Uued publikatsioonid geoloogia instituudi teadlastelt
Anneli Poska ja Tiiu Alliksaar kaasautoritega publitseerisid teadusartikli ajakirjas Quaternary Science Reviews (WoS mõjufaktor IF 4.797; kategooria Q1)
Belle, S., Freiberg, R., Poska, A., Agasild, H., Alliksaar, T., Tõnno, I. 2018. Contrasting responses to long-term climate change of carbon flows to benthic consumers in two different sized lakes in the Baltic area. Quaternary Science Reviews 187, 168-176.
The study of lake sediments and archived biological remains is a promising approach to better understand the impacts of climate change on aquatic ecosystems. Small lakes have been shown to be strongly sensitive to past climate change, but similar information is lacking for large lakes. By identifying responses to climate change of carbon flows through benthic food web in two different sized lakes, we aimed to understand how lake morphometry can mediate the effects of climate change. We reconstructed the dynamics of phytoplankton community composition and carbon resources sustaining chironomid biomass during the Holocene from the combined analysis of sedimentary pigment quantification and carbon stable isotopic composition of subfossil chironomid head capsules (δ13CHC) in a large lake in the Baltic area (Estonia). Our results showed that chironomid biomass in the large lake was mainly sustained by phytoplankton, with no significant relationship between δ13CHC values and temperature fluctuations. We suggest that lake morphometry (including distance of the sampling zone to the shoreline, and lake volume for primary producers) mediates the effects of climate change, making large lakes less sensitive to climate change. Complementary studies are needed to better understand differences in organic matter dynamics in different sized lakes and to characterize the response of the aquatic carbon cycle to past climate change.
Anneli Poska kaasautoritega publitseeris teadusartikli ajakirjas Freshwater Biology (WoS mõjufaktor IF 3.255; kategooria Q1)
Belle, S., Musazzi, S., Tõnno, I., Poska, A., Leys, B., Lami, A. 2018. Long-term effects of climate change on carbon flows through benthic secondary production in small lakes. Freshwater Biology 63, 530-538.
1. A palaeolimnological study, covering the last c. 12,000 years, was conducted in a small subalpine lake located in the Alps to study climate change impacts on carbon flows through food webs in small lakes. We used analysis of sedimentary pigments and carbon stable isotopic composition of chironomid remains (δ13CHC) to reconstruct past dynamics of phytoplankton community and carbon sources sustaining benthic consumers.
2. Chironomid biomass was sustained by a combination of allochthonous, autochthonous and CH4‐derived organic matters, and their relative contributions were correlated to changes in temperature. Relatively high terrestrial contributions to chironomid biomass were observed during period of the Holocene when in‐lake production was low. Relatively high incorporation of CH4‐derived carbon to chironomid biomass was found during anoxic events co‐occurring with the Holocene thermal maximum.
3. Results were then compared with those collected in a small boreal lake in Estonia. We tested the hypothesis that responses in carbon flows through benthic food web to past climate change would be similar between these lakes. We found a negative correlation between δ13CHC values of both lakes and inferred air temperature, suggesting that temperature was the major driver to different food sources being incorporated into chironomid biomass.
4. Our study demonstrated that air temperature was the principal driver of the energy flows through benthic food web in the studied small lakes. We conjectured that carbon cycling in food webs of small lakes might be strongly sensitive to climate change.
Triin Reitalu kaasautoritega publitseeris veebiversiooni artikli ajakirjas Journal of Vegetation Science (WoS mõjufaktor IF 2.924; kategooria Q1/Q2)
Giesecke, T., Kuneš, P., Reitalu, T. 2018. Millennial to centennial vegetation change. Journal of Vegetation Science 29, 3, 357-359.
It is generally accepted that history is important for understanding patterns in plant community structure and diversity. However, “history” comprises anything from the evolutionary history of plants over millions of years to land‐use change over years or decades. The same ambiguity applies to the usage of “long‐term”, which is frequently found in articles published in Journal of Vegetation Science (JVS): more than 10% of titles or abstracts and almost 30% of full texts. Here its meaning most frequently ranges from decadal as in the 18‐year study of permanent plots in post‐agricultural forest (Baeten and Verheyen, 2017) to centennial as in the analysis based on a historical map from 1909 assessing changes in sub‐alpine forests (Mietkiewicz, Kulakowski, Rogan, Bebi and Rocchini, 2017).
Meie endised välisdoktorandid Normunds Stivrinš ja Ieva Frudzinska avaldasid veebiversiooni artikli ajakirjas Estuarine, Coastal and Shelf Science (WoS mõjufaktor IF 2.176; kategooria Q2)
Kalińska-Nartiša, E., Stivrins, N., Grudzinska, I. 2018. Quartz grains reveal sedimentary palaeoenvironment and past storm events: A case study from eastern Baltic. Estuarine, Coastal and Shelf Science 200, 359-370.
Sediment record collected from the coastal lake serves as a powerful tool for reconstructing changes in palaeoenvironment and understanding the potential signals of past storminess. In this study, we use several proxies from sediment of the Holocene Thermal Maximum at coastal Lake Lilaste, Latvia. We focus on surface texture of quartz grains from the mineral inorganic fraction as indicators of depositional environments. We then use this as a proxy for potential storm transport and combine with information on granulometry, diatom stratigraphy and chronology to answer the question whether flux of quartz grains in the lake originated from the sea or from the land. Analyses in a binocular and scanning electron microscope reveal that most of the investigated quartz grains originate from dwelling in the seawater and wave action in the nearshore zone. Grains representing very energetic subaqueous environment similar to storm events are also present. Terrestrial record is of minor significance and visible through occurrence of aeolian quartz grains.
During drier and colder conditions, an influx of sand with aeolian imprint was delivered to the lake between 8500 and 7800 cal yr BP. Marine and terrestrial conditions alternated between 7800 and 6000 cal yr BP. Storm-induced grains were likely deposited three times: at 7300 cal yr BP, 6600–6400 cal yr BP, and 6200–6000 cal yr BP. Overall stable marine environmental conditions prevailed between 6000 and 4000 cal yr BP except of the last portion of terrestrial-induced sediment at 4100 cal yr BP.
