ALBERT

Description: 〈title xmlns:mml="http://www.w3.org/1998/Math/MathML"〉ABSTRACT〈/title〉〈p xmlns:mml="http://www.w3.org/1998/Math/MathML" xml:lang="en"〉The Permian–Triassic and Triassic–Jurassic critical intervals are among the most significant ecological upheavals in the Phanerozoic. Both evolutionary junctures are characterized by environmental deterioration associated with a marked biodiversity decline. In this study, Permian–Triassic and Triassic–Jurassic boundary sections from South China and the Northern Calcareous Alps were investigated. In order to reconstruct the interplay between biotic and abiotic processes, a multifaceted approach that included optical microscopy, X‐ray diffraction, Raman spectroscopy, stable carbon isotopes and lipid biomarkers was employed. The lower parts of these two sections are similar as both consist of limestone with abundant fossils of eukaryotic organisms. However, the Permian–Triassic record is dominated by dasyclad green algae and fusulinid foraminifera, while the Triassic–Jurassic record is typified by corals and coralline sponges. Moving upward, both sections consist mainly of micrite and marl. Concerning the Permian–Triassic section, it transits to volcanic ash intercalated by a distinct limestone bed with abundant calcispheres (tentatively attributed to ancestors of dinoflagellates). The Triassic–Jurassic section does not provide direct evidence for volcanic activity, but also becomes rich in calcisphere‐type cysts towards the top. Additionally, the section preserves abundant 4‐methyl sterenes (diagnostic for dinoflagellates) and C〈sub〉37–39〈/sub〉 〈italic toggle="no"〉n〈/italic〉‐alkanes (indicative for haptophytes). Hence, both critical intervals were associated with marked blooms of (ancestral) dinoflagellates and haptophytes (for example, coccolithophorids). These blooms were followed by ecological lag‐phases, as indicated by low carbonate contents and scarce fossils which only increased further up the sections. For both critical intervals, it is commonly assumed that the formation of voluminous volcanic provinces (Siberian Traps and Central Atlantic Magmatic Province, respectively), as well as associated processes (for example, burning of organic‐rich sediments such as coal), resulted in ecological devastation. However, results suggest that volcanism also had a positive effect on certain planktonic primary producers such as dinoflagellates and haptophytes, perhaps by delivering essential nutrients.〈/p〉

Description: China Council Scholarship

Description: Teach@Tübingen Fellowship

Description: research

Description: Fungi have been recognized as a frequent colonizer of subseafloor basalt but a substantial understanding of their abundance, diversity and ecological role in this environment is still lacking. Here we report fossilized cryptoendolithic fungal communities represented by mainly Zygomycetes and minor Ascomycetes in vesicles of dredged volcanic rocks (basanites) from the Vesteris Seamount in the Greenland Basin. Zygomycetes had not been reported from subseafloor basalt previously. Different stages in zygospore formation are documented in the studied samples, representing a reproduction cycle. Spore structures of both Zygomycetes and Ascomycetes are mineralized by romanechite-like Mn oxide phases, indicating an involvement in Mn(II) oxidation to form Mn(III,VI) oxides. Zygospores still exhibit a core of carbonaceous matter due to their resistance to degradation. The fungi are closely associated with fossiliferous marine sediments that have been introduced into the vesicles. At the contact to sediment infillings, fungi produced haustoria that penetrated and scavenged on the remains of fragmented marine organisms. It is most likely that such marine debris is the main carbon source for fungi in shallow volcanic rocks, which favored the establishment of vital colonies.

