Ioan Bucur | Babes-Bolyai University (original) (raw)

Papers by Ioan Bucur

Cretaceous Research, Feb 1, 2020

A new complex larger benthic Foraminifera is described as Cantabriconus? meridionalis n. sp. (?Fa... more A new complex larger benthic Foraminifera is described as Cantabriconus? meridionalis n. sp. (?Family Coskinolinidae Moullade) from lower Aptian Urgonian-type shallow-water carbonates of the Res¸ita e Moldova Nou a zone, southwestern part of Romania. In the literature this form has been assigned to both genera Falsurgonina Arnaud-Vanneau & Argot and Montseciella Cherchi & Schroeder. With its prominent, eccentric initial trochospire, undivided marginal zone, and pillars in the central zone it cannot be included either in the genera Falsurgonina Arnaud-Vanneau & Argot, nor Urgonina Foury & Moullade, or even Montseciella Cherchi & Schroeder. Due to some doubts about the wall structure (solid or pseudo-keriothecal?), the form is here tentatively assigned to the genus Cantabriconus Schlagintweit et al. becoming its possibly third representative apart from the type-species C. reocinianus (upper Aptianelowermost Albian of Spain, type-species), and C. altaretae (Arnaud-Vanneau) (lower Barremian).

International Journal of Earth Sciences, Jan 3, 2021

The Anisian depositional history in the Western Tethys realm provides the possibility to study th... more The Anisian depositional history in the Western Tethys realm provides the possibility to study the stepwise opening of the Neo-Tethys, and is well preserved in the sedimentary record of the Northern Calcareous Alps. Whereas the depositional characteristic in the Early (to early Middle) Anisian is characterized by shallow-water carbonates, formed in a semi-restricted environment, the situation changed in the Middle Anisian. A rapid increase of subsidence resulted in an abrupt deepening event with deposition of deeper-water limestones, in some cases even with chert nodules, sometimes with resedimented shallow-water debris intercalated in radiolaria-filament wackestones, or with clayey or marly intercalations. This abrupt deepening, termed the Annaberg Event, is followed by a shallow-water carbonate evolution. The deeper-water limestones can be dated by conodonts and shallow-water organisms like calcareous algae or foraminifera from the resedimented intercalations as Late Bithynian to Early Pelsonian. In contrast to the Early Anisian microbial carbonates, formed under semi-restricted conditions, the Middle Anisian (Pelsonian) shallow-water carbonates were formed under fully marine influence and a diverse fauna and flora was, therefore, able to counterbalance the rapid subsidence by increasing carbonate production. During Middle Anisian times, the newly tectonically created accommodation space became rapidly filled by shallow-water carbonates. At the end of the Middle Anisian (Late Pelsonian), the final break-up of the Neo-Tethys led to a rapid decrease of carbonate production and widespread deposition of deep-marine and condensed limestones. This drowning event (Reifling Event) was accompanied by the formation of a horst-and-graben morphology, dated by conodonts and ammonoids as late Middle Anisian from overlying condensed limestones. In contrast to the well-known drowning event in the late Middle Anisian, precursor events to the final oceanic break-up of the Neo-Tethys have not yet been described, but play an important role in the reconstruction of the opening history of the Neo-Tethys. This knowledge gap is filled by the analysis of exactly datable sedimentary successions in the central Northern Calcareous Alps.

