ALBERT

Description: Zur Charakterisierung der Anteile von Lössen und Verwitterungsprodukten der liegenden Keuper- und Liasgesteine innerhalb kolluvialer Mischsedimente und holozäner Terrassenkörper erweisen sich in Oberfranken neben Korngrößenverteilungen insbesondere Quarz-Feldspat- und Albit-Mikroklin-Quotienten als geeignete Indizes. Danach sind an den untersuchten bodenerosiv überprägten Flachhängen bevorzugte Abtragung von Löß und Liegendmaterial an den Oberhängen, vorherrschender Durchtransport an den Mittelhängen und Ablagerung von Mischsedimenten an den Unterhängen zu erkennen. In den holozänen Sedimenten der Vorfluter sind Lößderivate demgegenüber nur gering vertreten, woraus auf vorherrschenden Durchtransport dieses Materials in den untersuchten Talstrecken und — im Vergleich mit niedersächsischen Beispielen entsprechender Größenordnung — auf eine regionale Differenzierung der holozänen fluvialen Dynamik geschlossen wird, die möglicherweise auf Unterschiede des Regionalklimas zurückzuführen ist.

Description: research

Description: In dem Hügelgebiet um den Falken-Berg zwischen Fallingbostel und Bergen Kr. Celle zeichnen sich 3 Endmoränenbögen ab, der Örbker, der Becklinger und der wenig deutlich ausgeprägte Kl. Bockeler Endmoränenbögen. Örbker und Kl. Bockeler Endmoränenbögen verdanken ihre Entstehung Gletscherloben, die von NW heranrückten; der Becklinger Endmoränenbögen geht auf einen von NE heranrückenden Lobus zurück. Keine dieser Endmoränen ist vom nordischen Inlandeis überfahren worden. Ein nahe den Endmoränenbögen wurzelnder Fächer aus Schmelzwasser-Ablagerungen läßt sich bis nahe an die Aller-Niederung heran verfolgen. Er überlagert die drenthestadiale Hauptmoräne, ist also jünger als diese. Die Endmoränen zwischen Fallingbostel und Bergen sind in einer späten Phase des Drenthe-Stadiums der Saale-Eiszeit entstanden.

Description: research

Description: Dreizehn Travertinproben von den Lokalitäten Tata, Vértesszöllös, Dunaalmás und Buda werden mit Hilfe zweier neuerer Absolutdatierungsverfahren untersucht, der Th-230/U-234- und der ESR-Methode. Für acht der untersuchten Proben ergibt sich eine gute Übereinstimmung zwischen den Th/U- und den ESR-Altern, zwei Proben waren aufgrund extrem hoher Mangan-Gehalte nicht ESR-datierbar und in drei Fällen ergaben sich deutliche Diskrepanzen. Travertine aus dem Riß/Würm Interglazial haben ein Alter von ca. 100.000 a, die des vorletzten Interglazial zeigen ein Alter von 200.000 a und etwas darüber die des drittletzten Interglazials weisen ein Alter von über 300.000 a auf.

Description: research

Description: Aus dem nördlichen Galizien (NW-Spanien) werden von zwei Lokalitäten (Playa de Barañán, westl. La Coruña, und Cangas de Foz, westl. Ribadeo) jungpleistozäne Sediment-Boden-Folgen beschrieben, die auf einem 3—5 m ü. M. gelegenen Felssockel bzw. auf einer ca. 25 m ü. M. gelegenen Küstenterrasse auflagern. Mehrere 14C-Daten sowie Vergleiche mit früher aufgenommenen Sediment-Boden-Folgen in der näheren und weiteren Umgebung lassen den Schluß zu, daß in beiden Fällen eine nahezu vollständige würmzeitliche Schichtenfolge entwickelt ist, die von fossilen Braunerden bzw. kräftigen fossilen Ah-Horizonten gegliedert ist. Zwischen die fossilen Böden bzw. Bodensedimente sind möglicherweise äolisch entstandene Schlurfe bzw. Sande und Solifluktionsschuttdecken eingeschaltet. Die wahrscheinlich altwürmzeitlichen Profilteile zeichnen sich durch viel Holzkohle aus und weisen auf eine holzreiche Vegetation hin.

Description: research

Description: Beim Vorstoß sowie Rückzug des Eises werden Sandersedimente abgelagert. Sie setzen sich aus gröberen Vorschütt- und feineren Nachschüttsanden zusammen, die (meistens) durch eine Grundmoräne voneinander getrennt sind. Vorschüttsand, Grundmoräne und Nachschüttsand bilden einen glaziären Zyklus. Fehlt die Grundmoräne, so ist eine genetische Gliederung der Sedimente in eine Vorstoß- und Rückzugsphase erschwert. Bei der Sedimentuntersuchung zeigte sich, daß einzelne Korngrößenfraktionen für eine Gliederung des Sanders kaum von Bedeutung sind. Die Zusammenfassung von Korngrößenfraktionen zu Korngrößengruppen (Tab. 1) ermöglichte eine exakte Gliederung der Sandersedimente und damit die genetische Ansprache der Gletscherablagerungen am unteren Niederrhein. Aufgrund der Einlagerung von Grundmoränenmaterial in den Sandersedimenten konnten für das Drenthe-Stadial im Raum Louisendorf-Moyland drei Eisvorstöße nachgewiesen werden.

Description: research

Description: Die oberrotliegenden rhyolithischen Tuffe der Prims-Mulde werden als Ignimbrite interpretiert. Sie sind maximal 110 m mächtig, gliedern sich durch wenige air-fall-Tuffe in mehrere Einheiten und können auf beiden Flanken der Prims-Mulde bis zu ca. 13 km weit verfolgt werden. Abgeplattete Bimse, Phänokristalle und zahlreiche Xenolithe treten in einer rötlichen, gering verschweißten Matrix auf. Die nicht dem Rotliegenden entstammenden Xenolithe, ihre Verteilung und die Ausrichtung von Bimslängsachsen weisen auf ein Liefergebiet für die pyroklastischen Ströme im Hunsrück hin. Gleichartig ausgebildete pyroklastische Ströme treten im Rotliegenden des Wittlicher Troges auf. Beide Vorkommen werden auf den im Hunsrück gelegenen, in devonische Gesteine eingebetteten Veldenzer Rhyolithschlot bezogen, der eine initiale Ignimbrit- Phase aufwies und wahrscheinlich den Förderort für die Vorkommen in den beiden Rotliegendtrögen darstellt.

Description: Abstract: Rhyolithic tuffs within the Prims syncline of the Permocarboniferous late Hercynian intermontane Saar-Nahe trough, SW Germany, are interpreted as pyroclastic flow deposits. They are highly altered, weakly welded, and separated by thin air-fall tuffs. Their regional extent, petrography and xenolith content is described. The Devonian provenance of the xenoliths, their distribution, and the Orientation of the flattened pumice fragments all point to the Hunsrück north of the Saar-Nahe trough as the area the pyroclastic flows came from. The pyroclastic flows and similar flows in the next trough to the northwest, the Wittlich trough, are related to the Veldenz rhyolite in the Hunsrück which contains an initial ignimbrite phase and is considered to represent the feeder for these pyroclastic flows.

Description: 1. Einleitung 2. Geologische Situation 3. Die Ignimbritfolge 3.1. Verbreitung, Volumen, Paläogeographie 3.2. Ausbildung der Ignimbrite 3.3. Abfolge der Ignimbrite 3.4. Beschreibung der Profile 3.5. Petrographie und Chemie 3.5.1. Ignimbrit-Typ Eisen 3.5.2. Ignimbrit-Typ Lauxwald 4. Die Xenolithe der Ignimbritfolge 4.1. Grünliche, grobkörnige Sandsteine 4.2. Feinsandsteine, Silt- und Tonsteine 4.3. Quarzite 4.4. Phyllite . 4.5. Chloritschiefer 5. Gesteine aus dem Rotliegenden und Unterdevon 6. Die Herkunft der Ignimbrite Schriften

Description: research

Description: Es werden Morphologie, Proportionen und Belastungsverhältnisse der Fährtentaxa Saurichnites salamandroides Geinitz, 1861, Saurichnites incurvatus Fritsch, 1901, Saurichnites intermedius Fritsch, 1895, Limnopus palatinus nov. ichnospec., Amphisauroides sp., Protritonichnites lacertoides (Geinitz, 1861), Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882), Gilmoreichnus minimus Haubold, 1973, Hyloidichnus arnhardti Haubold, 1973 und Jacobiichnus caudifer (Fritsch, 1895) beschrieben. Außerdem werden die Körperproportionen der fährtenerzeugenden Tiere in hypothetischer Form rekonstruiert und ihre orthotaxonomische Position diskutiert.

Description: Abstract: Morphology, proportions and pressure distribution of the ichnotaxa Saurichnites salamandroides Geinitz, 1861, Saurichnites incurvatus Fritsch, 1901, Saurichnites intermedius Fritsch, 1895, Limnopus palatinus nov. ichnospec., Amphisauroides sp., Protritonichnites lacertoides (Geinitz, 1861), Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882), Gilmoreichnus minimus Haubold, 1973, Hyloidichnus arnhardti Haubold, 1973 and Jacobiichnus caudifer (Fritsch, 1895) are described. In addition to this the body-proportions of the trackway-producing animals are reconstructed hypothetically. The orthotaxonomic position of these animals is discussed.

