Coeval Deposits Research Articles

Givetian megaspore assemblages of the Mikhailovksy mine (Kursk oblast)

Background. Disperse megaspores from the Givetian deposits of the Mikhailovsky mine, Kursk Oblast, were studied for the first time. Following chemical maceration of the samples, their selection and identification, 12 species belonging to 8 genera of disperse megaspores were identified. The conducted analysis of the layer-by-layer distribution of disperse megaspores in the studied outcrop, two megaspore assemblages were established, describing the lower (M1) and upper (M2) parts of the section. Both assemblages are dominated by small-sized azonate megaspores of the Hystricosporites McGregor genus, although belonging to different species. The upper assemblage (M2) is more diverse in terms of taxonomic composition. Along with the Givetian deposits of the Mikhailovsky mine, the identified disperse megaspores were previously found in coeval deposits of Canada and Libya.Aim. To study of disperse megaspores from the Givetian deposits of the Mikhailovsky mine (Kursk Oblast) and to establish megaspore assemblages for this section.Materials and methods. Samples of the clay deposits of the Givetian stage of the Middle Devonian from the Mikhailovsky mine (Kursk Oblast, Zheleznogorsk) were collected by employees of the Paleontological Institute of the Russian Academy of Sciences (PIN RAS) in the summer of 2017. The samples were macerated at the Department of Paleontology using concentrated (55%) hydrogen peroxide. The samples heavily contaminated with megaspores were additionally treated with hydrofluoric acid and further purified in hot drops of denaturated alcohol. Selection, counting, and determination of macerated samples of disperse megaspores were carried out using an Olympus CZ65 stereomicroscope at a 20x magnification or greater. Microphotographs were taken using a TESCAN Vega-3 scanning electron microscope (PIN RAS).Results. A total of 12 species belonging to 8 genera were identified. These included Hystricosporites McGregor, Verrucisporites Chi et Hills, Nikitinsporites Chaloner, Biharisporites Potonié, emend. Glasspool, Ancyrospora Richardson, Contagisporites Owens, Grandispora Hoffmeister, Staplin et Malloy, emend. McGregor, and Lagenicula (Bennie et Kidston) Dybova-Jachowicz et al. On the basis of disperse megaspore distribution along the section, two megaspore assemblages were established: M1 (lower, layers 7–12) and M2 (upper, layers 18–21).Conclusion. The disperse megaspores established in the Givetian deposits of the Mikhailovsky mine were early described in the Arctic Canada. The majority of the studied megaspores were most likely produced by lycopsids. This conclusion is based on their comparison with identical in-situ megaspores, as well as on the ultrathin structure of the sporoderm, previously established for some species. Consequently, the Givetian forests of the studied region were populated with numerous lycopsids, including tree-like ones, among heterosporous plants, with an insignificant role of archaeopteridalean tree-like species.

Polyphased gold enrichment as a key process for high-grade gold formation: Insights from the 10 Moz Jundee-Bogada camp (Yilgarn Craton, Western Australia)

High-grade (> 10 g/t) gold mineralization in orogenic gold deposits is of significant economic importance. Understanding the formation of such enriched ore zones is critical for gold exploration success. The world-class Jundee-Bogada gold camp in the Yilgarn Craton of Western Australia comprises both high-grade (avg. > 10 g/t, Jundee deposit) and low-grade (avg. < 3 g/t, Bogada prospect) lodes, despite shared host stratigraphy. The paragenetic framework established for the Jundee gold deposit suggests that the overall gold endowment developed over three deformation events. An early episode of low-grade gold mineralization is associated with colloform-crustiform veins that formed during extensional deformation (DJB2A). A switch to transtensional deformation (DJB2B) resulted in brecciation of the colloform-crustiform veins and coeval deposition of native gold. Late reverse faults record evidence for a third mineralization stage resulting from a NE-SW-directed shortening (DJB3). Mineralization during this late stage was dominantly low-grade, with local occurrences of ultra-high-grade ore zones (> 100 g/t). Each event records transient changes in fluid chemistry during continued hydrothermal activity that spanned local deformation histories. We argue that at the Jundee gold deposit, protracted gold enrichment during three polyphased mineralization episodes resulted in the formation of high-grade gold ores. Whereas the complete metallogenic history is recorded at the Jundee deposit, gold within the Bogada prospect was introduced solely during the late contractional stage (DJB3), resulting in a bulk low-grade endowment. We hypothesize that gold enrichment in high-grade orogenic gold deposits is a direct consequence of the spatial superimposition of protracted ore-forming events.

