The upper Volgian Substage in Northeast Siberia (Nordvik Peninsula) and its Panboreal correlation based on ammonites

Section of the middle and upper Volgian substages and basal Boreal Berriasian in the Cape Urdyuk-Khaya (Nordvik Peninsula) is largely composed of dark argillites substantially enriched in C_org. Characteristic of the section is a continuous succession of ammonite, foraminiferal, ostracode, and dinocyst zones known also in the other Arctic areas. Boundaries of the upper Volgian Substage are recognizable only based on biostratigraphic criteria. The succession of the middle Volgian Taimyrosphinctes excentricus to basal Ryazanian Hectoroceras kochi zones is characterized. The range of the substage is revised. The lower Exoticus Zone, where ammonites characteristic of the Nikitini Zone upper part in the East European platform have been found, is referred to the middle Volgian Substage. Newly found ammonites are figured. Two possible positions of the Jurassic-Cretaceous boundary in the Arctic region, i.e., at the lower and upper boundaries of the Chetae Zone at the top of the upper Volgian Substage, are discussed.     

Detailed stratigraphy of the Jurassic-Cretaceous boundary beds of the Lena River lower reached based on ammonites and Buchiids

The Jurassic-Cretaceous (Volgian-Lower Valanginian) boundary deposits in the lower reaches of the Lena River (near the village of Chekurovka and on the Cape Chucha, North Yakutia) are described bed-by-bed. The taxonomic composition of ammonites and bivalves (mainly Buchia) is determined. The species assemblages are biostratigraphically analyzed and biostratigraphic units of the bed and zone ranks are recognized based on by Buchia and ammonites. Analogues of the Buchia Zones (buchiazones) Unschensis, Okensis, Tolmatschewi, Inflata and ammonite zones Exoticus, Okensis, Sibiricus, Analogus, Mesezhnikowi and ? Klimovskiensis are established in this region for the first time. A correlation of the distinguished buchiazones with the buchiazones of the Nordvik Peninsula, New Siberian Islands (Stolbovoy Island), the basin of the Anyuy River, and Northern California is proposed. The ammonite assemblages constantly contain phylloceratids; some stratigraphic intervals also contain lytoceratids; this is probably connected with a Paleo-Pacific influence. Unlike the ammonite assemblages of the same age of the Khatanga depression, the subzones cannot be distinguished in the Sibiricus and Kochi Zones of the Lower Lena due to differences in the stratigraphic ranges of some ammonite species. Hectoroceras in the Kochi zone is very rare and Praetollia predominates here.     

Middle Pleistocene-Holocene calcareous plankton and benthos biostratigraphy of the Markova Depression,equatorial atlantic

The analysis of nannoplankton, planktonic and benthic foraminifer assemblages provided detailed biostratigraphic characteristics of the upper part of sedimentary cover in the Markova Depression, rift valley of the Mid-Atlantic Ridge. The Gephyrocapsa oceanica and Emiliania huxleyi nannofossil zones, (LO) Helicosphaera inversa biohorizon, Emiliania huxleyi Acme Zone, and planktonic foraminiferal Globigerina calida calida, Globigerina bermudezi and Globorotalia fimbriata subzones were recognized. The compiled paleotemperature curve is correlated with the upper 10 oxygen isotope stages. The recovered deposits were accumulated during 400 ka. Changes in abundance and species composition of benthic foraminifer assemblages are suggested to be correlative with hydrothermal activity outbreaks in the rift zone.     

Ammonite <Emphasis Type="Italic">Fauriella boissieri</Emphasis> (Pictet), the index species of the Berriasian upper zone from the Crimean Mountains

Ammonite Fauriella boissieri (Pictet), the index species of the Berriasian upper zone, is described for the first time as taxon occurring in the Crimean Mountains. In the Berriasian sections of the central Crimea and Chatyr-Dag massif, species F. boissieri are encountered only in association with upper Berriasian ammonites. The Berriasian-Valanginian boundary has not been identified based on ammonites in the Crimean Mountains. Consequently, there is no reason to include the otopeta Zone into the boissieri Zone in the rank of its upper subzone.     

Representatives of genera <Emphasis Type="Italic">Malbosiceras</Emphasis> and <Emphasis Type="Italic">Pomeliceras</Emphasis> (Neocomitidae,Ammonoidea) from the Berriasian of the Crimean Mountains

The revised representatives of ammonite genera Malbosiceras and Pomeliceras from the Berriasian of the Crimean Mountains are classed with seven species, four of the first genus [M. malbosi (Pictet), M. chaperi (Pictet), M. broussei (Mazenot), M. pictetiforme Tavera] and three of the second one [P. aff. boisseti Nikolov, P. breveti (Pomel), P. (?) funduklense Lysenko et Arkadiev sp. nov.]. The identified species are described. The genus Mazenoticeras is considered as synonym of Malbosiceras. The above species prove that all the Berriasian zones (jacobi, occitanica and boissieri) are characteristic of corresponding deposits in the Crimean Mountains.     