Description: 1. Einleitung 2. Fundorte und Fundschichten 3. Terminologie der Fährten. 4. Beschreibung der Fährten 4.1. Saurichnites salamandroides Gbinitz, 1861 4.2. Saurichnites incurvatus Fritsch, 1901 4.3. Saurichnites intermedius Fritsch, 1895 4.4. Limnopus palatinus nov. ichnospec. 4.5. Amphisauroides sp. 4.6. Protritonichnites lacertoides (Geinitz, 1861) 4.7. Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882) 4.8. Gilmoreichnus minimus Haubö'lt), 1973 4.9. Hyloidichnus arnhardti Haubold, 1973 4.10. Jacobiichnus caudifer (Fritsch, 1895) 5. Schlußbemerkungen Schriften

Description: research

Description: Geologische Karte 1: 25 000 mit Erläuterungen. Digitalisat des FID GEO (Fachinformationsdienst Geowissenschaften), erstellt durch das GDZ (Göttinger Digitalisierungszentrum), Karte aus dem Bestand der SUB Göttingen.

Description: DFG, SUB Göttingen

Description: map

Description: DFG, SUB Göttingen

Description: Moorschutz kann nur als integrierter Naturschutz betrieben werden. Ohne Abgrenzung ihrer Schutzfähigkeit (hydrologisch, Immissionen) sind Moore nicht als schutzwürdig zu erklären. Besonders bedeutungsvoll ist die hydrologische Situation der verschiedenen Moortypen für den Flächenschutz als Voraussetzung einer Moorregeneration. Moorerhaltung und Moorregeneration sind für die nordwestdeutschen Niederungen aus klimatischer Sicht auch heute noch möglich, wenn bestimmte hydrologische Bedingungen erfüllt sind und Immissionen weitgehend abgeschirmt werden. Diese können unter Berücksichtigung moorkundlicher Parameter durch bodenkundlich-hydrologische Geländeuntersuchungen eingegrenzt werden. Die Vier häufigsten Moorschutzsituationen werden anhand modellhafter Geländeschnitte durch ein Quellmoor, ein Niedermoor, ein Hochmoor mit und ohne Abtorfung dargestellt. Ohne hydrologische und Immissions-Schutzzonen sind die meisten naturnahen Restmoore in Nordwestdeutschland nicht nachhaltig zu sichern. Schließlich wird die Frage nach dem Mindestareal für den Arten- und Flächenschutz diskutiert und die Sicherungsmöglichkeit vieler allzu kleiner Naturschutzgebiete (NSG) in Frage gestellt.

Description: The protection of bogs and fens is only possible in the case of integrated nature conservation. Without delimitation of the ability of protection (hydrological, and against immissions) peatlands are not worthy of protection. The hydrological situation of the different moor types is especially significant for the area protection as precondition for moor regeneration. Conservation and regeneration of peatlands are possible in the north-western German lowlands due to the climatic situation. Definite hydrological conditions must be given and immissions avoided. These conditions can be determined by hydrological and pedological field survey and peat parameters. Four of the most common situations of moor protection are shown tut model sections through a spring-water bog, a low moor, and a raised bog with and without peat cutting. Without protection zones, hydrological ones and against immission, residual parts of moors in Northwest Germany cannot be guaranted lasting. At last the question of the minimum dimensions of these zones for the protection of species and of whole areas is discussed. According to this the protection of many very small nature reserves is doubtful.

Description: research

Description: DFG, SUB Göttingen

Description: Die Kommission III/IPS veranstaltete mit Unterstützung der Niederländischen Bodenkundlichen Gesellschaft vom 24. bis 28.August 1981 in Wageningen ein Symposium, welches der Darstellung der besonderen geologischen Verhältnisse eines Küstenlandes, der Geschichte der holländischen Moorkultivierung und der derzeitigen Nutzungsprobleme in einer anthropogenen Niederungslandschaft diente, die bis zu 6 m unter dem Meeresspiegel liegt. Rd. 70 Teilnehmer aus 11 Ländern (Kanada, Finnland, Großbritannien, Irland, Israel, Norwegen, Polen, USA, UdSSR sowie den Niederlanden und der Bundesrepublik Deutschland waren der Einladung gefolgt. Von den 10 deutschen Teilnehmern waren 4 DGMT-Mitglieder. [...]

Description: conference

Description: DFG, SUB Göttingen

Description: Nahezu zwei Drittel aller Hochmoore und fast alle Niedermoore werden in Niedersachsen landwirtschaftlich − überwiegend als Grünland − genutzt. Aktuelle Nutzungsprobleme liegen z.Zt. innerbetrieblich im Bereich der Erhaltung der Bodenfruchtbarkeit bei Anpassung an die gesamtwirtschaftliche Entwicklung. Kleine moorreiche Betriebe unterliegen dem Zwang zu höchster Flächenproduktivität. Mit Überschreiten einer Düngungsintensität von 200 kg/ha N und 80 kg/ha P2O5 entstehen hohe Gewässerbelastungen und verstärkter Torfschwund. Eine mehr konservierende Bodennutzung, z.B. durch Sanddeckkulturen wird empfohlen, anderenfalls sind die ökologisch tolerierbaren Grenzen der Intensivierung auf Moorschwarzkultur bald überschritten. Größere Betriebe mit geringeren Mooranteilen versuchen mit dem Ziel einer besseren Arbeitsproduktivität diese durch Tiefumbruch in ihr Mineralbodennutzungskonzept zu integrieren. Nur extensiv genutztes Moorgrünland genügt den Ansprüchen von Naturschutz und Landespflege. Entsprechende Zugeständnisse der Landwirtschaft im Nahbereich von Naturschutzgebieten machen als Ausgleich intensivere Nutzungen auf den übrigen Flächen erforderlich. Einer Zwischenabtorfung von Hochmoorkulturen kann landeskulturell nur zugestimmt werden, wenn die landwirtschaftliche Folgenutzung über eine Sandmischkultur zu einer wirklichen Standortsverbesserung führt.

Description: About two third of the raised bog areas and nearly 100% of the fen areas in Lower Saxony are agriculturally used, mainly as grassland. Today actual problems in agricultural utilization of peatlands are internal problems of the farms in respect to the preservation of soil fertility along with the adaption to the general economical development. Small farms, rich in peatland, are forced to highest land productivity. However, a fertilizing intensity of more than 200 kg/ha nitrogen and 80 kg/ha phosphorus causes water contaminations and peat losses. A more conservative utilization of peatlands, e.g. by sand-cover cultivation, is therefore recommended. Otherwise an intensification of raised bog and fen utilization would soon exceed the ecologically allowable limits. Large farms with small amounts of peatland try to attain a better productivity of work by deep ploughing and integration of sand-mix cultivated peatlands into the conception of utilizing their mineral soils. The claims of nature conservation and landscaping are only satisfied in case of extensively used grassland on peat. Corresponding concessions of farmers to areas close to nature reserves require agreements for a more intensive utilization of other areas. An intermediate peat cutting on formerly cultivated raised bogs should only be allowed if deep ploughing and sand-mix cultivation creates a really improved soil for later agricultural utilization.

Description: research

Description: DFG, SUB Göttingen

Description: research

Description: research

Description: research

Description: Die regional-geologische Aufnahme im Maßstab 1:100.000 der chilenischen Hauptkordillere zwischen 34° und 34°30' südlicher Breite ließ eine etwa 10.000 m mächtige und verschiedenartig deformierte stratigrapnisehe Abfolge erkennen, die teilweise von Intrusivkörpern durchschlagen ist.

Description: thesis

Description: DFG, SUB Göttingen

Description: Der Einsatz des LANDSAT-Satellitensystems zur Abbildung nahezu der gesamten Erdoberfläche (Maßstab 1 : 1 000 000) hat den Geowissenschaften, nicht zuletzt der Geologie, neues Datenmaterial erschlossen, das als zusätzliche Information bei der Bearbeitung großer Gebiete herangezogen werden kann. Der multispektrale Ansatz des Satellitensystems, d. h. die Abbildung der Erdoberfläche in verschiedenen Spektralbereichen vom Grün bis zum nahen Infrarot, macht neue Arbeitsmethoden zur Datenanalyse notwendig.

Description: thesis

Description: DFG, SUB Göttingen

Description: Die Insel Elba nimmt im Zusammenhang mit der alpinen und apenninen Gebirgskette eine strukturell überaus bedeutende Lage ein. So befindet sich diese größte Insel des toskanischen Archipels auf einer überleitenden Position zwischen dem nordostvergenten Nordapennin und dem westvergenten alpinen Teil Korsikas. Das Gesamtbild Elbas wird von ophiol ithischen Gesteinen mit ihrem sedimentären Auflager bestimmt. Im Ost- und Mittelteil der Insel sind weitgehend Nordapenninverhältnisse gegeben. Die Deformation der toskanischen und ligurischen Einheiten ist streng ostvergent, wobei in den eugeosynkl in〈* len Liguriden, welche klar mit der Bracco-Einheit korreliert werden können, Erscheinungen einer Thermodynamometamorphose fehlen. Dagegen werden auf West-Elba in den Ophiol ithserien enorme Abweichungen schon im Aufschlußbild deutlich, da diese intensiv isoklinal verfaltet und kräftig geschiefert sind.

Description: Elba, the greatest Island of the Tuscan Archipelago» has an important position within the Alpine and Apenninie chains: It is situated in the transitional zone between the NE-vergent Northern Apennines and the Alpine part of Corsica with Western vergencies. Elba shows a widespread distribution of ophiolitic rocks and their sedimentary cover. In Eastern and Middle Elba there are conditions which are largely similar to those of the Northern Apennines. The tectonic trend of the Tuscan and Ligurian units is clearly eastward. The eugeosyncl inal Ligurides, which can be correllated with the Bracco unit of the Apennines, are not affected by thermodynamometamorphism. In this respect this area differs from the Western part of Elba, where also ophiolitiferous series occur. These however show tight isoclinal folding and strong cleavage.

