Glacial-Marine Sedimentation, Canadian Polar Margin, North of Axel Heiberg Island

Sediment cores, taken at depths of 140 to 300 m across the northwestern shelf of Axel Heiberg Island (82° N), record the deposition of sediments under perennial sea ice. Five sedimentary fades are recognized: (A) soft pebbly-sandy-mud with dropstone structures; (B) bioturbated silty muds; (C) wispy-laminated silty clay/clay; (D) laminated sands/silts and mud; (E) firm pebbly-sandy-mud with chaotic pebble fabrics. Other sediments include terrestrial bedrock of Paleogene Eureka Sound Group, and a younger Tertiary deposit, possibly the Beaufort Formation. Ages range from 1530 ± 60 BP (Fades A) to 9950 ± 80 BP (Fades D). Sedimentation rates vary as follows: - 0.8 cm ka-1, Fades B; 4 cm ka"\ Fades A; 90 cm ka-1, Fades C; 134 cm ka~', Fades D. The sedimentation history, as interpreted from the sedimentology, palynology and foraminiferal results, suggests intervals of more continuous ice cover, with a reduced influx of coarse ice-rafted detritus, alternating with more open water conditions, and high sediment input from meltwater and/or floating icebergs. Only marine sediments overlie Neogene bedrock in the cores. The absence of diamictons at the core sites suggests that grounded ice perhaps never occupied this part of the Axel Heiberg Island shelf. The interpreted history of sedimentation generally corresponds to the land-based record from Ellesmere Island, but differs significantly from marine-based studies in more southern latitudes.L'étude des carottes de sédiments recueillies à des profondeurs de 140 à 300 m sur la plate-forme de l'île Axel-Heiberg (82° N) renseigne sur la mise en place des sédiments sous une glace de mer pérenne. Elle révèle cinq faciès sédimen-taires: (A) boue sablo-caillouteuse avec structures de cailloux de délestage; (B) boues silteuses bioturbées; (C) lamines en mèches d'argile et d'argile silteuse; (D) sables et silts laminés et boue; (E) boue sablo-caillouteuse compacte. Les carottes renferment aussi des sédiments du substratum du Groupe de Eureka Sound du Paléogène et un dépôt tertiaire plus jeune, probablement de la Formation de Beaufort. Les âges se répartissent entre 1530 ± 60 BP (fades A) à 9950 ± 80 BP (fades D). Les taux de sédimentation varient selon les fades: ~ 0,8 cm ka-1 (fades B)14 cm ka-1 (faciès A), 90 cm ka_1 (faciès C), 134 cm ka_1 (faciès D). Le processus de sédimentation, interprété à partir de la sédimentologie, la palynologie et les foraminifères, comprend des intervalles durant lesquels la couverture de glace était continue avec apport réduit de débris grossiers alternant avec des périodes de mer dégagée avec apport sédimentaire élevé à partir des eaux de fonte ou des icebergs. Dans les carottes, le substratum du Néogène n'est recouvert que de sédiments marins. L'absence de diamicton laisse présumer que la glace continentale n'a jamais occupé cette partie de la plate-forme. L'interprétation qu'on fait du processus de sédimentation correspond de façon générale aux données tirées de l'île d'Ellesmere, mais diffère beaucoup des études sur le milieu marin de latitudes plus méridionales.Sedimentkerne, die in Tiefen von 140 bis 300 m quer durch den nordwestlichen Schelf der Axel Heiberg-lnsel gewonnen wurden (82° N)1 bezeugen die Ablagerung von Sedimenten unter dem ganzjâhrigen Meereseis. Man kann fùnf Sediment-Fazies erkennen: (A) weicher, kiesigsandiger Schlamm mit Treibeisstrukturen; (B) Bioturbationstrukturen schlickiger Schlamm; (C) dùnnblàttriger schlickiger Ton und Ton; (D) blàttriger Sand/Schlick und Schlamm; (E) kiesigsandiger Schlamm mit chaotischer Kiesstruktur. Andere Sedimente enthalten Erdfels der palàogenen Eureka-Sound-Gruppe sowie eine jungere tertiàre Ablagerung, môglicherweise von der Beaufort Formation. Die Alter liegen zwischen 1530 ± 60 v. u.Z. (A-Fazies) bis 9950 ± 80 v.u.Z. (D-Fazies). Die Sedimen-tierungsraten variieren folgendermaften: 0,8 cm ka-1 B-fazies; 4 cm ka~\ A-Fazies; 90 cm ka-1, C-Fazies; 134 cm ka_1, D-Fazies. Die Sedimentierungsgeschichte wie sie mittels Sédimentologie, Palynologie und den Foraminifera-Ergebnissen interpretiert wird, IaRt an Intervalle einer mehr kontinuierlichen Eisdecke denken, mit einem verringerten Einstrômen groben vom Eis befôrderten Steine, alternierend mit Bedingungen mehr offenen Wassers und einem hohen Sedimentzutrag durch Schmelzwasser und/oder treibende Eisberge. Nur marine Sedimente ûberlagern den FeIs aus dem Jungtertiàr in den Kernen. Das Fehlen von Diamiktons an den Bohrplàtzen legt nahe, daft Kontinentaleis vielleicht niemals diesen Teil des Schelfs der Axel-Heiberg-lnsel bedeckte. Die so interpretierte Geschichte der Sedimentierung stimmt im allgemeinen mit dem landbezogenen Beleg von der Ellesmere-lnsel ùberein, unterscheidet sich aber deutlich von den meeresbezogenen Studien in sudlicheren Breiten