Atko Heinsalu kaasautoritega publitseeris artikli ajakirjas Estonian Journal of Archaeology
Kriiska, A., Oras, E., Nirgi, T., Shanskiy, M., Heinsalu, A., Vanhanen S., Luoto, T.P. 2018. Environmental studies at the Kohtla-Vanaküla Iron Age sacrificial site, north-east Estonia. Estonian Journal of Archaeology 22, 66-79.
Kohtla-Vanaküla (Kohtla from here onwards) sacrificial site is an Iron Age weapons and tools deposit from the beginning of the Christian Era to around 800 AD (based on artefact chronology and AMS dates from the wooden handle remnants of the items’ sockets and the charcoal pieces collected from the layer containing the finds). It is a significant discovery among its kind in Estonia and on a wider scale not only due to the number of items, but also because for the first time in Estonia it was possible to study the assemblage at least partially in its original state. Parallel to the archaeological excavations, different multidisciplinary studies were performed to determine the area’s natural environment during the period when the items were deposited. The fieldwork was conducted in summer 2014. This article presents the results of geological, soil, micromorphological, archaeobotanical, and diatom studies.
Based on the retrieved data, it is not possible to completely reconstruct the natural environment of the sacrificial site for the period of use, but some pointers have been established. Presumably, the site was, at least during high water, a flooded meadow where water might have dwelt longer in ground concavities. One of the main factors favouring the wet conditions is impermeable thick argillaceous till that most likely prevented water from seeping into the ground. Moreover, the sacrificial site is located in a slightly concave topography and this also prevented the draining of the water even further in this specific spot. One can assume that the items were placed in a small marshy depression that was, at least part of the year, filled with water. The items were situated in a layer that indicates the formation of peat; this anoxic soil was the reason why the iron items were preserved.
Triin Reitalu kaasautoritega publitseeris veebiversiooni artikli ajakirjas Journal of Vegetation Science (WoS mõjufaktor IF 2.924; kategooria Q1/Q2)
Kuosmanen, N., Marquer, L., Tallavaara, M., Molinari, C., Zhang, Y., Alenius, T., Edinborough, K., Pesonen, P., Reitalu, T., Renssen, H., Trondman A.-K., Seppä, H. 2018. The role of climate, forest fires and human population size in Holocene vegetation dynamics in Fennoscandia. Journal of Vegetation Science 29, 382-392.
We investigated the changing role of climate, forest fires and human population size in the broad‐scale compositional changes in Holocene vegetation dynamics before and after the onset of farming in Sweden (at 6,000 cal yr BP) and in Finland (at 4,000 cal yr BP).
Southern and central Sweden, SW and SE Finland.
Holocene regional plant abundances were reconstructed using the REVEALS model on selected fossil pollen records from lakes. The relative importance of climate, fires and human population size on changes in vegetation composition was assessed using variation partitioning. Past climate variable was derived from the LOVECLIM climate model. Fire variable was reconstructed from sedimentary charcoal records. Estimated trend in human population size was based on the temporal distribution of archaeological radiocarbon dates.
Climate explains the highest proportion of variation in vegetation composition during the whole study period in Sweden (10,000–4,000 cal yr BP) and in Finland (10,000–1,000 cal yr BP), and during the pre‐agricultural period. In general, fires explain a relatively low proportion of variation. Human population size has significant effect on vegetation dynamics after the onset of farming and explains the highest variation in vegetation in S Sweden and SW Finland.
Doktorant Merlin Liiv koos kaasautoritega avaldas oma esimese esiautorlusega teadusartikli ajakirjas Vegetation History and Archaeobotany (WoS mõjufaktor IF 1.908; kategooria Q1/Q2)
Liiv, M., Alliksaar, T., Freiberg, R., Heinsalu, A., Ott, I., Tõnno, I., Vassiljev, J., Veski, S. 2018. Drastic changes in lake ecosystem development as a consequence of flax retting: a multiproxy palaeolimnological study of Lake Kooraste Linajärv, Estonia. Vegetation History and Archaeobotany 27, 437-451.
This study demonstrates the power of multiproxy palaeolimnological analyses in investigating environmental changes in the Lake Kooraste Linajärv ecosystem through historical time in response to flax retting. Flax retting history was proven by applying pollen and macrofossil evidence and by using several biotic and geochemical proxies on a sediment core. Continuous findings of flax pollen and macrofossil remains in lake sediments were considered as strong evidence for the occurrence of retting. Analyses of the well-dated sediment core show the consequences of flax retting in the lake. As a result, the once clear soft water oligotrophic endorheic lake with limited sedimentation has turned into a hypertrophic high-sedimentation lake with anoxic bottom water, strong stratification and intense water blooms. Despite the fact that flax retting was forbidden in Estonia around ad 1950s and retting has not occurred over the last six decades, anthropogenic alterations were so pervasive in the past, that they have prevented any lake water improvements until the present-day.
Anneli Poska kaasautoritega publitseeris teadusartikli ajakirjas Spatial Statistics (WoS mõjufaktor IF 1.176; kategooria Q2/Q3/Q4)
Pirzamanbein, B., Lindström, J., Poska, A., Gaillard, M.-J. 2018. Modelling spatial compositional data: reconstructions of past land cover and uncertainties. Spatial Statistics 24, 14-31.
In this paper we construct a hierarchical model for spatial compositional data which is used to reconstruct past land-cover compositions (in terms of coniferous forest, broadleaved forest, and unforested/open land) for five time periods during the past 6000 years over Europe. The model consists of a Gaussian Markov Random Field (GMRF) with Dirichlet observations. A block updated Markov chain Monte Carlo (MCMC), including an adaptive Metropolis adjusted Langevin step, is used to estimate model parameters. The sparse precision matrix in the GMRF provides computational advantages leading to a fast MCMC algorithm. Reconstructions are obtained by combining pollen-based estimates of vegetation cover at a limited number of locations with scenarios of past deforestation and output from a dynamic vegetation model. To evaluate uncertainties in the predictions a novel way of constructing joint confidence regions for the entire composition at each prediction location is proposed. The hierarchical model’s ability to reconstruct past land cover is evaluated through cross validation for all time periods, and by comparing reconstructions for the recent past to a present day European forest map. The evaluation results are promising, and the model is able to capture known structures in past land-cover compositions.