Description: thesis

Description: DFG, SUB Göttingen

Description: Die Untersuchungen der Grundwasserbeschaffenheit und der hydrogeologischen Zusammenhänge erstrecken sich auf das nördliche Stadtgebiet von Berlin (West), das ein Teil des Einzugsgebietes der oberen Havel ist. Das betrachtete Grundwassersystem erfaßt die im Hangenden des mittel oligozänen Septarientons in normaler stratigraphischer Abfolge ausgebildeten Ablagerungen des Oberoligozäns, Miozäns und Pleistozäns Die Mächtigkeiten der auftretenden Schichtfolgen sind abhängig von einer durch Salzbewegungen verursachten Aufwölbung im NE und einer im W gelegenen Salz-Emigrationszone. Folglich treten die größten Mächtigkeiten (ca. 380 m) im W des Untersuchungsgebietes auf. Die pleistozänen Ablagerungen erreichen ihre größten Mächtigkeiten im Bereich einer Erosionsrinne, die im mittleren Teil des Untersuchungsgebietes bis in den Septarienton eingeschnitten ist. Die Betrachtung der Druck- und Fließverhältnisse zeigt sowohl für das tiefere, gespannte Grundwasser der tertiären Schichtfolgen als auch für den oberen Grundwasserleiter einen hauptsächlich nach SW gerichteten Grundwasserabstrom. Für die Potentialdifferenzen zwischen dem oberen und dem gespannten Grundwasser kann in den Bereichen großer Grundwasserentnahmen ein relatives Ansteigen der Druckfläche des tieferen Grundwassers erkannt werden. Die höhere Druckfläche des tieferen Grundwassers weist, in Abhängigkeit von der Durchlässigkeit der stauenden Schichten, auf ein Aufsteigen tieferer Grundwässer hin. Dies wird bekräftigt durch die Ergebnisse der geothermischen Untersuchungen, die für die entsprechenden Bereiche eine großflächige positive geothermische Anomalie erkennen lassen. Der Chemismus der untersuchten Grundwässer läßt im allgemeinen mit zunehmender Tiefe eine Abnahme der Gesamtmineralisation erkennen. Die durchschnittliche Gesamtmineralisation der tieferen Grundwässer liegt mit 15.07 mval/1 unter der des Grundwassers der pleistozänen Schichten (17.38 mval/1). Die räumliehe Betrachtung der Mineralisationsverteilung läßt für die tieferen Grundwässer im NE- und SE-Teil des Untersuchungsgebietes eine erhöhte Mineralisation erkennen, die hauptsächlich auf höhere Kalziumsulfatgehalte zurückzuführen ist. In westlicher Richtung kommt es, durch Reduktionsvorgänge, zu einer Abnahme der Mineralisation. Im tieferen Bereich der Rinne und in den oberoligozänen Schichtfolgen läßt sich das Auftreten von alkalihydrogenkarbonathaltigen Wässern erkennen, deren Entstehung auf Ionenaustauschvorgänge zurückzuführen ist. Die Spurenmetallgehalte zeigen im Grundwasser der tertiären Schichtfolgen, bedingt durch die auftretenden Gesteine, für die Elemente Aluminium, Kupfer und Zink deutlich höhere mittlere Gehalte. Die gegenüber dem Grundwasser der oberoligozänen Schichtfolgen höheren mittleren Bor-, Kupfer- und Nickelgehalte im Grundwasser der miozänen Schichten stehen in Verbindung mit der primären Anreicherung dieser Elemente in den organischen Ablagerungen des Miozäns. Für das Auftreten der Elemente Chrom (III), Strontium und Eisen lassen sich keine Unterschiede zwischen dem tiefen und dem oberflächennahen Grundwasserleiter erkennen.

Description: The quality of groundwater and hydrogeological relationships of the northern part of the town of Berlin (West), a catchment area of the upper part of the river Havel, were investigated. The observed groundwater System belongs to the stratas above the middle oligocene "Septarienton", in the normal sequence of upper oligocene, miocene and pleistocene. The thicknesses of the occuring layers are influenced by a salt dorne in the NE and a rim syncline in the W, caused by salt tectonics. Consequently the greatest thickness (~380m) is found in the Western part of the investigated area. The pleistocene deposits obtain their greatest thickness in the area of an erosion channel which is in the middle of the investigated area, incised into the middle oligocene Septarienton. The investigations of the relations between artesian head and groundwater flow of the deeper confi ned groundwater in the tertiary strata and of the upper aquifer proved a groundwater flow mainly in southwestern direction. The potential differences between the upper and the confined groundwater shows in the areas of ground-water lowering a relative rising of the hydrostatic pressure of the deeper groundwater. The higher artesian head of the deeper groundwater points to a rise of deeper groundwater, dependent on the permeability of the less permeable layers. This is confi rmed by the results of the geothermical investigations, which show a great positiv geothermal anomal y for these areas. The Chemical composition of the investigated groundwater shows a decreasing total mineral isation with increasing depth. The average total -mineral isation of the deeper groundwater of 15.07 mval/1 lies beneath the level of the groundwater of pleistocene layers (17.38 mval/1). Spacial observations of the mineral isation-distribution show a higher mineral isation for the deeper groundwater in the NE- and SE-part of the investigated area, which is mainly based on a higher calcium-sulfat-content. In the W a decrease of mineral isation, caused by reduction processes, can be observed. In the deeper part of the channel and in the upper oligocene layers an occurrence of alkali-hydrogencarbonat-water, caused by ion-exchange reactions, is recognizable. Trace-metalls contents in the groundwater of the tertiary layers have a definite higher average content of the elements Al, Cu and Zn, caused by the occuring Sediments. The concentration of B, Cu and Ni is higher in the groundwater of the miocene layers than in the groundwater of the upper oligocene layers, this is caused by the primary enrichment of these elements in the organic deposits of the miocene. There are no differences recognicable between the upper and the lower aquifers concerning the occurrence of the elements Co(III), Sr and Fe.

Description: Les recherches concernant la composition de l'eau souterraine et les relations hydro-geologiques Interessent la partie nord de la ville de Berlin (Ouest), qui fait partie de l'aire d'al imentation de la Havel superieure. Le Systeme de l'eau souterraine considere englobe les Sediments de l'oligocene superieur, du miocene et du pleistocene, surmontant strati graphiquement les couches de l'oligocene moyen (Septarienton). Les puissances des differentes series strati graphiques sont influencees par un bombement au Nord-Est, du ä une tectonique salifere, et par une zone d'emigration salifere situee a' l’ouest. En consfequence les puissances maximales (environ 380m) apparaissent dans la partie ouest du terrain analyse. Les formations du pleistocene atteignent leur plus grande epaisseur au niveau d'une gouttiere d'erosion pentue, encaissee dans la partie moyenne du terrain analyse jusqu'au Septarienton. L'observation des conditions de pression et d'ecoulement montre, tant pour l'eau souterraine profonde et captive des suites de couches tertiaires, tant pour les aquiferes superieurs, un ecoulement principalement vers le Sud-Ouest. Pour les differences de pression entre les eaux souterraines superieures et captives on note dans les terrains, desquels on preleve beaucoup d'eau, un soulevement relatif de la surface de pression de l'eau souterraine profonde. Le plus haut plan de pression de celle-ci indique donc que les eaux souterraines profondes montent en fonction de la permeabilite des couches accumulees. Ceci est renforce par les resultats des analyses geothermiques, qui montrent une anomal ie geothermique positive sur une grande surface des terrains en question. Les caracteri stiques hydrogeochimiques des eaux souterraines analysees font apparaTtre en general une diminution de la mineral isation totale en fonction de 1 ’augmentation de la profondeur. La mineral isation totale moyenne des eaux profondes souterraines est avec 15.07 mval/1 inferieure ä celle des eaux profondes des couches pleistocenes(17. 38 mval/1). La repartition horizontale de la mineral isation laisse apparaTtre pour les eaux profondes de la partie Nord-Est et Sud-Est du terrain analyse une mineral isation surelevee, qui est due principalement a une haute teneur en Sulfate de calcium. Vers 1 'ouest, la mineral isation diminue par l'effet de processus de rfeduction. Dans les terrains du fond de la gouttiere et dans les series de couches de l'oligocene superieur on remarque l'apparition d'eaux contenant du NaHCOp provenant du processus de changements des ions. Les teneurs de metaux traces dans les eaux souterraines des series tertiaires montrent nettement-conditionne par les roches y apparaissant- des valeurs moyennes elevees pour l’aluminium, le cuivre et le zinc. Les teneurs moyennes en bore, cuivre et nickel des eaux souterraines des couches du miocene, surelevees par rapport aux eaux souterraines des couches de l'oligocene superieur, sont en relation avec l'enrichissement primaire de ces elements dans les gisements organiques du miocene. En ce qui concerne la repartition des eie ments chrome( III), Strontium et fer aucune difference est notable entre les aquiferes profonds et ceux pres de la surface.