Evolutionarily ancient deep‐water seep communities in the Eocene Tethys: examples from Buje (Croatia)

AbstractWe report a newly discovered hydrocarbon seep deposit from the Eocene bathyal flysch, exposed in the town of Buje in Istria, Croatia. Molecular fossils of methane‐oxidizing prokaryotes and abundant banded botryoidal cements indicate strong fluid flux at this site. We systematically describe the fauna of this and another seep deposit previously reported from Buje. The faunal assemblages are composed of eight species, these being an unidentified solemyid protobranch bivalve, the nuculid Nucula bowerbanki?, the nuculanid Nuculana? sp., the mytilid Brachidontes? amanoi sp. nov., the two thyasirids Channelaxinus dinaricus sp. nov. and Thyasira histriaensis sp. nov., the lucinid bivalve Amanocina bujensis sp. nov., and a possible provannid gastropod. The two assemblages are of low diversity (4 and 5 species, respectively), and are dominated by chemosymbiotic species whose occurrence is largely restricted to seeps. Despite their spatial and stratigraphic proximity, the two deposits share only a single species, Channelaxinus dinaricus, probably due to different fluid flux regimes at both seeps. The Buje seep assemblages are among the very few Late Cretaceous to Palaeogene chemosynthesis‐based faunal assemblages from the Tethys Ocean (the others being Late Cretaceous vent assemblages from Cyprus). From an evolutionary perspective, the Buje seep communities consist of genera with Mesozoic origins but lack Cenozoic novelties such as bathymodiolin mussels and vesicomyid clams, which are known from coeval deposits from the Pacific and dominate vents and seeps today. Thus, the Buje seep fauna support previous assertions that the Eocene Tethyan seep faunas preserved an ancient aspect, whereas evolutionary novelties arose in the Pacific.

Mid-to Late Holocene East Antarctic ice-core tephrochronology: Implications for reconstructing volcanic eruptions and assessing their climatic impacts over the last 5,500 years

Ice cores are powerful archives for reconstructing volcanism as they contain both soluble (i.e. aerosols) and insoluble (i.e. tephra) products of volcanic eruptions and for more recent periods have high-precision annually resolved chronologies. The identification and geochemical analysis of cryptotephra in these cores can provide their volcanic source and latitude of injection, complementing records of sulphur injections from volcanic eruptions developed using continuous flow ice-core analysis. Here, we aim to improve the volcanic record for the Southern Hemisphere using a sampling strategy for cryptotephra identification based on coeval deposition of sulphate and microparticles in ice cores from the interior of East Antarctica covering the Mid-to Late Holocene. In total, 15 cryptotephras and one visible horizon were identified and geochemically characterised. Through comparisons to proximal deposits a range of possible sources were isolated for these horizons including the South Sandwich Islands, South Shetland Islands, Victoria Land (Antarctica) and South America. This new tephra framework contributes to the volcanic history of the region by extending the known geographical range of tephra deposition for previously identified events and providing a potential indication of phases of eruptive activity from key sources. Using the tephra-based source attributions and comparison of the timing of the events to a database of sulphur injections from Holocene volcanic eruptions it is possible to refine injection latitudes for some events, which can lead to improved estimates of their radiative forcing potential. The relatively low magnitude of the volcanic stratospheric sulphur injections related to the events in the tephra framework indicates they would have had a limited impact on Southern Hemisphere climate. Further work is required to improve source attributions for some events and/or to determine the magnitude of sulphur injections for individual events during years when coeval eruptions occurred. One limitation of the framework is the dominance of cryptotephra from regional volcanic sources and a lack of tephra from tropical sources, which hampers the refinement of eruption parameters for these large magnitude and often climate-impacting eruptions. This issue could be explored further through increased sampling of these events and/or development of additional analytical techniques for the identification and robust geochemical analysis of glass tephra shards less than 5 μm in diameter. Such investigations could be coupled with model experiments to determine the likelihood that past tropical eruptions deposited glass tephra shards over Antarctica and the potential size range and geographical spread of deposition.

