Pattern and timing of the northwestern Barents Sea Ice Sheet deglaciation and indications of episodic Holocene deposition   总被引：1，自引：0，他引：1  

Denise Christina Rüther  Lilja Rún Bjarnadóttir  Juho Junttila  Katrine Husum  Tine Lander Rasmussen  Renata Giulia Lucchi  Karin Andreassen 《Boreas: An International Journal of Quaternary Research》2012,41(3):494-512

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice‐rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner‐fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.  相似文献   

Using Lead Isotopes to Determine Pottery Provenance in Cyprus: Clay Source Signatures and Comparison with Late Bronze Age Cypriote Pottery     

Virginie Renson  Ariane Jacobs  Jan Coenaerts  Nadine Mattielli  Karin Nys  Philippe Claeys 《Geoarchaeology》2013,28(6):517-530

This paper presents the lead isotopic composition of potential clay sources for pottery production, collected in the four major geological zones of Cyprus (Troodos Ophiolite, Circum Troodos Sedimentary Succession, Mamonia Terrane, Kyrenia Terrane) and evaluates its usefulness in Cypriote pottery provenance studies. The clay isotopic signatures from the four zones are compared to each other and to the isotopic composition of various utilitarian pottery wares from three Late Bronze Age sites, respectively located in southern Cyprus (Alassa‐Pano Mandilaris), east Cyprus (Enkomi), and southeast Cyprus (Hala Sultan Tekke). It also explores the potential of this method to better discriminate between potential raw materials used for the production of Base‐ring ware, one of the most characteristic fine pottery of Late Bronze Age Cyprus, which was widely spread in the Eastern Mediterranean (Courtois, 1981; Vaughan, 1991, 1994). Results show that three main lead isotopic fields can be distinguished among the Cypriote clay sources and the comparison of Plain sherds with the clay sources allows discrimination between local products and imports. They also clearly indicate that all the Base‐ring sherds analyzed in this study were made of the clays from the Kathikas Formation that crops out in only limited parts of southwest Cyprus.  相似文献   

Effect of intrinsic and sampling variability on wave parameters and wave statistics     

Elzbieta M. Bitner-Gregersen  Anne Karin Magnusson 《Ocean Dynamics》2014,64(11):1643-1655

  相似文献   

Magmatism and metamorphism at ca. 1.45 Ga in the northern Gawler Craton: The Australian record of rifting within Nuna (Columbia)     

Laura J. Morrissey  Karin M. Barovich  Martin Hand  Katherine E. Howard  Justin L. Payne 《地学前缘(英文版)》2019,10(1):175-194

U-Pb monazite and zircon geochronology and calculated metamorphic phase diagrams from drill holes in the northern Gawler Craton, southern Australia, reveal the presence of ca. 1.45 Ga magmatism and metamorphism. Magmatism and granulite facies metamorphism of this age has not previously been recognised in the Gawler Craton. The magmatic rocks have steep LREE-enriched patterns and high Ga/Al values, suggesting they are A-type granites. Calculated metamorphic forward models suggest that this event was associated with high apparent thermal gradients and reached pressures of 3.2 -5.4 kbar and temperatures of 775-815℃. The high apparent thermal gradients may reflect pluton-enhanced metamorphism, consistent with the presence of A-type granites. The recognition of ca. 1.45 Ga tectonism in the northern Gawler Craton is added to a compilation of ca. 1.50 -1.40 Ga magmatism, shear zone reactivation, rift basin development and isotope resetting throughout the South and North Australian Cratons that shows that this event was widespread in eastern Proterozoic Australia. This event is stylistically similar to ca. 1.45 Ga A-type magmatism and high thermal gradient metamorphism in Laurentia in this interval and provides further support for a connection between Australia and Laurentia during the Mesoproterozoic. The tectonic setting of the 1.50-1.40 Ga event is unclear but may record rifting within the Nuna(or Columbia) supercontinent, or a period of intracontinental extension within a long-lived convergent setting.  相似文献   

Faroe Shelf Water     

Karin Margretha H. Larsen  Bogi Hansen  Harald Svendsen 《Continental Shelf Research》2008

Faroe Shelf Water (FSW) is the water mass that occupies the shallow parts of the Faroe Shelf, surrounding the Faroe Islands (62°N, 7°W). Intensive tidal mixing induces a high degree of homogeneity and the circulation system allows a partial isolation from surrounding waters. This water mass, therefore, supports a unique ecosystem of great importance for commercial fish stocks and studies have shown a clear dependence of the ecosystem on the physical processes that maintain this system and control the exchange between the FSW and the off-shelf waters. In order to identify and quantify these processes, a large observational dataset has been analysed and related to alternative theories. From this analysis, the extent and properties of the FSW have been quantified and the degree of stratification explained in terms of the Simpson–Hunter theory. The residual clockwise circulation system, which is responsible for the partial isolation from off-shelf waters, is shown to be mainly generated by tidal rectification. The typical exchange rate of water between the FSW and the off-shelf regimes has been determined by the use of simple models based on the heat and the salt budgets but the actual exchange rate is found to vary considerably in time and space. These results support earlier suggestions that this exchange is the main limiting factor for the phytoplankton spring bloom on the Faroe Shelf and that variations in exchange rate are responsible for the large inter-annual variation in spring bloom timing and intensity. The observations indicate that the on-shelf/off-shelf exchange intensity is not symmetrically distributed around the shelf, but rather concentrated around the narrow southern tip of the Faroe Shelf, where off-shelf waters during intensive exchange events may be imported all the way to the shore.  相似文献   