Description: thesis

Description: DFG, SUB Göttingen

Description: Im Nordosten von Uruguay wurden Wasserpflanzengesellschaften und Niedermoore untersucht. Flache Tümpel werden von Pflanzengesellschaften besiedelt, in denen Jussiaea repens, Nymphoides humboldtiana, Hydrocleis nymphoides und Echinodurus andrieuxii dominieren. Zusätzlich gibt es Gewässer mit ausgedehnten Azolla-Beständen. In der Talaue des Rocha-Flusses finden sich Quellmoore, die von einer hochwüchsigen Cyperacee (Androtrichum giganteum) geprägt werden. Manche küstennahen Dünentäler sind mit Niedermooren ausgefüllt, deren Vegetation physiognomisch an Kleinseggenrieder erinnert. Dort finden sich Eleocharis sellowiana, Paspalum pumilum, Triglochin montevidense und eingestreut auch Juncus acutus.

Description: In the northeast of Uruguay plant associations of fens and flat puddles have been examined. The puddles in the pampa are colonized by plant associations with Jussiaea repens, Nymphoides humboldtiana, Hydrocleis nymphoides‚and Echinodurus andrieuxii. In addition there are ponds which are extended Azolla-habitats. Spring-water fens appear in the water meadows of the Rocha-river. They are dominated by a sedge species, named Androtrichum giganteum. Between the coastel dunes fens grow up, which remind of the Parvo-Caricetum in the northern hemisphere. There Eleocharis sellowiana, Paspalum pumilum, Triglochin montevidense and occasionally Juncus acutus are found.

Description: research

Description: DFG, SUB Göttingen

Description: bibliography

Description: DFG, SUB Göttingen

Description: Der Band enthält neben eines Beitrags zum Lebenswerk des Paläontologen Walter Georg Kühne aus Anlass seines 70. Geburtstags eine Reihe von Aufsätzen zu verschiedenen paläontologischen Themen von Angehörigen der geowissenschaftlichen Institute der Freien und Technischen Universität Berlin sowie der Technischen Fachhochschule Berlin.

Description: commemorativepublication

Description: DFG, SUB Göttingen

Description: research

Description: thesis

Description: thesis

Description: research

Description: research

Description: Aus den Bleichenbach-Schichten der Wetterau werden folgende Fährtentaxa beschrieben und abgebildet: Saurichnites salamandroides Geinitz, 1861, Saurichnites intermedius Fritsch, 1895, Saurichnites incurvatus Fritsch, 1901, Temnospondylen-Fährte unsicherer systematischer Stellung, cf. Hyloidichnus major (Heyler & Lessertisseur, 1963), Amphisauroides discessus Haubold, 1970, Varanopus microdactylus (Pabst, 1896), Ichniotherium cottae (Pohlig, 1885), Dimetropus leisnerianus (Geinitz, 1863), Gilmo- reichnus kablikae (Geinitz & Deichmüller, 1882), cf. Gilmoreichnus minimus Haubold, 1973, Protritonichnites lacertoides (Geinitz, 1861), Anhomoiichnium orobicum Dozy, 1935, Palmichnus renisus Schmidt, 1959, Laoporus sp. und Jacobiichnus caudifer (Fritsch, 1895). Die Fährtengemeinschaft erlaubt eine Parallelisierung der Bleichenbach-Schichten mit dem oberen Teil der Nahe-Gruppe des Saar-Nahe-Gebietes.

Description: Abstract: From the Bleichenbach beds of the Wetterau area (lower Permian, SW-Germany) the following ichnotaxa are described and figured: Saurichnites salamandroides Geinitz, 1861, Saurichnites intermedius Fritsch, 1895, Saurichnites incurvatus Fritsch, 1901, temnospondyl-trackway of uncertain systematic range, cf . Hyloidichnus major (Heyler & Lessertisseur, 1963), Amphisauroides discessus Haubold, 1970, Varanopus microdactylus (Pabst, 1896), Ichniotherium cottae (Pohlig, 1885), Dimetropus leisnerianus (Geinitz, 1863), Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882), cf. Gilmoreichnus minimus Haubold, 1973, Protritonichnites lacertoides (Geinitz, 1861), Anhomoiichnium orobicum Dozy, 1935, Palmichnus renisus Schmidt, 1959, Laoporus sp. and Jacobiichnus caudifer (Fritsch, 1895). This trackway-assemblage permits a correlation of the Bleichenbach beds with the upper part of the Nahe Group of the Saar-Nahe Basin.

Description: 1. Einleitung 2. Vorkommen 3. Terminologie 4. Kurzbeschreibung der Fährten 4.1. Amphibien-Fährten 4.1.1. Saurichnites salamandroides Geinitz, 1861 4.1.2. Saurichnites intermedius Fritsch, 1895 4.1.3. Saurichnites incurvatus Fritsch, 1901 4.1.4. Temnospondylen- Fährte unsicherer systematischer Stellung 4.2. Reptil-Fährten 4.2.1. cf. Hyloidichnus major (Heyler & Lessertisseur, 1963) 4.2.2. Amphisauroides discessus Haubold, 1970 4.2.3. Varanopus microdactylus (Pabst, 1896) 4.2.4. Ichniotherium cottae (Pohlig, 1885) 4.2.5. Dimetropus leisnerianus (Geinitz, 1863) 4.2.6. Gilmoreichnus kablikae (Geinitz & Deichmüller, 1882) 4.2.7. cf. Gilmoreichnus minimus Haubold, 1973 142 4.2.8. Protritonichnites lacertoides (Geinitz, 1861) 4.2.9. Anhomoiichnium orobicum Dozy, 1935 4.2.10. Palmichnus renisus Schmidt, 1959 4.2.11. Laoporussp 4.2.12. Jacobiichnus caudifer (Fritsch, 1895) 5. Fossilinhalt der einzelnen Fundhorizonte 6. Biostratigraphische Auswertung der Fährten 7. Zusammenfassung und Diskussion der Ergebnisse Schriften

Description: research

Description: Die untersuchten, feinkörnig-konglomeratischen, mäßig gut sortierten, lithischen Arenite, bilden zusammen mit Siltsteinen und untergeordnet Tonschiefern die Sao Khua Formation, die als Speichergestein der Uran-Vererzung Phu Wiang I in einem fluviatil-beherrschten Deltakomplex mit deutlich marinen Einflüssen im Zeitraum Ober-Jura bis Unter-Kreide sedimentiert wurde. Die in den Areniten der Sao Khua Formation aufgearbeiteten Klasten und der detritische Mineral bestand deuten auf sauer bis intermediäre Plutonite und Vulkanite, Phyllite, Quarzite und Cherts als Liefergesteine. Erosionsgebiete dieser Gesteinsserien sind wegen der rekonstruierten, unimodalen, hauptsächlich NE/SW verlaufenden Paläoströmungsrichtung in pratriassischen Formationen, nordöstlich des Untersuchungsgebietes, zu suchen. Zusammen mit diesen sind möglicherweise äolisch nach E verfrachtete Vulkanite, des westlich von Si Chiang Mai gelegenen Vulkanitgürtels, umgelagert und im Deltabereich sedimentiert worden. Die linsenförmige, penekonkordante Uran-Mineralisation ist an mittel- bis grobkörnige, teilweise konglomeratische Bereiche, des als “channelsequenz" interpretierten Sandsteins gebunden, die feinverteiltes, inkohltes Pflanzenmaterial enthalten und im Hangenden einer für (perkolierende) Porenwässer impermeablen Barriere aus feinkörnigen Sandsteinen, Siltsteinen und Tonschiefern liegen.

Description: Fine grained to conglomeratic, moderateley well-sorted, lithic arenites combine with siltstones and minor amounts of shale to make the Sao Khua formation. The latter was deposited during the Upper Jurassic and Lower Cretaceous in a delta donimated by fluvial distributary channels but with distinct marine features and is the host roch for the uranium mineralization. The clasts and the detritic minerals of the arenites of the Sao Khua Formation indicate that acid to intermediate plutonios and volcanics, phyllites, quarzites and cherts were the source rocks. Possibly volcanics from the volcanic arc, situated to the west of Si Chiang Mai, were aeolianly transported to the east and after their first deposition carried together with the above cited detrital mineral assemblage by fluvial action into the delta area. The lenticular, peneconcordant uranium mineralization is restricted to these medium to coarse grained, partly conglomeratic intervals of the sandstone which together have been interpreted as channel - sequences. These intervals contain finely distributed carbonaceous matter of plant origin and are situated above a barrier. The latter is made up of fine-grained sandstone, siltstone and shale, which connot be permeated by (percolating) pore-water-solutions.

