Cladocerans and chironomids as indicators of lake level changes in north temperate lakes

Water level fluctuations affect the size of the pelagic zone relative to the size of littoral habitats, and thus may influence the relative abundance of remains from planktonic and littoral cladocerans in sediment. The application of this planktonic/littoral ratio for the reconstruction of past water level changes is discussed using examples of: (1) surficial profundal sediments from lakes of different water depths; (2) Holocene variation in a profundal sediment core; (3) horizontal variation in surficial sediments within a lake; and (4) long term variation in an inshore sediment core. The latter seemed to be the most promising application of this ratio. Maximum effects of water depth changes on the lake fauna are expected in the littoral zone. It is, however, difficult to read this effect directly from subfossil cladoceran and chironomid assemblages from inshore sediments as shown by a sediment profile from a site exposed to a long term decrease of water depth.     

Adjustment of a Formulated Sediment for Sediment Testing with Caenorhabditis elegans (Nematoda)

The OECD soil, which is standardised for use in the sediment toxicity with the midge Chironomus riparius revealed inhibition of the nematode Caenorhabditis elegans in body growth length and egg production of 41.0% and 84%, respectively. 18 formulated sediments were tested to optimise the sediment composition for growth and reproduction of C. elegans. Their components were chosen to simulate native sediments, whereby different quantities and different clay minerals were tested. The mixture that we found to be optimal in our experiments consisted of 5% sphagnum peat, 70% calcitic sand, 0.5% dolomite limestone, 4.5% iron(III) oxide, and a clay combination of 1.5% chlorite and 18.5% aluminium(III) oxide. When applying this mixture to C. riparius, the new formulated sediment improved also growth in comparison to the OECD sediment.     

Benthonische Foraminiferen aus der Unterkreide des »Deep Sea Drilling Project« (Leg 1–79)

Zusammenfassung In den DSDP-Legs 1, 11, 13, 17, 25, 27, 32, 36, 41, 43, 44, 50 und 62 wurden die Unterkreide-Foraminiferen biostratigraphisch, taxonomisch und paläoökologisch bearbeitet. Eine Übersicht zeigt die in Leg 1–80 erbohrte Unterkreide und ihre Foraminiferen-Bearbeitungen.Im Nordatlantik fehlen regional ab dem Oberen Tithonium im Verlaufe einer Regression und der sie begleitenden Schichtlücken bis in das Valanginium charakteristische Foraminiferenfaunen. In Gebieten ohne Schwarzschiefer-Bedingungen setzen im Valanginium-Barremium mäßig reichhaltige bis sehr spärliche Mikrofaunen mitPraedorothia ouachensis (Sigal) der gleichnamigen Zone ein (Valanginium-Hauterivium). Hauterivium-Aptium gliedern sich in dieGavelinella barremiana-, dieGaudryina dividens- und dieConorotalites aptiensis- Zone.Wo im Albium nicht das ausgedehnte Schwarzschiefer-Milieu herrschte, findet man eine kosmopolitische Fauna aus agglutinierten und kalkschaligen Foraminiferen derPseudoclavulina gaultina- Zone. Für das höhere Albium und Cenomanium wurde dieGavelinella cenomanica- Zone ausgeschieden. Von biostratigraphischer Bedeutung sind im Berriasium-Albium die GattungenPraedorothia, Gaudryina, Pseudoclavulina, von den Kalkschalern nur wenige skulptierte Arten der Nodosariiden (Citharina, Lenticulina) sowieGavelinella, Conorotalites, Pleurostomella, Valvulineria undOsangularia. Die vonMoullade (1984) begründeten Zonen vom Berriasium-Albium der Tethys und des DSDP sind wegen der großen stratigraphischen Reichweite der verwendeten Foraminiferenarten nicht überall anwendbar.Im Indischen Ozean lassen die wenigen, bisher bekannten »australen« Foraminiferenfunde aus dem Neokom von Site 261 mit überwiegend primitiven agglutinierenden Formen eine genaue Datierung kaum zu. Die Kalkschaler sind meist aufgelöst oder auch umgelagert. Man ordnet sie dem Bereich des kühleren Wassers zu.Im Pazifischen Ozean sind die meisten Mikrofaunen wegen der geringen Kerngewinne, Verunreinigungen oder primärer Foraminiferenarmut (Schwarzschiefer) biostratigraphisch und paläoökologisch kaum verwertbar. Erst im Albium findet sich — wie im Atlantik — eine etwas reichhaltigere Kalk- und Sandschalerfauna mit wichtigen Arten derPseudoclavulina gaultina- Zone. Da außerGavelinella cenomanica (Brotzen) keine andere benthonische Foraminiferenart neu einsetzt, wird die Grenze zum Cenomanium in der Regel mit planktonischen Foraminiferen gezogen.Im Albium fallen die einheitlichen, kosmopolitischen Foraminiferenfaunen ohne ausgeprägte Faunenprovinzen auf.

