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Biostratigraphy and facies analysis of the Ionian Islands Paleogene with emphasis on the larger foraminifera
No full textNew records of Somalina, Globoreticulina and Austrotrillina (Larger Foraminifera) from the Eocene of Zakynthos (Ionian Islands, Greece) / Zakynthos (Ionian Adaları, Yunanistan) Eosen İstifinde Somalina, Globoreticulina ve Austrotrillina’nın (İri Bentik Foraminifer) Yeni Bulguları
No full textWe describe the new records of three larger foraminiferal genera from the Eocene of Zakynthos (pre-Apulian Domain; Ionian Islands, Greece), and their biostratigraphic and paleobiogeographic significance.
Somalina Silvestri 1939 is a porcelaneous form that differs from Opertorbitolites Nuttal 1925 mainly for the numerous chamberlet-like cavities enclosed in the prominent lateral laminae. It has been recorded from the upper Cuisian−Lutetian of north-eastern Africa and the Middle East, but there were
as yet no confirmed records for the central Neo-Tethys and Europe.
Several specimens of Somalina were found in a clast of a conglomerate deposits cropping out in Zakynthos near the village of Agia Marina, on the east side of the Mt. Vrachionas anticline, with Alveolina cremae Checchia-Rispoli 1905, Orbitolites cf. complanatus Lamarck 1801 and Opertorbitolites sp. (upper Cuisian, SBZ 12 sensu Serra-Kiel et al. 1998). As the assemblage within the clast seems autochthonous or parautochthonous, the co-occurrence of these three Orbitolites-like forms is noteworthy, because it may indicate that possible mutual competition among the three genera did not lead necessarily to ecological exclusion. (Excerpt from Abstract
A new Miscellanea (Foraminiferida) from the Selandian of the central Neotethys
No full textWe present a new species of Miscellanea from a Selandian clast of the Mt. Vrachionas succession conglomerate (Zakynthos, Greece; Dermitzakis, 1978). This species occurs also in various coeval deposits from central and southern Italy: Mattinata (Gargano), Rio Arno (Gran Sasso), Conca di Cittareale (Rieti).
The new species is a potential additional marker of SBZ 2 (Shallow Benthic Zones sensu Serra-Kiel et al., 1998), and represents a noteworthy occurrence in the frame of the biotic recovery after the K/T event, as well as the co-occurring larger foraminiferal assemblages.
The investigated specimens come from a conglomerate cropping out along the Romiri/Macherado-Agalas road, near the village of Kiliomeno, Zakynthos, Ionian Islands, Greece (37°44.603' N
20°47.795' E).
The age of the assemblage is Selandian, SBZ 2 sensu Serra-Kiel et al. (1998). Miscellanea n. sp. occurs with Haddonia praeheissigi Samuel, Köhler & Borza, 1977, Haymanella paleocenica Sirel, 1998, Kayseriella decastroi Sirel, 1998, Globoflarina sphaeroidea (Fleury, 1982), Pseudocuvillierina sireli (Inan, 1988) and Helenalveolina cf. rahaghii nom. nud. in Drobne et al.
(2005). (Excerpt from text.
A new species of Miscellanea (Foraminiferida) from the Selandian of the central Neo-Tethys
No full textthe new species occurs also in coeval deposits from central and southern Italy: Mattinata (Gargano), Rio Arno (Gran Sasso), Conca di Cittareale (Rieti). The new species is a potential additional marker of SBZ 2 (Shallow Benthic Zones sensu Serra-Kiel et al. 1998), and represents a noteworthy occurrence in the frame of the biotic recovery after the K/T event, as well as the co-occurring larger foraminiferal assemblages. The investigated specimens come from a clast from a conglomerate of the Mt. Vrachionas succession (Dermitzakis 1978) cropping out along the Romiri/Macherado-Agalas road, near the village of Kiliomeno, Zakynthos (Ionian Islands, Greece) (37°44.603' N 20°47.795' E). The age of the assemblage is Selandian, SBZ 2 sensu Serra-Kiel et al. (1998). Miscellanea n. sp. occurs with Haddonia praeheissigi Samuel, Köhler & Borza 1977, Haymanella paleocenica Sirel, 1998, Kayseriella decastroi Sirel, 1998, Globoflarina sphaeroidea (Fleury 1982), Pseudocuvillierina sireli (İnan, 1988) and Helenalveolina cf. rahaghii nom. nud. in Drobne et al. (2005). The microspheric form is lenticular, with strongly biconvex test in axial section, slightly larger than the megalospheric specimens: 1.78 mm (equatorial diameter), 1.11 mm (axial thickness). 33 chambers in the last whorl. There are about 4 regular whorls. The megalospheric form is lenticular, with strongly biconvex test in axial section and a small spherical megalosphere, with a mean internal diameter of 97 μm (n=9). The test thickness (axial section) ranges from 0.77 to 1.05 mm, with a mean value of 0.94 mm (n=7). The equatorial diameter ranges from 1.15 mm to 1.62 mm, with a mean value of 1.25 mm (n=7). At least 23 chambers are present in the last whorl; there are about 3.5 regular whorls. Miscellanea n. sp. differs from M. agriensis Sirel 1997, M. yvettae Leppig 1988, M. ‘juliettae pfenderae’ and M. ‘juliettae villattae’ Leppig 1988 for the diameter of the proloculus, the number of chambers in the last whorl and other characters (number of whorls, test shape and dimensions)
