ALBERT

Beschreibung: Major and trace elements, and volatile components have been measured in melt inclusions in olivine from fresh 2.7 Ga old komatiites from the Reliance Formation of the Belingwe Greenstone Belt, Zimbabwe. Reconstructed compositions of melt inclusions contain 20–23.5 wt% MgO and up to 0.3 wt% H2O; these compositions probably represent those of the erupted lava. In inclusions in relatively evolved (low Fo) olivines, an excess of Na2O, CaO, Li, La, Cu, Rb, Y, Sc as well as volatile components (H2O, F, Cl and S) relative to other highly incompatible elements is attributed to assimilation of seawater altered mafic material. No assimilation signature is observed for the most primitive melt inclusions hosted in the magnesium rich olivines. The primary melt composition, estimated using melt inclusions in the most magnesian olivine (Fo 93.5), contains up to 27.5 wt% MgO and ca. 0.2 wt% H2O. The presence of H2O slightly depressed the liquidus temperature to ca. 1513 °C. Our results suggest formation of the Belingwe komatiite magma at ca. 7 GPa pressure and ca. 1790 °C temperature in a mantle plume. The plume picked up water and probably chlorine through interaction with a hydrous transition mantle zone in the way similar to that previously proposed by Sobolev et al. (2016) for komatiites in Canada.

Beschreibung: The Quaternary history of Beringia and of the Arctic–Pacific marine connection via the Bering Strait is poorly understood because of the fragmentary stratigraphic record from this region. We report new borehole and seismic-reflection data collected in 2006 in the southwestern Chukchi Sea. Sediment samples were analyzed for magnetic properties, grain size, heavy minerals, and biostratigraphic proxies (spores and pollen, foraminifers, ostracodes, diatoms, and aquatic palynomorphs). Two shallow boreholes drilled between the Chukotka Peninsula and the Wrangel Island recovered sediments of two principal stratigraphic units with a distinct unconformity between them. Based on predominantly reverse paleomagnetic polarity of the lower unit and pollen spectra indicative of forested coasts and climate warmer than present, the age of this unit is estimated as Pliocene to early Pleistocene (broadly between ca. 5 and 2 Ma). Attendant sedimentary environments were likely alluvial to nearshore marine. These deposits can be correlated to the seismic unit infilling valleys incised into sedimentary bedrock across much of the study area, and possibly deposited during a transgression following the opening of the Bering Strait. The upper unit from both boreholes contains Holocene 14C ages and is clearly related to the last, postglacial transgression. Holocene sediments in Borehole 2 indicate fast deposition at the early stages of flooding (between ca. 11 and 9 ka) to very low deposition, possibly related to expansive sea ice. Closer to shore, deposition at Borehole 1 resumed much later (ca. 2 ka), likely due to a change in the pattern of coastal erosional processes and/or the demise of a landbridge between the Chukotka Peninsula and the Wrangel Island inferred from studies on mammoth distribution.

Beschreibung: Five strains (JA325, JA389, JA473, JA563 and JA582) of Gram stain-negative, vibrioid to spiral shaped, phototrophic purple bacteria were isolated from solar salterns of India. All strains contained bacteriochlorophyll-a and carotenoids of the spirilloxanthin series as photosynthetic pigments. C18:1ω7c, C18:1ω7c 11-methyl and C16:0 were the major fatty acids of all strains. Diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), ornithine lipid (OL), an unidentified phospholipid (PL), and an unidentified aminolipid (AL) were the major polar lipids of all the strains. According to 16S rRNA gene sequences, all strains clustered phylogenetically with the only species of the genus Rhodothalassium (99.8–99.3% sequence similarity) but only strains JA325 and JA563 were distinctly related (60 + 1.5% DNA–DNA hybridization [DDH]) to the type strain Rhodothalassium salexigens DSM 2132T. However, the genotypic data of strains JA325 and JA563 was not supported because of a large number of phenotypic differences compared to the type strain, therefore, it is proposed that all five newly isolated strains were R. salexigens-like strains. In addition, phylogenetically, the Rhodothalassium clade represented a distinct lineage and formed a deep branch with less than 90% 16S rRNA gene sequence similarity to other orders of the Alphaproteobacteria, and characteristic phenotypic properties also distinguished these bacteria from other purple non-sulfur bacteria. Therefore, the novel family Rhodothalassiaceae fam. nov. and the novel order Rhodothalassiales ord. nov. are proposed for the distinct phyletic line represented by the genus Rhodothalassium.

Beschreibung: The present paper is a contribution to the first initiative of the Port Baseline Survey (PBS) for Non-indigenous species (NIS) in the Mediterranean Sea. It presents a report on the soft-bottom macrobenthos from the five Adriatic ports: Bari, Ancona (Italy), Koper (Slovenia), Pula, Rijeka (Croatia), with a focus on the presence and contribution of NIS to native assemblages. Out of 451 species identified, only four were common to all ports. A total of eight NIS were recorded, five in surveyed ports and three in the lagoon connected to the Port of Koper. The highest number of NIS was recorded in Bari, and the highest abundance in Ancona and Bari. Generally, the number, abundance and contribution of NIS seems too low to cause a substantial impact on native communities in surveyed ports. The suitability of methods adopted for PBS for soft-bottom NIS was discussed and suggestion for methodological improvement is provided.

