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The paper presents detailed biostratigraphical division and lithological characteristics of the Turonian-Lower Santonian interval within the compiled Chukhonastovka section. The presence of the Lower Turonian deposits has been ascertained alongside with the unusual structure of the rock interval synchronous to the Lower Santonian “sponge” horizon.

A representative complex of the Turonian-Santonian carbonate-producing invertebrates has been revealed. It comprised benthic foraminifers, diverse echinoderms, brachiopods, calcareous and siliceous sponges.

Representatives of the genus Sororistirps, distinguished among the Ventriculites, have been detected in the Santonian – Maastrichtian rocks from the southeast of the Russian Plate. The structures of the skeletons and of the irrigation systems have been considered, the Sororistirps morphogenesis has been traced; the forms characteristic of the Santonian, Campanian and Maastrichtian spongiocomplexes have been determined.

The authors discuss the results of studying the composition of the volcanogenic-sedimentary rocks of the Dzykhra sequence, which come to the surface in the upper reaches of the river Bolshaya Khosta (Khostinsky district, Krasnodar territory). In the rocks of the Cretaceous age of the Akhun series, composed of limestones of the Dzykhra sequence and the Kazachy Brod suite, an outcrop of clastic rocks was found. The structure and mineral composition of the rock sample, as well as its chemical composition according to X-ray fluorescence analysis, were studied in detail. In the sequence, two layers are distinguished: the lower (3 m) cream-brown and the upper (0.05 m) green. Macroscopically, it is a lenticular-layered, fine-grained, lithocrystal-clastic, polymictic sandstone with carbonate cement. The sequence is underlain by interbedded dark gray limestones and black siltstones of the Lower Cretaceous Agur Formation, and overlain by cream limestones with interlayers of brown cherts of the Upper Cretaceous Kazachy Brod Formation. The data of microscopic studies, as well as X-ray fluorescence analysis, made it possible to establish the following minerals in the composition of sandstones: quartz, potassium-feldspar and plagioclase, less often amphibole, as well as a large amount of carbonate matter, and to conclude that in composition they correspond to tuffs of medium composition (andesite-dacite).

The deeplying Mesozoic and Paleogene deposits of the Middle Kura depression have significant resource potential. They are the main complexes in terms of prospectivity for oil and gas exploration. The lithological-facies characteristics of the host rocks, accumulation of which is tectonically conditioned, are among major indicators responsible for their oil and gas content. Based on actual core material from parametric, prospecting and exploratory wells, along with downhole logging data the marker horizons have been established for individual exploration areas within the depression. An overview of the lithostratigraphic features and thickness distribution of the Upper Cretaceous and Eocene deposits is given. Distribution of the fluid conducting strata, regional variation of their reservoir properties in buried structures of the Middle Kura depression is addressed as well. Within the study area a typical Upper Cretaceous section is comprised of three genetic rock types: sedimentary, igneous-sedimentary and igneous. The Eocene sediments are represented by shaly (Lower Eocene), terrigenous-carbonate (Middle Eocene) and terrigenous (Uppere Eocene) lithofacies. The regularities that have been revealed in lithofacies and thickness variation enabled highlighting the areas of highest subsidence and sedimentation, tracing basinal limits in Late Cretaceous and Eocene ages and depicting them on the maps presented. The compiled schematic maps clearly demonstrate the paleorelief in the study area at the close of Late Cretaceous and Paleogene times. Sections of the indicated sedimentary complexes contain effusive, carbonate, sandstone and siltstone reservoirs, exhibiting substantial occurrence and thickness, the latter having a marked trend to increasing toward the centerline of the Lower Kura depression. Thus, it is likely that the alteration in facies within the Upper Cretaceous and Eocene sections is closely interrelated with the breaks in sedimentation and erosions, favouring for formation of traps controlled by diverse screening features. At basin scale the major regionally persistent seal horizons are the Maykop shales of Oligocene-Lower Miocene age, which in a number of cases unconformably cover petroleum containing horizons.