Description: thesis

Description: DFG, SUB Göttingen

Description: Die Magmatite des Indosinia-Orogens in NE-Thailand wurden auf Grund von petrographischen und petrochemischen Untersuchungen durch die Einführung geochemischer Indizes nach folgenden Gesteinstypen und Sippen klassifiziert, sowie den entsprechenden magmatischen Phasen im orogenen Zyklus zugerechnet. - Alkali-Rhyolithe, die als Ignimbrite und Tuffe auftreten, sowie Dacite, die der Kalk-Alkali-Reihe angehören (frühe Phase des finalen Magmatismus) im Pak Chom-Si Chiang Mai Gebiet und im Loei-Chum Phae Gebiet. Letztere zeigen auch eine Tendenz zu einer höheren Alkalini tat (finaler Magmatismus) im Saraburi -Gebiet bzw. Loei-Tha Li Gebiet. - Andesite, die als Tuffe und Agglomerate vorliegen und der Kalk-Alkali-Reihe mit einem mittelstark pazifischen Charakter angehören (früher subsequenter Magmatismus) im Chum Phae-Lom Sak Gebiet. - Lenco-Basalte mit einem ophitischen Gefüge, die sowohl der Kalk- Alkali -Reihe (früher subsequenter Magnetismus) im Chiang Khan Gebiet, als auch einer Obergangsphase zur Alkali-Reihe (finaler Magnetismus) im Petchabun und Saraburi Gebiet zuzurechnen sind. - Granite-Monzonite, die der Kalk-Alkali-Reihe angehören (synorogener Magnetismus) im Loei-Chiang Khan Gebiet. Petrographische und geochemische Untersuchungsergebnisse, sowie paläogeographische und quantitative Voraussetzungen zeichnen die alkali-rhyolithischen Ignimbrite und Tuffe des Pak Chom-Si Chiang Mai Gebietes als potentielle Uran-Lieferanten aus. Folgende Untersuchungsergebnisse können als Begründung herangezogen werden: - Die ober-triassischen bis unter-jurassischen Ignimbrite und Tuffe des Pak Chom-Si Chiang Mai Gebietes sind dicht verschweißt und ihre Grundmasse liegt zu einem großen Teil in einem vollständig devitrifizierten Zustand vor, im Gegensatz zu den der Saraburi und Loei-Tha Li Gebiete, in denen die holohyalinen Anteile in der Grundmasse z.T. überwiegen. -Die Alkali-Rhyol ithe des Pak Chom-Si Chiang Mai Gebietes sind am höchsten differenziert, wie dem numerischen +Differentiationsindex (bis 16,65) zu entnehmen ist. - Sie zeigen die größten Gehalte an lithophilen Spurenelementen (Ba: 415 - 969 ppm; Rb: 109 - 213 ppm; Sr: 35 - 124 ppm; Zr: 77 - 209 ppm;) innerhalb vergleichbarer Differentiationsgrade der Alkali-Rhyolithe des Loei-Tha Li und Saraburi Gebietes. - Die Uran- und Lithium-Gehalte sind dagegen ungewöhnlich niedrig und liegen im Bereich von 2,09 - 3,6 ppm U bei einem Th/U-Verhältnis von 2,2 - 8,5 und 2,5 - 61,3 ppm Li (mit einem Mittelwert von 15,60 ppm Li), im Gegensatz zu den U- und Li-Gehalten des Loei-Tha Li Gebietes (U = 3,1 - 7 ppm; Th/U = 1 - 2; Li = 6,0 - 210,0 ppm, mit einem Mittelwert von 79 ppm Li) und des Saraburi Gebietes (U = 3,6 - 5 ppm; Th/U = 3,2 - 4,0; Li = 10,90 - 43,00 ppm, mit einem Mittelwert von 27,9 ppm Li). - Der xOxidationsgrad (0x0 = 0,51 - 0,99) ist mit dem U-Gehalt negativ korrelierbar im Gegensatz zu dem der Alkali-Rhyolithe in den anderen Gebieten. Zu ähnlichen, sich scheinbar widersprechenden, Untersuchungsergebnissen in Ignimbriten und Tuffen gelangten ROSHOLT et al. (1969), SCHATKOV et al. (1970) und ZIELINSKI (1978). Die geringen U-Gehalte werden auf die größere Mobilationsbereitschaft der leichtflüchtigen Elemente (Uran, Lithium, Fluor und Chlor) und deren Verbindungen während des Devitrifikationsprozesses im Zuge der langen Abkühlungszeit mächtiger Ignimbrit- und Tuffdecken zurückgeführt. Das in mobiler Phase vorliegende Uran (U6+) kann entweder supergene Anreicherungen innerhalb der Ignimbrit-Tuff-Decken bilden, die bei einer einsetzenden Erosion in Form von Uran-angereichertem Detritus weiter transportiert werden, oder direkt in migrierende Grundwässer gelangen. Der so eingetretene Verlust von Uran kann bei den Pak Chom-Si Chiang Mai alkali-rhyolitischen Ignimbriten und Tuffen mit einer Größenordnung von 46 - 52 % angegeben werden. Zu den von SCHATKOV (1970) ermittelten prospektionssignifikanten Faktoren (Devitrifikationsgrad, Th/U und 0x0 in Abhängigkeit vom U-Gehalt) kann als ergänzende Prospektionshilfe für supergene U-Anreicherungen in Ignimbriten bzw. Tuffen die geochemische Inkongruenz des U-Li-Gehaltes und des Differentiationsindex erwähnt werden. Im Gegensatz zur normalerweise positiven Korrelation von Oxidationsgrad, Thorium-Uran-Lithium-Gehalt und Differentiationsindex nimmt bei den Pak Chom-Si Chiang Mai Ignimbriten und Tuffen der U-Li -Gehalt bei den höchsten Differentiationsgraden ab. +Differentiationsindex: 1/3 Si + K - Ca - Mg xOxidationsgrad (0x0) : Fe3+ / Fe2+ + Fe3+ + Mn

Description: According to the results of petrographic and petrochemical investigations using geochemical indices, the magmatites of the Indos inia-orogeny in NE-Thailand have been classified in the following rock types and associations as well as attributed to the corresponding magmatic phases of the orogenic cycles. - alkalirhyolithic ignimbrites and tuffs as well as dacites belonging to the calc-alkaline series (early phase of the final magmatism) in the Pak Chom-Si Chiang Mai and Loei-Chum Phae area. Both rock types tend toward alkalinity (final magmatism) in the Saraburi, that is Loei-Tha Li area. - andesitic tuff and agglomerates »belonging to the calc-alkaline series with a medium to strong Pacific character (early subsequent magmatism) in the Chum Phae-Lom Sak area. - leuco-basalts with an ophitic texture, belonging partly to the calc-alkaline series (early subsequent magmatism) in the Chiang Khan area and partly to a transitions phase of the alkaline series (final magmatism) in the Pete ha bun and Saraburi province. - granite-monzonites, belonging to the calc-alkaline series (synorogenic magmatism) in the Loei-Chiang Khan area. The petrographic and goechemical investigations, as well as the palaeographic and quantitative conditions suggest that the alkalirhyol ithic ignimbrites and tuffs of the Pak Chom-Si Chiang Mai area are the potential uranium source-rocks in the area under investigation. The following results support this assuption: - the Upper Triassic - Lower Jurassic alkalirhyolithes of the Pak Chom-Si Chiang Mai area consist of densely welded and nearly completely devitrified ignimbrites and tuffs, in contrast to those of the Saraburi and Loei-Tha Li areas, which show a high amount of holohyaline groundmass. - the alkalirhyolithes of the Pak Chom-Si Chiang Mai area are the most differentiated of all those investigated, as shown by the high numerical differentiationindex+ (16,65). - the content of lithophile trace elements (Ba: 415 - 969 ppm; Rb: 109 - 213 ppm; Sr: 35 - 124 ppm; Zr: 77 - 209 ppm;) is higher than that of the alkalirhyolithes exhibiting the same degree of the differentiation

Description: thesis

Description: DFG, SUB Göttingen

Description: The oxygen- and carbon-isotope compositions of planktic and benthic foraminifera and calcareous nannofossils from Middle Oligocene-Early Miocene Equatorial Atlantic sediments (DSDP Site 354) indicate two important paleoceanographic changes, in the Late Oligocene (foraminiferal Zone P.21) and in the Early Miocene (foraminiferal Zone N.5). The first change, reflected by a delta18O increase of 1.45‰ in Globigerina venezuelana, affected only intermediate pelagic and not surface, deep or bottom waters. The second change affected surface and intermediate waters, whereas deep and bottom waters showed only minor fluctuations. In the case of the former the isotope effect of the moderate ice accumulation on the Antarctic continent is amplified in the Equatorial Atlantic by changes in the circulation pattern. The latter paleoceanographic change, reflected by a significant increase in 18O in both planktic and benthic forms (about 1.0‰ and 0.5‰, respectively), may have been caused by ice volume increase and temperature decrease. Both oxygen- and carbon-isotope compositions indicate a marked depth-habitat stratification for planktic foraminifera and calcareous nannofossils. Three different dwelling groups are recognized: shallow Globigerinoides, Globoquadrina dehiscens, Globorotalia mayeri and nannofossils; intermediate Globigerina venezuelana; and deep Catapsydrax dissimilis. The comparison of foraminifera and calcareous nannofossils suggests that the isotopic compositions of nannofossils are generally controlled by the same parameters which control the isotopic composition of shallow-dwelling foraminifera, but the former are more enriched in 18O.

Description: Igneous rocks were recovered from three sites on Hess Rise during Deep Sea Drilling Project Leg 62: altered basalt at Site 464, at the northern end of Hess Rise; and altered trachyte from Site 465, and rounded basalt pebbles in upper Albian to middle Miocene sediments from Site 466, both at the southern end of Hess Rise. Major-, minor-, and trace-element data for basalt from Hole 464 are consistent with these rocks being transitional tholeiites that have undergone low-temperature alteration by reaction with sea water. Trachyte from Hole 465A exhibits as many as three generations of plagioclase along with potash feldspar that are flow aligned in groundmasses alterted to smectites and random mixed-layer clays. Textural evidence indicates that these rocks were eruped subaerially. Chemical data show a range of values when plotted on two- and three-component variation diagrams. The observed variations may result in part from differentiation, but they also reflect the high degree of alteration. Several oxides and elements show strong correlation with H2O+: K2O, SiO2, Rb and Lu decrease and MgO increases with increasing H2O+. These trends, except for that of Lu, are consistent with experimentally determined changes in chemistry that accompany alteration. The trend for Lu has not been previously reported; it may result from a more-intense alteration of the HREE-rich mafic minerals than of the LREE-rich feldspars. Despite their alteration, the trachytes compare favorably with alkalic differentiates from oceanic islands. We interpret Hess Rise as a volcanic platform formed by eruption of off-ridge volcanic rocks onto MORB oceanic crust during the Aptian and Albian stages, after the basement had migrated away from the spreading center. By analogy with present oceanic islands, we propose that early tholeiitic basalts were followed by alkalic basalts and their differentiation products (trachytes), producing a volcanic archipelago of islands and seamounts. Subsequent tectonism and subsidence led to the present state of Hess Rise.