Description: Aus dem Unter-/Mittelalb von Nordspanien wird ein Profil mit bis zu 8 m mächtigen Lithocodium/ Bacinella Boundstones vorgesteUt. Die mikrofaziell-sedimentologische Analyse des Profils crgibt für die Lithocodium/ Bacinella Bänke eine bathymetrische Position vom tieferen Subtidal bis flachsten Subtidal/lntertidal. Die maximale Tiefenposition ist an die photische Zone gebunden, die wiederum durch das Ausmaß toniger Suspensionen beeinflußt wird. Die bathymetrische Obergrenze ist mechanisch kontrolliert (z.B. WeUenenergie, Tidenströme). Lithocodium/Bacinella ist zusammen mit anderen Algen/Mikroben ein charakteristischer Bestandteil thrombolithischer Mud Mounds (z.B. Gandara Mound). Die funktionelle Rolle von Lithocodium/Bacinella bei der Mud Mound Genese umfaßt Baffling und Binding, AutomikritProduktion durch Kalzifizierung innerhalb organischer Schleimhüllen und eine Mikritproduktion über intensive Bohraktivitäten an eingelagerten karbonatischen Hartteilen. Das massenhafte Auftreten von Lithocodillm/ Bacinella und diversen Algen/Mikroben kann mit einer längerfristigen Eutrophierung des Lebensraumes oder mit Schwankungen der Karbonat-Alkalinät des Meerwassers erklärt werden.

Description: A section including Lithocodium/ Bacinella boundstones with a thickness of up to 8 m is reported from the Lower /Middle Albian of northern Spain. According to microfacies and sedimentological analyses the bathymetric position of the Lithocodium/ Bacinella banks ranges from deeper subtidal to shaUowest subtidal/intertidal conditions. The maximum depth is related to the photic zone, which ,itself is controled by the amount of muddy suspension. The upper bathymetric limit is mechanically defin'ed and corresponds to increased depositional energy (i.e. waves and tidal currents). Together with other algae and microbes Lithocodium/ Bacinella is a major constituent of thrombolitic mud mounds (Gandara mound). In the context of mud mound genesis the functional role of Lithocodium/ Bacinella includes baffling and binding, the production of micrite via the calcification inside of mucilagenous sheaths, and via intensive boring activities upon and inside of skeletal hardparts. The mass occurrence of Lithocodium/ Bacinella with associated algae and microbes may be explained by a longer ranging eutrophism of the environment or by shifts in seawater carbonate alkalinity.

Description: The relation of two well-known ancient carbonate deposits to hydrocarbon seepage was confirmed by this study. Archaea are found to be associated with the formation of Oxfordian seep carbonates from Beauvoisin and with a Miocene limestone from Marmorito ("tube-worm limestone"). Carbonates formed due to a mediation by archaea exhibit extremely positive or extremely negative 813Ccarbonate values, respectively. Highly positive values (+ 15%0) reflect the use of 13C-enriched CO2 produced by methanogenesis. Low 813C values of the Marmorito carbonates (-30%0) indicate the oxidation of seepagederived hydrocarbons. Likewise, the 813C content of specific tail-to-tail linked isoprenoids, biomarkers for archaea, was found to be strikingly depleted in these sampies (as low as -115%0). The isotopic signatures corroborate that archaea were involved in the cycling of seepage-derived organic carbon at the ancient localities. Another Miocene limestone ("Marmorito li mestone") shows a strong imprint of methanotrophic bacteria as indicated by 813C va lues of carbonate as low J. Peckmann (IEI) . J. Reitner Institut und Museum für Geologie und Paläontologie, Georg-August-Universität. Goldschmidtstrasse 3, D-37077 Göttingen, Germany e-mail: jpeckma@gwdg.de. Fax: + 49-551-397918 V. Thiel, W. Michaelis Institut für Biogeochemie und Meereschemie, Universität Hamburg, Bundesstrasse 55, D-20146 Hamburg, Germany P. Clari, L. Martire Dipartimento di Scienze della Terra, via Accademia delle Scienze 5, 1-10123 Torino, Italy C. Gaillard UFR des Sciences de la Terre, UMR 5565 Centre de Paleontologie stratigraphique et Paleoecologie, Universite Claude Bemard, Lyon 1, 27-43 Boulevard du 11 Novembre, F-69622 Villeurbanne Cedex, France as -40%0 and biomarker evidence. Epifluorescence microscopy and field-emission scanning electron microscopy revealed that bacterial biofilms were involved in carbonate aggregation. In addition to lucinid bivalves previously reported from both localities, we infer that sponges from Beauvoisin and tube worms from Marmorito depended on chemosynthesis as weil. Low 813C values of nodules related to sponge taphonomy (-27%0) indicate that sponges might have been Iinked to an enhanced hydrocarbon oxidation. Tube worm fossils from Marmorito closely resemble chemosynthetic pogonophoran tube worms from Recent cold seeps and are embedded in isotopically light carbonate (813C -300/00).

