A section of the Lower Cretaceous Taft Formation of Central Iran, belonging to the Yazd Block yields new data about the microfacies, orbitolinid biostratigraphy, and palaeogeographic setting of this ...poorly known lithostratigraphic unit. The studied section is characterized throughout by the common occurrence of corals, stromatoporoids and small benthic foraminifera (lenticulinids,
Neotrocholina
) that indicate deposition in an open marine external carbonate platform environment. The orbitolinid assemblage is characterized by
Montseciella
?
arabica
(Henson) in the basal part of the section followed by
Rectodictyoconus giganteus
Schroeder (up to the top), in association with
Paleodictyoconus actinostoma
Arnaud-Vanneau & Schroeder,
Dictyoconus
?
pachymarginalis
Schroeder, and
Palorbitolina ultima
Cherchi & Schroeder. The observed ranges of some taxa reveal slight modifications of widely used and, therefore, “standard” orbitolinid biozonations. Like any other group of larger benthic foraminifera, orbitolinids display a facies sensitivity (e.g., inner vs. outer platform) that may lead to different local or regional biozonations evidencing the need for plausibility check of the data when transferred to other regions. Moreover, the orbitolinid assemblages observed from different sections of the Taft Formation give evidence for its diachronous base (late Barremian or early Aptian) becoming younger towards presumably exposed land areas.
The top parts of the Taft Formation of Central Iran in its type area southwest of Yazd (Central Iran) contain an orbitolinid assemblage consisting of Dictyoconus? pachymarginalis Schroeder, 1965, ...Mesorbitolina birmanica (Sahni, 1937), and Mesorbitolina ex gr. texana (Roemer, 1849), assigned to the late Gargasian (mid-late Aptian). M. birmanica belongs to a group of mesorbitolinids (e.g., M. pervia, M. ovalis) exhibiting a rather large and complex embryo with a plano-convex protoconch. It has been largely overlooked in the literature and its integration into the early Aptian (Bedoulian) to early Cenomanian Mesorbitolina lineage (M. lotzei–M. aperta) is discussed. The occurrence of mesorbitolinids with a comparatively large and complex embryonic apparatus exhibiting a plano-convex protoconch already in the Gargasian is in conflict to the current phylogenetic concept of the genus Mesorbitolina. Further studies and emendation of this concept are needed. The new biostratigraphic data from the top of the Taft Formation indicate a stratigraphic hiatus of ca. 5 myr at the contact to the overlying, ammonite-dated Darreh-Zanjir Formation, comprising the latest Aptian to earliest Albian.
In shallow-water limestones of the Plassen Formation in the Tirolic nappe of the Northern Calcareous Alps, bauxite was formed on karstified and tilted platform margin grainstones to boundstones ...around the ?Kimmeridgian/Tithonian boundary, or in the Early Tithonian as proven by
Protopeneroplis striata
Weynschenk,
Labyrinthina mirabilis
Weynschenk, and
Salpingoporella pygmaea
Gümbel. The platform established on top of the obducted ophiolite nappe stack. The onset of unroofing at the Kimmeridgian/Tithonian boundary exposed ophiolites to weathering, forming laterites, and bauxites. The weathered ophiolitic material was shed on the tilted, emerged, and karstified platform, where the bauxite accumulated. Continued subsidence led to flooding, and a Tithonian transgressive carbonate sequence sealed the bauxites. XRD analysis of the bauxite yields a composition of mainly boehmite with hematite and some berthierine, kaolinite, and chromite. SEM analysis verified magnetite, hematite, rutile, chromite, zircon, ferropseudobrookite, ilmenite, monazite, xenotime, and garnet distributed in pisoids and within the matrix. The pisoids reach a millimeter in size and partly show cores of older, larger pisoids. The composition of the chromites indicates an ophiolitic origin. Geochemical examination using major- and trace elements points to a mafic andesitic to basaltic parent material contaminated with highly fractionated rocks from an island arc. Formation of Early Tithonian bauxites in shallow-water limestones confirms Middle to Early Late Jurassic ophiolite obduction. This was followed by uplift and unroofing of the orogen from the Kimmeridgian/Tithonian boundary onwards after a period of relative tectonic quiescence with an onset of carbonate platforms during the Kimmeridgian on top of the nappe stack and the obducted Neo-Tethys ophiolites.
The published literature concerning Lower to mid-Cretaceous (late Barremian-Albian, early Cenomanian) Tibetan Orbitolinidae suggests an apparent extreme high diversity with almost exclusive reference ...to taxa displaying a complex embryo (subfamily Orbitolininae). The majority of them, among Orbitolina pileus Fossa Mancini described in the late twenties from the border areas of Ladakh (India) and Tibet (China), however need taxonomic reconsideration. The original images of O. pileus are herein interpreted as a mixture of a high-conical mesorbitolinid (of unclear species identity) and a section of Palorbitolinoides orbiculatus Zhang described in the early 80ies from Tibet. The concluding new nomenclatural act considers P. orbiculatus a junior synonym of O. pileus validated herein as Palorbitolinoides pileus (Fossa-Mancini) comb. nov. with the designation of a lectotype. The present study refers to data from the literature and own material from the Albian Langshan Fm. of the northern Lhasa Block of Tibet.
