Triassic deposits are widespread in the Măcin Unit of Northern Dobrogea (SE Romania). At the Enisala Fortress hill, near the village of Enisala, they are predominantly represented by grey bioclastic ...limestones of Wetterstein-type facies of the latest Ladinian to Carnian age. Samples collected from the lower part of this unit, i.e. from strata cropping out on the right side of the road from Sarichioi to Enisala, yield an association of calcareous algae, among which one is described in this paper as a new representative of the organogenus Ioanella. Ioanella dobrogiaca organospecies nov. differs from the type-species of the genus, Ioanella lusitanica, by its morphological and dimensional characteristics. Its features allow us to refine the diagnosis of the organogenus Ioanella. Additionally, comparisons with other dasycladalean organogenera demonstrate that Ioanella is a discrete genus.
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.
Dragastanella transylvanica n. gen. n. sp. is described. Its calcified skeleton contains numerous voids, partly related to the molds of soft parts of the alga, but also related to lack of ...calcification. Interpretation of these voids, especially their attribution to original structures (e.g., primary lateral versus reproductive organ), has important implications for the taxonomic position of the alga, even at the family level. Examination of key sections that include the boundary between sterile and fertile parts of the alga excludes the occurrence of external reproductive organs. Unusual, paired pores in the outer part of the mineralized skeleton reflect an asymmetry within the whorl, excluding the presence of secondary laterals. The alga is characterized by a cylindrical to club-shaped thallus bearing only phloiophorous primary laterals arranged in whorls and flaring outwards, forming a cortex. Mineralized lenticular reproductive organs containing cysts set in the equatorial plane (Russoella-type gametophores) occur inside primary laterals (cladosporous arrangement of the reproductive organs). These characters support establishment of the new genus Dragastanella. Dragastanella transylvanica n. gen. n. sp. resembles species previously referred to Zittelina (Zittelina hispanica and Zittelina massei) and Triploporella (Triploporella matesina and Triploporella carpatica). Except for Triploporella carpatica, whose mineralized skeleton does not permit confident attribution to either Triploporella or Dragastanella n. gen., the other species must be ascribed to Dragastanella n. gen. Therefore, the following new combinations are proposed: Dragastanella hispanica n. comb., Dragastanella massei n. comb., and Dragastanella matesina n. comb. Despite widely overlapping biometrical measurements, these species can be differentiated by the size and location of their reproductive organs, the pattern of calcification around the primary laterals, and relationships among structural parameters such as the size of laterals, number of laterals per whorl, and distance between whorls.
The tectonic development of the northeast margin of the Korabi-Pelagonian continent and the adjacent Vardar ocean is discussed based on study of nine traverses across the former northeastern margin ...of the Korabi-Pelagonian continent, represented by the West Vardar subzone in the Republic of Macedonia. A detailed correlation of units is also made across the international border with Greece, coupled with regional comparisons.
Precambrian–Palaeozoic units were metamorphosed and intruded by granitic rocks, followed by Mid-Triassic rifting and the construction of a carbonate platform bordering a Late Triassic–Early Jurassic ocean. Neritic deposition was followed by Late Jurassic (syn‐ or pre-Early Tithonian) subsidence with radiolarian and then terrigenous turbidite sedimentation. Overlying ophiolitic rocks are characterised by a relatively thin (<500m), laterally persistent (>200km N–S) sheet of sheared, blocky serpentinite (mainly mantle harzburgite), associated with ophiolite-derived debris flows. The emplaced ophiolitic rocks were subaerially weathered to form local Fe–Ni accumulations. Following marine transgression, a shallow-water carbonate–siliciclastic deposits, including coralgal reefs, accumulated during Late Tithonian–Early Cretaceous. After a hiatus, mixed terrigenous-carbonate gravity flows accumulated in deep water during the Late Cretaceous.
The Vardar ocean opened during the Late Triassic–Early Jurassic separating the Korabi-Pelagonian and Serbo-Macedonian continents. Northeastward subduction created a Late Jurassic magmatic arc along the southern margin of the Serbo-Macedonian continent, while future ophiolites formed by supra-subduction zone spreading within the Vardar ocean. These ophiolites were emplaced in response to collision of the subduction trench with the Korabi-Pelagonian continent. The pre-Mesozoic basement detached and subducted undergoing high pressure–low temperature metamorphism during the Late Jurassic (Tithonian), followed by amphibolite/greenschist facies metamorphism and exhumation prior to the Late Cretaceous. A much reduced Vardar ocean survived into the Late Cretaceous until this finally closed during the latest Cretaceous–Early Cenozoic, triggering continental collision and thick-skinned folding/thrusting of the Pelagonian, Vardar and Serbo-Macedonian zones towards the W/SW.