New Late Ypresian (Cuisian) Rotaliids (Foraminiferida) from Central and Southern Italy and Their Biostratigraphic Potential
No full textTwo new rotaliid genera and three new species are described from the Upper Ypresian of Sicily and Central Italy: Ornatorotalia spinosa n. gen. n. sp., Ornatorotalia granum n. sp. and Granorotalia sublobata n. gen. n. sp. The new taxa are all dated as SBZ 11 (middle Upper Ypresian, i.e., middle Cuisian) by the presence of Cuvillierina vallensis and alveolinid biostratigraphical markers such as Alveolina cremae, A. decastroi and A. distefanoi. The systematic position of these distinctive new taxa within the family Rotaliidae Ehrenberg, 1839 and their biostratigraphic potential are discussed
Late Ypresian (Cuisian) rotaliids (Foraminiferida) and their biostratigraphic potential / Geç İpreziyen (Kuiziyen) Rotalid Foraminiferleri ve Biocoğrafik Önemi
No full textOne of the least known groups of larger benthic foraminifers of the Late Ypresian (Cuisian) are a number of as yet undescribed rotaliids, which commonly occur in shallow-water deposits from the central Neo-Tethys. Despite their relative abundance and short distribution range, the biostratigraphic potential of these taxa is as yet unknown, mainly due to relevant taxonomic difficulties. The complexity of the test and the canal system in the Rotaliidae and the necessity to investigate specimens from thin sections are the most common obstacles to investigate in detail these taxa. In the light of these difficulties, systematic description at the high qualitative standard level normally achieved in larger foraminifera may seem a daunting or unfeasible task. From these considerations arises the necessity to recognize provisionally flexible operative criteria, in order to establish working hypotheses for employing these taxa. Because many of these taxa are distinctive, a primary goal is adequate illustration, especially in axial sections, useful for practical recognition purposes. Consequently, we present a selection of rotaliid taxa from the Maiella Mt. (Apulian domain, Central Italy) and central Sicily (clasts from the Monte Bosco Fm., Pre-Panormide domain) from Cuisian deposits, dated by means of alveolinids, with highly distinctive axial sections, in order to establish a baseline for future biostratigraphical use. The taxa are provisionally described and their generic attribution is discussed
Late Ypresian (Cuisian) rotaliids (Foraminiferida) and their biostratigraphic potential
No full textOne of the least known groups of larger benthic foraminifers of the Late Ypresian (Cuisian) are a number of as yet undescribed rotaliids, which commonly occur in shallow-water deposits from the central Neo-Tethys. Despite their relative abundance and short distribution range, the biostratigraphic potential of these taxa is as yet unknown, mainly due to relevant taxonomic difficulties. The complexity of the test and the canal system in the Rotaliidae and the necessity to investigate specimens from thin sections are the most common obstacles to investigate in detail these taxa. In the light of these difficulties, systematic description at the high qualitative standard level normally achieved in larger foraminifera may seem a daunting or unfeasible task. From these considerations arises the necessity to recognize provisionally flexible operative criteria, in order to establish working hypotheses for employing these taxa. Because many of these taxa are distinctive, a primary goal is adequate illustration, especially in axial sections, useful for practical recognition purposes.
Consequently, we present a selection of rotaliid taxa from the Maiella Mt. (Apulian domain, Central Italy) and central Sicily (clasts from the Monte Bosco Fm., Pre-Panormide domain) from Cuisian deposits, dated by means of alveolinids, with higly distinctive axial sections, in order to establish a baseline for future biostratigraphical use. The taxa are provisionally described and their generic attribution is discussed
Heterostegina from the Oligocene of southern Italy: biometric remarks
No full textThe genus Heterostegina (Foraminifera: Nummulitidae) ranges from the Middle Eocene to Recent, but the Oligocene species are poorly known. Here, Oligocene Heterostegina population from two localities of Southern Italy are investigated biometrically.