Sedimentary patterns and geometries of the Bahamian outer carbonate ramp (Miocene–Lower Pliocene, Great Bahama Bank)     

Christian Betzler  John J. G. Reijmer  Karin Bernet  Gregor P. Eberli  & Flavio S. Anselmetti 《Sedimentology》1999,46(6):1127-1143

Core, logging and high-resolution seismic data from ODP Leg 166 were used to analyse deposits of the Neogene (Miocene–Lower Pliocene) Bahamian outer carbonate ramp. Ramp sediments are cyclic alternations of light- and dark-grey wackestones/packstones with interbedded calciturbidite packages and minor slumps. Cyclicity was driven by high-frequency sea-level changes. Light-grey layers containing shallow-water bioclasts were formed when the ramp exported material, whereas the dark-grey layers are dominantly pelagic. Calciturbidites are arranged into mounded lobes with feeder channels. Internal bedding of the lobes shows a north-directed shingling as a result of the asymmetrical growth of these bodies. Calciturbidite packages occur below and above sequence boundaries, indicating that turbidite shedding occurred during third-order sea-level highstands and lowstands. Highstand turbidites contain shallow-water components, such as green algal debris and epiphytic foraminifera, whereas lowstand turbidites are dominated by abraded bioclastic detritus. Gravity flow depocentres shifted from an outer ramp position during the early Miocene to a basin floor setting during the late Miocene to early Pliocene. This change was triggered by an intensification of the strength of bottom currents during the Tortonian, which was also responsible for shaping the convex morphology of the outer ramp. The Miocene and Lower Pliocene of the leeward flank of Great Bahama Bank provides an example of the poorly known depositional setting of the outer part of distally steepened carbonate ramps. The contrast between its sedimentary patterns and the well-known Upper Pliocene–Quaternary slope facies associations of the flat-topped Great Bahama Bank shows the strong control that the morphology of a carbonate platform exerts on the depositional architecture of the adjacent slope and base-of-slope successions.  相似文献   

Impact of Air Pollution on Genetic Material of Shallot (Allium cepa L. var. ascalonicum) Exposed at Differently Polluted Sites in Slovenia     

Erika Glasenčnik  Cvetka Ribarič-Lasnik  Karin Savinek  Meta Zaluberšek  Maria Mueller  Franc Batič 《Journal of Atmospheric Chemistry》2004,49(1-3):363-376

Test shallot plants Allium cepa L. var. ascalonicum were exposed to field conditions at six research plots in the most polluted areas in Slovenia in the vegetation seasons in 1999 and 2000. The intention of this research was to evaluate the influence of air pollution on mitotic activity and frequency of chromosomal aberrations in meristematic tissues of root tips of bioindication plants. Significant differences in the mitotic index and in frequency of chromosomal aberrations at different sampling plots in pot experiments were found and the correlation between the ozone concentration and the mitotic index was determined. The results showed the presence of cytotoxic substances at chosen sampling sites, which caused the decrease of mitotic cell division and the presence of genotoxic substances, which resulted in the increase of frequency of chromosomal aberrations.  相似文献   

Geology of the Atlantis Massif (Mid-Atlantic Ridge, 30° N): Implications for the evolution of an ultramafic oceanic core complex     

Blackman  Donna K.  Karson  Jeffrey A.  Kelley  Deborah S.  Cann  Johnson R.  Früh-Green  Gretchen L.  Gee  Jeffrey S.  Hurst  Stephen D.  John  Barbara E.  Morgan  Jennifer  Nooner  Scott L.  Ross  D. Kent  Schroeder  Timothy J.  Williams  Elizabeth A. 《Marine Geophysical Researches》2002,23(5-6):443-469

Marine Geophysical Research - The oceanic core complex comprising Atlantis Massif was formed within the past 1.5–2 Myr at the intersection of the Mid-Atlantic Ridge, 30° N, and the...  相似文献   

A review of the biology and genetics of sea lice   总被引：5，自引：0，他引：5  

Boxaspen  Karin 《ICES Journal of Marine Science》2006,63(7):1304-1316

  相似文献   

Die kurzwellige Strahlung von Sonne und Himmel auf verschieden orientierte und geneigte Flächen     

Karin Schram  J. C. Thams 《Theoretical and Applied Climatology》1967,15(1-2):99-126