Stratigraphy of the Bathonian-Callovian boundary deposits in the Prosek section (Middle Volga Region). Article 1. Ammonites and infrazonal biostratigraphy

In European Russia, the most complete succession of Boreal sediments of the terminal Bathonian and lower Callovian is exposed near the Prosek Settlement. After its revision, the infrazonal division of the upper Bathonian and lower Callovian and position of the Bathonian-Callovian boundary are difined more carefully. The Calyx Zone and bodylevskyi Biohorizon are established in the upper Bathonian. The base of the lower Callovian is defined at the first occurrence level of Macrocephalites jacquoti. Based on four successive ammonite assemblages occurring in lower part of the Elatmae Zone, the breve, frearsi, quenstedti, and elatmae biohorizons are identified. The joint occurrence of Boreal, Subboreal, and Tethyan ammonites in the section facilitate its correlation with the other sections of the Panboreal paleobiogeographic superrealm.     

Smaller foraminifers from type sections of the Bolorian stage,the Lower Permian of Darvaz

Smaller foraminifers from Upper Yakhtashian and Bolorian deposits of the stratotype area (Pamir, Darvaz, Tajikistan) are investigated. Four assemblages are defined. The first assemblage is from Chalaroschwagerina vulgaris-Pamirina darvasica Zone. The second assemblage found in the transitional Yakhtashian-Bolorian beds includes Globivalvulina, Palaeotextulariidae, Hemigordiidae, and Glomospira, associated with the first Pachyphloia and Langella forms. Characteristic taxa of third assemblage from the Misellina (Brevaxina) dyhrenfurthi Zone are Geinitzinidae, Globivalvulina, Palaeotextulariidae, Glomospira, and rare Pachyphloia. The forth assemblage of Hemigordiidae, Pachyphloia, Palaeotextulariidae, Geinitzinidae, Pseudoagathammina is identified in the M. (Misellina) parvicostata Zone. The assemblages were compared with concurrent analogs from China, Japan, and Russia. New species and subspecies Glomospira paleograndis sp. nov., G. darvasica sp. nov., Agathammina darvasica sp. nov., Pachyphloia darvasica sp. nov., Nodosinelloides cubanicus elongatus subsp. nov., and Hemigordius saranensis darvasicus subsp. nov. are described.     

Redkinian Biota of Macroscopic Fossils from the Northwestern East European Platform (South Ladoga Region)

The stratigraphic distribution of microfossils and macroscopic fossil biota in Vendian deposits of the South Ladoga region (northwestern East European Platform) is analyzed. In the sequence of the Shotkusa- 1 well, three taxonomically heterogeneous microfossil assemblages are distinguished: two of them refer to the Redkinian age (Starorusskaya Fm.) and one to the Kotlinian age (Vasileostrovskaya Fm.). Deposits of the Starorusskaya Fm. contain Redkinian biota of macroscopic fossils, of which the most characteristic representatives are Chuaria circularis, Doushantuophyton lineare, Morania zinkovi, Orbisiana simplex, and Redkinia spinosa. These new findings expand the paleontological characteristics of Upper Vendian deposits, also providing additional criteria for distinguishing the Redkinian horizon in the northwestern East European Platform.     

Paleogene biostratigraphy of the North Circum-Caspian region (implication of the dinocysts and nannoplankton from the Novouzensk reference borehole), Part 1: Age substantiation and correlation of deposits

