediterranean population of Spongites fruticulosus (Rhodophyta, Corallinales), the type species of Spongites, and the taxonomic status of S. stalactitica and S. racemosa. Phycologia 45, 403–416. Betzler, C., Martín, J.M., Braga, J.C., 2000. Non-tropical carbonates related to rocky submarine cliffs (Miocene, Almería, southern Spain). Sediment. Geol. 131, 51–65. Blanc, J.J., Moliner, R., 1955. Les formations organogènes construites superficialles en Méditerranée occidentale. Bulletin Inst. Océanogr. Monaco 52, 1–26. Bosence, D.W.J., 1983. The occurrence and ecology of recent rhodoliths—a review. In: Peryt, T.M. (Ed.), Coated Grains. Springer-Verlag, Berlin, pp. 225–242. Bosence, D.W.J., 1985. The “Coralligène” of the Mediterranean—a Recent analog for Tertiary coralline algal limestones. In: Toomey, D.F., Nitecki, M.H. (Eds.), Paleoalgology: Contemporary Research and Applications. Springer-Verlag, Berlin, pp. 216–225. Bouderesque, C.F., 2004. Marine biodiversity in the Mediterranean: status of species, populations and communities. Scientific Reports Port-Cross National Park, France. 20, pp. 97–146. Braga, J.C., Aguirre, J., 2001. Coralline algal assemblages in upper Neogene reef and temperate carbonates in Southern Spain. Palaeogeogr. Palaeoclimatol. Palaeoecol. 175, 27–41. Braga, J.C., Aguirre, J., 2004. Coralline algae indicate Pleistocene evolution from deep, open platform to outer barrier reef environments in the northern Great Barrier reef margin. Coral Reefs 23, 547–558. Braga, J.C., Aguirre, J., 2009. Algas Calcáreas del Parque Natural de Cabo de Gata-Níjar. Guía de Campo. In: Villalobos, M., Pérez-Muñoz, A.B. (Eds.), ACUMED y Consejería de Medio Ambiente. Junta de Andalucía (142 pp.). Braga, J.C., Bassi, D., 2011. Facies and coralline algae from Oligocene limestones in the Malaguide Complex (SE Spain). Ann. Naturhist. Mus. Wien Ser. A 113, 267–289. Braga, J.C., Martín, J.M., 1988. Neogene coralline–algal growth-forms and their palaeoenvironments in the Almanzora River Valley (Almeria, S.E. Spain). Palaeogeogr. Palaeoclimatol. Palaeoecol. 67, 285–303. Braga, J.C., Vescogni, A., Bosellini, F., Aguirre, J., 2009. Coralline algae in Mediterranean Messinian reefs. Palaeogeogr. Palaeoclimatol. Palaeoecol. 275, 113–128. Braga, J.C., Bassi, D., Piller, W., 2010. Palaeoenvironmental significance of Oligocene– Miocene coralline red algae—a review. In: Mutti, M., Piller, W., Betzler, C. (Eds.),

19

Oligocene–Miocene Carbonate Systems. International Association of Sedimentologists, Special Publication, 42, pp. 165–182. Brandano, M., Vannucci, G., Pomar, L., Obrador, A., 2005. Rhodolith assemblages from the lower Tortonian carbonate ramp of Menorca (Spain): environmental and paleoclimatic implications. Palaeogeogr. Palaeoclimatol. Palaeoecol. 226, 307–323. Bressan, G., Babbini, L., 2003. Corallinales del Mar Mediterraneo: Guida Alla Determinazione. Biol. Mar. Mediterr. 