A new attaching species displaying a polygonal subepidermal network was described by Ramalho (2015) from the upper Tithonian of the eastern sector of theAlgarve Basin, southern Portugal as Amijiella? ...adherens. The genus Amijiella Loeblich and Tappan displays different gross test morphology, internal structure as well as an unattached free way of life. Therefore, the Portuguese taxon is herein described as the new genus Ramalhoa with the new combination R. adherens (Ramalho). So far, Ramalhoa with its polygonal subepidermal network is unique among the attaching agglutinated foraminifera and assigned to a new family Ramalhoidae herein. Other agglutinated attached foraminifera displaying a subepidermal network are recorded from the Lower Cretaceous and treated in open nomenclature due to poor material available.
The new crustacean microcoprolite
Broennimannia persica
n. ichnogen., n. ichnosp., is described from the Paleocene (Danian-Selandian) of eastern Iran. The new microcoprolite is characterized by a ...bilateral symmetrical system of longitudinal “canals” that in transverse sections display an irregular (labyrinthine) outline with concave infoldings and rounded protuberances. The crescentic outline of parts of the canal system recalls the long-ranging ichnogenus
Palaxius
Brönnimann & Norton (Carboniferous to Pleistocene). In the latter ichnogenus, however, the canals are isolated. A general determination key for microcoprolites in transverse section is provided. The new microcoprolite occurs in poorly sorted foram-algal grainstones/packstones with a fine-grained siliciclastic content. The associated microfauna and –flora includes common miliolids, among the agglutinating
Haymanella
,
Stomatorbina
sp., serpulids, and dasycladalean algae (
Cymopolia
sp.,
Trinocladus atacis
Segonzac). From Iran, fossil microcoprolites have been described so far only from the Upper Jurassic, Lower Cretaceous, and Miocene.
Broennimannia persica
represents the first Paleocene record from this area.
From the upper Maastrichtian (Tarbur Fm.) and Paleocene of Iran, 20 species of scleractinian corals belonging to 17 genera and 14 families, and one species of the octocoral
Heliopora
are newly ...recorded. Furthermore, coral species previously described from the upper Maastrichtian Tarbur Fm. and the Paleocene are revised and included in the evaluation, resulting in a total of 37 species from 28 genera belonging to 20 families (including 3 subfamilies) for the Iranian K/Pg-boundary time period. The majority of the taxa (21 out of 37 = 57%) crossed the K/Pg-boundary. The genera
Acropora
and
Stylocoeniella
are recorded from strata older than the Paleogene (upper Maastrichtian) for the first time; for
Lobopsammia
it is the first report from strata older than the Eocene (Selandian‒Thanetian). The vast majority of the coral taxa occurring in both the upper Maastrichtian (Tarbur Fm.) and the Paleocene of Iran have been reported from a variety of both reefal and non-reefal paleoenvironments. On the species level, a slight majority of the corals from the upper Maastrichtian (Tarbur Fm.) are endemic (14 out of 27 species = 52%). In contrast, the vast majority of the Paleocene Iranian corals are cosmopolitan to subcosmopolitan; only 4 taxa are endemic during the Paleocene. While the upper Maastrichtian coral fauna of Iran shows greatest affinities to contemporaneous assemblages of Europe and the Caribbean, the Paleocene coral fauna is most closely related to contemporaneous coral associations of central Asia, Europe, and North America.
In the Inner Dinarides of southwestern Serbia, Tithonian polymictic carbonate turbidites, deposited in a deep-water foreland basin below overthrust ophiolites, contain Kimmeridgian–Tithonian ...shallow-water clasts, Triassic open-marine limestone and radiolarite clasts, and chrome spinels of a harzburgitic source (suprasubduction and MOR ophiolites). The results from the component analysis of these Tithonian polymictic carbonate turbidites constrain a Middle to Late Jurassic orogeny in the Western Tethys realm with following geodynamic evolution: (1) The closure of the western part of the Neo-Tethys Ocean caused west- to northwestward-directed ophiolite obduction onto the wider Adriatic shelf from Middle Jurassic times onwards. The former Triassic–Middle Jurassic outer passive continental margin of the Neo-Tethys imbricated and a nappe stack in lower plate (wider Adriatic) position was formed in front of the propagating obducting ophiolites. (2) During a period of relative tectonic quiescence, formation of a Late Jurassic carbonate platform started around the Oxfordian/Kimmeridgian boundary on top of the obducted ophiolites. This detection of a Late Jurassic carbonate platform formed above the obducted Dinaridic ophiolites close an important gap in knowledge about the geodynamic evolution of the Inner Dinarides. (3) From the Kimmeridgian/Tithonian boundary onwards uplift of the imbricated rocks below the obducted ophiolites triggered unroofing. During Tithonian times the obducted ophiolites were transported west-directed along low-angle fault plains near to its present position in the Dinarides. Mountain uplift and unroofing caused the partly erosion of the Late Jurassic carbonate platform, the underlying ophiolites and the Triassic–Jurassic nappe stack consisting of outer shelf sedimentary rocks.
Choffatella singularis was described from the Hauterivian of the Paris Basin based on abundant isolated specimens and oriented thin-sections enabling a very detailed description. Although an alveolar ...wall-structure was mentioned in the original description, the new species was assigned to Choffatella Schlumberger that lacks this feature, instead displaying a fine and regular choffatellid subepidermal network. This feature instead would refer to Pseudocyclammina Yabe and Hanzawa that however has a different apertural type. To accommodate Ch. singularis into the current classification of agglutinated benthic foraminifera and its basic criteria, the new genus Magniezjanninius is established including the new combination M. singularis (Magniez-Jannin).
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