The article is concerned with the first finds of rhyolite ashes in Upper Cretaceous sediments of Novaya Sibir Island. In the course of the field work in the area of cape Utes Derevyannykh Gor in 2016, four layers of unlithified fine-grained ashes were found in the Turonian-Coniacian coal-bearing Derevyannye Gory Formation. The article presents the results of petrographic, X-ray diffractometric and microprobe analysis of pyroclastics from ash layers. A typification of volcanogenic-terrigenous deposits is proposed. Thin section of the samples were investigated on a polarizing microscope. X-ray phase analysis of the clay fraction was carried out using a DRON-3 diffractometer. X-ray microanalysis of vitroclasts were carried out on a scanning electron microscope “Jeol JSM-6480LV” with the microprobe analyzer “Oxford Instruments INCA-Energy 350”. It was established that Derevyannye Gory Formation is composed of rhyolitic tuffites, among which fine-grained crystal-vitroclastic and vitroclastic ashes of low and normal alkaline high-potassium rhyolites with thickness up to 2.5 m. Low pyroclastics sediments are not widespread. New data on the structure and composition of the Derevyannye Gory Formation confirm the hypothesis of previous researchers, that sedimentation in the Late Cretaceous in the area of Novaya Sibir Island was accompanied by explosive acidic volcanism. The main purpose of the article is to discuss the sources of pyroclastic material for the territory of the New Siberian Islands in the Turonian-Coniacian age. The conclusion is made about the territorial proximity of the paleovolcanic eruption center to the area of sedimentation. It is assumed that the paleovolcanic centers were located within the present territory of Kotelny, Zemlya Bunge, Faddeevsky islands and, probably, were inherited from the Early Albian stage.

The Mezino-Lapshinovka section is constituted by the Upper Cretaceous carbonate clayey siliceous succession. It has been studied by XRD, SEM, microprobe, and geochemical analyses in order to reconstruct the main geologic events that influenced the formation of gaizes in the NE Peri-Tethys. A new scenario for their formation proposes that open-ocean siliceous ooze might have been delivered to the active subduction zone of the African-Arabian plate and then deposited in the shallow basin of NE Peri-Tethys. The bentonite interbeds were probably formed due to diagenetic alteration of the volcanic ash. It has been suggested that the sea water during the Santonian- Campanian was characterized by the oxic conditions, while there were two short episodes of anoxia or so-called anoxic non-sulfidic conditions. The early Santonian anoxic episode can be linked to the global anoxic event OAE 3 in the NE Peri-Tethys. The Campanian Mn anomaly coupled with the simultaneous increase in δ13C is considered to be a manifestation the Campanian eustatic rise.

The first description of the complex of bones from one individual plesiosaur marine reptile from the Upper Cretaceous deposits of the Central Urals is done; the reptiles remains of different species encountered in these sediments so far. The new finding comes from the neighborhood of Kamensk-Uralsky, Sverdlovsk Region. Earlier, these representatives of the Late Mesozoic marine life were not known. The research was conducted by Undory paleontological museum in cooperation with regional specialists of the Middle Urals.

Glauconite is the dioctahedral micaceous mineral with a high Fe content and structure of 2:1 layers linked by interlayer K cations. Wide distribution among marine sedimentary deposits and specific structural and chemical features of glauconites attract considerable attention of scientists both for paleogeographic reconstructions and for practical economical applications. The main aim of the study is a detailed investigation of mineralogical and structural-chemical characteristics of glauconite from the Upper Cretaceous formations of the Varvarinskoe deposit to determine origin of glauconite and to obtain initial information about possibilities of its practical applications. The methods: scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, X-ray fluorescence analysis, optical microscopy and petrographic analysis. As a result of this investigation the following main conclusions were obtained. The formation of glauconite-quartz sandstones and sands occurred in coastal facies near the terrigenous input in dysoxic and anoxic conditions. The studied rocks mainly consist of glauconite (9,2...9,4 %) and terrigenous quartz (82,6...86,8 %). Glauconite is characterized by the following chemical composition (%): K2O - 6,73…8,89, SiO2 - 49,61…55,99, Fe2O3(total) - 19,36…26,85, MgO - 3,26…4,91, Al2O3 - 3,90…7,31. The total content of adsorption and crystallization water is 3,46 and 7,12 %, respectively, according to the thermal analysis. Glauconite is evolved and highly evolved by degree of maturity. Glauconite is in situ origin. The glauconitization proceeded along the organic substrate according to the «verdissement» model due to chemical diffusion and transformation of the initial ferrous and ferrous-aluminum smectite, as evidenced by the structural and crystallochemical characteristics of glauconite. The studied structural and chemical characteristics of glauconite of the Varvarinskoe deposit indicate the possibility of its practical applications.