Description: DSDP Site 516 contains a complete middle Eocene to lower Miocene interval with a well-developed Oligocene sequence that is more than 300 m thick. In this paper, the most important and characteristic benthic foraminiferal species from this interval are described and illustrated, and their quantitative and biostratigraphic distribution is given. Middle Eocene benthic assemblages, derived from pelagic intercalations in a partly turbiditic sequence, are low in diversity. Benthic assemblages of fairly high diversity occur in limestones, chalks, and oozes of the upper Eocene to lower Miocene. The consistently high rate of new species appearances at Site 516 during late Eocene and Oligocene contrasted greatly with the very slow rate of change in abyssal faunas at that time; there were no significant faunal changes at the Eocene/Oligocene boundary. The assemblages are dominated by Cibicidoides (mostly C. ungerianus or C. kullenbergi) and Lenticulina. Buliminids were also important during the Eocene and early Oligocene. Faunal comparison with other Atlantic DSDP sites and drill holes in the Gulf of Mexico suggest an approximately mid-bathyal (500-1500 m) depth of deposition during late Eocene and Oligocene.

Description: Atomic-absorption spectrophotometry and instrumental neutron activation analysis were used to determine concentrations of SiO2, Al2O3, FeOt, MgO, CaO, Na2O, K2O, MnO, La, Ce, Sm, Eu, Tb, Yb, Lu, Sc, Co, Cr, Th, Hf, and Ta for 14 basalt samples from the lower portion of Hole 462A in the Nauru Basin. The basalts are similar to normal midocean ridge basalt (MORB) for the elements analyzed, and light rare-earth elements (LREE) are depleted relative to heavy rare-earth elements (HREE). Two samples are extensively altered to smectites and show significant reductions in Al2O3, CaO, MnO, Na2O, REE, Sc, Co, and Hf and gains in MgO and FeOt relative to unaltered samples. The increase in MgO and decrease in CaO indicate that alteration was caused by hydrothermal solutions.

Description: Benthic foraminifers of the Coniacian-Santonian through the Paleocene were recovered from a continuous pelagic carbonate section from Hole 516F on the Rio Grande Rise. Sixty-five genera and 153 species have been identified, most of which have been reported from other localities. Bathyal depths are reflected in the benthic assemblages dominated by gavelinellids (Gavelinella beccariiformis, G. velascoensis), Nuttallides truempyi, and various gyroidinids and buliminids. Rapid subsidence during the Coniacian-Santonian from nearshore to upper to middle bathyal depths was followed by much reduced subsidence, with the Campanian-Paleocene interval accumulating at middle bathyal to lower bathyal depths. A census study based on detailed sampling reveals major changes in benthic faunal composition at the Cretaceous/Tertiary boundary transition. It was a time of rapid turnover, with the extinctions of numerous species and the introduction of many new species. Overall, species diversity decreases about 20%, and approximately one-third of latest Maestrichtian species do not survive to the end of the Cretaceous. This shift indicates a significant environmental change in the deep sea, the precise nature of which is not apparent from the foraminifers or their enclosing sediments.

Description: Calcareous nannofossils from upper Campanian-lower Maestrichtian Deep Sea Drilling Project Leg 71 Cores 511-23 and 511-24 are described and correlated with assemblages of similar age from piston and drill cores on the Falkland Plateau, South Atlantic Ocean. The Leg 71 cores partially fill a drilling gap of at least 20 meters left within a thick (50 m) carbonate section first drilled by DSDP Leg 36 at Site 327. Cores 511-23 and 511-24 both fall within the upper portion of the Biscutum coronum Zone of Wind and demonstrate an overlap in the range of Monomarginatus quaternarius with the ranges of M. pectinatus, Misceomarginatus pleniporus, and Biscutum coronum across the Campanian/ Maestrichtian boundary. Resolution of the sequence of highest occurrence datums for the latter species must await the recovery of a more complete section. Comparison of the Site 511 assemblages with those from Mas Orcadas Core 07-75-44 to the north confirms earlier speculation that the Falkland Plateau served as an important boundary between major water masses during the Late Cretaceous.

Description: Diverse and abundant late Miocene to Pleistocene silicoflagellates at DSDP Site 504 can be correlated by tropical biostratigraphic zones and relative paleotemperature values to eastern tropical Pacific reference site DSDP 503A farther to the west. Early Pliocene assemblages, which were poorly known until now, are present and can be correlated locally between DSDP Holes 504, 503A, and 495, using species events associated with the new Dictyocha pulchella Subzone and Dictyocha angulata Subzone. Silicoflagellate relative paleotemperature values show major warming at 4.7 to 5.0 Ma (Cores 45-48), 3.4 to 3.8 Ma (Cores 32-33), 1.5 to 1.7 Ma (Cores 12-16), and 0.5 to 0.8 Ma (Cores 3-6). Major coolings occurred at 5.0 to 5.1 Ma (Core 51), 3.9 to 4.4 Ma (Cores 38-44), and 1.0 to 1.3 Ma (Cores 8-10). The appearance of Dictyocha longa is proposed to replace the asperoid/fibuloid ratio reversal as the bottom of the Dictyocha fibula Zone, because the non-evolutionary ratio reverses several times in the upper Miocene of Hole 503A, and at least once in Hole 504. Three new Pliocene silicoflagellates are defined: Dictyocha concinna Bukry, n. sp., D. helix Bukry, n. sp., and D. tamarae Bukry, n. sp.

Description: At Deep Sea Drilling Project (DSDP) Site 462, from mudline to 447 meters below the sea floor, Cenozoic nannofossil oozes and chalks have acoustic anisotropies such that horizontal sonic velocities are 0 to 2.5% faster than those in the vertical direction. In laminated chalk, anisotropy of 5% is typical, and in limestones, radiolarian oozes, porcellanites, and cherts, the anisotropies range from 4 to 13%. Middle Maestrichtian volcaniclastics from 447 meters to 560 meters below the sea floor have an acoustic anisotropy of 2 to 32%; 4 to 13% is typical. Basalt flows and sills occur between 560 meters and 1068 meters, and have no apparent anisotropy, but minor interbedded volcaniclastics have anisotropies from 0 to 20% (5% is typical). These volcaniclastics frequently have very small anisotropies, however, compared with the volcaniclastic sequence above the basalt section. Data in cross-plots of the laboratory-measured compressional sound velocity versus wet-bulk density, wet-water content, and porosity of sediments and sedimentary rock typically lie between the equations derived by Wyllie et al. (1956) and Wood (1941); the Wyllie et al. (1956) equation has a fair fit with similar basalt velocity cross-plots. Crossplots of thermal conductivity and sound velocity indicate only a fair correlation. Cross-plots of thermal conductivity versus porosity, wet-water content, and wet-bulk density correlate well with equations derived by Maxwell (1904), Ratcliff (1960), Parasnis (1960), and Bullard and Day (1961). Electrical formation factor versus porosity for sediments and sedimentary rock agrees with the Archie (1942) equation, with m values of 2.6; for basalt, an m of about 2.1 is typical. Basalt pore-water resistivities do not appear to be greatly different from sea water. Formation factors are greater than those derived from equations in Maxwell (1904), Winsauer et al. (1952), Boyce (1968), and Kermabon et al. (1969). An "apparent interstitial water resistivity" (Rwa) curve was derived from the density and induction logs. This Rwa curve indicated an anomaly, at 393.5 to 396.5 meters, which could be interpreted as (1) 76% hydrocarbons, (2) relatively fresh pore water (1.8 per mil salinity), or (3) low-grain-density (2.2 g/cm**3) semi-lithified porcellanite-chert. Porcellanite-chert is the most plausible interpretation. In situ temperatures measured by the Uyeda temperature probe were about 2 to 5°C (50%) higher than the equilibrium temperature (Lachenbruch and Brewer, 1959) extrapolated from two Gearhart-Owen continuous temperature logs; this discrepancy probably arises because the hole was washed out in this depth interval, so these extrapolated temperatures are probably not reliable. If one ignores all precautions as to temperature artifacts, then the equilibrium temperatures of the Gearhart-Owen temperature logs suggest that hydrothermal circulation is occurring in at least the upper 40 meters of the basalt section and heat is transferred by convection and not conduction. Hydrothermal circulation is probably not indicated, however, and the temperature anomalies probably result from excessive artificial cooling of the fractured basalt zones by circulation of water during drilling.

Description: The stratigraphic position of the glacially transported 'Scholle' (large-size erratic block) at Schobüll near Husum (Schleswig-Holstein) is now considered to be Devonian rather than 'Rotliegendes'. The 'Scholle', consisting of red clay and dolomite, is overlain by red-colored till without any flint but with up to 90% carbonate clasts (containing 15% dolomite), which indicates an eastern Baltic origin. The relationship of the 'Scholle' with the glacial till also points to an eastern Baltic origin for it, with up to 1 000 km transport distance.