Pachycormid fish fed on octobrachian cephalopods: new evidence from the ‘Schistes bitumineux’ (early Toarcian) of southern Luxembourg

A re-examination of the early Toarcian fish fossils preserved in public paleontological collections in Luxembourg revealed 70 specimens of large Toarcian pachycormid fish with an excellent three-dimensional preservation within calcareous nodules. Six of them are associated with octobrachian coleoid gladii in their oesophagus or stomach, an association not previously described from Luxembourg. The pachycormids are ascribed to Pachycormus macropterus (Blainville, 1818) and Saurostomus esocinus Agassiz, 1843 while the octobrachian gladii are ascribed to Teudopsis bollensis Voltz, 1836, Teudopsis sp. indet. and Loligosepiidae indet. The position and orientation of the gladii provide direct evidence of these fishes feeding on coleoids and thus a teuthophagous diet, rather than an accidental joint burial. Together with evidence from coeval deposits in Germany, these findings suggest that teuthophagy was a widespread feeding strategy at the base of the clade that contains the suspension-feeding pachycormid giants of the Jurassic–Cretaceous.

Revisiting the stratigraphical, sedimentological and provenance evolution of Lingshan Island, offshore of east China: Implications for the destruction of the north China craton

The Cretaceous strata of Lingshan Island, offshore of East China, are a key sedimentary archive for understanding the destruction of the North China Craton (NCC). However, there has been limited progress in characterizing its stratigraphical, sedimentological and provenance evolution in the context of the progressive lithospheric thinning and magmatism associated with the destruction of the NCC. We report field logging data, sandstone framework petrography, and detrital and volcanic zircon U–Pb geochronology data from the Cretaceous strata of Lingshan Island, and correlate these data with coeval sediments in the Jiaolai Basin and volcanic units in the East China. Our results indicate rapid deposition of the Laiyang and Qingshan groups from c. 124–123 Ma with an upward thickening and coarsening succession from the lacustrine turbidites of the Laiyang Group to the deltaic rocks of the Qingshan Group, accompanied by an increase in volcanic activity up-section. Sandstone petrology and detrital zircon U–Pb ages indicates that the source areas for the Laiyang and Qingshan Groups were syn-depositional volcanic rocks and plutonic rocks, with some contributions from the Yangtze Craton and Sulu terrane. Our compilation of detrital zircon U–Pb ages (n = 8513) from the Cretaceous strata of Lingshan island and the Jiaolai Basin in the hinterland implies provenance contributions from four different sources. The zircon Th/U ratios from this large dataset suggests that Cretaceous magmatic zircons formed in an extensional setting (Th/U ratios >1 but with significant variation). The Eu anomalies in magmatic zircons (n = 550) from the Jiaodong Peninsula indicate continuous lithospheric thinning in Eastern China since c. 130 Ma, leading to the destruction of the NCC. Based on all available data, Lingshan Island most likely was a rift basin during the Cretaceous.

The Oko Limestones: a Late Miocene-Pliocene fluvial to palustrine-lacustrine carbonate wetland enclosed in the South Pyrenean Thrust Front (Navarre, Spain)

This work presents the sedimentological study of the Upper Miocene-Pliocene Oko Limestones, exposed in the Antzin-Murieta Basin, in Navarre. Two stratigraphic sections of the carbonate unit have been studied: the Oko cemetery and Ega road sections. The former exposes facies that characterize a fluvial carbonate environment, with a distinct development of microbial oncolitic deposits. The coeval deposits exposed in the Ega road section, instead, largely represent a palustrine-lacustrine setting that evolved under alternating conditions of ponding and desiccation. Data integration from these sections and the intermediate areas, allows the interpretation of a fluvial to palustrine-lacustrine wetland with a marked east-southeast trend, which developed coevally to the uplift of the Piedramillera thrust sheet.

