Nonmarine ostracodes at the Permian–Triassic boundary of the central part of the East European Platform

Extensive geological and paleontological materials from the upper Permian and the Lower Triassic of the East European Platform had been accumulated by the end of the 20th century. Recently obtained new data indicate the stratigraphic continuity of the East European Permian–Triassic succession. The Permian–Triassic boundary is in many sections associated with the boundary between the Zhukovian and Vokhmian regional stages. New stratigraphic data have led to the revision of the temporal distribution of Zhukovian and Vokhmian ostracodes. In contrast to previous ideas, the rapid development of genus Gerdalia already began in the Zhukovian time rather than in the Vokhmian. At the same time, the first Darwinula of the Triassic type also appeared in the Zhukovian. A proportion of the Permian species were found to cross the boundary between Zhukovian and Vokhmian. The degree of similarity between the Permian and Triassic ostracode assemblages turns out to be much higher than previously recognized.     

Lower–middle Frasnian organic carbon isotope record of conodonts in East European Platform

The early–middle Frasnian boundary interval of the northern part of the East European Platform (northwest of Russia) corresponding to the transitans-punctata isotope event is revealed by biostratigraphically constrained conodont carbon stable isotope data (δ¹³C_con). The dynamics of δ¹³C_con demonstrate a three-fold pattern with positive peaks at the onset of the main phase of the transitans-punctata isotope event (upper part of Montagne Noire 4 conodont Zone, MN4; up to -22.5‰ VPDB), and during the late part of the event (lower and middle parts of MN6 Zone; up to -24.0‰ VPDB and -22.1‰ VPDB). The stratigraphic level near the MN5 and MN6 boundary is marked by a prominent negative excursion in δ¹³C_con (down to -31.8‰ VPDB) that resembles the negative excursion in the terminal phase of the transitans-punctata isotope event worldwide. The δ¹³C_con variations in different taxa are generally consistent but demonstrate some differences in values and amplitudes. It is assumed that variations in the carbon isotopic compositions of conodonts were mainly controlled by changes in the isotope composition of the planktons as the main food source for conodonts.     

Microbialite concretions in a dolostone crust at the Permian–Triassic boundary of the Xishan section in Jiangsu Province,South China

Carbonate concretions with structures and fossil groups associated with microbialite developed in a dolostone crust at the Permian–Triassic boundary of the Xishan section in Jiangsu Province, South China. These structures include clotted fabrics and laminated carbonate needles, as well as abundant carbonate crystal fans. Fossil groups associated with microbialite include microconchids, small gastropods, and small foraminifers. These fabrics and fossils suggest that the concretions are carbonate microbialite blocks developed in the dolostone crust. On the basis of the analysis of the microfabrics and the fossil groups together with a comparison to modern analogues, we attribute the formation of the micritic patches in the microbialite concretions to the calcification of cyanobacterial mats via carbonate nanoparticles and we attribute the carbonate crystal fans to the direct recrystallization of micritic carbonates. The sparitic patches were interpreted as either the direct recrystallization of micritic carbonates or the precipitation of carbonate spars in the inter-/intra-spaces of metazoan shells together with the recrystallization of these shells. The similarities to modern stromatolites, both in morphology and in internal texture, suggest that the laminated carbonate needles are stromatolite laminae built by filamentous cyanobacteria. The preservation of these microbialite microfabrics indicates that early lithification by carbonate precipitation was widespread and intense following the end-Permian boundary events. The weak development of microbialites as small concretions may be attributed to the deeper water depth and the lower water energy in the Xishan area during the earliest Triassic.     

Flora treatment of the Leguminosae–Papilionoideae of Gabon

This short note highlights the work undertaken to prepare the treatment of the Leguminosae subfamily Papilionoideae for the Flore du Gabon. Examples are given in the form of some maps prepared from the BRAHMS database available in Wageningen. Statistics of collection efforts in the country are presented specifically for papilionoids. The results show that the number of new records of papilionoid legumes for the Flora of Gabon is still increasing and that the current knowledge of papilionoids in Gabon is far from complete.     