Eight zonal dinocyst assemblages and three bio stratigraphic units ranked as “beds with flora” are first distinguished in the Danian—lower Lutetian interval of the Paleogene succession, penetrated by the reference borehole Novousensk no. 1, where eight standard and one local nannoplankton zones are simultaneously recognized. The direct correlation of nannoplankton and dinocyst zones is used to refine the paleon-tological substantiation and stratigraphic position of regional lithostratigraphic units, ranges of hiatuses, and the correlation with the general stratigraphie scale. The nannoplankton of the Danian NP2 Cruciplacolithus tenuis and NP3 Chiasmolithus danicus zones is characteristic of the Algai Formation (Fm). The nannoplankton of the NP4 Coccolithus robustus Zone and dinocysts of the D3a Alterbidinium circulum Zone from the Tsyganovo Fm characterizes the Danian top. The Lower Syzran Subformation (Subfm) corresponds to the upper part of the NP4 Coccolithus robustus Zone (Neochiastizygus junctus local zone) and to the D3b (part) Cerodinium depressum Zone of the Selandian dinocysts. The latter spans part of the Upper Syzran Subformation, whose characteristic nannofossils are the nannoplankton of the NP5 Fasciculithus tympaniformis Zone and the dinocysts of the D3b (part) Isabelidinium? viborgense Zone of the Selandian. The Novouzensk Fm is represented by a succession of the dinocyst Cerodinium markovae Beds and the standard D4c Apectodinium hyperacanthum Zone of the upper Thanetian. The coccolitophorids of the lower Thanetian NP6 Heliolithus kleinpelli Zone occur at the formation base. The Bostandyk Fm includes successive bio stratigraphie units of the Ypresian. In the dinocyst scale, these are the D5a Apectodinium augustum Zone, the Pterospermella Beds (DEla Zone of the North Sea scale), and zones DBlb-c Deflandrea oebisfeldensis, D7c Dracodinium varielon-gitudum, and D8 Dracodinium politum—Charlesdowniea coleothrypta, while units of the nannoplankton scale correspond to the NP12 Martasterites tribrachiatus and NP13 Discoaster lodoensis zones. The Kopterek Fm yields Lutetian nannofossils: the nannoplankton of the NP14 Discoaster sublodoensis Zone and the dinocysts of the Wetzeliella coronata—Areosphaeridium diktyoplokum Beds. Three meaningful hiatuses are established at the Danian base, Selandian top, and in the lower Ypresian.     

Terminal paleocene of the Volga middle reaches: Biostratigraphy and paleosettings

Diatoms and marine palynomorphs from several sections of the Kamyshin Formation (Sengilei-1, Sengilei-2, Balasheika, Kuz’kino, boreholes 38 and 50) are jointly studied for the first time in the Volga middle reaches. According to results, the formation lower part corresponds here to Viborg Zone 4-Viborg Zone 5 (Heilmann-Clausen, 1985)/Alisocysta margarita (part)-Apectodinium hyperacanthum (Powell, 1992) diatom zones of Northern Europe. Higher levels of the formation are correlative with Trinacria ventriculosa and Hemiaulus proteus dinocyst zones (Strelnikova, 1992). Thus, the Kamyshin sedimentary cycle in the Volga middle reaches corresponds to the interval of NP8 (part) and NP9 zones of the general scale. As is established, different terrigenous to siliceous facies of that cycle (sands, diatomites, opokas and clay) are mostly confined to eastern and southeastern areas of the study region. Judging from taxonomic composition, assemblages of diatoms and marine palynomorphs originated in coastal paleosettings with active hydrodynamics and high productivity of water mass. Diatom assemblages from different facies are dissimilar. Three phases of Thanetian transgression are distinguished based on quantitative proportions of different ecologic groups (Paralia/Pyxidicula ratio variations). Within transition from the Trinacria ventriculosa to Hemiaulus proteus Zone, there are recorded considerable changes in composition of diatom assemblages: the appearance of new genera with considerable morphologic innovations (Podosira, Craspedodiscus, Fenestrella, Moisseevia, Solium, Gyrocylindrus) and compositional renewals of genera Pyxidicula, Trinacria, and Hemiaulus. These changes are indicative of a global biotic crisis in the Paleocene-Eocene transition related with thermal maximum and negative C-isotope excursion and extinction of benthic fauna groups.     

The Early Callovian genus <Emphasis Type="Italic">Сadochamoussetia</Emphasis> (Ammonoidea,Cardioceratidae) in the lower reaches of the Anabar River,Northern Central Siberia

The species Cadochamoussetia aff. subpatruus (Nik.), Cadochamoussetia surensis (Nik.), and Cadoceras cf. simulans Spath are found for the first time in the lower reaches of the Anabar River. The first two species are characteristic of the Lower Callovian Cadochamoussetia subpatruus Subzone of Central Russia, which is equivalent to the Siberian Cadochamoussetia tschernyschewi Zone. Species of the genus Cadochamoussetia, found for the first time in the Arctic, are described. Shells of Siberian representatives of Cadochamoussetia are distinguished from the typical East European species by their larger umbilicus, which is similar to that of the ancestral genus Cadoceras. It is suggested that the Siberian taxa belong to the oldest representatives of this genus, which appeared in the early Callovian Arctic seas and later migrated to seas of Central Europe and England.     