A new giant (centimetre-sized) benthic foraminifera displaying arborescent morphology is describe... more A new giant (centimetre-sized) benthic foraminifera displaying arborescent morphology is described as Bispiraloconulus serbicus from Berriasian shallow-water carbonates of the Kurilovo area, eastern Serbia. The sample yielding the new taxon belongs to a carbonate succession outcroping north-north-east of Nis city, in the vicinity of Kamenica village. The limestones from this area belong to the Kurilovo fold structure or anticline that is part of the Gornjak-Stuva Planina unit, the westernmost part of the Carpatho-Balkanids of Eastern Serbia. North of the Danube River it continues with the Sasca unit belonging to the Getic domain of the South Carpathians. The dimorphic taxon is characterized by an adult part with rectilinear chambers, a thin wall (epiderm) with short polygonal subepidermal network (exoskeleton), and thin septa exhibiting cribrate foramina. The chamber interior contains a 3D-construction of (bio-)clasts fixed (agglutinated) to the septa and the exoskeleton by means of micritic columnar elements. All these features are characteristic for the genus Spiraloconulus Allemann & Schroeder (Aalenian-Berriasian) with its three species S. perconigi Allemann & Schroeder , S. giganteus Cherchi & Schroeder , and S. suprajurassicus Schlagintweit . The branching-arborescent test morphology, however, differentiates the Serbian form from Spiraloconulus being unbranched conical to cylindro-conical. Following current classifications of agglutinating foraminifera, test bifurcation is considered a generic criterion ( e.g. , compare Reophax vs Bireophax ; see Loeblich & Tappan , 1987; Kaminski , 2014) and consequently a new genus was established: Bispiraloconulus . With this characteristic Bispiraloconulus can be compared with the Barremian-Aptian Torremiroella Brun & Canerot or the Cenomanian Thomasinella Schlumberger . Among the agglutinating foraminifera Bispiraloconulus is unique by its arborescent test combined with a wall displaying a subepidermal network. Bispiraloconulus belongs to a group of larger benthic foraminifera displaying internal agglutination that fills large parts of the chamber interior: Spiraloconulus Allemann & Schroeder (Aalenian-Berriasian), Bostia Bassoullet (Bathonian), Robustoconus Schlagintweit & Velic (Bajocian), and Torremiroella Brun & Canerot (Barremian-Aptian). Another allied taxon also displaying an exoskeleton and "large globular particles incorporated into the septa" ( Loeblich and Tappan , 1986, p. 335) is Dhrumella Redmond , 1965 (Bathonian). Still poorly known, Dhrumella might also belong to this group and can be considered a compressed, peneropliform Spiraloconulus . This peculiar internal structure obviously contributed considerably to test rigidity allowing an adaptation to agitated shoal and near-shoal paleoenvironments. Delicate large-sized arborescent agglutinated taxa (with simple wall and lacking internal constructive elements) instead are reported from bathyal depths.

Géologie méditerranéenne, 1994

Bucur Ioan I. The Barremian-Aptian carbonate platform from the Resita-Moldova Noua Zone (S.W. Rom... more Bucur Ioan I. The Barremian-Aptian carbonate platform from the Resita-Moldova Noua Zone (S.W. Romania). Paleontological markers and configuration. In: Géologie Méditerranéenne. Tome 21, numéro 3-4, 1994. Perimediterranean carbonate platforms. First International Meeting. Marseille – France (5-8 septembre 1994) sous la direction de Jean-Pierre Masse. pp. 17-19

Cretaceous Research, Sep 1, 2019

Barkerina dobrogiaca Neagu (Valanginian of Romania), a medium-sized complex benthic foraminifera,... more Barkerina dobrogiaca Neagu (Valanginian of Romania), a medium-sized complex benthic foraminifera, is described from the Valanginian of the Pontides, NE Turkey. B. dobrogiaca differs from the type-species B. barkerensis Frizzell & Schwartz (Albian of Texas) by its small size, and comparably thin septula and test wall. The present paper is a further contribution to the knowledge of inventory and faunal assemblages of Valanginian shallowwater carbonates. Compared to the classical Urgonian (Hauterivian to lower Aptian) these are still incompletely known. Together with another form reported from the Barremian of Romania, it also shows that representatives of Barkerina Frizzell & Schwartz are well present in the Neotethysian realm.