Beschreibung: The Kamchatka Peninsula in far eastern Russia represents the most volcanically active arc in the world in terms of magma production and the number of explosive eruptions. We investigate large-scale silicic volcanism in the past several million years and present new geochronologic results from major ignimbrite sheets exposed in Kamchatka. These ignimbrites are found in the vicinity of morphologically-preserved rims of partially eroded source calderas with diameters from ∼ 2 to ∼ 30 km and with estimated volumes of eruptions ranging from 10 to several hundred cubic kilometers of magma. We also identify and date two of the largest ignimbrites: Golygin Ignimbrite in southern Kamchatka (0.45 Ma), and Karymshina River Ignimbrites (1.78 Ma) in south-central Kamchatka. We present whole-rock geochemical analyses that can be used to correlate ignimbrites laterally. These large-volume ignimbrites sample a significant proportion of remelted Kamchatkan crust as constrained by the oxygen isotopes. Oxygen isotope analyses of minerals and matrix span a 3‰ range with a significant proportion of moderately low-δ18O values. This suggests that the source for these ignimbrites involved a hydrothermally-altered shallow crust, while participation of the Cretaceous siliceous basement is also evidenced by moderately elevated δ18O and Sr isotopes and xenocryst contamination in two volcanoes. The majority of dates obtained for caldera-forming eruptions coincide with glacial stages in accordance with the sediment record in the NW Pacific, suggesting an increase in explosive volcanic activity since the onset of the last glaciation 2.6 Ma. Rapid changes in ice volume during glacial times and the resulting fluctuation of glacial loading/unloading could have caused volatile saturation in shallow magma chambers and, in combination with availability of low-δ18O glacial meltwaters, increased the proportion of explosive vs effusive eruptions. The presented results provide new constraints on Pliocene–Pleistocene volcanic activity in Kamchatka, and thus constrain an important component of the Pacific Ring of Fire.

Beschreibung: This paper is based on the results of a comprehensive investigations of sediments from seven cores sampled during the International Russian-Chinese Cruise 53 of the R/V “Akademik Lavrentyev” (2010) in the frames of the Russian-Chinese collaboration between the Pacific Oceanological Institute of the Far-Eastern Branch of the Russian Academy of Sciences (POI FEB RAS, Vladivostok, Russia), and the First Institute of Oceanography (FIO, Qingdao, China). Baitoushan (Chanbaishan) Volcano had several powerful explosive eruptions during the Middle Pleistocene-Holocene, which produced widespread tephra layers. The paper reports chemical composition of volcanic glasses and minerals from six tephra layers labeled as B-Og, B-Sado, B-J, B-Un1, B-V, and B-Tm, which belong to Baitoushan Volcano and were identified in sediments of the northwestern part of the Sea of Japan. The tephras were dated using geochronological data for the host sediments. The estimated ages for the Middle Pleistocene tephra is 488 ka; the Late Pleistocene tephras are 71.1–71.9 cal. kа (B-Sado), 50.8 cal. ka (B-J), 38.3 cal. ka (B-Un1), and 29.0–29.4 cal. ka (B-V). The ash layers consist of alkali-rich glass of trachydacitic to alkaline rhyolitic composition and specific assemblage of minerals including Fe-rich augite-hedenbergite, aegirine-augite, aegirine, arfvedsonite, and fayalite. The mineral assemblage is typical for alkalic volcanic rocks from continental rift setting. Aenigmatite, a rare mineral from the group of inosilicates, was firstly identified in distal tephra of Baitoushan Volcano, supplied into marine sediments. The composition of glasses and minerals from all layers are similar. It testifies about steady-state conditions of the magma accumulation under Baitoushan Volcano and about the bimodal character of magmatic chambers during the Late Pleistocene and Holocene (since 100 ka).

Beschreibung: Highlights: • New predatory protist (Tunicaraptor) with unique morphology is related to animals • Tunicaraptor calls into question many of the well-accepted relationships in Holozoa • Tunicaraptor possesses a unique combination of “animal-specific” gene products • Eukaryovorous flagellates may represent a major share of unicellular animal relatives The origin of animals is one of the most intensely studied evolutionary events, and our understanding of this transition was greatly advanced by analyses of unicellular relatives of animals, which have shown many “animal-specific” genes actually arose in protistan ancestors long before the emergence of animals [1–3]. These genes have complex distributions, and the protists have diverse lifestyles, so understanding their evolutionary significance requires both a robust phylogeny of animal relatives and a detailed understanding of their biology [4, 5]. But discoveries of new animal-related lineages are rare and historically biased to bacteriovores and parasites. Here, we characterize the morphology and transcriptome content of a new animal-related lineage, predatory flagellate Tunicaraptor unikontum. Tunicaraptor is an extremely small (3–5 μm) and morphologically simple cell superficially resembling some fungal zoospores, but it survives by preying on other eukaryotes, possibly using a dedicated but transient “mouth,” which is unique for unicellular opisthokonts. The Tunicaraptor transcriptome encodes a full complement of flagellar genes and the flagella-associated calcium channel, which is only common to predatory animal relatives and missing in microbial parasites and grazers. Tunicaraptor also encodes several major classes of animal cell adhesion molecules, as well as transcription factors and homologs of proteins involved in neurodevelopment that have not been found in other animal-related lineages. Phylogenomics, including Tunicaraptor, challenges the existing framework used to reconstruct the evolution of animal-specific genes and emphasizes that the diversity of animal-related lineages may be better understood only once the smaller, more inconspicuous animal-related lineages are better studied.

