The impact of simulated climate change on the air-sea flux of dimethylsulphide in the subantarctic Southern Ocean     

ALBERT J. GABRIC  PETER H. WHETTON  REINOUT BOERS  GREGORY P. AYERS 《Tellus. Series B, Chemical and physical meteorology》1998,50(4):388-399

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10Be dating of Younger Dryas Salpausselkä I formation in Finland     

SILVIO TSCHUDI  SUSAN IVY‐OCHS  CHRISTIAN SCHLÜCHTER  PETER KUBIK  HEIKKI RAINIO 《Boreas: An International Journal of Quaternary Research》2000,29(4):287-293

Boulders of the Younger Dryas Salpausselkä I (Ss I) formation west of Lahti, southern Finland, were sampled for surface exposure dating. The ¹⁰Be concentrations, determined by accelerator mass spectrometry, yield minimum exposure ages of 11 930 ± 950, 11 220 ± 890, 11 050 ± 910 and 11 540 ± 990 years, using recently published production rates scaled for latitude and elevation. This includes a correction to the production rate resulting from postglacial uplift of the Fennoscandian lithosphere (i.e. changing elevation) during the time of exposure. The error‐weighted mean exposure age of 11 420 ± 470 years of the analysed boulders agrees with previous varve dates of Ss I, which range from 11 680 to 11 430 calendar years BP. However, erosion has to be taken into account as a process affecting rock surfaces and therefore influencing exposure ages. Available information suggests an erosion rate of 5 mm/kyr, which increases the error‐weighted mean exposure age to a value of 11 610 ± 470 years. Within the errors, the formation of Ss I in the Vesala area west of Lahti falls into the Younger Dryas time bracket, as defined by the GRIP and GISP 2 ice core (Greenland).  相似文献   

Stability properties of a barotropic surface-water jet observed in the Denmark Strait     

TIM FRISTEDT  RIIKKA HIETALA  PETER LUNDBERG 《地球，A辑:动力气象学与海洋学》1999,51(5):979-989

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''Cosmogenic ¹⁰Be ages on the Pomeranian Moraine, Poland'': Reply to comments     

VINCENT R. RINTERKNECHT  LESZEK MARKS  JAN A. PIOTROWSKI  GRANT M. RAISBECK  FRANCOISE YIOU  EDWARD J. BROOK  PETER U. CLARK 《Boreas: An International Journal of Quaternary Research》2006,35(3):605-606

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Palaeoenvironments of a complete Eemian sequence at Mommark, South Denmark: foraminifera, ostracods and stable isotopes     

PETER H. KRISTENSEN  KAREN LUISE KNUDSEN 《Boreas: An International Journal of Quaternary Research》2006,35(2):349-366

A new investigation of the coastal cliff section at Mommark in southern Denmark has revealed a complete Eemian interglacial sequence for the first time in the southwestern Baltic area. Environmental changes through the lacustrine and marine interglacial deposits are discussed on the basis of foraminiferal assemblages and stable isotope composition as well as ostracods. In general, the assemblages indicate relatively high temperatures throughout the Eemian, and the Lusitanian foraminiferal species Pseudoeponides falsobeccarii Rouvillois has been reported for the first time from the Eemian of northwest Europe. A floating chronology of the deposits is based on a previously published correlation of the local pollen stratigraphy with annually laminated sequences in northern Germany. An initial early Eemian lacustrine phase, with ostracodal indication of deposition in a large freshwater lake, lasted until c. 300 years after the beginning of the interglacial, i.e. to the transition between the regional pollen zones E2 and E3. After that, marine conditions persisted almost throughout the interglacial, and the Cyprina Clay was deposited. The foraminiferal and ostracodal assemblages indicate that relatively deep water prevailed in the area until c. 6000 years after the beginning of the interglacial. However, both the foraminiferal assemblages and the oxygen isotope results show that a trend from relatively high salinity to lower salinity conditions had begun already at about 4000 years. After c. 6000 years the fauna indicates a gradual change to shallower water and further reduction in salinity, the latter also being reflected by a general decrease in the oxygen isotope values. The marine deposition ended at c. 10 600 years after the beginning of the Eemian, i.e. within the topmost part of pollen zone E7. This was succeeded by a late Eemian and early Weichselian freshwater phase.  相似文献   