Stromatolite-dominated microbialites at the Permian–Triassic boundary of the Xikou section on South Qinling Block,China

Permian–Triassic boundary microbialites (PTBMs) are organosedimentary carbonates formed immediately after the end-Permian mass extinction. All those reported PTBMs constrained by convincing conodont biozones are present stratigraphycally not higher than the Hindeodus parvus zone and most of them are dominated by thrombolites. This paper provides the first record of a brief, but spectacular development of stromatolite-dominated PTBMs within the basal Isarcicella isarcica conodont zone of the earliest Triassic from the Xikou section of South Qinling Block that was at the margin of the North China Block during the Permian–Triassic transition and was geographically separated from the major occurrence of post-extinction microbialites in the South China Block. This stromatolite cap overlies a 3.7-m-thick oolitic limestone and is composed of a lower 0.2-m-thick bed and an upper 0.5-m-thick bed, separated by a 0.2-m-thick greyish green siliciclastic mudstone. These two stromatolite beds mainly consist of columnar stromatolites with subordinate domal stromatolites. The intercolumn and interstitial spaces within the stromatolites are filled with oolitic grainstones. At the microscopic scale, laminoid structures in stromatolites comprise wavy, millimetric-domical and tangled laminae. The increased grain and fossil contents and/or bioturbation in the domical and tangled laminae indicate that the formation of these laminae is likely related to an increase in the populations and the disruptions by benthic metazoans, as well as an influx of sediment grains. The δ¹³C_carb values fluctuate between 2‰ and 3‰ in the uppermost Permian strata; a distinct negative shift of 1.9‰ occurs at the topmost oolitic grainstone, just below the lower stromatolite bed, and the lowest value of −0.1‰ is located at the base of the upper stromatolite bed. The stratigraphic succession from stromatolites to thrombolites of the PTBMs may represent a transgressive succession and/or a transient ecosystem recovery immediately after the end-Permian mass extinction. The thrombolites-dominated PTBMs mainly developed in near-equator shallow marine geographic locations, and stromatolite-dominated PTBMs mainly developed at higher latitude settings, which probably indicates that a relatively lower diversity and abundance of marine benthic metazoans existed at higher latitudes after the end-Permian mass extinction.     

Permian and early Triassic isotopic records of carbon and strontium in Australia and a scenario of events about the Permian‐Triassic boundary

The negative shift in δ¹³C values of carbonate carbon at the Permian/Triassic boundary is one of the better documented geochemical signatures of a mass extinction event. The similar negative shift in δ¹³C values in organic carbon from Permian/Triassic boundary marine sediments in Austria and Canada is shown to occur also in marine and non‐marine sediments from Australian sedimentary basins. This negative shift in δ¹³C values is used to calibrate Australian sections lacking diagnostic faunal elements identifying the Permian/Triassic boundary. The minimum in the carbonate ⁸⁷Sr/⁸⁶Sr seawater curve from carbonates across the Guadalupian/Ochoan Stage boundary, mainly from North America, is shown to occur also in brachiopod calcite mainly from the Bowen Basin of eastern Australia, hence providing a second calibration point in the Australian sedimentary record. These two geochemical events support a model of a runaway greenhouse developing about the Permian/Triassic boundary; this is inferred to have contributed to the end‐Permian mass extinction.     

Ostracod recovery in the aftermath of the Permian–Triassic crisis: Palaeozoic–Mesozoic turnover