Ammonites and Stratigraphy of the Terminal Part of the Middle Volgian Substage (Upper Jurassic; Epivirgatites nikitini Zone and Its Equivalents) of the Panboreal Realm: 2. <Emphasis Type="Italic">Titanites</Emphasis> and <Emphasis Type="Italic">Glaucolithites</Emphasis>

The genera Titanites and Glaucolithites, which were previously known only from the Portlandian of Northwestern Europe are now established in Epivirgatites nikitini Zone of European Russia. The Volgian species of Titanites are represented by both the endemic taxa Titanites (Paratitanites) manipulocostatus subgen. et sp. nov. and T. (Pseudogalbanites) triceps subgen. et sp. nov. and Titanites (Titanites) ex gr. titan Buckman of the Portland type. A new species Glaucolithites gardarikensis is described. It is likely that these ammonites migrated to the Central Russian Sea from northwestern Europe via the Norway-Greenland seaway and further to the Mezen-Pechora system of straits, which is supported by occurrences of Titanites in the north of Central Russia and Glaucolithites in East Greenland and on Spitsbergen. The direct and indirect correlations show that the middle part of the Nikitini Zone (Lahuseni Subzone) should at least partly be correlated with the Portlandian Kerbeus Zone.     

Ammonites from the <Emphasis Type="Italic">Deshayesites</Emphasis> genus from Aptian (Lower Cretaceous) sediments in the Mountainous Crimea

Stratigraphically important ammonites Deshayesites ex gr. deshayesi (d’Orbigny, 1840), Deshayesites sp. juv., and Paradeshayesites aff. callidiscus [Casey, 1961] from lower Aptian pelagic sediments at the Verkhorech’e Village have been described and depicted. The new finds and revision of previously found ammonites allow the recognition of ammonite zones Deshayesites volgensis and Deshayesites deshayesi in the Southwestern Crimea.     

Community vulnerability to hazards: introducing local expert knowledge into the equation

The accuracies of three different evolutionary artificial neural network (ANN) approaches, ANN with genetic algorithm (ANN-GA), ANN with particle swarm optimization (ANN-PSO) and ANN with imperialist competitive algorithm (ANN-ICA), were compared in estimating groundwater levels (GWL) based on precipitation, evaporation and previous GWL data. The input combinations determined using auto-, partial auto- and cross-correlation analyses and tried for each model are: (i) GWL _t?1 and GWL _t?2; (ii) GWL _t?1, GWL _t?2 and P _t ; (iii) GWL _t?1, GWL _t?2 and E _t ; (iv) GWL _t?1, GWL _t?2, P _t and E _t ; (v) GWL _t?1, GWL _t?2 and P _t?1 where GWL _t , P _t and E _t indicate the GWL, precipitation and evaporation at time t, individually. The optimal ANN-GA, ANN-PSO and ANN-ICA models were obtained by trying various control parameters. The best accuracies of the ANN-GA, ANN-PSO and ANN-ICA models were obtained from input combination (i). The mean square error accuracies of the ANN-GA and ANN-ICA models were increased by 165 and 124% using ANN-PSO model. The results indicated that the ANN-PSO model performed better than the other models in modeling monthly groundwater levels.     

Conodont-based stratigraphy of the Mosolovian Regional Stage (Eifelian,Middle Devonian) of the Voronezh Anteclise

Conodonts from the deposits of the Mosolovian Regional Stage (Middle Devonian) of the Voronezh Anteclise are studied on the basis of the data from six boreholes. Three assemblages are recognized. The index species of the lowermost assemblage is Icriodus formosus Naz. The index species of the middle assemblage are I. formosus Naz. and Pseudobipennatus ziegleri Kon. et Kim, as well as I. arkonensis Stauff. and I. jejunus Naz. This assemblage is the most diverse and is recognized in all boreholes. The deposits containing this assemblage correspond to the maximum of the Nara transgression. The upper assemblage is also recognized in all the studied boreholes. Its index species is Ps. ziegleri Kon. et Kim. The Mosolovian Regional Stage is assigned to the kockelianus Zone. The distribution diagrams of species in the most diverse middle assemblage support the hypothesis that, in the southeastern regions of the Voronezh anteclise, the depth was greater than in its western part. The characteristic conodont species are shown in the plates.     