10 (supplement 2), 1–237. Brickner, I., Høeg, J.T., 2010. Antennular specialization in cyprids of coral-associated barnacles. J. Exp. Mar. Biol. Ecol. 392, 115–124. Brickner, I., Simon-Blecher, N., Achituv, Y., 2010. Darwin's Pyrgoma (Cirripedia) revisited: revision of the Savignium Group, molecular analysis and description of new species. J. Crustac. Biol. 30, 266–291. Calvo, M., Templado, J., Oliverio, M., Machordom, A., 2009. Hidden Mediterranean biodiversity: molecular evidence for a cryptic species complex within reef building vermetid gastropod Dendropoma petraeum (Mollusca: Caenogastropoda). Biol. J. Linn. Soc. 96, 898–912. Chemello, R., Silenzi, S., 2011. Vermetid reefs in the Mediterranean Sea as archives of sealevel and surface temperature changes. Chem. Ecol. 27, 121–127. de Gibert, J.M., 1996. Icnologia de les conques marines pliocenes del marge nordoccidental de la Mediterrània. Unpublished Ph.D. Thesis, Universitat de Barcelona (264 pp.). Available athttp://hdl.handle.net/10803/1577 de Gibert, J.M., Martinell, J., 1996. Trace fossil assemblages and their palaeoenvironmental significance in the Pliocene marine deposits of the Baix Ebre (Catalonia, NE of Spain). Géol. Mediterr. 23, 211–225. de Gibert, J.M., Martinell, J., 1998. Ichnofabrics of the Pliocene marginal marine basins of the northwestern Mediterranean. Rev. Soc. Geol. Esp. 11, 43–56. de Gibert, J.M., Martinell, J., Domènech, R., 1998. Entobia ichnofacies in fossil rocky shores, lower Pliocene, northwestern Mediterranean. Palaios 13, 476–487. Figueiredo, M.A. de O., Villas-Boas, A.B., Tâmega-Rodrigo-Mariath, F.T. de S., Khader, S., 2009. Burial effects on the primary production of coralline algae of a shallow rhodolith bed in Búzios, Brazil. III International Rhodolith Workshop, Abstract Book, Búzios, Brazil. Fleta, J., Arasa, A., Escuer, J., 1991. El Neógeno del Empordà y Baix Ebre (Catalunya): estudio comparativo. Acta Geol. Hisp. 26, 159–171. Gignoux, M., Fallot, P., 1922. Le Pliocène marin sur les côtes méditerranées d'Espagne. C. R. Acad. Sci. Paris 175, 281–283. Guimerà, J., Álvaro, M., 1990. Structure et évolution de la compression alpine dans la Chaine ibérique et la Chaîne côtière catalane (Espagne). Bull. Soc. Geol. Fr. 6 (sec. 8), 339–340. Hrs-Brenko, M., Legac, M., 2006. Inter- and intra-species relationships of sessile bivalves on the eastern coast of the Adriatic Sea. Natura Croat. 15, 203–230. Jones, B., Hunter, I.G., 1995. Vermetid buildups from Grand Cayman, British West Indies. J. Coast. Res. 11, 973–983. Keen, M., 1961. A proposed reclassification of the gastropod family Vermetidae. Bull. Br. Mus. Nat. Hist. 7, 15–213. Kidwell, S.M., Bosence, D.W.J., 1991. Taphonomy and time-averaging of marine shelly fauna. In: Allison, P.A., Briggs, D.E.G. (Eds.), Taphonomy. Releasing the Data Locked in the Fossil Record, pp. 115–209 (New York). Laborel, J., 1961. La concretionnement algal ‘coralligène’ et son importance geomorphologique en Méditerranée. Rec. Trav. Stat. Mar. Endoume-Marseille (23), 37–60 Fascicule Hors Série. Laborel, J., 1977. Are reef building vermetids disappearing in the South Atlantic? Proceedings of the 3rd International Coral Reef Symposium, Miami, pp. 233–237. Laborel, J., 1986. Vermetids. In: van de Plaasche, O. (Ed.), Sea-level Research, a Manual for the Collection and Evaluation of Data. 12. Geo Books, Norwich, pp. 281–310. Laborel, J., 1987. Marine biogenic constructions in the Mediterranean. Scientific Reports Port-Cross National Park. 13, pp. 97–126. Laborel, J., Laborel-Deguen, F., 1996. Biological indicators of Holocene sea-level and climatic variations on rocky coasts of tropical and subtropical