The present study is a contribution to the stratigraphy of the Carpathian type Upper Cretaceous and Paleocene deposits in Kula Zone, NW Bulgaria. It is the result of the development of geosites of scientific value for the purpose of Geopark "Belogradchik rocks". A new formal lithostratigraphic unit Ruzhintsi Formation is characterized to designate a unique facies of the Carpathian type Upper Cretaceous and Paleogene near Beloptichene village, previously related to Kula, Kladorub and Staropatitsa Formations. The new formation is composed of uninterrupted coarse-grained terrigenous sequence of intraclastic marl breccia, conglomerates, gravelites, sandstones, marls and siltstones within the stratigraphic range Upper Campanian--Middle Paleocene. This unit does not meet the definitive features of Kula or Kladorub Formations, and significantly differs from the stratigraphic position of the Staropatitsa Formation. The only surface outcrop near Beloptichene village is pointed as a lectostratotype. In the Upper Cretaceous portion of the section 2 nannofossil zones and 5 subzones are recognized, whereas the Paleocene part belongs to NP 2-NP 5 nannofossil zones (Lower--Middle Paleocene). Besides, exotic outcrops of the Mirkovo Formation and the Krasava Member of Zavala Formation are described in Kurkov Dol, south of Ruzhintsi village, known in the Central and West Srednogorie respectively as "couch-rouge" and "bituminous shale". On the basis of 3 nannofossil zones and 2 subzones recognized in the motley limestone-marl alternation of the Mirkovo Formation, its age is determined as Coniacian--Santonian, while the overlying barren bituminous shale of the Krasava Member of Zavala Formation are related to the Lower Campanian after their stratigraphic position. [ABSTRACT FROM AUTHOR]

The present lithostratigraphic subdivision is a continuation of the investigation of the Upper Cretaceous rocks in West Srednogorie and complements the lithostratigraphic scheme proposed in Part 1. In the present Part 2 new formal lithostratigraphic units are introduced for the Campanian deposits cropping out on the map sheets Breznik and Dragoman of the Geological map of the Republic of Bulgaria at a scale 1:50 000. Ten lithostratigraphic units in Lyubash and Sofia tectonic units are described: Nedelkovo, Rezhantsi (including Kolonitsa Member), Voynishka, Dolniromantsi (including Garlo Member), Tsrancha and Zavala Formations (including Krasava Member and Yaroslavtsi fossiliferous marker). [ABSTRACT FROM AUTHOR]

In this paper a new lithostratigraphic scheme of the Upper Cretaceous rocks in the West Srednogorie is proposed. In the present Part 1 seven new formal lithostratigraphic units in the Melove, Lyubash and Sofia tectonic Units are introduced: Paramun, Izvor, Rosoman, Melove, Golesh and Kosharevo Formations, and Kreshna Member of the Izvor Formation. The lowermost Paramun Formation (Lower-Middle Turonian), known as "coal-bearing formation", is a transgessive facies of light-gray to rusty-brown conglomerates, sandstones and siltstones with clay, marl and coal interbeds. It is up to 150-200 m thick and crops out as a thin strip at the base of the Upper Cretaceous sections in all of the West Srednogorie tectonic units. The overlying Izvor Formation (Middle Turonian-Coniacian) in Lyubash and Melove Units consists of more than 230 m strong marls, limestone beds and carbonate concretions with 90 m soft marls in the upper part of the unit north of Lyalintsi village, defined as Kreshna Member. The Golesh Formation (Coniacian-Lower Santonian) is a lateral analogue of the Izvor and Melove Formations, composed of about 180 m weakly cemented sandstones and soft clayey-sandy marls between Izvor and Melove Formations in Melove Unit. The Melove Formation (Coniacian-Santonian) is composed of up to 250 m thinbedded carbonate turbidites cropping out in Melove, Lyubash and Sofia Units. The Rossoman Formation (Santonian-Lower Campanian) is composed of more than 750 m alternating volcanic-sedimentary rocks with argillite-marl-limestone interbeds widespread in Sofia Unit. The Kosharevo Formation (Lower Campanian) is composed of more than 92 m marls, limestones, sandstones and polygenetic conglomerates. [ABSTRACT FROM AUTHOR]