Daria Ivanova

Middle Triassic paleomagnetic data from northern Bulgaria: constraints on Tethyan magnetostratigraphy and paleogeography

Magnetostratigraphic and biostratigraphic data are presented from the Anisian (Middle Triassic) Peri-Tethyan Edivetur section of northwestern Bulgaria. A dual-polarity component of magnetization carried by magnetite delineates a magnetic stratigraphy of mainly reversed polarity. Magnetozones are dated by means of foraminifer and conodont biostratigraphy. Data from Edivetur are compared with data from Middle Triassic Tethyan limestone sections with the aim of contributing to the completion of the Middle Triassic magnetic polarity time scale. We also propose that paleomagnetic data from Edivetur can be used as proxy data for the paleogeographic position of the Moesian platform. The Moesian platform was located at 21‐24°N along the southern margin of Europe. It was probably marginally separated, but not detached or rotated away from Europe by the North Dobrugea transtensional trough, which is interpreted as a back-arc basin resulting from the northward subduction of the Neo-Tethys ( Vardar) or Paleo-Tethys ocean. Paleomagnetic data from this study and other minor tectonic elements are used to generate a paleogeographic sketch map of the Pangea-bounded western Tethys and Peri-Tethys at Middle/early Late Triassic time.

Late Jurassic–Early Cretaceous Foraminifera from Štramberk-type Limestones, Polish Outer Carpathians

Foraminifera studies were carried out on the Stramberk-type limestones which occur as pebbles to small boulders (exotics) within the uppermost Jurassic-Palaeogene flysch deposits of the Polish Outer Carpathians. The studies were focused on foraminifera from (1) reef and peri-reef facies, and (2) lagoonal algal-foraminiferal facies. The paper deals with 34 species (including 8 in open nomenclature) representing 30 genera, 22 families, 14 superfamilies, 11 suborders, and 7 orders. A more precise age determination has been obtained for 30 exotics, representing a Tithonian (mostly) to Valanginian age. Foraminiferal assemblages from at least two exotics suggest a Valanginian age as indicated by the co-occurrence of the species: Meandrospira favrei (CHAROLLAIS, BRONNIMANN & ZANINETTI), Montsalevia salevensis (CHAROLLAIS, BRONNIMANN & ZANINETTI), Patellina turriculata DIENI & MASSARI, Neotrocholina valdensis REICHEL, Hechtina praeantiqua BARTENSTEIN & BRAND, Istriloculina eliptica (IOVCHEVA) and I. emiliae NEAGU. Previous studies based on ammonites and calpionellids indicated the Tithonian to the Early Berriasian age of the Stramberk Limestone in Moravia (the Czech Republic), and their equivalents in Poland. However, Valanginian shallow-water limestones occur as pebbles in some deposits of the Outer Carpathians in the Czech Republic. Further evidence for Valanginian shallow-water marine carbonate sedimentation (algal facies) in the Polish part of the Tethyan margin comes from recent studies of the substrate drilled in the Carpathian Foredeep.

New age data from the tectonostratigraphic units of the Istranca “Massif” in NW Turkey: a correlation with SE Bulgaria

Abstract The Istranca Crystalline Complex in NW Anatolia and SE Bulgaria includes structural units that differ in lithostratigraphy, metamorphism, age and structural position. They are collectively named as the “Istranca nappes” comprising from bottom to top the Sarpdere, Mahyadağ and Doğanköy Nappes. The Sarpdere Nappe consists of Lower Triassic arkosic metasandstones with slate interlayers, followed by Middle to Upper Triassic carbonates and an alternation of Upper Triassic clastics and carbonates. The Mahyadağ Nappe comprises a low-grade metamorphic Late Paleozoic- Triassic carbonate-siliciclastic sedimentary succession. The Doğanköy Nappe includes Precambrian?-Paleozoic metasediments, intruded by Late Carboniferous-Early Permian calc-alkaline granitoids. Its Triassic cover comprises metaclastics and metacarbonates. The Istranca nappes were juxtaposed at the end of the Triassic and transgressively covered by Lower Jurassic coarse clastics, followed above by Middle to Late Jurassic carbonates, black shales and carbonate-siliciclastic sedimentary succession. The phosphate concretions in black shales yielded radiolarian assemblages indicating Late Bajocian-Early Bathonian, Early Bathonian and Early Kimmeridgian ages. These nappes and their Jurassic cover are unconformably overlain by the Cenomanian-Santonian volcano-sedimentary successions intruded by Santonian-Campanian Dereköy-Demirköy intrusive suite. The preliminary data suggest that the Variscan basements of the Mahyadağ and Sarpdere Nappes were juxtaposed prior to the Triassic and overridden by the Doğanköy Nappe of possible Rhodopean origin from S to N during the Cimmerian compressional events

Benthic foraminifera and calcareous algae from the Anisian−Norian succession in the Tatras (Poland, Slovakia): New data from high−Tatric and Krížna units

others were found in new locations. A few of them belong to index fossils. Based on the assemblage containing calcareous algae Oligoporella species, characteristic for the Oligoporella pilosa – Phisoporella pauciforata zone, as well as the foraminifera Meandrospira dinarica, and the presence of Diplopora annulatissima, the age of the lishment of the foraminifera species Pilamminella semiplana, Glomospirella triphonensis and Nodosaria skyphica, Ophthalmidium cf. exiguum, Hoyenella gr. sinensis, Agathammina sp. and Gaudryina Turriglomina mesotriasica – Glomospirella kuthani/ gemerica – Aulotortus gaschei praegaschei cludes ?Triasina hantken

The Ammonites of the Bifrons Zone (Toarcian, Lower Jurassic) from Mihailovići (Northern Montenegro)

The base of the red pelagic nodular limestones exposed near the Mihailovići Pass (Northern Montenegro) yielded condensed Toarcian fossil assemblage consisting uniquely of ammonites. The ammonites were collected from marker horizon associated with prominent hardground surface. This assemblage is composed both of species of worldwide distribution and proper Tethyan dispersal. It includes frequent Lytoceratina and common Phylloceratina and Ammonitina. The latter allowed the biostratigraphic definition of the fossiliferous horizon as mid-Bifrons Subzone of the Lower Toarcian Bifrons Zone. Thirteen ammonite taxa were studied: Phylloceras heterophyllum (Sowerby), P. prinzi Géczy, Calliphylloceras nilssoni (Hebert), Lytoceras toarcense Rulleau, Nodicoeloceras angelonii (Ramaccioni), Hildoceras lusitanicum Meister, H. bifrons (Bruguière), Cingolites aff. picenus Sassaroli & Venturi, Osperleioceras subexaratum (Bonarelli), Harpoceras mediterraneum Pinna, Phymatoceras anomalum Merla, Ph. gr. narbonense Buckman and Ph. cf. formosum Rulleau & Elmi. One specimen was defined as Harpoceras sp. n. since it did not match any species from the literature, but might be erected as a new specific name if further materials appear.