Results of a detailed bathymetric survey of Crater Lake conducted in 2000, combined with previous results of submersible and dredge sampling, form the basis for a geologic map of the lake floor and a model for the filling of Crater Lake with water. The most prominent landforms beneath the surface of Crater Lake are andesite volcanoes that were active as the lake was filling with water, following caldera collapse during the climactic eruption of Mount Mazama 7700 cal. yr B.P. The Wizard Island volcano is the largest and probably was active longest, ceasing eruptions when the lake was 80 m lower than present. East of Wizard Island is the central platform volcano and related lava flow fields on the caldera floor. Merriam Cone is a symmetrical andesitic volcano that apparently was constructed subaqueously during the same period as the Wizard Island and central platform volcanoes. The youngest postcaldera volcanic feature is a small rhyodacite dome on the east flank of the Wizard Island edifice that dates from 4800 cal. yr B.P. The bathymetry also yields information on bedrock outcrops and talus/debris slopes of the caldera walls. Gravity flows transport sediment from wall sources to the deep basins of the lake. Several debris-avalanche deposits, containing blocks up to 280 m long, are present on the caldera floor and occur below major embayments in the caldera walls. Geothermal phenomena on the lake floor are bacterial mats, pools of solute-rich warm water, and fossil subaqueous hot spring deposits. Lake level is maintained by a balance between precipitation and inflow versus evaporation and leakage. High-resolution bathymetry reveals a series of up to nine drowned beaches in the upper 30 m of the lake that we propose reflect stillstands subsequent to filling of Crater Lake. A prominent wave-cut platform between 4 m depth and present lake level that commonly is up to 40 m wide suggests that the surface of Crater Lake has been at this elevation for a very long time. Lake level apparently is limited by leakage through a permeable layer in the northeast caldera wall. The deepest drowned beach approximately corresponds to the base of the permeable layer. Among a group of lake filling models, our preferred one is constrained by the drowned beaches, the permeable layer in the caldera wall, and paleoclimatic data. We used a precipitation rate 70% of modern as a limiting case. Satisfactory models require leakage to be proportional to elevation and the best fit model has a linear combination of 45% leakage proportional to elevation and 55% of leakage proportional to elevation above the base of the permeable layer. At modern precipitation rates, the lake would have taken 420 yr to fill, or a maximum of 740 yr if precipitation was 70% of the modern value. The filling model provides a chronology for prehistoric passage zones on postcaldera volcanoes that ceased erupting before the lake was filled.     

The palynological assemblages from the J–K boundary beds of the Bureya Basin,Russian Far East

Palynological assemblages were studied from the coal-bearing Upper Jurassic (Talanja Formation) to the Lower Cretaceous (Dublikan Formation) deposits of the Bureya Basin, Russia. The palynological assemblages from the upper part of the Talanja Formation are dominated by gymnosperms, mainly Ginkgocycadophytus (up to 40%) and conifers related to Pinaceae (up to 70%). The contribution of non-seed plants is not great, but their diversity is considerable. The miospore assemblages of the Talanja sequence are characterized by the last appearance of the spore taxa Staplinisporites pocockii, Camptotriletes cerebriformis, Camptotriletes nitida, and Cingulatisporites sanguinolentus. The palynological assemblage from the Dublikan Formation is dominated by ferns (up to 84%), represented mainly by Cyathidites and Duplexisporites. Among gymnosperms the role of Classopollis increases (making up about 20%). Another feature is the first appearance of the spore taxa Stereisporites bujargiensis, Neoraistrickia rotundiformis, Contignisporites dorsostriatus, Appendicisporites tricostatus, and Concavissimisporites asper.     

Sequence of Permian Tetrapod Faunas of Eastern Europe and the Permian–Triassic Ecological Crisis

Eastern Europe shows the most complete in the world continuous sequence of continental Permian and Triassic deposits, which allows the development of tetrapod faunas over more than 17 successive stages to be traced. The newly obtained data on transitional Vyazniki and Sundyr tetrapod faunas provide more complete characteristics of the Severodvinian (Late Guadalupian, pre-Lopingian) and Permian-Triassic ecological crises and the ways of replacement of the dominant vertebrate groups of Eastern Europe.     

Dynamics of the horizontal structure of the tree stand in a pristine herb–bilberry forest of the subzone of the middle tiaga in the Komi Republic

According to observations from 1987 to 2010 on a constant sampling plot, using spatial statistics, we have shown dynamics of the horizontal structure of all-aged stands of a pristine spruce herb–bilberry forest. We note that the trees forming it provide a continual change of generations and, therefore, random community structure and its spatial stability. We determined that small-leaved arboreal plants, which represent part of the tree stand, tend to grouping at distances from 4 m. It was discovered that the mutual arrangement of trees of different sizes and species do not differ from a random occurrence.     