Beschreibung: Fossil carbonate skeletons of marine organisms are archives for understanding the development and evolution of palaeo-environments. However, the correct assessment of past environment dynamics is only possible when pristine skeletons and their biogenic characteristics are unequivocally distinguishable from diagenetically-altered skeletal elements and non-biogenic features. In this study, we extend our work on diagenesis of biogenic aragonite (Casella et al. 2017) to the investigation of biogenic low-Mg calcite using brachiopod shells. We examined and compared microstructural characteristics induced by laboratory-based alteration to structural features derived from diagenetic alteration in natural environments. We used four screening methods: cathodoluminescence (CL), cryogenic and conventional field emission-scanning electron microscopy (FE-SEM), atomic force microscopy (AFM) and electron backscatter diffraction (EBSD). We base our assessments of diagenetic alteration and overprint on measurements of, a) images of optical overprint signals, b) changes in calcite crystal orientation patterns, and c) crystal co-orientation statistics. According to the screening process, altered and overprinted samples define two groups. In Group 1 the entire shell is diagenetically overprinted, whereas in Group 2 the shell contains pristine as well as overprinted parts. In the case of Group 2 shells, alteration occurred either along the periphery of the shell including the primary layer or at the interior-facing surface of the fibrous/columnar layer. In addition, we observed an important mode of the overprinting process, namely the migration of diagenetic fluids through the endopunctae corroborated by mineral formation and overprinting in their immediate vicinity, while leaving shell parts between endopunctae in pristine condition. Luminescence (CL) and microstructural imaging (FE-SEM) screening give first-order observations of the degree of overprint as they cover macro-to micron scale alteration features. For a comprehensive assessment of diagenetic overprint these screening methods should be complemented by screening techniques such as EBSD and AFM. They visualise diagenetic changes at submicron and nanoscale levels depicting the replacement of pristine nanocomposite mesocrystal biocarbonate (NMB) by inorganic rhombohedral calcite (IRC). The integration of screening methods allows for the unequivocal identification of highly-detailed alteration features as well as an assessment of the degree of diagenetic alteration.

Beschreibung: Abyssal macrofaunal composition of 21 epibenthic sledge hauls from twelve stations taken in the Kuril–Kamchatka Trench (KKT) and at the adjacent abyssal plain, Northwest Pacific, is presented. Sampling with the fine meshed epibenthic sledge yielded higher abundances and species richness than was reported from previous expeditions from board of RV Vityaz. In total 84,651 invertebrates were sampled with RV Sonne between July and September of 2012 (31,854 invertebrates if standardised for 1000 m2 trawled distances) from 41 taxa of different taxonomic ranks (15 phyla, 28 classes, 7 orders) were sampled from a trawled area of 53,708 m² and have been analyzed. Few taxa were frequent and most taxa were rare in the samples, twelve taxa occurred with more than 1% frequency. Of these, the Polychaeta were most abundant followed by the benthic Copepoda and Isopoda. Total numbers of individuals varied between stations and were highest with 4238 individuals at station 2-10 close to the KKT in 4865 m depth and lowest with 374 individuals at station 6-11 in 5305 m depth. At this station also the lowest number of taxa occurred (18 taxa) while the highest number occurred with 31 taxa at station 3-9 in 4991 m depth. Numbers of individuals decreased with increasing depth between 4830 and 5780 m. Crustaceans of the superorder Peracarida were one of the dominating taxa with four orders occurring frequently in most samples. In total, Isopoda were most important and occurred with 59% of all peracarid orders sampled, followed by Amphipoda with 21%, Tanaidacea with 11%, Cumacea with 9%, and Mysidacea with 〈1%. The communities of the stations (and hauls) of the KKT abyssal area differ in terms of taxon composition from each other. A cluster analysis (nMDS) performed for all sampled stations revealed no clear pattern of community similarity between stations or hauls. All hauls close to the trench (2-9 and 2-10 close to the eastern slope of the KKT; and 3-9 and 4-3 at the western slope) were most different to the other hauls. Hauls 8-9 and 8-12 as well as 5-10 and 7-10 in the approximate centre of the overall research area were most similar (88% similarity). The non-isolated KKT area is characterized by higher abundances and higher benthic species richness than the geographically isolated and young deep-sea basin of the Sea of Japan.