Multiproxy approach to reconstruct the climate and environment of a new late Middle Pleistocene vertebrate site in northwestern Italy

The Moleto site (Ottiglio, AL, Piemonte, Italy) was discovered in the 1990s in an abandoned quarry carved into a Burdigalian–Langhian carbonate succession called Pietra da Cantoni. Sediment collection in three closely spaced fissures provided a rich vertebrate association whose age can be constrained to the late Middle Pleistocene on the basis of the presence of the extinct water vole Arvicola mosbachensis and its enamel characteristics (SDQ values ranging from 100 to 130). The very similar faunal content, evidenced by the common presence of Arvicola mosbachensis and its similar SDQ values, is indicative of a coeval deposition of the fillings of the three fissures. The vertebrate assemblage is represented by 30 taxa, including amphibians, squamate reptiles, birds, and mammals. Interestingly, a diverse fish assemblage from the embedded sediments of the Miocene Pietra da Cantoni has been found in the fissure fillings. We present here a multi-method approach using the small vertebrate assemblages (rodents, insectivores, amphibians, and squamate reptiles) from Moleto to characterize the environment and climate of the site. In order to reconstruct the palaeoenvironmental and palaeoclimatic conditions, we applied the Mutual Ecogeographic Range using UDA-ODA technique, the Bioclimatic Model, the Habitat Weightings, and the Quantified Ecology methods. The results revealed a landscape dominated by woodland habitats with presence of open humid meadows, under temperate and moist climatic conditions, although somewhat colder and drier than today. According to all evidence, the associations from Moleto would correspond to the interglacial MIS 7.

Late holocene progradation in a mixed siliciclastic-carbonate beach ridges system, Northeast Brazil

A morpho-sedimentary analysis based on grain size, texture, composition, luminescence ages, and morphologic pattern was performed in a beach ridge system located on the Brazilian semiarid coast to understand the siliciclastic and bioclastic mixtures during a progradation of strandplain. Moreover, the rhodolith beds were adopted as a new sea-level proxy to analyze the coastline displacement trajectory of the mixed siliciclastic-carbonate sedimentary environment. The beach ridges system shows a succession of ridges and swales interrupted in the central part by a lagoon plain, the western sector exhibits the crest relief related to the ancient foredune on top and underlying foreshore deposits, and the eastern sector shows a great presence of transgressive dunes overlying beach ridges. Foredune/aeolian facies and the foreshore facies (with rhodolith beds associated) show siliciclastic and bioclastic mixture related to the late Holocene coastal progradation with a progressive increase in carbonate influence, mainly calcareous algae, foraminifera, and molluscs. Moreover, comparing the modern counterpart of the older beach ridges, finer and better-sorted sediments were found in the ancient deposits than in the modern ones. Thus, the progradation was marked by an eminently dissipative beach system. This coeval sedimentation is controlled by key local settings, such as the semi-arid climate, the absence of local fluvial input, the shallow shelf, and the carbonate factory for bioclastic supply. The presence of rhodolith beds in the foreshore facies with an elevation lowering trend towards the modern coastline reinforces the hypothesis that the mixed progradational pattern was accompanied by a small fall in sea level, which corroborates with late Holocene regional curves and provides pioneering preliminary contributions for the studied area.

CYCLOSTRATIGRAPHIC ESTIMATE OF THE DURATION OF THE NEGATIVE δ&lt;sup&gt;13&lt;/sup&gt;C ANOMALY OF THE ZHUA GROUP (SHURAM-WONOKA EVENT) IN THE VENDIAN REFERENCE SECTION IN SOUTH OF THE SIBERIAN PLATFORM

A cyclostratigraphic study of the Late Precambrian Zhuya Group (Nikolskoye and Chencha Formations) and Torgo formation in the south of the Siberian Platform was carried out to determine the duration of the C-isotope anomaly imprinted in them. The similarity of the ratios of the period lengths of the cyclic components of the magnetic susceptibility in the coeval deposits of the remote sections of the Nikol’skoye and Torgo Fms. indicates the connection between the revealed cyclicity and the basin-scale environment changes. According to the obtained astrochronological model, the duration of the formation of the studied intervals of the Nikol’skoye (57 m) and Chencha (147 m) formations was 850 and 2500 ky, respectively. Extrapolation of the data obtained shows that the duration of the C-isotope anomaly of the Zhuya Group in the Vendian reference section of the on the Ura uplift was about 10 My, which is consistent with most estimates of the Shuram anomaly’s duration and its stratigraphic analogues.