Description: During DSDP Leg 70, a 1.60 m thick manganese oxide layer was sampled in hole 509B. This deposit is formed of alternating layers of hard plates of pure todorokite, about 2 mm thick, and of a more powdery material deeply impregnated with manganese oxide, about 3 mm thick. A SEM study of the plates and the associated powder shows that the powdery material is a transformation of a pre-existing sediment, while the plates are a direct precipitation from a hydrothermal solution. The uranium series disequilibrium method was used to determine the ages of the plates. They are found to be in good chronological sequence and in accordance with the sedimentation rate of the area (4.9 cm/10^3 years) which implies that they have been formed at the sediment-seawater interface during a pulsed injection of hydrothermal solution. The powder presents systematically an “older age” which is explained by a slowing down of the injection while the normal sediment settles; the older age is due to the 230Th excess of the sediment.

Description: Ferromanganese nodules in the deep-sea and in freshwater lakes usually accrete layers rich in manganese oxides alternating with layers rich in iron oxides. The mechanism producing these alternating layers is unknown; indeed, the mechanism producing the nodules themselves is unknown. In Oneida Lake, New York, precipitants from the lake water and the surfaces of nodules at the sediment-water interface are enriched in Mn, whereas nodules buried in lake sediments have surface layers enriched in Fe. It is hypothesized here, using field and laboratory evidence, that reduction and mobilization of Mn from the nodule surface during periods of anoxic sediment cover produce the high Fe layers observed in the nodules.

Description: This report is Volume 3 of Descriptions of WHOI rock dredge samples. This series represents a major effort to catalog the rock dredge samples in the WHOI Sea Floor samples collection, and to disseminate this information throughout the scientific community. Volume 3 contains sample descriptions and station data for the dredge stations from five cruises during the period September 1978 through December 1980. The material in this and subsequent volumes of rock descriptions was largely prepared onboard ship by the participating scientists. Volume 3 was printed prior to volumes 1 and 2 because of the excellent documentation of the samples represented in this volume.

Description: This paper reviews the state of the art in processing and extraction of ocean floor manganese nodules. It briefly reviews the mining sites where the abundant rich nodules occur and also discusses the metal distribution in nodules in view of economical processing and extraction of these metal values. The paper discloses in a detailed manner the physical and chemical characteristics of nodules, including porosity, surface area, water content and the effect of temperature on crystal structure of major constituents of nodules. In the extraction aspect of nodules, the paper reviews two different extraction schemes revealed in the literature, namely hydrometallurgical treatment and pyrometallurgical treatment. The hydrometallurgical treatments include acid leaching, ammonia leaching, leaching with reducing agents and leaching after high temperature pre-treatments such as in sulfating rousting, while the pyrometallurgical processes include smelting, chlorination-vaporization and segregation. The paper also covers metal recovery processes from leach liquor. An economic survey of processing nodules has been made in terms of problems associated with metal-marketing, and impact of metal production from nodules on mineral industries.

Description: The minor-element composition of concentric layers within a single ferromanganese nodule from the eastern North Pacific exhibits strong correlations with Fe and Mn contents but appears to be independent of pronounced mineralogic variations. On the basis of these correlations, the elemental composition of individual layers apparently is controlled by the relative contribution of two sources: seawater, and interstitial water of associated sediment. In contrast, the mineralogy of the nodule, consisting of birnessite in the outer few layers and todorokite in the inner layers, is considered to be a function of nodule diagenesis.

Description: Compositional data for coexisting manganese nodules, micronodules, sediments and pore waters from five areas in the equatorial and S.W. Pacific have been obtained. This represents the largest study of its type ever undertaken to establish the distribution of elements between the various phases within the sediment column. The composition of manganese nodules, micronodules and sediments (on a carbonate-free basis) shows marked differences between the equatorial high productivity zone and the low productivity region of the S.W. Pacific. In the case of the nodules, th is reflects an increased supply of transition elements (notably Ni, Cu and Zn) to the nodules as a result of the in situ dissolution of siliceous tests within the sediment column in the equatorial Pacific high productivity zone. Micronodules display similar, but somewhat different, compositions to those of the associated nodules in each area. Micronodule composition is therefore influenced by the same basic factors that control nodule composition, but is modified by dissolution of the micronodules in situ within the sediment column. Locally, as in the area immediately south of the Marquesas Fracture Zone, the micronodule population is contaminated by small, angular volcanic rock fragments; this leads to apparently anomalous micronodule compositions. Micronodules appear to be a transient feature in the sediment column, especially in the equatorial Pacific. Dissolution of micronodules in the sediment column therefore represents an important source of elements for the growth of manganese nodules in the equatorial Pacific. Sediment composition is markedly influenced by the carbonate content. On a carbonate-free basis, the sediments from the equatorial high productivity zone are quite distinct in composition from those in the S.W. Pacific. This reflects differences in the lithology of the sediments. In the Aitutaki Passage, the local influence of volcanoclastic material in sediment composition has been established. The major cations and anions in pore waters measured here show no major differences between equatorial and S.W. Pacific sediments. Silica is, however, higher in equatorial Pacific pore waters reflecting the dissolution of siliceous tests in these sediments.

Description: The study of lake deposits containing iron-manganese nodules is of significant interest for the understanding of one of the continental manganese and iron concentration processes. In the USSR, much attention has been given to the formation conditions of ore accumulations in the Leningrad region and Karelia. Semenovich came to the conclusion that Fe super(+3) and Mn super(+4) entered the lake during a long period of drought and were buried together with organic matter of plant origin. In the lake muds, manganese and iron are reduced; readily soluble compounds of Fe super(+2) and Mn super(+2) are transported by bottom waters. Oxidation of iron and manganese to Fe super(+3) and Mn super(+4) occurs, precipitating oxides on the bottom that form nodules and incrustations. This scheme of lacustrine ore genesis by the accumulation of manganese and iron is well founded.

Description: During the period of 22-28 July, 1978, five dives were made in the manned submersible ALVIN into the Atlantic Ocean 3800 meter depth radioactive waste disposal site located in the Hudson Canyon channel approximately 320 kilometers from the Maryland-Delaware coast. A geological description of the site was made by direct examination of the bottom topography, bedrock exposures, sedimentary and erosional processes, and sediment cores collected from the dumpsite area. Observations within a depth range of 3985-3830 meters revealed angular blocks and piles of displaced channel wall rock, boulder and cobble olistoliths of Eocene-age chalks derived from higher elevations on the slope, and bedforms such as ripples and scour marks which imply the existence of periodic strong currents. Local benthic fauna were sparse. Three low-level radioactive waste drums were examined from the submersible, and one was subsequently recovered for corrosion, and concrete deterioration analyses. Photographic and visual evidence suggest that downslope transport of objects such as talus blocks, olistoliths, and radioactive waste drums has occurred in this area. These observations complement those made by G. Keller in earlier ALVIN dives performed in 1972 and by the AOML(MG&GL project. COMSED (Continental Margin Sedimentary Processes) cruise performed in 1974 by the R/V Researcher.

Description: Initial data on the hydrogen-isotopic compositions in hydrous Mn minerals from various occurrences fall in a wide range from -298 to -84 per mil, relative to SMOW. DeltaD-values of todorokite and cryptomelane from Tertiary deposits show -89 and -150 per mil. 10 Angström-manganite and Delta-MnO2 from deep-sea nodules have relatively restricted DeltaD-values ranging from -96 to -84 per mil. The DeltaD-values for manganese bog ores from recent hot springs show almost -105 per mil. It is recognized that the isotopic values obtained for the deep-sea nodules and recent bog ores are slightly different ranged. Manganite and groutite are unique in their hydrogen-isotopic compositions, having the most depleted DeltaD-values ranging from -298 to -236 per mil. MnO(OH) minerals are more deuterium-depleted hydrous minerals than any other hydrothermal minerals from various ore deposits. Hydrogen-isotope fractionation factors between manganite and water were experimentally determined to be 0.7894, 0.7958 and 0.8078 at 150°, 200° and 250°C, respectively. the present experimental results indicate that if manganites were formed at temperatures below 250°C, under isotopic equilibrium conditions, most of the manganite mineralization in the Tertiary manganese deposits must have precipitated from meteoric hydrothermal solutions.

Description: This report is Volume 1 in the series of reports entitled "Descriptions of W.H.O.I. rock dredge samples". This series represents a major effort to catalog and prepare initial descriptions for all rock dredge samples in the W.H.O.I. Sea Floor Samples Collection, and to distribute this information throughout the scientific community. Volume 1 contains sample descriptions from approximately 382 dredging stations executed during the period 1960 through 1977. It also represents a digitized listing of all dredge station data for the entire W.H.O.I. Dredge Collection through 1980. This data is sorted by Marsden Square and can serve as a regional index for all rock descriptions included in Volumes 1-3.

Description: A submersible study has been conducted in February - March 1978 at the axis of the East Pacific Rise near 21°N. The expedition CYAMEX, the first submersible program to be conducted on the East Pacific Rise, is part of the French-American-Mexican project RITA (Rivera - Tamayo), a 3-year study devoted to detailed geological and geophysical investigations of the East Pacific Rise Crest. On the basis of the 15 dives made by CYANA in the axial area of the Rise, a morphological and tectonic zonation can be established for this moderately-fast spreading center. A narrow, 0.6 to 1.2 km wide zone of extrusion (zone 1), dominated by young lava flows, is flanked by a highly fissured and faulted zone of extension (zone 2) with a width of 1 to 2 km. Further out, zone 3 is dominated by outward tilted blocks bounded by inward-facing fault scarps. Active or recent faults extend up to 12 km from the axis of extrusion of the East Pacific Rise. This represents the first determination from direct field evidence of the width of active tectonism associated with an accreting plate boundary. Massive sulfide deposits, made principally of zinc, copper and iron, were found close to the axis of the Rise. Other signs of the intense hydrothermal activity included the discovery of benthic fauna of giant size similar to that found at the axis of the Galapagos Rift. We emphasize the cyclic character of the volcanicity. The main characteristics of the geology of this segment of the East Pacific Rise can be explained by the thermal structure at depth below this moderately-fast spreading center. The geological observations are compatible with the existence of a shallow magma reservoir centered at the axis of the Rise with a half-width of the order of 10 km.