regions. Quat. Int. 31, 53–60. Lambeck, K., Antonioli, F., Purcell, A., Silenzi, S., 2004. Sea-level change along the Italian coast for the past 10,000 yr. Quat. Sci. Rev. 23, 1567–1598. Langar, H., Bessibes, M., Djellouli, A., Pergent-Martini, C., Pergent, G., 2011. The Neogoniolithon brassica-florida (Harvey) Setchell & Mason (1943) reef of Bahiret el Bibane lagoon (southeastern Tunisia). J. Coast. Res. 27, 394–398. Martinell, J., 1988. An overview of the marine Pliocene of N.E. Spain. Géol. Mediterr. XV (4), 227–233. Martinell, J., Domènech, R., 1984. Malacofauna del Plioceno de Sant Onofre (Baix Ebre, Tanagona). 4. lberus 1–17. Martinell, J., Domènech, R., 1995. Bioerosive structures on the Pliocene rocky shores of Catalonia (Spain). Rev. Esp. Paleontol. 10, 37–44. Massari, F., Rio, D., Sgavetti, M., Prosser, G., D'Alessandro, A., Asioli, A., Capraro, L., Fornaciari, E., Tateo, F., 2011. Interplay between tectonics and glacio-eustasy: Pleistocene succession of the Crotone basin, Calabria (southern Italy). Geol. Soc. Am. Bull. 114, 1183–1209. Mediterranean Action Plan (MAP), 2010. Initial Assessment of the Mediterranean Sea: Fulfilling Step 3 of the ECAP Process. Report prepared by Dr. Tundi Agardy. at: http://195. 97.36.231/dbases/Members%20Area/ECAP/Med%20Assessment%20Final[1].pdf. Milliman, J.D., 1977. Role of calcareous algae in Atlantic continental margin sedimentation. In: Flügel, E. (Ed.), Fossil Algae. Recent Results and Developments. SpringerVerlag, Berlin, pp. 232–247. Minnery, G.A., 1990. Crustose coralline algae from the Flower Garden Banks, northwestern Gulf of Mexico: controls on distribution and growth morphology. J. Sediment. Petrol. 60, 992–1007. Minnery, G.A., Rezak, R., Bright, T.J., 1985. Depth zonation and growth form of crustose coralline algae: Flower Garden Banks, Northwestern Gulf of Mexico. In: Toomey, D.F., Nitecki, M.H. (Eds.), Paleoalgology: Contemporary Research and Applications. Springer, pp. 237–246.

20

J. Aguirre et al. / Palaeogeography, Palaeoclimatology, Palaeoecology 395 (2014) 9–20

Mokady, O., Loya, Y., Achituv, Y., Gefen, E., Grauer, D., Rozenblatt, S., Brickner, I., 1999. Speciation versus phenotypic plasticity—Darwin's observations in an ecological context. J. Mol. Ecol. 49, 367–375. Morhange, C., Pirazzoli, P.A., Marriner, N., Montaggioni, L.F., Nammour, T., 2006. Late Holocene relative sea-level changes in Lebanon, eastern Mediterranean. Mar. Geol. 230, 99–114. Pérès, J.M., Picard, J., 1964. Nouveau manuel de Bionomie benthique de la Mer Méditerranée. Rec. Trav. Stat. Mar. Endoume 31/47, 1–137. Pirazzoli, P.A., Montaggioni, L.F., Saliège, J.F., Segonzac, G., Thommeret, Y., VernaudGrazzini, C., 1989. Crustal block movements from Holocene shorelines: Rhodes Island (Greece). Tectonophysics 170, 89–114. Powell, E.N., Staff, G.M., Davies, D.J., Callender, W.R., 1989. Macrobenthic death assemblages in modern marine environments: formation, interpretation, and application. Aquat. Sci. 1, 555–589. Ross, A., Newman, W.A., 2000. Coral barnacles: Cenozoic decline and extinction in the Atlantic/East Pacific versus diversification in the Indo-West Pacific. Proceedings 9th International Coral Reef Symposium. 