Hares from the Late Pleistocene of Ukraine: a phylogenetic analysis and the status of Lepus tanaiticus (Mammalia, Lagomorpha)

AbstractHares (genus Lepus) are widely distributed in Europe, and they are adapted to various types of habitats. Many species are known to hybridise, and previous molecular genetic studies have revealed recurrent introgressions between species at all stages of the genus’s radiation. The Don hare (Lepus tanaiticus) was described from the Late Pleistocene of the Southern Urals and subsequently reported from coeval deposits of various regions of northern Eurasia. It is morphologically close to the mountain hare (Lepus timidus) and recent studies of mitochondrial DNA questioned its status as an independent species. Here we compare cytochrome b and control-region sequences of mtDNA of arctic Lepus, including, for the first time, eight specimens from Late Pleistocene localities of Ukraine, in order to analyse the phylogenetic relationships between representatives of different taxa. The phylogenetic tree and haplotype network analyses do not support the taxonomic distinctness of the Don hare, and only specimens of Lepus arcticus and Lepus othus form monophyletic groups based on the control-region sequences. Instead, L. tanaiticus are scattered among specimens of L. timidus. The obtained results support the hypothesis that the Don hare is an ancient morphotype of L. timidus, and its distinctive morphological traits are the result of increased geographical variation of the latter due to range expansion and adaptation to the specific conditions of the periglacial biome, similarly to other Late Pleistocene small-mammal species.

Facies, biostratigraphy and isotope chemostratigraphy of the Tithonian‒Berriasian transition in the easternmost Getic Carbonate Platform (Southern Carpathians, Romania)

The easternmost side of the Getic Carbonate Platform at Postăvaru and Piatra Mare Massifs of Southern Carpathians (Romania) has been studied through eighteen sections using macro and microscopic analyses, micropaleontological studies combined with sedimentological and oxygen and carbon isotope analyses. The studied area is located in central Romania, in the easternmost part of the Southern Carpathians, in the vicinity of the Carpathian Bend. Eight major facies associations are identified defining lower slope, upper slope/reef crest, platform margin and inner platform depositional environments. The microfossil assemblages contain foraminifera, dasycladalean algae, microproblematica and calpionellids characterizing the Tithonian and Berriasian stages. The carbonate succession shares similar characteristics with coeval deposits from the Southern Carpathians and other regions of the Tethys Realm (especially Northern Calcareous Alps, Polish Outer Carpathians, Carpatho-Balkanides, Albanides and Hellenides). The sedimentological and isotope chemostratigraphic analyses provide evidence that subaerial exposure was common in shallow-water and inner platform depositional settings, in a prograding context, under the influence of carbonate sedimentation and eustasy. All the investigations allow deciphering the Tithonian–Berriasian transition in the easternmost Getic Carbonate Platform.

Revision of Permosialidae (Insecta: Palaeomanteida) from Uppermost Lower and Lower Middle Permian of European Russia

Generic and species composition of Permosialidae (Insecta: Palaeomanteida) from the uppermost Lower and lower Middle Permian of European Russia is discussed. Permosialis defurcata Martynova, 1952, P. brevifurcata Martynova, 1952, P. bifasciata Martynov, 1933, P. cauleoides Martynova, 1952, P. marmorata Martynova, 1952, P. immaculata Martynova, 1952 and P. fasciata Martynova, 1952 (all from the Lower Kazanian deposits of Soyana in Arkhangelsk Region) are synonymized under P. paucinervis Martynov, 1928 from the coeval deposits of Tikhie Gory in Tatarstan. Permosialis quadriramosa Martynova, 1952 from Soyana is synonymized under Palaeomantopsis furcatella Martynov, 1928 from Tikhie Gory. Palaeomantopsis furcatella, Permosialis paucinervis, P. perfecta Martynova, 1952, and P. latiformis Martynova, 1952 (the latter two from Soyana) are redescribed. Permosialis vizzya sp. nov. from Upper Kungurian of Vorgashor coal field and P. martynovae sp. nov. from Soyana are described as new.