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From the DSDP Legs 1, 11, 13, 17, 25, 27, 32, 36, 41, 43, 44, 50, and 62 the Lower Cretaceous foraminifers have been investigated for biostratigraphical, taxonomical, and palaeoecological purposes. An overview of the cored Lower Cretaceous sections of Leg 1–80 is given.In the Northern Atlantic Ocean characteristic foraminiferal faunas are missing from the Upper Tithonian to the Valanginian due to a marked regression which caused hiatuses. In areas without black shale conditions Valanginian to Barremian medium rich to poor microfaunas withPraedorothia ouachensis (Sigal) of thePraedorothia ouachensis Zone (Valanginian-Hauterivian). The Hauterivian-Aptian interval is characterized by zones ofGavelinella barremiana,Gaudryina dividens, andConorotalites aptiensis. During the Albian a world-wide fauna consisting of agglutinated and calcareous foraminifers of thePseudoclavulina gaultina Zone is established in areas lacking the wide-spread black-shale conditions. The Upper Albian and the Cenomanian are represented by theGavelinella cenomanica Zone. Some ornamented species of the nodosariids (Citharina, Lenticulina), Gavelinella, Conorotalites, Pleurostomella, Valvulineria, andOsangularia are of some importance for the biostratigraphy of the Berriasian-Albian interval. The Berriasian to Albian zones introduced for the Tethys and the DSDP byMoullade (1984) could only be of some local importance due to the long stratigraphical range of the foraminiferal species used.In the Indian Ocean an exact stratigraphical age cannot be assigned to the few Neocomian foraminiferal faunas of a cooler sea water (Site 261). These faunas mainly contain primitive agglutinated foraminifers, because in most cases the calcareous tests are dissolved or redeposited.In the Pacific Ocean most of the Berriasian to Aptian microfaunas are of minor biostratigraphical and palaeoecological importance for reasons of poor core recoveries, contaminations or original foraminiferal poverty (black shales). Since the Albian there are somewhat higher-diverse faunas of calcareous and agglutinated foraminifers with index species of thePseudoclavulina gaultina Zone. As a rule, the boundary Albian/Cenomanian is set by means of planktonic foraminifers because no other foraminifer has its first appearance datum during this interval, exceptGavelinella cenomanica.During the Albian very uniform, world-wide foraminiferal faunas without a marked provincialism are obvious.

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Résumé Dans les Legs DSDP 1, 11, 13, 17, 25, 27, 32, 36, 41, 43, 44, 50 et 62, les foraminifères du Crétacé inférieur ont été étudiés aux points de vue biostratigraphique, taxonomique et paléoécologique. La note présente une vue d'ensemble de la section d'âge crétacé inférieur du Leg 1–80.Dans l'Atlantique nord, les faunes caractéristiques de foraminifères sont absentes depuis le Tithonique supérieur jusqu'au Valanginien, en raison d'une régression importante et des lacunes qui en résultent. Dans les régions dépourvues de milieux à shales noirs, on rencontre une microfaune, pauvre à moyennement riche, valanginienne à barrémienne, àPraedorothia ouachensis (Sigal), appartenant à la Zone àPraedorothia ouachensis. L'intervalle Hauterivien-Aptien est caractérisé par les Zones àGavelinella barremiana, Gaudryina dividens et Conorotalites aptiensis. Au cours de l'Albien une faune d'extension mondiale de foraminifères agglutinés et calcaires appartenant à la Zone àPseudoclavu-lina gaultina, s'est établie dans les aires où ne règnaient pas les conditions de formation de shales noirs. L'Albien supérieur et le Cénomanien sont représentés par la Zone àGavelinella cenomanica. Dans l'intervalle Berriasien-Albien, un rôle biostratigraphique de quelque importance est joué par quelques espèces de Nodosariides à coquilles ornementées (Citharina, Lenticulina) ainsi queGavelinella, Conorotalites, Pleurostomella, Valvulineria et Osangularia. Les zones établies parMoullade (1984) pour le Berriasien-Albien de la Téthys et du DSDP ne sont pas partout utilisables, en raison de l'extension verticale trop grande des foraminifères utilisés.Dans l'Océan Indien, un âge exact ne peut être assigné aux faunes de foraminifères néocomiennes considérées jusqu'ici comme «australes» (site 261): ces faunes renferment surtout des formes agglutinées primitives, car les tests calcaires ont été généralement dissous ou remaniés.Dans l'Océan Pacifique, la plupart des microfaunes berriasiennes à aptiennes sont de faible intérêt biostratigraphique et paléo-écologique, en raison des mauvais rendements des carottes, de contaminations ou de leur pauvreté originelle (facies des shales noirs). A partir de l'Albien, on trouve une faune plus diversifiée de foraminifères agglutinés et calcaires, comportant des espèces caractéristiques de la Zone àPseudoclavulina gaultina. Comme d'ordinaire, la limite Albiencénomanien est définie par les foraminifères planctoniques, aucun autre foraminifère n'apparaissant dans cet intervalle, saufGavelinella cenomanica.A l'Albien, la faune de foraminifères est uniforme à l'échelle mondiale, sans distinction de provinces.