Anneli Poskal kaasautoritega ilmus teadusartikkel ajakirjas Landscape Ecology (WoS mõjufaktor IF 3.615; kategooria Q1)
Poska, A., Väli, V., Tomson, P., Vassiljev, J., Kihno, K., Alliksaar, T., Villoslada, M., Saarse, L., Sepp, K. 2018. Reading past landscapes: combining modern and historical records, maps, pollen-based vegetation reconstructions, and the socioeconomic background. Landscape Ecology 33, 529-546.
Anthropogenic and environmental changes are reshaping landscapes across the globe. In this context, understanding the patterns, drivers, and consequences of these changes is one of the central challenges of humankind.
We aim to test the possibilities of combining modern multidisciplinary approaches to reconstruct the land-cover and linking the changes in land-cover to socioeconomic shifts in southern Estonia over the last 200 years.
The historical records from five, and maps from six time periods and 79 pollen-based land-cover reconstructions from four lakes are used to determine the land-cover structure and composition and are thereafter combined with the literature based analyses of socioeconomic changes.
All information sources recorded similar changes in the land-cover. The anthropogenic deforestation was comparable to today’s (approximately 50%) during the nineteenth century. Major political and socioeconomic changes led to the intensification of agriculture and maximal deforestation (60–85%) at the beginning of the twentieth century. The land nationalisation following the Soviet occupation led to the reforestation of the less productive agricultural lands. This trend continued until the implementation of European Union agrarian subsidies at the beginning of the twenty first century.
Pollen-based reconstructions provide a trustworthy alternative to historical records and maps. Accounting for source specific biases is essential when dealing with any data source. The landscape’s response to socioeconomic changes was considerable in Estonia over the last 200 years. Changes in land ownership and the global agricultural market are major drivers in determining the strength and direction of the land-cover change.
Normund Stivrinšil ja Siim Veskil ilmus teadusartikkel ajakirjas Review of Palaeobotany and Palynology (WoS mõjufaktor IF 1.817; kategooria Q1/Q2)
Stivrinš, N., Soininen, J., Tõnno, I., Freiberg, R., Veski, S., Kisand, V. 2018. Towards understanding the abundance of non-pollen palynomorphs: A comparison of fossil algae, algal pigments and sedaDNA from temperate lake sediments. Review of Palaeobotany and Palynology 249, 9-15.
Given the increased interest in non-pollen palynomorphs (microscopic objects other than pollen identified from pollen slides) in palaeoecological studies, it is necessary to seek a deeper understanding of the reliability of these results. We combined quantitative information of algal pigments and sedimentary ancient DNA (sedaDNA) of phylotaxonomical resolution to validate the richness and abundance of fossil algae in the sediment of a small temperate lake. For the first time, fossil and sedaDNA algae data were combined in a composite data-set and used to reconstruct algae turnover rates over the last 14,500 years. This comparison serves as both an example of how fossil algae can be used to answer various research questions and as a method of revealing to what extent we can rely on palaeoecological interpretations based solely on the fossil algae record from pollen slides.
Anneli Poskal kaasautoritega ilmus teadusartikkel ajakirjas Science of the Total Environment (WoS mõjufaktor IF 4.900; kategooria Q1)
Tang, J., Yurova, A.Y., Schurgers, G., Miller, P.A., Olin, S., Smith, B., Siewert, M.B., Olefeldt, D., Pilesjö, P., Poska, A. 2018. Drivers of dissolved organic carbon export in a subarctic catchment: Importance of microbial decomposition, sorption-desorption, peatland and lateral flow. Science of the Total Environment 622-623, 260-274.
Tundra soils account for 50% of global stocks of soil organic carbon (SOC), and it is expected that the amplified climate warming in high latitude could cause loss of this SOC through decomposition. Decomposed SOC could become hydrologically accessible, which increase downstream dissolved organic carbon (DOC) export and subsequent carbon release to the atmosphere, constituting a positive feedback to climate warming. However, DOC export is often neglected in ecosystem models. In this paper, we incorporate processes related to DOC production, mineralization, diffusion, sorption-desorption, and leaching into a customized arctic version of the dynamic ecosystem model LPJ-GUESS in order to mechanistically model catchment DOC export, and to link this flux to other ecosystem processes. The extended LPJ-GUESS is compared to observed DOC export at Stordalen catchment in northern Sweden. Vegetation communities include flood-tolerant graminoids (Eriophorum) and Sphagnum moss, birch forest and dwarf shrub communities. The processes, sorption-desorption and microbial decomposition (DOC production and mineralization) are found to contribute most to the variance in DOC export based on a detailed variance-based Sobol sensitivity analysis (SA) at grid cell-level. Catchment-level SA shows that the highest mean DOC exports come from the Eriophorum peatland (fen). A comparison with observations shows that the model captures the seasonality of DOC fluxes. Two catchment simulations, one without water lateral routing and one without peatland processes, were compared with the catchment simulations with all processes. The comparison showed that the current implementation of catchment lateral flow and peatland processes in LPJ-GUESS are essential to capture catchment-level DOC dynamics and indicate the model is at an appropriate level of complexity to represent the main mechanism of DOC dynamics in soils. The extended model provides a new tool to investigate potential interactions among climate change, vegetation dynamics, soil hydrology and DOC dynamics at both stand-alone to catchment scales.
Triin Reitalu kaasautoritega publitseeris teadusartikli ajakirjas Journal of Bryology (WoS mõjufaktor IF 0.975; kategooria Q3)
Tyler, T., Bengtsson, F., Dahlberg, C.J., Lönnell, N., Hallinbäck, T., Reitalu, T. 2018. Determinants of bryophyte species composition and diversity on the Great Alvar of Öland, Sweden. Journal of Bryology 40, 12-30.