1 (6 pp.). Safriel, U.N., 1975. The role of vermetid gastropods in the formation of Mediterranean and Atlantic reefs. Oecologia 20, 85–101. Santos, A., Mayoral, E.J., Baarli, G., Da Silva, C.M., Cachão, M., Johnson, M.E., 2012. Symbiotic association of a pyrgomatid barnacle with a coral from a volcanic Middle Miocene shoreline (Porto Santo, Madeira Archipelago, Portugal). Palaeontology 55, 173–182. Sarà, G., Sarà, A., Milanese, M., 2011. The Mediterranean intertidal habitat as a natural laboratory to study climate change drivers of geographic patterns in marine biodiversity. Chem. Ecol. 27, 91–93. Schiapparelli, S., Cattaneo-Vietti, R., 1999. Functional morphology of vermetid feedingtubes. Lethaia 32, 41–46. Schiapparelli, S., Albertelli, G., Cattaneo-Vietti, R., 2006. Phenotypic plasticity of Vermetidae suspension feeding: a potential bias in their use as a biological sealevel indicator. Mar. Ecol. 27, 44–53. Silenzi, S., Antonioli, F., Chemello, R., 2004. A new marker for sea surface temperature trend during the last centuries in temperate areas: vermetid reef. Glob. Planet. Chang. 40, 105–114.

Sisma-Ventura, G., Guzner, B., Yam, R., Fine, M., Shemesh, A., 2009. The reef builder Dendropoma petraeum—a proxy of short and long term climatic events in the eastern Mediterranean. Geochim. Cosmochim. Acta 73, 4376–4383. Sivan, D., Schattner, U., Morhange, C., Boaretto, E., 2010. What can a sessile mollusk tell about neotectonics? Earth Planet. Sci. Lett. 296, 451–458. Steller, D.L., Riosmena-Rodríguez, R., Foster, M.S., 2009. Living rhodolith bed ecosystems in the Gulf of California. In: Johnson, M.E., Ledesma-Vázquez, J. (Eds.), Atlas of Coastal Ecosystems in the Western Gulf of California. Tracking Limestone Deposits on the Margin of a Young Sea. The University of Arizona Press, Tucson, pp. 72–82. Steneck, R.S., 1986. The ecology of coralline algal crusts: convergent patterns and adaptive strategies. Annu. Rev. Ecol. Syst. 17, 273–303. Surlyk, F., Christense, W.K., 1974. Epifaunal zonation on an Upper Cretaceous rocky coast. Geology 2, 529–534. Templado, J., Calvo, M., Garvía, A., Luque, A.A., Maldonado, M., Moro, L., 2004. Guía de los invertebrados y peces marinos españoles protegidos por la legislación nacional e internacional Madrid. Naturaleza y Parques Nacionales. Colección Técnica. Ministerio de Medio Ambiente (214 pp.). Templado, J., Guallart, J., Capa, M., Luque, A.A., 2009. 1170 Arrecifes. In: VV.AA. (Ed.), Bases ecológicas preliminares para la conservación de los tipos de hábitat de interés comunitario en España. Ministerio de Medio Ambiente, y Medio Rural y Marino, Madrid (142 pp.). Van Rooij, D., De Mol, L., Le Guilloux, E., Wisshak, M., Huvenne, V.A.I., Moeremans, R., Henriet, J.P., 2010. Environmental setting of deep-water oysters in the Bay of Biscay. Deep-Sea Res. I 57, 1561–1572. Vescogni, A., Bosellini, F.R., Reuter, M., Brachert, T.C., 2008. Vermetid reefs and their use as palaeobathymetric markers: new insight from the late Miocene of the Mediterranean (southern Italy, Crete). Palaeogeogr. Palaeoclimatol. Palaeoecol. 267, 89–101. Wisshak, M., López Correa, M., Gofas, S., Salas, C., Taviani, M., Jakobsen, J., Freiwald, A., 2009. Shell architecture, element composition, and stable isotope signature of the giant deep-sea oyster Neopycnodonte zibrowii sp. n. from the NE Atlantic. Deep-Sea Res. I 56, 374–407.