Description: The duration and position of the Rhaetian Stage are di scussed. With the recognition of Rhabdoceras suessi - up to now the index species of the Upper Norian (Sevatian) - in one of the Alpine type sections of the Rhaetian, this Stage becomes more and more restricted and its separation doubtfu!. Four possibilities for defining the Alpine uppermost Triassic are treated. The authors propose either to redefine the Alpi'ne Rhaetian as the uppermost Substage of thc Norian Stage, thereby replacing the Sevatian (proposal 4), or to include the previous Sevatian into an enlarged Rhaetian Stage (proposal 3). This proposal is favoured by the International Subcommission of Triassic Stratigraphy. Ir is supported by the recent discovery of Choristoceras marshi - index species of the restricted Rhaetian - in the lower part of the Koessen Beds of the Lahnewiesgraben, equivalent to the previous Zone of Rhabdoceras suessi. Ir is moreover supported by the discovery of the immediate ancestor of this species in the upper part of the Middle Norian (Alaunian) of Timor. This makes the suessi Zone synonymous with the marshi Zone, the lower part of wh ich may be treated now as the Subzone of Rhabdoceras suessi. Since no particular ammonite species can be used for defining the upper part, this can be defined only by the exclusive occurrence of Choristoceras marshi without Rhabdoceras messi. As reference section of the redefined Rhaetian Stage the Weißloferbach section near Koessen, Tirol (Austria) is proposed, since it is weil exposed and fossiliferous, bearing cephalopods, bivalves, brachiopods, ostracods, conodonts and other groups. The authors propose moreover to redefine and re-name the "Rhaetian" of the Germanic facies Realm, which can by no means bc correlated with the Alpine Realm. The names "Upper Keuper" or "Rhaetkeuper" may be more adequate. There is, however, some palynological evidence for a correlation of the Germanie Preplanorbis Beds with the Alpine "Schichtenfolge unter Anm. planorbis" in SUESS & MOJSISOVICS (1868), where Choristaceras marshi has disappeared. The occurrence of the first psiloceratid (Neophyllites antecedens) in these beds indicates that they represent the base of the Jur~sic System. Provisionally these Preplanorbis Beds remain included into the Zone of Psiloceras planorbis.