Factors driving the species richness and distribution of bryophytes are poorly studied and not well understood, particularly in grasslands. We analysed the occurrence of bryophyte species and variation in species richness across 674 plots (0.5 m × 0.5 m) in alvar vegetation (grassland on limestone pavement with thin or no soil) on Öland (Sweden) in relation to substrate characteristics and chemistry, inundation frequency, grazing pressure and geographical variables. We found 148 taxa, including 11 nationally red-listed ones. Species richness per plot was significantly associated with substrate type, positively associated with pH and grazing intensity, but negatively associated with soil depth. However, richness of species typical of, or restricted to, alvar habitats responded differently to richness of species more common in other habitats. Typical alvar species were favoured by high pH, shallow soil and low phosphate availability, while generalists preferred relatively low pH, higher phosphate availability and organic or mull soil types. Distance from the alvar margin had only weak effects. Concerning the effects on individual species and community composition, inundation frequency and pH were found to have the largest effects, although other factors (substrate type, soil depth, bare soil, bare stone, phosphate availability and grazing pressure) were more important for some individual species, stressing the importance of microsite variability and variability in management for regional species richness. From a conservation perspective, it is concluded that grazing is generally positive whilst factors increasing phosphate availability may disadvantage the typical alvar species, and proximity to the alvar margin is not a major problem.
Aivo Lepland avaldas koos kaasautoritega teadusartikli ajakirjas American Mineralogist (WoS mõjufaktor IF 2.021; kategooria Q2)
Birski, Ł., Wirth, R., Słaby, E., Wudarska, A., Lepland, A., Hofmann, A., Schreiber, A. 2018. (Ca-Y)-phosphate inclusions in apatite crystals from Archean rocks from the Barberton Greenstone Belt and Pilbara Craton: First report of natural occurrence. American Mineralogist 103, 307-313.
Here, we report the first occurrence of two (Ca-Y)-phosphate phases in apatite crystals from ancient rocks from both the Barberton greenstone belt and the Pilbara Craton. First, a cubic Ca3Y(PO4)3 phase was observed in a sample of silicified tuff from the Mendon Formation from the Barberton greenstone belt. A second phase, corresponding to a synthetic compound with the formula CaYP7O20, was observed in a sample of black banded chert from the Hooggenoeg Formation of the Onverwacht Group and in a sample of chert from the Strelley Pool Chert Formation (East Pilbara Terrane). Based on the presence of these phosphates and specific textures revealed by transmission electron microscopy, we argue for the importance of dissolution-reprecipitation processes in the formation of these phosphate phases. Temperature was likely not the primary parameter controlling the crystallization of the Ca3 Y(PO4)3 and CaYP7O20 phases. Instead, the REE-F complexes in an H2O solution and the specific budget of REEs and Y in apatite were likely responsible for the nucleation and formation of the (Ca-Y)-phosphate phases in the Archean rocks of the Barberton greenstone belt and Pilbara Craton.
Aivo Lepland publitseeris koos kaasautoritega teadusartikli ajakirjas Science (WoS mõjufaktor IF 37.205; kategooria Q1)
Blättler, C.L., Claire, M.W., Prave, A.R., Kirsimäe, K., Higgins, J.A., Medvedev, P.V., Romashkin, A.E., Rychanchik, D.V., Zerkle, A.L., Paiste, K., Kreitsmann, T., Millar, I.L., Hayles, J.A., Bao, H., Turchyn, A.V., Warke, M.R., Lepland, A. 2018. Two-billion-year-old evaporites capture Earth’s great oxidation. Science 360, 320-323.
Major changes in atmospheric and ocean chemistry occurred in the Paleoproterozoic era (2.5 to 1.6 billion years ago). Increasing oxidation dramatically changed Earth’s surface, but few quantitative constraints exist on this important transition. This study describes the sedimentology, mineralogy, and geochemistry of a 2-billion-year-old, ~800-meter-thick evaporite succession from the Onega Basin in Russian Karelia. The deposit consists of a basal unit dominated by halite (~100 meters) followed by units dominated by anhydrite-magnesite (~500 meters) and dolomite-magnesite (~200 meters). The evaporite minerals robustly constrain marine sulfate concentrations to at least 10 millimoles per kilogram of water, representing an oxidant reservoir equivalent to more than 20% of the modern ocean-atmosphere oxidizing capacity. These results show that substantial amounts of surface oxidant accumulated during this critical transition in Earth’s oxygenation.
Doktorant Ursula Toom koos kaasautoritega publitseeris veebiversiooni teadusartikli ajakirjas Journal of Systematic Palaeontology (WoS mõjufaktor IF 2.963; kategooria Q1/Q2)
Cole, S.R., Toom, U. 2018. New camerate crinoid genera from the Upper Ordovician (Katian) of Estonia: evolutionary origin of family Opsiocrinidae and a phylogenetic assessment of Ordovician Monobathrida. Journal of Systematic Palaeontology xx, xx-xx.
Most major crinoid clades first appear in the fossil record during the Ordovician, but the evolutionary origins of many higher taxa remain unresolved. Here, the first camerate crinoids from the Katian (Upper Ordovician) of Estonia with complete calyces are described. Phylogenetic analyses are conducted to determine the affinities of two new genera and to assess the evolutionary origins of the families Opsiocrinidae (Diplobathrida) and Glyptocrinidae (Monobathrida). Sakucrinus krossi gen. et sp. nov. is identified as the earliest known member of Opsiocrinidae and demonstrates that: (1) the family originated much earlier than was previously assumed; (2) features previously considered plesiomorphic for the family are instead derived; and (3) the family is likely closely related to the Dimerocrinitidae. Family Pachycephalocrinidae fam. nov. is established to accept the monocyclic glyptocrinid Pachycephalocrinus jaanussoni gen. et sp. nov. Pachycephalocrinus jaanussoni displays morphological features that are unique among monobathrid crinoids, including a large periproct in the calyx side. Inclusion of Pachycephalocrinus in the first phylogenetic analysis focusing on Ordovician monobathrid crinoids elucidates evolutionary relationships among Ordovician monobathrids and calls into question the validity of superorder Compsocrinina. The new genera described here provide important insight into the timing of origination and morphological diversity of higher taxa during the early evolutionary history of camerate crinoids.
Linda Hints koos kaasautoriga avaldas teadusartikli ajakirjas Estonian Journal of Earth Sciences (WoS mõjufaktor IF 1.053; kategooria Q4)
Hints, L., Harper, D.A.T., Paškevičius, J. 2018. Diversity and biostratigraphic utility of Ordovician brachiopods in the East Baltic. Estonian Journal of Earth Sciences 67, 176-191.