Carnets de Géologie, Aug 17, 2021

This work is dedicated to the memory of Rolf SCHROEDER, an outstanding micropalaeontologist who r... more This work is dedicated to the memory of Rolf SCHROEDER, an outstanding micropalaeontologist who recently passed away. His numerous works on the Orbitolinidae are basic literature for their taxonomy and his name will always be linked to this group of larger benthic foraminifera.

Acta Palaeontologica Romaniae, 2019

The carbonate succession of the Tirgan Formation was studied in the Gelian section located 25 km ... more The carbonate succession of the Tirgan Formation was studied in the Gelian section located 25 km south of Shirvan town (central Kopet Dagh). In this section, the Tirgan Formation contains a rich assemblage of calcareous algae and foraminifera. Based mainly on the orbitolinid association a latest Barremian-ealy Aptian age was assigned to the Tirgan Formation in the Gelian section. Based on the available stratigraphic analyses and age assignments of the overlying Sarcheshmeh Formation by different authors, one should presume that both the Tirgan and the Sarcheshmeh formations are heterochronous across the Kopet Dagh basin.

The Piatra Craiului Massif is located in the eastern part of Southern Carpathians (Romania). It b... more The Piatra Craiului Massif is located in the eastern part of Southern Carpathians (Romania). It borders on the west the Dămbovicioara zone, and belongs to the eastern part of the so-called Getic Carbonate Platform, a system of carbonate platforms covering the Getic Nappe of the Southern Carpathians. Within the sedimentary succession in Piatra Craiului three lithostratigraphic intervals can be identified: (I) a lower unit consisting of coral-microbial boundstones and coarse, poorly sorted rudstones; (II) a middle unit made up of coarse bioclastic grainstones, and (III) an upper unit consisting of peloidal packstone-wackestone and cyanobacteria-bearing mudstone (peritidal limestones). The micropaleontological assemblages also permit biostratigraphic separatation of three intervals which cannot be superposed on the lithostratigraphic ones. The biostratigraphical interval A consists of encrusting organisms ( Crescentiella morronensis , Koskinobulina socialis , Lithocodium aggregatum and bacinellid structures, Perturbatacrusta leini , Radiomura cautica ). Corals are commonly encrusted by bacinellid -Lithocodium . Microfossils are represented by dasycladalean algae ( Campbeliella striata , Clypeina sulcata , Neoteutloporella socialis , Petrascula bursiformis , Salpingoporella pygmea , Salpingoporella annulata , Steinmaniporella kapelensis ) and foraminifera ( Bramkampella arabica , Everticyclammina praekelleri , Labirynthina mirabilis , Neokilianina rahonensis , Mohlerina basiliensis , Parurgonina caelinensis , Redmondoides lugeoni ). This biostratigraphic interval corresponds to lithostratigraphic intervals I and II, the micropaleontological assemblages pointing to a Kimmeridgian-early Tithonian age. The next biostratigraphic interval (B) contains the algae Clypeina parasolkani , Clypeina sulcata , Salpingoporella annulata , Selliporella neocomiensis , and the foraminifera Anchispirocyclina lusitanica , Pseudocyclammina lituus , Pseudotextulariella courtionensis and Rectocyclammina chouberti . It corresponds to the lower part of lithostratigraphic interval III, and indicate a late Tithonian-early Berriasian age. The biostratigraphic interval C corresponds to the upper part of the lithostratigraphic interval III and contains, mainly in its uppermost part, the algae Salpingoporella praturloni and Pseudocymopolia pluricellata , and the foraminifera Coscinoconus cherchiae , C. campanellus , Everticyclammina kelleri , Haplophragmoides joukowskyi , Montsalevia salevensis , Moulladella jourdanensis , Nautiloculina broennimanni , Orbitolinidae div. sp. indet . , Pfenderina cf. neocomiensis , Protopeneroplis ultragranulata , Pseudocyclammina lituus , and Scythiolina div. sp. This interval is considered of late Berriasian-earliest Valanginian in age. The entire carbonate succession from Piatra Craiului is a prograding, shallowing upward megasequence. The identified microfossil assemblages permit separatation into three biostratigraphic intervals, but the repartition of the microfossils do not trace exactly any boundary between stages, either Kimmeridgian-Tithonian, or Tithonian-Berriasian, or Berriasian-Valanginian. More detailed studies within the Dâmbovicioara area could maybe permit a better understanding of the Jurassic-Cretaceous transition in this area.