The occurrence of Heterostegina is reported for the first time from the lower Rupelian of the Caltavuturo Fm. from the Madonie Mts. (Sicily). This population (42 specimens) can be referred to the lower Rupelian because it was found in association with Nummulites vascus Joly & Leymerie, 1848, N. fichteli Michelotti, 1841, and Halkyardia maxima Cimerman, 1969 markers of chronobiozone SBZ 21 (Cahuzac & Poignant, 1997).
A second population (19 specimens) comes from the upper Chattian of the Calcareniti di Porto Badisco Fm. from Southern Apulia. The assemblage includes Nephrolepidina morgani and Eulepidina dilatata which are markers of SBZ 23.
Traditional biometric measurements such as the diameter of the protoconch (P), the diameter of the first spiral whorl (d1.0), the diameter of the first and half spiral whorl (d1.5) and the diameter of the second spiral whorl (d2.0) cannot be interpreted easily because of the depth-dependence of embryo size and involute/evolute form ratio (Pécheux, 1995). The number of primary chambers in the first whorl (N1.0), first and half whorl (N1.5) and two whorls (N2.0) have a low potential for distinguishing between the two populations and also in comparison to populations from the Eocene and the Miocene for which biometric data are available. On the contrary, whereas the number of operculinoid undivided chambers (X) shows a decreasing trend the number of chamberlets in the subdivided chambers increases in. Because of the difficulty to get complete equatorial sections, it is expedient to use parameter S3+4, i.e., the sum of the number chamberlets in the third and fourth chambers. X and S3+4 are negatively correlated.
The phylogenetic affinities of the two populations are discussed. The population of the Lower Rupelian from Madonie Mts. could belong to a basal member of the lineage of H. assilinoides Blanckenhorn, 1890, whereas the population from Porto Badisco shows features of the lineage of H. praecursor Tan Sin Hok s.l.. Moreover, the investigated taxa can be differentiated using the spiral coiling diagram, which is routinely employed for Nummulites
Embryo size variation in larger foraminiferal lineages: Stratigraphy versus paleoecology in Nephrolepidina praemarginata (R. Douvillé, 1908) from the Majella Mt. (Central Appennines)
No full textThe Mediterranean Nephrolepidina lineage has been thoroughly investigated in a number of studies. Here, we investigate biometrically two late Rupelian Nephrolepidina populations (E77', n=54; E76J, n=9) from the northern Majella Mt. (Central Italy), considering three parameters and three factors and their mean values. The A i factor (degree of enclosure of the deuteroconch on the protoconch) and the parameter C (number of adauxiliary chamberlets) suggest that both populations belong to N. praemarginata (R. Douvillé, 1908). The mean sizes of protoconch and deuteroconch are distinctly larger than other known populations of N. praemarginata. This is interpreted to reflect environmental factors. Increase in embryo size is a general feature among many larger foraminiferal lineages. In addition, studies on recent larger foraminifera indicate that embryo size varies along the depth gradient; however, this variation is poorly investigated. In recent nummulitids, the diameter of the embryonic chambers may either increase up to the ecological optimum and then decrease, or increase linearly with depth. Investigating embryo size may thus be rewarding either in a sequence of populations when sea-level change occurs or when anomalously large values of embryo size are attained in a population. Utilizing evidence from models derived from recent species, although it is uncertain how far they can be extended to extinct radial foraminifers, and sequence stratigraphy, it is inferred that the two populations come from a depth not far from the ecological optimum of the species. Recognition of this ecological optimum in the fossil record is generally hampered by conspicuous transport and mixing along the depth gradient
Thanetian larger foraminifera from Zakynthos (Ionian Islands, Greece).
No full textThe aim of this work is to present some diverse and well-preserved larger foraminiferal assemblages from Thanetian (SBZ 3; Serra-Kiel et al., 1998) deposits from central-southern
Zakynthos (Ionian Islands). The investigated assemblages originate from a heterometric conglomerate of uncertain age (Oligocene-Miocene?), disconformably overlying well-bedded
Upper Cretaceous pelagic limestone, cropping out along the Macherado/Romiri-Agalas road, near the village of Kiliomeno. Clasts yielding SBZ 3 assemblages largely prevail. Besides well-known index taxa such as Coskinon rajkae (Hottinger & Drobne, 1980), Fallotella alavensis Mangin, 1954, Vania anatolica Sirel & Gündüz, 1985 and Glomalveolina primaeva primaeva (Reichel, 1936), these clasts yield some rare or unrecorded forms, mostly with porcelaneous test. The unusual occurrence of several well recognizable specimens of Glomalveolina primaeva ludwigi (Reichel, 1936) is recorded. Biometrical data for some taxa (including small-sized Glomalveolina specimens) are given
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