The stratigraphy of the Ordovician carbonates of Baltoscandia was initially based, during the 19th century, on the stratigraphical ranges of macrofossils, mainly trilobites, but other fossils (brachiopods, echinoderms and cephalopods) were also used. During the 20th century, their importance in biostratigraphy gradually decreased due to a greater reliance on microfossils, especially conodonts and chitinozoans, which enable accurate correlation of carbonate successions where graptolites are absent or very rare. New methods have further reduced the attraction of macrofossils for biostratigraphy, although they are useful tools in different fields of geology such as palaeobiogeography and palaeoecology. The revised data on species diversity and the stratigraphical distribution of articulated brachiopods with carbonate shells (rhynchonelliformeans) in the East Baltic are used here for the evaluation of their role and potential in the modern stratigraphy of the Ordovician System. The 106 stratigraphical units (mainly formations and members) belonging to 17 Ordovician and the lowermost Silurian regional stages are analysed based on the taxonomic composition of their brachiopod faunas comprising in total more than 400 species. The cluster analysis used in this stratigraphical experiment captures the major dissimilarities between and continuity of the regional subseries, stages and subregional units by the similarity of their brachiopod faunas. Bryozoans, another important group of benthic organisms in shallow-water facies, are analysed for comparison, providing a test for the correlations based on brachiopods.
Olle Hintsil koos kaasautoritega ilmus teadusartikkel ajakirjas Lethaia (WoS mõjufaktor IF 2.281; kategooria Q1)
Hints, O., Antonovitš, L., Bauert, G., Nestor, V., Nõlvak, J., Tammekänd, M. 2018. CHITDB: a database for documenting and analysing diversification of Ordovician–Silurian chitinozoans in the Baltic region. Lethaia 51, 218-227.
Chitinozoans are a key group in Ordovician and Silurian biostratigraphy, and the Baltic region hosts some of the largest collections of these microfossils in the world. Here, we present an online database – ‘CHITDB’ – for documenting and analysing the distribution of chitinozoans in the Baltic region. The system is integrated with the Estonian geocollections database and includes a public query portal (<http://chitinozoa.net>), which allows browsing and searching for chitinozoan taxa, samples, sections, references and SEM images, downloading raw data by sections, and generating range charts, summary reports and CONOP9 input files. The chitinozoan database holds currently over 35000 occurrence records of 300 chitinozoan taxa from 6400 micro‐palaeontological samples and 100 sections. Quantitative stratigraphical analysis of this data set enabled compilation of the highest resolution chitinozoan diversity curves through the Ordovician and Silurian to date, and assessment of the rates of evolutionary changes. The new model incorporates K‐bentonite and carbon isotope data that help to constrain time relationships between bioevents and environmental changes. The highest chitinozoan diversity in the Baltic region is encountered in late Darriwilian to mid‐Katian and in the Telychian, when the standing diversity reached 30–35 species. Overall, the latest Ordovician and Silurian faunas show more dynamic diversity patterns, with higher extinction and origination rates, than was typical for most of the Ordovician Period.
Külalisteadlane Oliver Lehnert koos kaasautoritega avaldas teadusartikli ajakirjas Lethaia (WoS mõjufaktor IF 2.281; kategooria Q1)
Lefebvre, B., Gutiérrez-Marco J.C., Lehnert, O., Martin E.L.O., Nowak H., Akodad M., El Hariri K., Servais T. 2018. Age calibration of the Lower Ordovician Fezouata Lagerstätte, Morocco. Lethaia 51, 296-311.
The Fezouata Lagerstätte, discovered in the Lower Ordovician rocks of Morocco, is a Konservat-Lagerstätte of prime scientific importance. It provides access not only to the ‘shelly’ (skeletonized) part of its fossil assemblages, but also to non-biomineralized to
lightly sclerotized organisms and to exceptionally preserved soft tissues of a complex ecosystem, mixing elements of both the ‘Cambrian Explosion’ and the ‘Great Ordovician Biodiversification Event’ (GOBE). The Fezouata Lagerstätte occurs at different intervals in the Fezouata Shale, a formation ranging from the lower Tremadocian to the upper Floian (Lower Ordovician). In spite of recent major advances in the detailed biostratigraphy of the Fezouata Shale, there is currently no consensus on the precise age of the fossiliferous levels yielding exceptionally preserved assemblages. Consequently, all available biostratigraphical evidence based on several fossil groups is here critically reviewed and discussed. It can be concluded that exceptional preservation is restricted to a few thin, discontinuous, lens-shaped horizons occurring in two distinct parts of the Fezouata Shale: a lower interval (260–330 m above the base of the formation) and an upper interval (570–620 m). Integrated biostratigraphical studies, essentially based on investigations of graptolites, acritarchs and conodonts, indicate that the lower interval can be correlated with the upper Tremadocian, whereas the upper interval corresponds to the middle Floian.
Järeldoktorant Yan Liang koos kaasautoritega avaldas teadusartikli ajakirjas Lethaia (WoS mõjufaktor IF 2.578; kategooria Q1/Q2)
Liang, Y., Hints, O., Luan, X., Tang, P., Nõlvak, J., Zhan, R. 2018. Lower and Middle Ordovician chitinozoans from Honghuayuan, South China: Biodiversity patterns and response to environmental changes. Palaeogeography, Palaeoclimatology, Palaeoecology 500, 95-105.
A complete chitinozoan succession through the uppermost Tremadocian to lower Darriwilian (Lower and Middle Ordovician) at Honghuayuan, northern Guizhou Province in South China, was systematically studied and 47 species of 14 genera were identified. Two chitinozoan biodiversity acmes were recognized, which occur in the lower part of the Acrograptus filiformis (uppermost Hunghuayuan Formation) and middle part of the Azygograptus suecicus (middle member of the Meitan Formation) graptolite biozones. In the upper Dapingian and lower Darriwilian (uppermost part of the Meitan Formation), chitinozoan diversity was relatively high after a less conspicuous peak in the upper Dapingian. Comparisons between diversity trends of chitinozoans, acritarchs and brachiopods, and the environmental changes revealed both similarities and differences. In the Floian, the chitinozoan biodiversity curve at Honghuayuan shows good correlation with sea-level changes. The group temporarily disappeared when the sea level was at the highest, then reappeared and reached a biodiversity acme when sea level was low. Furthermore, a large organic carbon isotope excursion is coincident with the absence of chitinozoans and a highstand period after the sea-level rise in the lower and middle Floian. Diversity curves show fewer connections with the sea-level and organic C-isotope undulations during the Dapingian and early Darriwilian. New data suggest that the environmental changes played a significant role in the early stage of Ordovician chitinozoan radiation, roughly corresponding to the Floian at the Honghuayuan section. In the Dapingian and early Darriwilian, the intrinsic factors seem to have played a more important role in shaping biodiversity patterns of chitinozoans in South China.