In the Romanian Carpathians, the species of Triploporella genus are relatively rare in the Lower ... more In the Romanian Carpathians, the species of Triploporella genus are relatively rare in the Lower Cretaceous limestones. Recent studies on various areas of development of urgonian limestones allowed us to identify dasycladalean algae that we assigned to Triploporella in four regions: 1. Resiţa-Moldova Nouă Zone. Here we have identified Triploporella carpatica BUCUR (Bucur, 1993) characterized by a wide axial cavity and primary laterals with poorly calcified proximal and distal extremities. No secondary laterals were observed. Nevertheless, the primary laterals contain cyst containers that support our assignment to genus Triploporella. 2. Persani Mountains. Numerous fragments also belonging to species Triploporella carpatica BUCUR have been identified in the Urgonian limestones from Persani (Marian et al., 2008). These show a relatively more advance degree of calcification, corresponding to the entire length of the primary laterals; still, the secondary laterals were not calcified. The morphology and sizes of the cyst containers correspond to those of the type species. More than that, in this area some specimens of Triploporella were assigned with reserves to species Triploporella marsicana PRATURLON. 3. Dâmbovicioara couloir. In the Barremian patch-reefs from Dâmbovicioara couloir we have recognized rare fragments of Triploporella, most probably belonging to species Triploporella praturlonii BARATTOLO. 4. Pădurea Craiului Mountains (North Apuseni Mountains). Recently we have identified specimens of Triploporella in Barremian limestones. Based on the morphology of the primary and secondary laterals, it is highly probable that they belong to a new species. Further studies and possible new material are needed in order to allow a final decision in this respect. Acknowledgements: The paper is a contribution to the research project ID 95 granted by CNCS.

Cretaceous Research, Aug 1, 2023

Proceedings of the Geologists' Association, Jun 1, 2022

Facies, Mar 9, 2022

The Postăvaru Massif is located in the easternmost part of the Getic Carbonate Platform from the ... more The Postăvaru Massif is located in the easternmost part of the Getic Carbonate Platform from the Southern Carpathians. The described sections are unevenly distributed in all four tectonic compartments of the Postăvaru Massif (Brașov, Cristian, Râșnov and Postăvaru). Eighteen sections were studied to highlight the biostratigraphic and facies evolution of the Upper Jurassic–Lower Cretaceous (Kimmeridgian–upper Berriasian) transition. Ten facies associations (FA 1–10) were described and they indicate a general shallowing upward tendency, from slope to platform-margin and inner-platform depositional settings. In other cases, the vertical facies stacking patterns indicate a general deepening-upward tendency, at the Upper Jurassic–Lower Cretaceous transition. The micropaleontological assemblage consists of encrusting organisms, dasycladalean algae, foraminifera and pelagic microfossils (calpionellids). As a general rule, this assemblage characterizes four main intervals and stages: Kimmeridgian–upper Tithonian, lower Berriasian, upper Tithonian–Berriasian and upper Berriasian. The carbonate succession from the Postăvaru Massif shares similar characteristics with other parts of the Getic Carbonate Platform (Cioclovina-Bănița area, Buila-Vânturarița Massif, Piatra Craiului-Dâmbovicioara Zone, Western part of Bucegi Massif). Finally, the presence of Lower Cretaceous (Berriasian) deposits is well documented by interpreting various assemblages of microfossils. This study combines microfacies and biostratigraphic analysis techniques to decipher the interplay between environmental conditions, facies distribution and biostratigraphic evolution at the Upper Jurassic–Lower Cretaceous transition, in the easternmost GCP. The Tithonian–Berriasian transition is marked by a continuity of sedimentation, in shallow and deep water depositional environments.