Description: Of numerous island-arc systems in the western Pacific, the Mariana arc-trench system and the basins and submerged ridges lying west of them in the Philippine Sea seemed to be best suited to answer questions regarding arc-trench and back-arc basin formation. Three years of planning by the JOIDES Active Margin Panel, Ocean Crust Panel, and Planning Committee resulted in a proposed transect of drill sites aligned more or less along the 18th parallel. This South Philippine Sea transect was designed to investigate each major basin and ridge between the central part of the West Philippine Sea and the Mariana Trench and the Pacific Ocean plate immediately to the east.

Description: The goal of Site 462 was to study the paleontologic, sedimentary, petrologic, tectonic, and magnetic histories of that area through Recent to Late Jurassic time by drilling a deep re-entry site into the Nauru Basin west of the Ralik Chain of the Marshall Islands. This area formed at a fast-spreading Pacific Plate boundary 145 to 155 m.y. ago, in the Late Jurassic. Cores from this area allow to better understand the biostratigraphic evolution and sedimentary processes in a Mesozoic open-ocean environment, the petrologic nature of fast-spreading oceanic crust, the tectonic history of the Late Jurassic Pacific Plate, and the nature of the Jurassic magnetic quiet zone.

Description: The four sites drilled during Leg 62 were needed to establish better regional coverage of the North Pacific Ocean. Although paleoenvironments were to be stressed on Leg 62, studies of igneous rocks from acoustic basement were planned, to determine ages, petrogenesis, alteration effects, rock magnetism, and Paleomagnetism of old parts of the Pacific crust. These studies were emphasized in order to establish the early history of oceanic plateaus and whether they are the result of midocean-ridge or intraplate volcanism.

Description: Deep Sea Drilling Project (DSDP) Legs 64 and 65 were planned as a coordinated drilling investigation of the Gulf of California. The primary goals of Leg 64 were to investigate the early evolution of a passive continental margin and to study hydrothermal systems in the Guaymas Basin. Leg 65 was designed to study the processes of crustal accretion along the relatively fastspreading East Pacific Rise for comparison with the slow-spreading Mid-Atlantic Ridge. It was planned to drill a transect across the East Pacific Rise just south of the Tamayo Fracture Zone and to penetrate deep into the crust at one site near the ridge crest. The purpose was to sample crustal sections formed at a relatively fast spreading ridge in order to investigate the processes of crustal accretion in this environment.

Description: A primary objective of Leg 63 was to investigate the fluctuations of this eastern boundary current along a north-south transect off the Gulf of California. This information would aid in biostratigraphically correlating open-ocean planktonic zones with local California zonations. Spanning the last 30 m.y., the complicated tectonic history of the continental margin off California and Baja California comprises changes from a subduction zone to a transform boundary and then to an inactive margin. A second objective of Leg 63 was to define and clarify this history using information on sedimentation, unconformities, basement ages, and paleomagnetic reconstructions gained from drilling, in conjunction with geophysical data and pre-existing bottom samples.

Description: Undamaged deep-sea manganese nodules were retrieved from a box core from the central North Pacific and quickly preserved in formaldehyde solution. Light and scanning electron microscope studies of the nodule surface reveal the presence of a variety of fragile filamentous and coccoid bacterial morphotypes, associated with an organic film that covers the botryoid surface.

Description: The sites 504 and 505 of Deep Sea Drilling Project Leg 69 were selected for the purpose of investigating geothermal phenomena in basaltic basement and overlying sediments at two locations in the same segment of an oceanic spreading center-the Costa Rica Rift. Two additional experiments were conducted in Hole 504B to measure the bulk properties of the ocean crust: the large-scale resistivity experiment and the oblique seismic experiment.

Description: The high-latitude South Atlantic Ocean and the adjacent Antarctic Ocean have throughout Mesozoic and Cenozoic time undergone pronounced geographic alterations that have produced a change from a temperate marine climate in the late Mesozoic and Paleogene to a frigid ocean in the Neogene. DSDP Leg 71 was the first of five legs designed to study late Mesozoic and Cenozoic paleoenvironments through the history of sedimentation at the eastern end of the Falkland Plateau, the effect of the plateau as a barrier between water masses during the early opening of the South Atlantic, and the evolution of the Antarctic Convergence.

Description: DSDP Leg 72 of the Glomar Challenger addressed paleoceanographic objectives in the southwestern Atlantic. It was planned to extend the observations and interpretations from the Leg 39 report in order to btain a complete deposition record of pelagic sedimentation on the Rio Grande Rise, down to and including the underlying volcanic basement.

Description: The continental edge of eastern North America is the passive margin with the oldest geological history available in the modern oceans. Rifting and seafloor spreading between the North American and African continents began in the late Triassic to Early Jurassic. A possible spreading-center jump and reorganization in spreading at the time of the Blake Spur Magnetic Anomaly (?Bathonian ) left some of the oldest crust on the western margin of the North Atlantic. Penetration and sampling of such old ocean crust and the immediately overlying pelagic sedimentary cover, consisting of Middle Jurassic and younger strata, has long been a key objective in oceanographic research. This objective was accomplished at Site 534.

Description: Cosmogenic beryllium-10 activities have been measured in marine accumulations of up to about 6 m.y age by conventional beta counting technique and by accelerator mass spectrometry. The two sets of data at 10Be levels of 109-1010 atoms/g agree within the absolute errors of the two methods. The detection limit for 10Be by the accelerator mass spectrometry is about five orders of magnitude lower than that with the beta counting method.

Description: Erosion of sediment at two sites within the siliceous-clay province of the northeast equatorial Pacific is investigated by examining radionuclide, radiolarian and percent smectite profiles of three cores. A numerical model of the sediment is presented that examines the effect of various particle rain rates, erosion rates and biological mixing parameters on these profiles. 230Th, because of its longer half-life, is a more sensitive tracer of erosion than231Pa. Because the input of these radionuclides into the sediment is not well defined however, conservative tracers, such as the percent smectite of the clay fraction and fossil radiolarians are used to constrain the rate of sediment recycling. Dissolution of radiolarians though can greatly affect the interpretation of the observed biostratigraphy.

Description: The unusual petrological diversity of abyssal lavas erupted along some segments of the Galapagos spreading center is a direct consequence of the propagation (elongation) of these segments into older oceanic crust. With increasing distance behind propagating rift tips, relatively unfractionated MORB erupted close to the tips are joined first by FeTi basalts (bimodal assemblage) and then by a wide range of basaltic and siliceous lavas. Further behind propagating rift tips, this broad range diminishes again, approaching the narrow compositional range of adjacent normal ridge segments. These compositional variations reflect the evolution of the subaxial magmatic system beneath the newly forming spreading center as it propagates through a pre-existing plate. We envisage this evolution as proceeding from small, isolated, ephemeral magma chambers through increasing numbers of larger, increasingly interconnected chambers to the steady-state buffered system of a normal ridge. Throughout this evolution, magma supply rates gradually increase and cooling rates of crustal magma bodies decrease. High degrees of crystal fractionation are favored only when a delicate balance between cooling rate and resupply rate of primitive magma is achieved. At other propagating and non-propagating ridge-transform intersections the degree to which the balance is achieved and the length of ridge over which it evolves control the distribution of fractionated lavas. These effects may be evaluated provided a number of tectonic variables including transform length, spreading and propagation rates are taken into account.

Description: The southernmost part of the Sohm Abyssal Plain in the Northwest Atlantic Basin is geographically distal with respect to the major source of Quaternary terrigenous material transported from the Canadian Maritime Provinces. An assessment of the proportion of more locally introduced sediment relative to that derived from distal sources is based largely on size and compositional analyses of Quaternary piston core samples. These data are supplemented by radiocarbon dating of selected core samples, bottom photographs, conductivity-temperature-depth profiles, and seismic records. The premises of the study are that (a) locally derived sediment should be most abundant near high-relief bathymetric features such as seamounts and abyssal hills, and (b) such material should contain enhanced proportions of reworked volcanic debris and alteration products. Core analyses reveal that the amounts of these are directly related to proximity of volcanic ocean-bottom features, and that a significant, although not total, amount of such volcanic materials recovered from cores are derived from submarine weathering of basalt. Associated with this assemblage are nannofossils, dating from the Quaternary to the Upper Cretaceous, reworked from older strata. This increased proportion of volcanic and related products and reworked faunas near seamounts and basement rises strongly implies that such topographic features continue to serve as major source terrains. Locally derived volcanic materials, however, are usually disseminated and masked on the Sohm Abyssal Plain, particularly in sectors receiving large amounts of terrigenous turbidites and biogenic suspensates, and/or undergoing reworking by bottom currents. We propose that the volcanic fraction can serve as a useful index, or "yardstick," to interpret the role of locally derived material in abyssal plain sedimentation. A sedimentation model is developed to illustrate the premise that as access to land-derived sources diminishes, the proportion of terrigenous components is reduced while pelagic and volcanic fractions are enhanced. Thus, sediment accumulating in abyssal plains almost totally isolated from terrigenous sources would comprise significant amounts of pelagic (including wind-blown) and volcanic components.