Elga Mark-Kurik koos kaasautoritega avaldas postuumselt teadusartikli ajakirjas Estonian Journal of Earth Sciences (WoS mõjufaktor IF 1.053; kategooria Q4)
Mark-Kurik, E., Newman, M.J., Toom, U., den Blaauwen, J.L. 2018. A new species of the antiarch Microbrachius from the Middle Devonian (Givetian) of Belarus. Estonian Journal of Earth Sciences 67, 3-13.
A new antiarch species Microbrachius kedoae n. sp. is described from the Middle Devonian (Givetian) of Belarus. The species is based on isolated dermal plates recovered from a borehole near the village of Gavrilchitsy about 25 km southwest of the city of Soligorsk. Microbrachius kedoae compares well to the type species Microbrachius dicki from Scotland, but differs from this and all other Microbrachius species in the mixilateral plate being overlapped by the anterior median dorsal plate. The presence of Microbrachius species of the same age in Scotland and Belarus strengthens the argument of faunal connections between the two areas in the Middle Devonian.
Tiiu Märss koos kaasautoriga avaldas teadusartikli ajakirjas Estonian Journal of Earth Sciences (WoS mõjufaktor IF 1.053; kategooria Q4)
Pinakhina, D.V., Märss, T. 2018. The Middle Devonian acanthodian assemblage of the Karksi outcrop in Estonia. Estonian Journal of Earth Sciences 67, 96-111.
The taxonomic composition of the acanthodian assemblage of the Karksi outcrop, Estonia, is discussed. Two new species, Rhadinacanthus deltosquamosus n. sp. (Diplacanthiformes, Diplacanthidae) and Ginkgolepis tenericostatus n. sp. (Acanthodiformes, Cheiracanthidae), are described based on isolated scales. A re-description of Nostolepis gaujensis Valiukevičius (Climatiiformes, Climatiidae) scales from this locality is also given. Three diplacanthiform taxa, Diplacanthus sp. cf. D. crassisimus (Duff), Diplacanthus sp. cf. D. tenuistriatus Traquair and Diplacanthiformes indet., are described in open nomenclature.
Aivo Lepland publitseeris koos kaasautoritega teadusartikli ajakirjas Precambrian Research (WoS mõjufaktor IF 3.843; kategooria Q1)
Prave, A.R., Meng, F., Lepland, A., Kirsmäe, K. 2018. A refined late-Cryogenian – Ediacaran Earth history of South China: phosphorous-rich marbles of the Dabie and Sulu orogens. Precambrian Research 305, 166-176.
The late-Cryogenian – Ediacaran geological framework for South China is constructed principally from sedimentary successions preserved in the central and western regions of the Yangtze Block. New stratigraphic and carbonate-carbon isotope data allow us to extend that framework into the exhumed HP-UHP subduction complexes of the eastern Dabie and Sulu orogens that separate the South and North China cratons. Those data show that marble and phosphorous-rich (P-rich) units in those complexes were originally part of an Ediacaran shallow-marine shelf-carbonate platform. The basal pebbly schist (metadiamictite) and lowermost P-rich marble of the Jinping Formation (Haizhou Group) in the Sulu Orogen matches in both facies character and C-isotope profile that of the Marinoan-equivalent glacial-cap carbonate couplet of the Nantuo and Doushantuo formations. The Daxinwu Formation (Susong Group) in the eastern Dabie Orogen contains a marble unit that has, for several hundreds of metres, a strikingly uniform C-isotope profile of low δ13C positive values and is overlain by a P-rich graphitic schist; these features match those of the late Ediacaran to early Cambrian Dengying Formation. These correlations establish that the HP-UHP metasedimentary rocks, many of which were once considered to be Palaeo- to Mesoproterozoic in age, are a Neoproterozoic-age cover sequence of the continental margin of the Yangtze Block. Further, their widespread development limits their utility as indicators of offset across the Tan-Lu fault zone and, instead, favours tectonic models that interpret that feature as a continental-scale tear fault formed during the Mesozoic collision and suturing of the North and South China cratons.
Tiiu Märss koos kaasautoriga avaldas teadusartikli ajakirjas Journal of Vertebrate Paleontology (WoS mõjufaktor IF 2.114; kategooria Q1)
Tinn, O., Märss, T. 2018. The earliest osteostracan Kalanaspis delectabilis gen. et sp. nov. from the mid-Aeronian (mid-Llandovery, lower silurian) of Estonia. Journal of Vertebrate Paleontology 38, e1425212.
The Osteostraci are an early clade of jawless vertebrates widely regarded as the sister group of all jawed vertebrates. Despite their prominent role in the Silurian to Devonian marginal marine ecosystems, the early evolutionary history of this subclass remains poorly understood. Here we report the discovery of a head shield (part with broken right margin and counterpart) of Kalanaspis delectabilis gen. et sp. nov. from the Kalana Quarry in Central Estonia. Reliably dated to the Pranognathus tenuis Conodont Zone, Raikküla Regional Stage, mid-Aeronian, mid-Llandovery, the specimen is about 10 million years older than the previously known oldest record of the Osteostraci. Kalanaspis delectabilis gen. et sp. nov. is identified as belonging to the new Family Kalanaspididae fam. nov., Order Ateleaspidiformes. It has a relatively large dorsal head shield, which is somewhat wider than long, with very small and very closely placed orbits, short prepineal length, one pair of notably long lateral fields, and gently undulating posterior margin. It lacks a posteromedian dorsal ridge as well as cornual processes and pectoral sinuses. No impressions of nasohypophyseal and pineal features were detected. The preservation of the specimen is unusual; the energy-dispersive spectroscopy (EDS) elemental analysis revealed that calcium phosphate, the original major constituent of the dermal skeleton of vertebrates, has disappeared and has been substituted by carbonaceous matter.