Zusammenfassung In Locarno-Monti am Alpensüdfu? wurde w?hrend zwei Jahren die kurzwellige Strahlung von Sonne + Himmel (Globalstrahlung) auf eine horizontale, je eine um 30° bzw. 60° nach Süden und je eine um 30° nach Osten bzw. Westen geneigte Auffangfl?che mit Solarimetern registriert. Die Tages- und Jahresg?nge der Globalstrahlung zeigen an wolkenlosen Tagen gro?e Unterschiede im Strahlungsgenu? der verschieden orientierten und verschieden geneigten Fl?chen. Im Mittel aller Tage sind diese Unterschiede zwar kleiner, jedoch wegen der gro?en relativen Sonnenscheindauer in Locarno-Monti immer noch sehr ausgepr?gt. Bei vollkommen bedecktem Himmel verschwinden die Unterschiede fast v?llig. Aufgrund der Beziehungen zwischen der Globalstrahlung und der relativen Sonnenscheindauer genügen Parallelmessungen von wenigen Jahren, um daraus klimatologische Mittelwerte der Globalstrahlung auf verschieden orientierte und geneigte Fl?chen berechnen zu k?nnen. Das Verh?ltnis der Strahlung auf geneigte H?nge zu der auf die horizontale Fl?che h?ngt von der Jahreszeit und der Bew?lkung ab. Diese Beziehung kann dazu dienen, bei Kenntnis der Globalstrahlung auf eine horizontale Fl?che jene auf eine geneigte Auffangfl?che zu bestimmen. Schlie?lich wird auf die Bedeutung dieser Untersuchungen für die praktische Meteorologie hingewiesen.

---

Summary For a two years' period the total (short wave) radiation of sun and sky falling on a horizontal surface, on southern slopes of 30° and 60° inclination, resp., and on eastern and western slopes of 30° inclination has been recorded with solarimeters at Locarno-Monti (Switzerland). On cloudless days the diurnal and annual variations of the total radiation indicate rather big differences between the radiation falling on the surfaces of different inclination and orientation. Considering the radiation covering all days, these differences are smaller but still distinctly marked because of the high relative duration of sunshine at Locarno-Monti. On overcast days all surfaces receive almost the same amount of radiation. Climatological averages of the total radiation falling on surfaces of different orientation and inclination can be deduced using the relation between the total radiation and the duration of sunshine. The ratio between the radiation falling on inclined planes and the radiation falling on a horizontal surface depends on season and cloudiness. By means of these relations the radiation falling on inclined surfaces can be calculated using the radiation falling on the horizontal surface. Finally the importance of such investigations for applied meteorology is pointed out.

---

Résumé Le rayonnement de courte longueur d'onde du soleil et du ciel (rayonnement global) a été enregistré pendant deux ans à Locarno-Monti, au pied sud des Alpes, au moyen de solarimètres présentant différentes orientations. Les surfaces réceptrices étaient respectivement horizontale, inclinées de 30° et 60° vers le sud, ainsi que de 30° vers l'est et l'ouest. Les variations journalières et saisonnières du rayonnement global mettent en évidence les grandes différences d'éclairement des surfaces réceptrices selon leur azimut et leur inclinaison, lors des journées ensoleillées surtout. Ces différences sont plus faibles lorsque l'on prend tous les jours en considération, mais restent cependant bien marquées par suite de la grande durée relative d'insolation à Locarno-Monti; elles disparaissent presque complètement par ciel entièrement couvert. En s'appuyant sur les relations entre le rayonnement global et la durée relative d'insolation, l'on peut calculer des moyennes climatologiques du rayonnement global tombant sur des surfaces d'orientation différente à l'aide de quelques années seulement d'enregistrements parallèles. Le quotient des rayonnements re?us par une pente inclinée et par une surface horizontale dépend de la saison et de la couverture nuageuse. Une fois cette relation connue, il est possible d'évaluer le rayonnement global re?u par une surface inclinée à partir des valeurs relatives à une surface horizontale. Enfin, l'on signale l'importance de ces recherches pour la météorologie appliquée.

---

Riassunto A Locarno-Monti al piede meridionale delle Alpi durante due anni fu registrata con solarimetri la radiazione ad onde corte del sole + cielo (radiazione globale) su superfici orizzontale, inclinate di 30° e rispettivamete 60° e rivolte verso sud, nonchè su superfici orizzontale, inclinate di 30° e rivolte verso est, rispettivamente verso ovest. Gli andamenti giornaliero ed annuale della radiazione globale mostrano nei giorni senza nuvole grandi differenze nella quantità di radiazione ricevuta dalle superfici diversamente inclinate e orientate. Nella media di tutti i giorni tali differenze sono si più piccole, tuttavia sempre ancora ben pronunciate causa l'elevata durata relativa dell'insolazione. Con cielo completamente coperto le differenze scompaiono quasi completamente. In base alle relazioni tra la radiazione globale e la durata relativa dell'insolazione, sono sufficienti misure parallele di soli pochi anni per poter calcolare valori climatologici della radiazione globale su diverse superfici orientate e inclinate. Il rapporto tra la radiazione su pendii inclinati e quella su superfici orizzontale dipende dalla stagione e dalla nuvolosità. Questa relazione può servire, conoscendo la radiazione globale su una superficie orizzontale, a determinare quella su una superficie di ricezione inclinata. Da ultimo viene accennato all'importanza di queste ricerche per la meteorologia pratica.

---

---

Mit 11 Textabbildungen  相似文献