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, 1, 11, 13, 17, 25, 27, 32, 36, 41, 43, 44, 50 62 DSDP, , . , 1–80 . . , , - Praedorothia ouachensis (Sigal) — . : Gavelinella barremiana, Gaudryina dividens Conorotalites aptiensis,, , , Pseudoclavulina gaultina. Gavelinella ni. - Praedorothia, Gaudryina, Pseudoclavulina, (Citharina, Lenticulina), Gavelinella, Conorotalites, Pleurostomella, Valvulineria Osangularia. , moullade (1984) - , .. , , . .: 261, , «», . . , . , . . , - - , , ( ). , , , Pseudoclavulina gaultina. T. . Gavelinella ni (brotzen) , , , . .

     

Gamma-ray bursts from nearby neutron stars

We interpret the puzzling-ray bursts as emitted by cooling sparks from the surface of spasmodically accreting, old neutron stars. Their spiky, anisotropic radiation is oriented w.r.t. the galactic disk via interstellar accretion, whose orbital angular momentum tends to counteralign with the galactic spin; in this way, larger source numbers in directions of the galactic disk are compensated by smaller beaming probabilities, resulting in a near-isotropic arrival distribution, as observed by BATSE. The source distances range between 10 pc and 500 pc. Their radiated energies are of order 10³⁵ erg, corresponding to accreted clumps (blades) of typical mass 10¹⁵ g per burst. Magnetic surface field strengths range between 10¹⁰ and 10¹² G, somewhat weaker than those of newborn neutron stars.     

Mars: Evidence for dynamic processes from mariners 6 and 7

Mariners 6 and 7 photographs of the equatorial region of Mars document a three-stage evolution of that part of the Martian surface: (1) High- and intermediate-albedo cratered terrains in Meridiani Sinus, Margaritifer Sinus-Thymiamata, Deucalionis Regio-Sabaeus Sinus, and Hellespontus; (2) low-albedo moderately cratered terrain and dark crater fill in Meridiani Sinus, Thymiamata, and Deucalionis Regio-Sabaeus Sinus and possible volcanism in the Hellas-Hellespontus border; and (3) high-albedo surficial deposits, banked-up crater fill, a possible bright-ray crater in Meridiani Sinus, chaotic terrain on the edge of the Margaritifer Sinus mesa, featureless terrain in Hellas and Edom, sinuous channel-like reentrants on scarps at the Hellas-Hellespontus boundary. Regional faulting seems to have occurred following formation of the old cratered plains and prior to formation of low-albedo plains in Meridiani Sinus and also prior to formation of canyon-like reentrants and featureless terrain along the Hellas-Hellespontus boundary.Mars has had a complex history of dynamic evolution, possibly analogous to the more stable regions of Earth. Its geochemical differentiation and thermal regime should account for long-term postaccretional tectonic and volcano-tectonic processes as well as for fluid media on its surface sufficient to cause erosion, including the cutting of large canyons.     

Chlorit-Hornblende-Felse des Bergsträßer Odenwaldes und ihre Phasenpetrologie

Ultrabasic metamorphic rocks with typical mineral assemblage of cummingtonitic hornblende+Mg-chlorite+talc (described byMatthes u.Okrusch, 1965, and called “hösbachit”) were found for the first time in Odenwald/Germany. Three steps of metamorphic development can be described: the primary magmatic ultrabasic rock consisted of (1) orthopyroxene (bronzite), clinopyroxene (diallage), poikilitic olivine, and some hornblende. This is indicated by textural relicts, structural and geochemical investigations. A regional metamorphic process under conditions of the staurolite-almandine-subfacies ofWinkler’s andTurner andVerhoogen’s almandine-amphibolite facies transformed this assemblage to (2): cummingtonitic hornblende I+Mg-chlorite I (clinochlore)+talc. The third step followed under more diaphthoritic conditions and brought mineral assemblage (3): tremolitic hornblende II+Mg-chlorite II (pennine)+talc.