The natural resources of San Dieguito and Batiquitos Lagoons

The California Department of Fish and Game has played a central role in attempting to protect and enhance the remaining 25% of southern California wetlands which have survived the ingress of urbanization and commercial development since 1900 (U.S. Dept. Interior, 1972). To this end, the Department has published a series of reports documenting California's coastal wetlands resources, including four covering wetlands in southern California (Upper Newport Bay, Frey et al., 1970; Goleta Slough, Speth et al., 1970; Los Penasquitos Lagoon, Mudie et al., 1974; and San Diego Bay, Browning et al., 1973). The following report is an extension of that effort. (131pp.

The natural resources of Los Penasquitos Lagoon

The purpose of this report is to document the natural resources of Los Penasquitos Lagoon, San Diego County; to outline and evaluate proposed developments affecting those resources; and to recommend measures that will protect and enhance the lagoon and its environs. The necessity for a report of this nature has become apparent with the progressive destruction of California's coastal wetlands over the past fifty years. These wetland resources, which are virtually irreplaceable, are essential to the continued existence of many forms of resident fish and wildlife and to the preservation of migratory shorebirds and waterfowl. Approximately 60 percent of the tidal wetlands in California has already been destroyed (Speth, 1970); and, it is estimated that only 10 percent is left of the original acreage of coastal marshland in San Diego County. The future of the remaining wetland habitats continues to be threatened. There is an urgent need, therefore, for sound planning to protect these wetlands and to prevent their otherwise inevitable disappearance as a valuable natural resource. (100pp.

The dinoflagellate cyst genera Achomosphaera Evitt 1963 and Spiniferites Mantell 1850 in Pliocene to modern sediments: a summary of round table discussions

Source at https://doi.org/10.1080/01916122.2018.1465739. We present a summary of two round-table discussions held during two subsequent workshops in Montreal (Canada) on 16 April 2014 and Ostend (Belgium) on 8 July 2015. Five species of the genus Achomosphaera Evitt 1963 and 33 of the genus Spiniferites Mantell 1850 emend. Sarjeant 1970 occuring in Pliocene to modern sediments are listed and briefly described along with remarks made by workshop participants. In addition, several holotypes and topotypes are reillustrated. Three species previously assigned to Spiniferites are here considered/accepted as belonging to other genera: Impagidinium inaequalis (Wall and Dale in Wall et al.1973) Londeix et al. 2009, Spiniferites? rubinus (Rossignol 1962 ex Rossignol 1964) Sarjeant 1970, and Thalassiphora balcanica Baltes ̧ 1971. This summary forms the basis for a set of papers that follows, where points raised during the workshops are explored in greater detail

Palynology and dinocyst biostratigraphy of ODP Leg 104 holes

Cores from ODP Leg 104 Holes 642A, 642B, 642C, 644A, and 644B were sampled at intervals of 40 cm to 100 cm for a detailed study of palynomorphs and palynodebris types in upper Cenozoic sediments of the Vetoing Plateau. Corecatcher samples were also studied from Hole 643A on the seaward flank of the plateau. Most of the 600 samples studied contained dinoflagellate cysts, pollen, spores, and various types of palynodebris. Total numbers of indigenous dinocysts and pollen-spore concentrations show cyclical variations which appear to correspond to climate fluctuations in Pliocene and younger sediments, and to either climatic changes or phytoplankton productivity cycles in the older sediments. Stratigraphic ranges for 68 cyst morphotypes were used to erect a provisional dinocyst zonation that can be correlated with other Northern Hemisphere high-latitude zonations. Four dinocyst zones are defined, with boundaries corresponding to biochronological or magnetostratigraphic ages of ca. 15 Ma, 9 Ma, 4.2 Ma, and 1.4 Ma. Environmental changes are interpreted in terms of (a) a progressive decline in species diversity due to the disappearance of subtropical species; (b) appearance of subarctic North Pacific taxa, presumably from the Arctic Ocean; and (c) an increase in heterotrophic protoperidinioid cyst species during the Pleistocene