Vachard et al.—Eifelian–Givetian foraminifers of the Carnic Alps (Austria)


Depositional environment.—Kreutzer (1992a, b) interpreted the Feldkogel Limestone as intertidal deposits. Pohler et al. (2015) described the Polinik Formation (including the Feldkogel Limestone) as cyclic, shallow marine (inter- to supratidal) deposits of a sheltered lagoon (see also Bandel, 1972). The microfacies encountered in this study have been


described by numerous authors (Wilson, 1975; Préat and Mamet, 1989; Vachard, 1993; Préat and Kasimi, 1995; Flügel, 2004; Mamet and Préat, 2005, 2007, 2009; Préat et al., 2007; Vachard et al., 2010; Mörtl, 2014; Kröck, 2016). They are classically interpreted as follows, from deep lagoonal to intertidal and supratidal: (1) Amphipora floatstone to rudstone formed in a low-energy, restricted subtidal environment of an inner platform or lagoon (Machel and Hunter, 1994; Da Silva and Boulvain, 2004); (2) grainstone to packstone with parathuramminids, issinellids, and earlandiids are interpreted as deposits of a high-energy intertidal environment; laminated grain- and packstone are typical intertidal lithologies and may also occur in the shallow subtidal (Pratt, 2010); (3) ostracode wackestone-packstone indicates a low-energy restricted inter- tidal lagoonal environment; (4) bindstone (stromatolite) formed in an upper intertidal to supratidal environment (e.g., Shinn, 1983; Pratt, 2010); and (5) intraclast breccia represents tidal channel deposits, which are common in the intertidal environ- ment (Shinn, 1983; Pratt, 2010). The described lithofacies of the Feldkogel Limestone at


Mount Polinik are locally arranged to form shallowing-upward cycles, starting with subtidal Amphipora limestone, overlain by intertidal wackestone, grainstone and packstone with locally intercalated intraclast breccia and finally by shallow intertidal to supratidal stromatolite. Amphipora grew upright on the bottom in a subtidal


lagoonal environment, attached to the carbonate mud, and toppled in situ after death. Their ecology was well explained by Mörtl (2014). Amphipora floatstone is a typical lithology in the backreef (lagoonal) facies of many Upper Devonian reefal environments, representing relatively shallow- and quiet-water conditions (Machel and Hunter, 1994). The paleocology of the parathuramminids, issinellids, and earlandiids is more difficult to reconstruct (see below). Parathuramminid, issinellid, and earlandiid ecologies.—


As the Devonian foraminifers of the class Fususulinata have no modern representatives, it is preferable to reconstruct the paleoecology of the Devonian foraminifers using the method of the morphogroup rather than that of comparative autoecol- ogy. The term morphogroup refers to broad groupings of similar shapes or growth patterns of foraminifers that are independent on the exact taxonomy and of the possible homeomorphs. Morphogroups offer a way of overcoming taxonomic differ- ences and thereby making comparisons between assemblages of different geological ages (Murray et al., 2011); consequently, they have been generally used to reconstruct fossil paleoenvir- onments (Chamney, 1976; Jones and Charnock, 1985; Murray, 1991; Nagy, 1992; Kaminski et al., 1995; Nagy et al., 1995; Jones, 1999; Preece et al., 1999; Van Den Akker et al., 2000; Mancin, 2001; Jones et al., 2005; Kender et al., 2008a, b; Cetean et al., 2011). Within the morphogroups, it is also interesting to try to reconstruct the microhabitats of the different components of the morphogroups. As indicated by Sen Gupta (2002, p. 163),


365


“a ‘microhabitat’ is a microenvironment characterized by a combination of physical, chemical and biological conditions (oxygen, food, toxic substances, biological interactions, etc.).” Several authors have suggested a close relationship between microhabitat and test morphology (Sen Gupta, 2002, with references therein). Because the foraminiferal test morphology is directly controlled by morphofunctional factors such as nutrient strategy and life position (Tyszka, 1994; Coccioni et al., 1995; Reolid et al., 2008), it is easy to admit that the same morphogroups have been present since the Devonian into the Holocene (Coccioni et al., 1995, with references therein). Consequently, in our material, the morphogroups A and C of Charnock and Jones (1985); and their equivalents A-1 and A-2 of Coccioni et al. (1995), ED1, ED2, and ED4 of Holcová and Slavík (2013), A and B1 of Murray et al. (2011), are represented. Morphogroup A is constituted by the earlandiids, which are tubular, epifaunal suspension-feeders. Morphogroup C is represented by the caligellids, which are elongate forms, infaunal herbivores, or detritivores. The pseudoammodiscids (i.e., primitive archaediscates) and saccamminids were not encountered in our material, and it is noteworthy that all representatives of morphogroup B are absent. Similarly, the epiphytic foraminfers of morphogroup D are totally absent from the Mount Polinik microfacies. Due to their shape, calcisphaeroids and parathuramminids


have often been interpreted as elements of phytoplankton or zooplankton (Munnecke and Servais, 2008; Mörtl, 2014), and do not belong to benthic foraminifer morphogroups. Never- theless, these microorganisms appear related, if not restricted, to confined enviroments: lagoon and/or microbialitic and even stromatolitic build-ups. They appear more as resistance cysts than as planktonic tests or skeletons. The arguments to justify the assignment to plankton given by Munnecke and Servais (2008) were: (1) abundance; (2) occcurences in different facies; and (3) spherical shape. Finally, the saccamminid and parathuramminid foraminifers, which are possibly detrital/ bacterial scavengers, might be partially transported in suspen- sion. Given such hypotheses, it is no wonder that calcispheroids and parathuramminids were confused with calcified radiolarians by Vizhnevskaya and Sedaeva (2002a, 2002b) and Afanasieva and Amon (2011). The other taxon to discuss is Vasicekia? sp. This taxon can


also correspond to Palachemonella (Flügel and Hötzl, 1971, pl. 2, figs. 8–10). It belongs to the incertae sedis Moravammi- nida and Issinellina (Vachard and Cózar, 2010). Vasicekia Pokorny, 1951 was erroneously assigned to the Nanicellidae by Poyarkov (1979), who included all the Moravamminidae in the superfamily Hippocrepinoidea, which encompassed: Hippocrepinidae (Astrorhizata), Moravamminidae (incertae sedis in our opinion; see Vachard and Cózar, 2010), Earlandiidae, and Caligellidae (also linked together in this paper). Another Moravammina confused with a Nanicella was recently published by Préat et al. (2007). This misinterpretation explains how the Moravammina, which is so frequent in the type Givetian, were almost never mentioned by Préat or Mamet in their works about this stage: these authors confused the first coiled part of Moravammina with Nanicella, and the uncoiled last parts of Moravammina with Triangulinella or Kamaena.


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