An Oligocene-Miocene intermontane narrow lowland in the central Tibetan Plateau: Insights from provenance analysis and palynological record of a Cenozoic sedimentary succession

• The Niubao Formation in the Avengco Basin, the western part of the BNSZ, was deposited during Oligocene-Miocene with bidirectional sources. • The Oligocene-Miocene paleoelevation of the Avengco Basin was 3090-3290 m. • A 3 km high intermontane lowland on the BNSZ were formed during the Oligo-Miocene. • This intermontane lowland was probably formed by the reactivation of thrust belts and cloud extend westward to the Avengco Basin. A series of Cenozoic basins are distributed along the Bangong-Nujiang suture zone and amalgamate into an east-west trending topographic lowland. The reconstruction of the formation process for the lowland is critical to understanding the evolution of the Tibetan Plateau and paleoclimate. Here we present results from sedimentology, zircon U-Pb ages, and palynological records of the Niubao Formation in the Avengco Basin, the western part of central Tibet. The Niubao Formation consists of conglomerate, sandstone, siltstone, marl, and limestone, which were deposited in alluvial fan and shallow lake. The palynological assemblages suggest that the Niubao Formation in the Avengco Basin was deposited during the Oligocene-Miocene. Provenance analyses suggest that the Niubao Formation can have bidirectional sources, including the Southern Qiangtang terrane and/or Bangong-Nujiang suture zone in the north and the Northern Lhasa terrane in the south. By using the co-existence approach, palynological records from the Niubao Formation yielded a paleoelevation of 3090-3290 m after temperature and lapse rate correction, which was 1-2 km lower than those of the Lhasa and Qiangtang terranes during the Oligocene-Miocene. Based on the above observations and previous studies from the coeval sediments of the Lunpola and Nima Basins in central Tibet, we propose that the intermontane lowland along the Bangong-Nujiang suture zone was formed as a whole during the Oligocene at the latest and extended to the Avengco Basin in the west.

Newly discovered ca. 1.6 Ga K-bentonite layers from the Lakharpata Group in Nepal Lesser Himalaya: Implications for basin evolution during the Columbia breakup

• Zircon U-Pb age for newly discovered K-bentonite (ca. 1.6 Ga) constrained the deposition time of the Lakharpata Group. • The Lakharpata Group in Nepal Lesser Himalaya is coeval sediment with the Lower Vindhyan in India. • The Lakharpata Group was deposited in a passive continental margin basin during the Columbia breakup. The Lakharpata Group, a set of marine sediments with a thickness of over 5000 m, occupies the middle part of the Lesser Himalayan sequence and records important tectono-sedimentary evolution in the northern margin of the Indian continent. However, the duration of deposition and tectonic background of the Lakharpata Group are poorly defined. This study presents zircon U-Pb ages and Hf isotopes, as well as petrochemical data for the newly discovered K-bentonite layers in the Aru Formation, the upper part of the Lakharpata Group. Integrating the detrital zircon ages of the underlying metasedimentary rocks and the sedimentation rate of dolomite in the South China Block, we suggest that the Lakharpata Group was deposited during the late Paleoproterozoic to early Mesoproterozoic (ca. 1680–1580 Ma) rather than from Mesoproterozoic to Early Paleozoic as previously presumed. Stratigraphic correlations show the Lakharpata Group in Nepal Lesser Himalaya correlates to the Lower Vindhyan Supergroup, as well as to the Deoban and Rautgara formations in Kumaun Lesser Himalaya and the Baxa Group in Sikkim Lesser Himalaya, India. The Lakharpata Group comprises two depositional sub-sequences that record two transgression-regression sedimentary processes, which are comparable to the Lower Vindhyan. Geochemical and sedimentological studies suggest that the Lakharpata Group may represent the deposition of a passive continental margin basin during the breakup of the Columbia supercontinent.