► Evolution of Vardar ocean ► Vardar ocean ophiolites ► Continental margin evolution ► Alternative tectonic models
New biostratigraphic and microfacies data from the Durmitor Mt. in northern Montenegro result in a detailed reconstruction of the Middle Triassic depositional history with special emphasis on the ...Middle-Late Anisian stepwise deepening related to the opening of the Neo-Tethys Ocean and the intense Illyrian volcanism in the Dinarides. The continental break-up and early opening history of the Neo-Tethys Ocean is recorded in the Middle-Late Anisian drowning sequence of the Pelsonian shallow-water Ravni Carbonate Ramp. The first pulse in the late Pelsonian creates a horst-and-graben topography forming a classical break-up unconformity. In addition, shallow-water carbonate production decreased significantly, and deep-marine red nodular limestones (Bulog Formation) and related sedimentary deep-water successions deposited throughout the late Pelsonian – early/middle Illyrian, in cases up to the Ladinian, as proven by ammonoids and conodonts. In the Durmitor Mt., intense volcanism in the middle Illyrian created short-living islands surrounded by atolls with shallow-water carbonate production up to the late Illyrian, as proven by conodonts. The older break-up and volcanism related topography get destructed around the middle/late Illyrian boundary by a second pulse of extensional tectonics, and resulted in deposition of Mass Transport Deposits (MTDs) with reworked middle Anisian (Pelsonian) shallow- and deep-water limestones (Komarani Formation). The shallow-water limestones are dated by dasycladalean algae and foraminifera, while the deep-water limestones are dated by ammonoids and conodonts. From the late Illyrian onwards deposition is characterized first by red condensed limestones with ammonoid-rich Fossillagerstätten beds subsequently overlain by Ladinian condensed grey siliceous deep-marine limestones. In the Early Carnian first turbidites with shallow-water grains overlain by reefal float- and rudstones indicate the onset and progradation of the Wetterstein Carbonate Platforms. In contrast to the well-known Middle Anisian (late Pelsonian) drowning event in the Western Tethys Realm the middle-late Illyrian depositional history associated with the intense volcanism and extensional tectonics is not well understood. This knowledge gap is filled by precisely dated sedimentary successions in the Durmitor Mt. in northern Montenegro.
The Upper Cretaceous-Paleogene genus
Trinocladus
that is based on
T. tripolitanus
Raineri,
1922
, originally described from Libyan material, is morphologically well constrained. Its species are ...commonly distinguished on the basis of their biometrics. However, the narrow Gaussian distribution reported for some measurements may result from post-mortem dynamic sorting as suggested by a review of the surrounding microfacies. An examination of Brazilian material of the type-species suggests a slightly club-shaped thallus morphology. Two “false
Permocalculus
” species originally described by Johnson and the type-material of which has been reexamined are formally reascribed to the genus
Trinocladus
.
T. budaensis
, the smallest one, has slightly club-shaped thallus, too.
T. elliotti
is poorly mineralized and insufficiently documented. In addition to
T. tripolitanus
, Raineri described a tiny species which was later revised by Pia,
i.e.
,
Dissocladella ondulata
.
D. bonardii
, a name recently introduced by Radoičić et al. and which is based on Raineri’s original material, is considered here as an objective junior synonym of
D. ondulata
.
A rich association of calcareous algae is described from the Lower Cretaceous (Barremian–? Lower Aptian) deposits of the Taft Formation, located south of Aliabad (in the vicinity of Yazd, central ...Iran). The association mainly consists of dasycladaleans and bryopsidales (udoteaceans and gymnocodiaceans); additionally, rare “solenoporaceans” and cyanophyceans are present. Three new species are described: two are dasycladaleans (
Pseudoactinoporella
?
iranica
and
Holosporella farsica
) and one is an udoteacean (
Boueina minima
). Many of the described and illustrated algae are mentioned for the first time from Iran.
PDF