Infrazonal biostratigraphy of the Upper Cretaceous in the East European province based on benthic foraminifers,Part 2: Santonian-Maastrichtian

A chart of infrazonal biostratigraphic subdivisions in the Cenomanian-Coniacian succession of the East European paleobiogeographic province is substantiated based on distribution of benthic foraminifers. The suggested chart characterizes successive trend of changes in ecologic assemblages of benthic foraminifers and morphologic evolution of certain agglutinated (Gaudryina, Ataxophragmium, Ataxoorbignyina, Arenobulimina, Novatrix, Voloshinovella, Orbignyina, Bolivinopsis) and secretory (Neoflabellina, Globorotalites, Stensioeina, Osangularia, Eponides, Gavelinella, Pseudovalvulineria, Pseudogavelinella, Brotzenella, Cibicides, Cibicidoides, Angulogavelinella, Falsoplanulina, Anomalinoides, Coryphostoma, Bolivinoides, Praebulimina) foraminiferal genera. The chart includes 23 biostratigraphic units (zones and subzones), most of which are recognizable over the vast territory from the Mangyshlak to southern Baltic areas. It is correlated with the acknowledged belemnite, inoceramid, ammonoid and echinoid zonations. Eight stadia of taxonomic changes in foraminiferal assemblages, which are distinguished in this work, show that principal biotic events took place across the middle-late Santonian and Santonian-Campanian boundaries, in the earliest Campanian, at the early-late Campanian boundary time, during the late and terminal Campanian, and in the mid-early Maastrichtian.     

New data on microbiota of the Middle Volgian substage in the Loino Section (Kirov oblast)

The calcareous nannoplankton was established for the first time in Upper Volgian deposits of the Loino Section (Kirov oblast). Here, single coccolites of representatives of genus Watznaueria of wide stratigraphic and geographic distributions dominate. Representatives of genus Zuegrhabdotus are less common, whereas species of genus Polypodorhabdus are rare. The taxonomic composition of the calcareous nannoplankton assemblage does not allow us to distinguish the nannoplankton zone in the Loino Section, but it gives us an idea about its distribution at the Volgian Stage in the Russian Plate. As corresponding microfauna, foraminifers, assigned to the Lenticulina infravolgaensis–Saracenaria pravoslavlevi Zone, and ostracods were identified to substantiate the age of host deposits. The ostracod assemblage is assigned to the Macrodentina (Polydentina) subtriangularis Beds established on the Volga River left bank in deposits corresponding to the ammonite zones Panderi and Virgatus assigned to the middle Volgian substage. On the basis of ostracods, the warm-water well-aerating environment of the upper sublittoral (as deep as 50 m) was reconstructed.     

Cenomanian-lower coniacian radiolarian assemblages from the Naiba reference section (Sakhalin)

Reexamination of radiolarians from the Naiba and Bykovo formations of the Naiba reference section (West Sakhalin Mountains) is carried out. Distinguished in the section are the Cromyomma (?) nodosa-Amphipyndax sp. A (terminal early Cenomanian), Cuboctostylus kasinzovae-C. sakhalinensis (Middle Cenomanian), Cuboctostylus trifurcatus-Cassideus yoloensis (terminal middle-late Cenomanian), and Spongodiscus concentricus-Multastrum robustum (late Turonian to early Coniacian probably) assemblages. According to results of comparative analysis for North Pacific regions, concurrent radiolarian assemblages from the Naiba section and California contain up to 40% of species in common, whereas taxonomic similarity with assemblages from Japan is insignifican in contrast.     

Mineral thermometry and the composition of fluids of the sodalite syenites of the Lovozero alkaline massif

In order to determine the conditions of mineral formation, a suite of sodalite syenite samples was investigated from the differentiated complex and in part from the eudialyte lujavrite complex of the Lovozero alkaline massif. The compositions of major and accessory minerals were analyzed using an electron microprobe. Various mineral geothermometers (Bt-Cpx, Amph-Cpx, and Amph-Bt) were applied to estimate the temperature of formation of clinopyroxene-bearing assemblages from the sodalite syenites. The temperature varied from ～990 to 595–630°C, which reflects various stages of crystallization. The temperatures of formation of sodalite assemblages were estimated from the compositions of coexisting sodalite phases as 625–530°C and appeared to be in good agreement with estimates obtained by other mineral geothermometers. Based on the data on the composition and crystallization temperature of sodalites, the minimum concentration of salts (NaCl and Na₂SO₄) in the mineral-forming fluid was estimated as 10–20 wt % NaCl eq. for the two-sodalite assemblages and 1.5–3.0 wt % NaCl eq. for the nosean-bearing assemblages. The molar fraction of sulfur in the fluid was also estimated: 0.02 for the two-sodalite assemblages and 0.04–0.27 for the nosean-bearing assemblages.