The Prisayan Formation (Lower and Middle Jurassic) of the Irkutsk Coal Basin: New Data on Litho- and Phytostratigraphy

Abstract —The demand for detailed bio- and lithostratigraphic research of the Prisayan Formation is significant because of the lack of its stratotype section. This leads to confusion about the meaning of the stratigraphic volume of the Prisayan Formation. On the basis of the results of a comprehensive research, a lectostratotype section that covers the whole section of the Prisayan Formation is proposed. The following three subformations are identified in the formation on the basis of lithological criteria: lower (Ust-Balei), middle (Idansk), and upper (Sukhov). Stratigraphic correlation of the Prisayan Formation with the coeval deposits of the West Siberian Plate is carried out. The common development trends of typical units of the flora of the Siberian paleofloral region are revealed in West Siberia and the Irkutsk Basin. The observed tendencies make it possible to compare the beds with Coniopteris murrayana, Sphenobaiera czekanowskiana from the lower subformation with the fossil plant assemblage of the Sharapovo Horizon; the beds with Coniopteris snigirevskiae from the middle subformation with the fossil plant assemblage of the Nadoyakh Horizon; and the beds with Raphaelia diamensis and Phoenicopsis irkutensis with the fossil plant assemblage of the Laidin Horizon of West Siberia. The Prisayan-1 palynoassemblage (PA) from the lower and middle subformations correlate with palynozones 5–7 of West Siberia. The Prisayan-2 PA corresponds to palynozone 8 of West Siberia. The paleobotanical and palynological data suggest that the stratigraphic volume of the Prisayan Formation is the upper Pliensbachian–Aalenian of the Lower–Middle Jurassic. This paper touches upon the history of accumulation of the Prisayan Formation, as well as the evolution of the paleorelief and vegetation.

Use of palynology and thermal maturity in deformed geological units: A case study from the Permian succession in the Monte Leoni area (Middle Tuscan Ridge, inner Northern Apennines, Italy)

The reconstruction of the upper Palaeozoic sedimentary evolution of Western Mediterranean area is suffering for scarce age documentation of its stratigraphic units. This is also the consequence of the metamorphism and deformation they experienced during the Alpine tectonic events. Based on palynology and thermal maturity assessment, we contribute to this issue reporting biostratigraphic and sedimentological results in key-outcrops of the upper Palaeozoic successions of southern Tuscany (Italy), thus offering new data for the Palaeozoic units of the inner Northern Apennines, as well as for their palaeogeographic and palaeotectonic evolution predating the opening of the Alpine Neo-Tethys. This study is focused on the Falsacqua Formation mainly consisting of quartzitic phyllite, sandstone and carbonate, representing the basal succession of two tectonic units exposed in the Middle Tuscan Ridge, and which age attribution was strongly debated in literature and referred either to late Carboniferous-early Permian or Devonian. Palynological data document the first finding of a microflora of middle-late Permian age adding key chronological constraints. This age assignment permits to correlate the Falsacqua Formation with the coeval deposits of southern Tuscany (i.e., Farma and Poggio al Carpino formations) and Elba Island (Rio Marina Formation) that are all characterized by a similar microfloral content. Optical thermal maturity index as Spore Colour Index is around 9 to 10 and suggests a T peak of about 300–350 °C while the Raman spectroscopy on carbonaceous material indicates a T peak around 375 °C for both tectonic units. These data provide new constraints for the maximum T values occurred during syn-collisional metamorphism developed in this sector of the Northern Apennines.

Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan

Lanternfishes (Myctophidae) are one of the most common groups of fishes in the mesopelagic zone of the world ocean, and their otoliths have been dominant in pelagic sediments since at least Miocene times. Many species have a wide geographic distribution, with several being circumglobal. This wide distribution makes myctophid otoliths potentially useful for supraregional stratigraphic purposes. The Sea of Japan and the Northwest Pacific is an important region for investigations into the diversity and evolution of the Myctophidae. Here, we describe a large collection of myctophid otoliths from the late early to early middle Miocene (late Burdigalian to early Langhian) from six localities on western and central Honshu, which were under warm water influence during that time. A total of 22 species are recognized, of which eight are new. In the order in which they are described, the new species are Bolinichthys higashibesshoensissp. nov., Ceratoscopelus brevissp. nov., Lampadena eximasp. nov., Lampanyctus lenticularissp. nov., Lampanyctus tsuyamaensissp. nov., Stenobrachius ohashiisp. nov., Diaphus epipedussp. nov., and Diaphus watatsumisp. nov. At least nine species are also known from coeval sediments outside of Japan, most notably New Zealand and Europe. This distribution reflects the extraordinary geographic spread of myctophid species already in the early Miocene and indicates the potential for their future use for biostratigraphic purposes. The paleoecological and paleobiogeographical implications of the studied myctophid otolith assemblages are discussed. Furthermore, the stratigraphic ranges of the observed species are discussed and compared with data from other regions of the world in an attempt to outline the potential future application of myctophid otoliths for supraregional biostratigraphic purposes.

Review on the Comparative Sedimentology of Late Jurassic Transgressive Deposits of Tendaguru Hill - Mandawa Basin (Tanzania) and Wagad Hill - Kachchh Basin (India)

This review study has focused on existing sedimentological information of Late Jurassic transgressive deposits of Tendaguru Formation (110 m thick), Mandawa basin, Tanzania exposed around Tendaguru hill and Kanthkot Formation (150 m thick), Kachchh basin, India exposed near Wagad hill. Based on comparison between the two coeval deposits shows variable transgressive characteristics. Studies have revealed that during transgression there existed a storm-dominated sedimentary facies in Kanthkot Formation and tidally influenced facies type in Tendaguru Formation. Both represent similar cyclic sedimentation patterns and high-energy transgressive deposits into different depositional regimes. Lithofacies review reveals that Kachchh basin (Wagad region) was an open marine and relatively deeper and steeper shelf environment in late Jurassic time. However, Mandawa basin (Tendaguru region) was a restricted marginal marine with an estuarine setting. Faunal affinities in both formations indicate a shallow marine environment of deposition with variable depth.The close similarity of transgressive episodes and upward stacking pattern of facies successions in both basins indicates overall shallowing of the sea that correlates with the global trend of relative sea-level fall during late Jurassic time.

Syn-rift sedimentary response to growth folding along a rift-margin transfer zone: An example from the early Miocene of the Gulf of Suez, Egypt

Growth folds developed at rift margin transfer zones are mostly studied for their structural style and stratal architecture. The influence of the growth of these folds on the syn-rift sedimentary facies development, however, remains less documented. To address this, we investigated the syn-rift facies of the Lower Miocene Rudeis Formation in relation to the growth of structures within the North Baba transfer zone at the eastern margin of the Suez rift. Sedimentological analysis defined seven facies associations in three successive depositional systems: (i) gravel-rich submarine fans with up-dip thinning geometry, comprising upper, middle and lower fan facies associations, (ii) a gravitationally modified Gilbert-type fan delta, with tangential foreset and bottomset. Both fan systems pass gradationally into basinal marl-dominated facies, and (iii) shoreface-to-offshore. Paleocurrent measurements and the spatial facies variability indicate that the North Baba transfer zone was acting as the main sediment fairway conveying the sediments southwards from the adjacent rift shoulder to the Baba hangingwall syncline. Mapping of key stratal surfaces and growth structures helped in distinguishing four lower Rudeis stratal units, which provide a framework for studying the spatial and vertical relationships among the recognized facies. Deposition of these stratal units was influenced by progressive steepening and localized faulting of a fault-tip growth monocline above the North Baba transfer zone and a submerged intrabasinal high. These structures controlled the hangingwall gradient, bathymetry, flow pathways and facies relations, triggered multiple gravity flows and slumps, and created terraces on which patch reefs and localized shoreface deposits intermittently developed. This study reveals that the transfer zone was still acting as growth monocline even during the rift-climax. The coeval deposits were mainly sourced from a hinterland drainage catchment rather than local footwall scarps. They form progressively tilted clastic wedges that onlap and pinch out up-dip toward the growth monocline, unlike those observed at faulted margins where the facies commonly thicken toward the fault.