Analysis of the Fungal Flora in Environmental Dust Samples by PCR–SSCP Method

Conventional microbiological techniques yield only limited information on the composition of fungal communities in dust. The aim of this study was to establish and optimize PCR-single strand conformation polymorphism (PCR–SSCP) analysis for investigation of fungal diversity in rural dust samples. Three different DNA extraction protocols were tested on 38 fungal cultures. A total of six known universal fungal primer pairs were tested targeting the 18S rRNA gene, the 28S rRNA gene and the ITS region, respectively. Objective evaluation was performed with respect to the following parameters: efficiency to amplify all 38 strains; separation of seven species from different phylogenetic groups on the SSCP gel; additional bands in PCR–SSCP analysis; possibility to classify the amplified gene fragments to species level. Primer ITS1/ITS4 and PowerSoil? DNA isolation showed the best performance in most cases and were chosen for further analysis. The detection limit of the developed system was 200 CFU/g dust. Moreover, the reproducibility of the system could be demonstrated, leading to average profile similarities of 94.94 % [SD = 2.51] within gels, 93.03 % [SD = 4.69] between different days and 87.66 % [SD = 6.62] between different gels when testing shed and mattress dust samples. Sequencing allowed identification on species level, in detail: Alternaria alternata, Cladosporium sphaerospermum, Cladosporium cladosporioides as well as the yeasts Candida cabralensis and Candida catenulata. This demonstrates the adaptability of the method. In this study, a standardized system for fungal community analysis was developed that provides reproducible results applicable for epidemiological purposes.     

Revisiting the stratigraphic position of the Matuyama–Brunhes geomagnetic polarity boundary in Chinese loess

It is commonly accepted that the climate records in Chinese loess can be correlated well with that in marine sediments. However, discrepancies for the stratigraphic position of paleomagnetic polarity reversal boundary seriously restrict an accurate teleconnection between these two archives. For example, the exact stratigraphic position of the whole Matuyama–Brunhes (MB) transitional polarity zone remains uncertain in Chinese loess. In this study, an accurate transitional zone of the MB reversal from the Mangshan profile, southeast margin of the Chinese Loess Plateau (CLP), was statistically determined using multiple subsets of parallel samples. By integrating results from the central CLP, the whole MB transitional zone is consistently located across the pedostratigraphic and climatostratigraphic transitional zones between S8 and L8 over a wide region of the CLP. This conclusion further supports that the paleosol unit S8 should be teleconnected to the marine oxygen isotope stage 19 rather than 21, and thus unambiguously supplies an accurate age control in constructing a new loess time scale.     

Plant–arthropod interactions in gymnosperm leaves from the Early Permian of Patagonia,Argentina

Evidence of plant–arthropod interactions in three orders of gymnosperms is documented in at least five localities from Lower Permian strata of the Río Genoa Formation (Patagonia, Argentina). Arthropod damages were identified in Glossopteris, Gangamopteris, Cordaites and Gingkoites leaves, corresponding to four interactive categories: margin feeding, hole feeding, surface feeding, and oviposition. In addition, a Permian insect trace not previously recorded is described on Glossopteris wilsonii leaves. The diversity of arthropod damage is consistent with the diverse flora of the Río Genoa Formation. In turn, the patterns of arthropod and plant–arthropod interaction provide constraints on the ecology and paleoclimate of Western Gondwana during the Early Permian.     

Endemism in the Flora of China—Studies on the Endemic Genera

China, under highly varied ecological conditions resulted from wide latitudinal and altitudinal ranges and from the adequate precipitation, has developed a very rich flora of great diversity. As far as flowering plants are concerned, there are 2980 genera, 214 of which, belonging to 64 families, are endemic. Among these endemic genera, there are 9 genera of taxads and conifers, 19 genera of monocots and others of dicots. Of the approximately 129 herbaceous endemic genera in the Chinese flora as a whole, about 22 (17%) are annual and 107 (83%) are biennial or perennial. In the present paper the ecological distribution, the nature of endemic genera and the centers of endemism are discussed. 1. Three types of endemic genera are distinguished, neoendemics, palaeoendemics and active epibiotics, The endemic genera in the flora of China are, for the most part, considered to be very old ones, and most of them are of temperate nature. 2. the degree of endemism in our 22 floristic regions is shown in Figure 1. The areas richest in endemic genera in the Chinese flora as a whole are the 13, 16 and 17 regions. The poorest are the 2, 4, 9 and 10 regions, and no one in the 1 and 3 regions These results on floristic richness are of general applicability. As shown in table 1, the difference in the degree of endemism among the seven Chinese floristic subkingdoms are most pronounced. 101 endemic genera are known to occur in one subkingdom, 72 to occur in two subkingdoms, and 3 to occur in four subkingdoms, only one genus widely distributed in five subkingdoms. However, there is no genus occurring in seven subkingdoms. The difference in the degree of endemism in each subkingdom reveals that the distribution of endemic genera is not well-distributed in the Chinese flora as a whole. Analysis of the vertical distribution of the 200 endemic genera of the Chinese flora bears out that there is no evident increase in endemism as a whole with altitude. 3. Three centers of endemism are found (Fig. 2). These are as follows: a). Eastern Sichuan-western Hubei center. b). Southeastern Yunnan-western Guangxi center. c). Western Sichuan-northwestern Yunnan center. The degree of endemism andcharacters of endemic genera in each center are discussed.     