Doktorant Ursula Toom koos kaasautoritega publitseeris teadusartikli ajakirjas Palaeontologia Electronica (WoS mõjufaktor IF 1.400; kategooria Q2)
Vinn, O., Toom, U., Ernst, A. 2018. Intergrowth of Orbignyella germana Bassler, 1911 (Bryozoa) and Lambelasma carinatum Weyer, 1993 (Rugosa) in the pelmatozoan-bryozoan-receptaculitid reefs from the Late Ordovician of Estonia. Palaeontologia Electronica 21.1.4A 1-7.
The earliest known rugosan-bryozoan intergrowth is reported from the early Katian of Estonia. A specimen of Orbignyella germana Bassler, 1911, from pelmatozoan-bryozoan-receptaculitid reefs of the Vasalemma Formation shows intergrowth with rugosans Lambelasma carinatum Weyer, 1993. The morphology of the bryozoan colony does not show any malformations or changes in zooid size near the embedded rugosans. It is likely that intergrowth between L. carinatum and O. germana was purely accidental. Relatively high population densities and restricted space for growth in the reef may have caused this intergrowth. Rugosans may have benefitted from this association in achieving a stable substrate in shallow and hydrodynamically active waters of the reef environment, whereas bryozoans obviously used corals as a substrate. Lambelasma may have been especially prone for intergrowth with bryozoans as it participates in three associations in the Late Ordovician of Estonia.
Külalisteadlane Oliver Lehnert koos kaasautoritega avaldas teadusartikli ajakirjas GFF (WoS mõjufaktor IF 1.142; kategooria Q2/Q3)
Wu, R.-C., Calner, M., Lehnert, O., Lindskog, A., Joachimski, M. 2018. Conodont biostratigraphy and carbon isotope stratigraphy of the Middle Ordovician (Darriwilian) Komstad Limestone, southern Sweden. GFF 140, 44-54.
The Komstad Limestone forms a distal part of the widespread ‘orthoceratite limestone’ of the Baltoscandian continent. In this paper, we present an integrated conodont biostratigraphy and carbon isotope stratigraphy for a major part of this formation and address its significance for evaluating Middle Ordovician correlation and overall stratigraphy. Four conodont zones are distinguished, including the Lenodus antivariabilis Zone, Lenodus variabilis Zone, the Yangtzeplacognathus crassus Zone, and the Eoplacognathus pseudoplanus Zone. Carbon isotopes have previously not been published from the Komstad Limestone. The data herein show that carbonate strata may retain a comprehensive pristine δ13C signal despite relatively strong thermal influence during diagenesis (Conodont Color Alteration Index 4–5)
Aivo Lepland publitseeris koos kaasautoritega teadusartikli ajakirjas Precambrian Research (WoS mõjufaktor IF 3.843; kategooria Q1)
Wudarska, A., Wiedenbeck, M., Słaby, E., Lepland, A., Birski, Ł., Simon, K. 2018. Halogen chemistry and hydrogen isotopes of apatite from the >3.7 Ga Isua supracrustal belt, SW Greenland. Precambrian Research 310, 153-164.
The origin and evolution of volatiles, particularly water, in the abiotic early Earth environment have been intensively studied, and this is a topic of high relevance when considering the timing and conditions of life’s emergence. Investigation of hydrogen isotopes in the oldest crystals of minerals from the apatite group Ca10(PO4)6(F,Cl,OH)2 should bring new insight to this topic as the D/H ratio of apatite has proved useful for establishing the evolution of volatiles in other solar system bodies. Apatite crystals from metasedimentary and metavolcanic rocks collected from a low-strain domain of the Eoarchean Isua supracrustal belt have been investigated for their D/H signatures using secondary ion mass spectrometry and for major and trace element abundances using EPMA and laser ablation ICP-MS. Apatite crystals from Isua have a broad range in volatile compositions, both within samples from the same lithology (e.g., banded iron formation; BIF) and between different lithologies (BIF, metacarbonate, mafic dyke). Most of the crystals are chlorine-rich, which is in contrast to typical modern sedimentary apatite that is predominantly carbonate fluorapatite. We have used the REE distribution patterns from Isua apatite to distinguish those crystals having sedimentary, metasomatic and magmatic origins. The D/H ratios for all samples were determined to be very low with δDVSMOW values falling within the range from −93 to −56‰. δD values of Isua apatite do not correlate with REE signatures of crystals nor could we relate δD to the host lithologies. We conclude that this geochemical system has been reset during long and multi-phase geologic history, making it difficult, if not impossible, to use hydrogen isotopes for assessment of the primary signatures of the Archean hydrosphere.
Enn Kaup ja kaasautorid avaldasid veebiversiooni teadusartikli ajakirjas Journal of Soils and Sediments (WoS mõjufaktor IF 2.522; kategooria Q2)
Lepane, V., Künnis-Beres, K., Kaup, E., Sharma, B. 2018. Dissolved organic matter, nutrients, and bacteria in Antarctic soil core from Schirmacher Oasis. Journal of Soils and Sediments 18, 8, 2715–2726.
This study focuses on the application of HPLC in dissolved organic matter (DOM) research in Antarctic environment together with nutrients and heterotrophic bacteria (HB) analyses. The specific aims were to investigate changes in DOM components characteristics and in nutrients in soil core from ground active layer and upper permafrost, to relate obtained data to active heterotrophic bacteria records after applying statistical data treatment methods, and to explore the potential impact of environment.
Materials and methods
A single Antarctic 1.9-m deep soil core drilled at a site without human impact from Schirmacher Oasis, located 70° 46′ 02″ S and 11° 45′ 11″ E, was explored. The chromophoric DOM (CDOM) was characterized by soil water analysis using multi-wavelength HPLC. Total organic carbon and total nitrogen were determined by elemental analysis, the total phosphorus by inductively coupled plasma spectrometry. The vertical changes in those nutrients and their ratios were investigated. The microbiological analysis was accomplished through the determination of psychrotrophic and psychrophilic aerobic HB numbers by colony-forming units counting method, and by epifluorescence microscopy examination. Cluster analysis using the Ward method and principal component analysis was performed on the chromatographic and microbiology data to reveal similar layers in studied soil core.