Cretaceous Research, Jul 1, 2017

A new larger benthic foraminifera is described as Banatia aninensis n. gen., n. sp. (Family Pfend... more A new larger benthic foraminifera is described as Banatia aninensis n. gen., n. sp. (Family Pfenderinidae Smout & Sugden) from upper Barremian Urgonian-type shallowwater carbonates of the Reşita-Moldova Nouă Zone, southwestern part of Romania. The low to medium trochospiral test of Banatia n. gen. is characterized by marginally undivided chambers and a wide axial part. The latter is made up of pillars continuous between successive chambers and a labyrinthic endoskeleton (plates and pillars) and a fine canal system between. Banatia n. gen. is compared with Pfenderina Henson, Pseudopfenderina Hottinger, and Accordiella Farinacci. The new taxon occurs in algal-foraminiferal wackestones interpreted as deposits of an internal lagoonal realm. So far unrecorded in the literature, the taxon might be palaeogeographically restricted (endemic).

Micropaleontology

The Yangtze carbonate platform (Southern China) recorded a long sedimentary evolution from Neopro... more The Yangtze carbonate platform (Southern China) recorded a long sedimentary evolution from Neoproterozoic to the basal Upper Triassic. During the Early and Middle Triassic, this platform was dominated by shallow-water carbonates. In various sectors of the platform, the Middle Triassic (Anisian-Ladinian) succession contain abundant assemblages of benthic foraminifera and calcareous algae. Following a previous paper about the Middle Triassic dasycladalean algae from SW Guizhou Province, the present study describes algae and microproblematic organisms from three sections: Honyan, Longtou and Guanling. Some dasycladalean algae are well known from the Alpine-Dinaric domain: Diplopora annulatissima, D. annulata, Euteutloporella triasina, Macroporella dinarica, Oligoporella minutula, O. pilosa pilosa, Poncetella hexaster and Pseudodiplopora proba. However, the dasycladalean association is dominated by species belonging to the genus Kantia, including K. cf. dolomitica and K. cf. comelicana....

Facies, 2021

We studied deposits belonging to the Bihor Unit from the Northern Apuseni Mountains (Romania). Th... more We studied deposits belonging to the Bihor Unit from the Northern Apuseni Mountains (Romania). The described outcrops are located in the SW of Șes Mountain and the northeastern Pădurea Craiului Massif. We determined the depositional environment and the mechanisms controlling the accumulation of Upper Triassic–Lower Jurassic continental deposits. The sedimentary formations contain carbonate breccia and calcretes embedded in continental clay deposits. Late Triassic–Early Jurassic depositional processes were influenced by the inherited paleobasement of the subaerially exposed Middle Triassic deposits. Numerous fragments of Anisian and Ladinian carbonate deposits are encased in weathered clay deposits accumulated on karstification surfaces developed at the top of Middle Triassic limestones. We integrated facies analysis and clay mineralogy to obtain an accurate interpretation of the continental processes acting at the Triassic–Jurassic boundary in the northern part of the Apuseni Mountains. The composition of the carbonate pebbles is described in terms of the carbonate facies, whereas the clay mineralogy was determined by applying X-ray powder diffraction. Thirteen facies associations are described consisting of carbonate, siliciclastic and ferilitic rock types. Such facies indicate sediment accumulation in a continental, mixed carbonate-siliciclastic depositional environment. A Late Triassic exposure event was followed by an Early Jurassic (Hettangian) transgression. Two major facies types are identified on the basis of their depositional environment. The first category includes subaerially exposed Triassic carbonates and ferilitic facies, while the second category consists of transgressive siliciclastic facies from the basal Lower Jurassic (Hettangian) sediments. The existing data suggest continental deposition in alternating, arid–humid warm climate conditions at the Triassic–Jurassic transition.