Zooplankton in Svalbard fjords on the Atlantic–Arctic boundary

Zooplankton abundance and community structures were studied in three west Spitsbergen fjords at the beginning of the warm phase, which seem to have entered in 2006. Sampling was conducted in summer 2007 at stations distributed along transects in Hornsund, Isfjorden and Kongsfjorden. Variations in zooplankton standing stocks and community structures (assessing taxonomic diversity and zoogeographical affiliations) were analysed in relation to the environmental variables using multivariate techniques. The hydrographic conditions in Hornsund were influenced by the cold Arctic Water, whereas those in Isfjorden and especially in Kongsfjorden were, to a greater extent, under the influence of the warm Atlantic Water. High abundances of both meroplankton and holoplankton organisms were observed in Kongsfjorden, with high contributions of boreal and ubiquitous species (Calanus finmarchicus and Oithona similis, respectively). In Hornsund at the same time, the zooplankton consisted mainly of boreo-Arctic and Arctic species, the abundances of which were comparable along the West Spitsbergen Shelf. Our results indicate that the difference in hydrography had measurable effects on the zooplankton community in the study area. Furthermore, by comparing regions of contrasting oceanographic conditions, we present evidence as to how the zooplankton structure will change in the Arctic ecosystems if the warming trends continue to operate with the same dynamics. The advection of Atlantic waters to the Arctic seas may lead to changes in zooplankton structure, with increased abundance and contributions of boreal and small ubiquitous species. The ‘warmer Arctic fjords’ scenarios may also induce more rapid development of both holoplankton and meroplankton populations and, consequently, modify the trophic interactions in plankton communities.     

The Cenomanian–Turonian boundary in the northwestern part of the Adriatic Carbonate Platform (Ćićarija Mtn., Istria,Croatia): characteristics and implications

The Cenomanian–Turonian boundary (CTB) in the ?i?arija Mountain region (northern Istria, Croatia) is characterized by calcisphere limestone successions with a firmground and glauconite horizon, bioturbated intervals, tempestites, and slumped structures as well as microbially laminated and organic-rich interbeds deposited in the northwestern part of the intra-Tethyan Adriatic Carbonate Platform (AdCP). Compilation of the results from three studied sections (Vodice–Jelovica, Martinjak and Planik) of litho-, bio-, and microfacies analyses, X-ray diffraction, SEM, EDS, and stable isotope analyses allowed reconstruction of marine paleoenvironmental conditions during this time period. Shallow-marine carbonate deposits of the Milna Formation underlie a drowned-platform succession of the Sveti (Sv.) Duh Formation. The contact between these two formations is sharp and commonly marked by slumped deposits. The Sv. Duh Formation consists of about 100 m of calcisphere wackestone enriched in organic matter. The results of preliminary δ¹³C and δ¹⁸O stable isotope analyses indicate the influence of the global Oceanic Anoxic Event (OAE2) on the deposition of this carbonate succession. Anoxic and hypoxic conditions in the water column lead to major changes in the shallow-marine carbonate system of the AdCP. Numerous benthic foraminifera declined during that time, but planktonic foraminifera and calcareous dinoflagellates diversified and expanded greatly. The results of this research provide new insights into the character of the CTB interval in this part of the Tethyan realm. Local and regional synsedimentary tectonics combined with global upper Cretaceous sea-level dynamics allows the correlation of the investigated deeper-marine lithostratigraphic units with OAE2.