Results and discussion
In active soil layer, the CDOM was missing thus indicating rather active decomposition of organic material or organic debris by the local microbial community. In deep permafrost layers, the quantity of CDOM preserved in soil water increased. The content of total organic carbon in soil was low, between 0.05 and 0.2%, and decreased down the core. The vertical changes in nutrients (total N and P), the ratios C/N and C/P, followed total organic carbon profile suggesting similar sources. Microbiological analyses showed decreasing vertical concentrations of active HB. Statistical data treatment methods enabled clustering of soil core into three zones according to depth.
The obtained results contribute to better understanding of organic carbon-related processes in an almost un-polluted Antarctic environment. The CDOM, macronutrients, C/N, C/P, and HB profile characteristics of the Antarctic soil core clearly demonstrate the effect of environment (active or permafrost soil layers). The study demonstrated that combining HPLC with multi-wavelength detection and microbial analyses with statistical data treatment is potentially a promising tool of investigating changes in Antarctic soil DOM and in soil waters generally.
Doktorant Joonas Pärn koos kaasautoritega publitseeris teadusartikli ajakirjas Chemical Geology (WoS mõjufaktor IF 3.347; kategooria Q1)
Pärn, J., Affolter, S., Ivask, J., Johnson, S., Kirsimäe, K., Leuenberger, M., Martma, T., Raidla, V., Schloemer, S., Sepp, H., Vaikmäe, R., Walraevens, K. 2018. Redox zonation and organic matter oxidation in palaeogroundwater of glacial origin from the Baltic Artesian Basin. Chemical Geology 488, 149-161.
Ordovician-Cambrian aquifer system (O-Cm) in the northern part of the Baltic Artesian Basin (BAB), Estonia, is part of a unique groundwater reservoir where groundwater originating from glacial meltwater recharge from the Scandinavian Ice Sheet is preserved. The distribution of redox zones in the anoxic O-Cm aquifer system is unusual. Strongly reducing conditions are found near the modern recharge area characterized by low concentrations of sulphate (<5 mg·L−1) and the presence of CH4 (up to 3.26 vol%). The concentrations of SO42− increase and concentrations of CH4 decrease farther down the groundwater flow path. Sulphate in fresh glacial palaeogroundwater originates probably from pyrite oxidation while brackish waters have gained their sulphate through mixing with relict saline formation waters residing in the deeper parts of the aquifer system. Stable isotopic composition of sulphate, especially relations between δ18OSO4-δ18Owater (∆18OSO4-H2O from +20.5 to +31.1‰) and δ34SSO4-δ34SH2S (∆34SSO4-H2S value of +47.9‰) support a widespread occurrence of bacterial sulphate reduction in fresh glacial palaeogroundwater. We propose, that the observed unusual redox zonation is a manifestation of two different flow systems in the O-Cm aquifer system: 1) the topographically driven flow system which drives the infiltration of waters through the overlying carbonate formation in the modern recharge area; 2) the relict flow system farther down the groundwater flow path which developed as a response to large hydraulic gradients imposed by the Scandinavian Ice Sheet in Pleistocene. Thus, the strongly reducing conditions surrounding the modern recharge area may show the extent to which post-glacial recharge has influenced the aquifer system. O-Cm aquifer system is an example of an aquifer that has not reached a near-equilibrium state with respect to present day flow conditions and still exhibits hydrogeochemical patterns established under the influence of a continental ice sheet in Pleistocene.
Tõnu Martma avaldas koos kaasautoritega teadusartikli ajakirjas The Cryosphere (WoS mõjufaktor IF 4.803; kategooria Q1)
Vega, C.P., Isaksson, E., Schlosser, E., Divine, D., Martma, T., Mulvaney, R., Eichler, A., Schwikowski-Gigar, M. 2017. Variability of sea salts in ice and firn cores from Fimbul Ice Shelf, Dronning Maud Land, Antarctica. The Cryosphere 12, 1681-1697.
Major ions were analysed in firn and ice cores located at Fimbul Ice Shelf (FIS), Dronning Maud Land – DML, Antarctica. FIS is the largest ice shelf in the Haakon VII Sea, with an extent of approximately 36 500 km2. Three shallow firn cores (about 20 m deep) were retrieved in different ice rises, Kupol Ciolkovskogo (KC), Kupol Moskovskij (KM), and Blåskimen Island (BI), while a 100 m long core (S100) was drilled near the FIS edge. These sites are distributed over the entire FIS area so that they provide a variety of elevation (50–400 m a.s.l.) and distance (3–42 km) to the sea. Sea-salt species (mainly Na+ and Cl−) generally dominate the precipitation chemistry in the study region. We associate a significant sixfold increase in median sea-salt concentrations, observed in the S100 core after the 1950s, to an enhanced exposure of the S100 site to primary sea-salt aerosol due to a shorter distance from the S100 site to the ice front, and to enhanced sea-salt aerosol production from blowing salty snow over sea ice, most likely related to the calving of Trolltunga occurred during the 1960s. This increase in sea-salt concentrations is synchronous with a shift in non-sea-salt sulfate (nssSO42−) toward negative values, suggesting a possible contribution of fractionated aerosol to the sea-salt load in the S100 core most likely originating from salty snow found on sea ice. In contrast, there is no evidence of a significant contribution of fractionated sea salt to the ice-rises sites, where the signal would be most likely masked by the large inputs of biogenic sulfate estimated for these sites. In summary, these results suggest that the S100 core contains a sea-salt record dominated by the proximity of the site to the ocean, and processes of sea ice formation in the neighbouring waters. In contrast, the ice-rises firn cores register a larger-scale signal of atmospheric flow conditions and a less efficient transport of sea-salt aerosols to these sites. These findings are a contribution to the understanding of the mechanisms behind sea-salt aerosol production, transport and deposition at coastal Antarctic sites, and the improvement of the current Antarctic sea ice reconstructions based on sea-salt chemical proxies obtained from ice cores.