Paleocene orthophragminids from the Lakadong Limestone, Mawmluh Quarry section, Meghalaya (Shillong, NE India): implications for the regional geology and paleobiogeography

The late Paleocene orthophragminids, hitherto poorly known from the Himalayan foreland basins, are studied from the Lakadong Limestone in Meghalaya, northeastern India, in order to establish a systematic, biostratigraphic, and paleobiogeographical framework for them in the eastern Tethys. In the Mawmluh Quarry section (MQS) on the Shillong Plateau, to the southeast of Tibet, orthophragminids are associated with typical Paleocene orbitoidiform taxa endemic to the Indian subcontinent, i.e., Lakadongia Matsumaru & Jauhri ( =  Setia Ferràndez-Cañadell) and Orbitosiphon Rao, and various species of alveolinids, miscellaneids, and rotaliids, characterizing the Shallow Benthic Zones (SBZ) 3 and 4. The orthophragminids belong to two lineages of the genus Orbitoclypeus Silvestri: O. schopeni (Checchia-Rispoli) and O. multiplicatus (Gümbel), both well known from the peri-Mediterranean region and Europe (western Tethys). The latter species is identified here for the first time from the eastern Tethys. Previous records of the genus Discocyclina Gümbel from the Lakadong Limestone actually correspond to misidentified Orbitoclypeus; this implies that the late Paleocene orthophragminid assemblages from Meghalaya and eastern Tethys were less diverse than in the western Tethys. The lineage of Orbitoclypeus schopeni in the lower part of the Lakadong Limestone (SBZ 3) is identified as O. schopeni cf. ramaraoi based on the morphometry of a few specimens, whereas in the upper part (SBZ 4) it corresponds to a transitional development stage between O. schopeni ramaraoi and O. schopeni neumannae (with average Dmean values ranging between 192 and 199 µm). The embryon diameters of O. multiplicatus, recorded only in SBZ 4, range between 300 and 319 µm on average, corresponding to transitional development stages of O. multiplicatus haymanaensis and O. multiplicatus multiplicatus. Our data, along with a review of previous Paleocene and Eocene records from India and Pakistan, suggest that Orbitoclypeus is the only orthophragminid in the Paleocene of the eastern Tethys, whereas Discocyclina first appears in early Eocene times, being mainly represented by endemic taxa confined to the Indian subcontinent. Facies change in the MQS from a marine to continental setting within SBZ 4 corresponds to the oldest record from the Indian plate in the Paleogene, which may be linked to the flexural uplift of the passive margin of the Indian plate, marking the onset of the collision of the Indian and Eurasian plates

Spatial and temporal facies evolution of a Lower Jurassic carbonate platform, NW Tethyan margin (Mallorca, Spain)

The variety of depositional facies of a Lower Jurassic carbonate platform has been investigated on the island of Mallorca along a transect comprising six stratigraphic profiles. Twenty-nine facies and sub-facies have been recognized, grouped into seven facies associations, ranging in depositional environment from supratidal/terrestrial and peritidal to outer platform. Spatial and temporal (2D) facies distribution along the transect reflects the evolution of the carbonate platform with time showing different facies associations, from a broad peritidal platform (stage 1) to a muddy open platform (stage 2), and finally to a peritidal to outer carbonate platform (stage 3). Stage 1 (early Sinemurian to earliest late Sinemurian) corresponds to a nearly-flat peritidal-shallow subtidal epicontinental platform with facies belts that shifted far and fast over the whole study area. The evolution from stage 1 to stage 2 (late Sinemurian) represents a rapid flooding of the epicontinental shallow platform, with more open-marine conditions, and the onset of differential subsidence. During stage 3 (latest Sinemurian), peritidal and shallow-platform environments preferentially developed to the northeast (Llevant Mountains domain) with a rapid transition to middle-outer platform environments toward the northwest (Tramuntana Range domain). Stages 1 and 3 present facies associations typical of Bahamian-type carbonates, whereas stage 2 represents the demise of the Bahamian-type carbonate factory and proliferation of muddy substrates with suspension-feeders. The described platform evolution responded to the interplay between the initial extensional tectonic phases related to Early Jurassic Tethyan rifting, contemporaneous environmental perturbations, and progressive platform flooding related to the Late Triassic–Early Jurassic worldwide marine transgression and associated accommodation changes

Deciphering voids in dasycladales, the case of dragastanella transylvanica, a new lower cretaceous triploporellacean genus and species from Romania

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

Il Mesozoico dell'Isola di Capri.

Il Mesozoico è costituito per la maggior parte da rocce in facies di piattaforma carbonatica e scarpata-bacino. La complessità dei rapporti laterali tra i tipi formazionali e le notevoli differenze di spessore delle successioni stratigrafiche tra zone anche molto vicine rendono consigliabile per una più organica trattazione delle caratteristiche stratigrafiche suddividere l'isola in cinque zone. L'individuazione di queste zone non va necessariamente connessa sempre ad una differenza paleogeografica e/o ambientale. Di ciascuna di queste ultime vengono fornite una o più colonne stratigrafiche indicative. La zona A è racchiusa tra Punta Campetiello, Caprile, la Migliara e Punta Carena. La zona B confina ad W ed ad N rispettivamente con le zone A e C, ad est e a sud rispettivamente con le falesie dei Monti S.Maria e Solaro. La zona C confina a Sud con le zone A e B, ad E, N, ed W rispettivamente con le falesie del Castello di Barbarossa, della Grotta Azzurra, e di Orrico. La zona D comprende la quasi totalità della porzione orientale dell'isola ad eccezione della piccola zona di Cala del Fico che rappresenta la zona E. I terreni che compongono queste cinque zone sono stati raggruppati in nove tipi formazionali che in ordine stratigrafico ascendente sono: 1. Dolomia di Cala Ventroso, 2. Calcare con selce della Migliara, in parte coevo di 3,4 e 5, 3. Calcare bioclastico di Grotta delle Felci, 4. Calcare oolitico della Torina, 5. Calcare ad Ellipsactinie di Capri, 6. Calcare bianco del Limmo , parzialmente coevo di 7, 7. Rudite di Tiberio, 8. Scaglia di Punta Carena, 9. Conglomerato del Faro

Site 4-Middle Lias of Conca dei Marini (Salerno, Campania)

Lower Jurassic oncolites and foraminifera of the Sorrento peninsula carbonate succession is illustrate

Site 9-Middle Jurassic-Early Cretaceous of Tramutola (Potenza, Basilicata)

Dasycladales (Salpingoporella grudii, Clypeina Jurassica, Campbelliella striata, Salpingoporella sellii) are pointed out in a carbonate succession near Tramutola (Potenza, Basilicata

Site 2-Middle Dogger of Agerola

It is showed the Selliporella donzelii horizon near Agerola (Sorrento Peninsula