Description: Umfang und Stellung des Rhaet werden erörtert. Nach dem Fund von Rhabdoceras suessi - bislang Zonen-Art des Oberen Nor (Sevat) - in einem der alpinen Typprofile des Rhaet, ist der Umfang der Stufe erheblich geschrumpft und ihre Definition problematisch geworden. Von den Verf. werden vier Möglichkeiten, die höchste Trias zu definieren, zur Diskussion gestellt. Es wird empfohlen, entweder das alpine Rhaet als oberste Unterstufe des Nor neu zu definieren und das Sevat einzubeziehen (Vorschlag 4) oder aber das Rhaet - gleichfalls unter Einbeziehung des Sevat - als selbständige Obertrias-Stufe fortbestehen zu lassen (Vorschlag 3). Dieser Vorschlag wurde von der Internationalen Subkommission für Trias-Stratigraphie eindeutig favorisiert. Er wird durch den lange erwarteten Fund von Choristaceras marshi im tieferen Teil der Koessener Schichten des Lahnewiesgraben unterstützt, der stratigraphisch der bisherigen suessi-Zone entspricht. Nach der Entdeckung von direkten marshi-Vorläufern im oberen Mittelnor (Alaun, columbianus-Zone) von Timor sind diese Neufunde nicht mehr überraschend. Damit würde das neudefinierte Rhaet zwar wiederum nur die Zone des Choristoceras marshi enthalten, definiert durch das Erstauftreten dieser Art; es wäre aber eine Untergliederung in eine Subzone des Rhabdoceras suessi und eine obere Subzone des Choristoceras marshi s. str. (ohne Rh.suessi) möglich. Dieser Vorschlag ist der praktikabelste und schließt sich am engsten an die bisherigen Gepflogenheiten an. In dieser Form würde das Rhaet nun auch eine durchaus kartierfähige Einheit darstellen. Als Referenzprofil für das erweiterte Rhaet wird das Profil am Weißloferbach bei Koessen, Tirol (Osterreich) empfohlen, das nicht nur gute Aufschlußverhältnisse, sondern auch eine diverse Faunenvergesellschaftung enthält (Cephalopoden, Bivalven, Brachiopoden, Ostracoden, Conodonten u. a.). Es wird außerdem empfohlen, das germanische Rhaet neu zu definieren und zu benennen, da eine direkte Korrelation mit dem alpinen Rhaet nicht möglich ist. Die Begriffe "Oberkeuper" oder "Rhaetkeuper" werden zur Diskussion gestellt. Die Palynologie bietet erste Korrelationsmöglichkeiten, insbesondere für die hangenden Praeplanorbis- Schichten der germanischen Fazies, die mit der alpinen "Schichtenfolge unter Amm. planorbis" (SUESS & MOJSISOVICS 1868) parallelisiert werden können. Hier tritt Choristoceras marshi nicht mehr, Psiloceras plallorbis noch nicht auf. Mit dem ersten Einsetzen echter Psiloceraten (Neophyllites antecedcns) dürfen diese Schichten als Basis des Lias angesehen werden. Vorläufig bleiben sie jedoch in die Zone des Psiloceras planorbis des Unteren Hettangs eingeschlossen. Trotz des deutlichen Ausdünnens der Ammonitenführung in der obersten Trias - im Zusammenhang mit dem triadisch/ liassischen Faunenschnitt - soll die primäre "orthochronologische" Gliederung dieses Zeitraums auch weiterhin auf der Grundlage der Ammoniten-Fauna erfolgen. Sie wird allerdings wesentlich durch die bereits verfeinerte Conodonten-Gliederung ergänzt; die biostratigraphischen Möglichkeiten des Nannnoplanktons werden augenblicklich überprüft. Ein wesentliches Hilfsmittel für die Parallelisierung von germanischer und alpiner Fazies stellt sdlon jetzt die Palynologie dar, obwohl hier erst wenige vergleichende Untersuchungen vorliegen. Die Konferenz der lUGS "Subcommission on Trias Stratigraphy", welche vom 3.- 4. Juli 1978 in München stattfand, und an die sich ein 3-tägiger Field Workshop anschloß, sollte einen Beitrag leisten zur Korrelation zwischen der Trias im Tethysbereich und der Germanischen Trias-Fazies. G. RrcHTER-BERNBURG, der derzeitge Chairman der S. T. S., hatte als besonders wichtiges Teilproblem die Stellung und Abgrenzung des Rh a e t benannt. Nach gemeinsamer Absprache wird nun hiermit eine Stellungnahme kompetenter Kollegen zu dieser Frage, gemeinsam mit einem An- hand aus palynologischer Sicht, vorgelegt. In einem "Nachwort" werden vom Chairman einige zusätzliche Bemerkungen sowie eine von der S. T. S. gefaßte Resolution zum Begriff Rhaet angefügt. Während die Mehrzahl der Autoren dieses Beitrags dem Abstimmungsergebnis beipflichtet, ist für einen der Autoren (LK) nach wie vor nur Vorschlag 4 (Tab. 2) annehmbar.

Description: Widefield deconvolution epifluorescence microscopy (WDEM) combined with fluorescence in situ hybridization (FISH) was performed to identify and characterize single bacterial cells within sections of the mediterranean sponge Chondrosia reniformis. Sponges were embedded in paraffin wax or plastic prior to the preparation of thin sections, in situ hybridization and microscopy. Serial digital images generated by widefield epifluorescence microscopy were visualized using an exhaustive photon reassignment deconvolution algorithm and three-dimensional rendering software. Computer processing of series of images taken at different focal planes with the deconvolution technique provided deblurred three-dimensional images with high optical resolution on a submicron scale. Results from the deconvolution enhanced widefield microscopy were compared with conventional epifluorescent microscopical images. By the application of the deconvolution algorithm on digital image data obtained with widefield epifluorescence microscopy after FISH, the occurrence and spatial arrangement of Desulfovibrionaceae closely associated with micropores of Chondrosia reniformis could be visualized.