On the influence of the freshwater supply on the Baltic Sea mean salinity     

JOHAN RODHE  PETER WINSOR 《地球，A辑:动力气象学与海洋学》2003,55(5):455-456

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Improving the representation of radiation interception and photosynthesis for climate model applications     

LINA M. MERCADO  CHRIS HUNTINGFORD  JOHN H. C. GASH  PETER M. COX  VENKATA JOGIREDDY 《Tellus. Series B, Chemical and physical meteorology》2007,59(3):553-565

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Chronology of deglaciation based on ¹⁰Be dates of glacial erosional features in the Grimsel Pass region, central Swiss Alps     

MEREDITH A. KELLY  SUSAN IVY-OCHS  PETER W. KUBIK  FRIEDHELM VON BLANCKENBURG  CHRISTIAN SCHLÜCHTER 《Boreas: An International Journal of Quaternary Research》2006,35(4):634-643

Surface exposure dating, using in situ produced cosmogenic ¹⁰Be, is applied to determine the time since deglaciation of bedrock surfaces in the Grimsel Pass region. Nine ¹⁰Be dates from bedrock surfaces corrected for cover by snow are minimum ages for deglaciation of the pass. Four ¹⁰Be dates from surfaces below 2500 meters above sea level (m a.s.l.) on Nägelisgrätli, east of Grimsel Pass, yield ages that range from about 14 000 to 11 300 years. Three ¹⁰Be dates from locations above 2600 m a.s.l. on Nägelisgrätli are between about 11 700 and 10 400 years. Two ¹⁰Be dates from locations at 2560 m a.s.l. below Juchlistock are about 12 100 and 11 000 years. The geographical distribution of ¹⁰Be dates on Nägelisgrätli either may show the timing of progressive deglaciation of Grimsel Pass or may reflect differences in subglacial erosion of bedrock in the pass region. All dates are discussed in the context of deglaciation of the late Würmian Alpine ice cap and deglaciation from Last Glacial Maximum (LGM) ice extents in other regions.  相似文献   

Sulfur isotopic signals in two shallow ice cores from Dronning Maud Land, Antarctica     

ULF JONSELL  MARGARETA E. HANSSON  CARL-MAGNUS MÖRTH  PETER TORSSANDER 《Tellus. Series B, Chemical and physical meteorology》2005,57(4):341-350

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Cosmic-ray exposure ages of diogenites and the recent collisional history of the howardite,eucrite and diogenite parent body/bodies     

KEES C. WELTEN  LOUIS LINDNER  KLAAS VAN DER BORG  THOMAS LOEKEN  PETER SCHERER  LUDOLF SCHULTZ 《Meteoritics & planetary science》1997,32(6):891-902

Abstract— We determined the cosmic-ray exposure age of 20 diogenites from measured cosmogenic noble gas isotopes and calculated production rates of ³He, ²¹Ne and ³⁸Ar. The production rates were calculated on the basis of the measured chemical composition and the cosmogenic ²²Ne/²¹Ne ratio of each sample. The shielding conditions of each sample were also checked on the basis of the measured ¹⁰Be and ²⁶AI concentrations. The exposure ages range from 6 to 50 Ma but do not form a continuous distribution: ten ages cluster at 21–25 Ma and four at 35–42 Ma. The two diogenite clusters coincide with the 22 Ma and 38 Ma peaks in the exposure age distribution of eucrites and howardites. After the selection from literature data of 32 eucrites and 11 howardites with reliable ages, we find a total of 23 howardite, eucrite and diogenite (HED) group meteorites at 20–25 Ma and 10 at 35–42 Ma. The shape of the two peaks is consistent with single impact events, and random number statistics show that they are statistically significant at the 99% level. Altogether, this provides strong evidence for two major impact events 22 Ma and 39 Ma ago. Although these two events can explain more than half of all HED exposure ages, it takes at least five impact events to explain all ages <50 Ma. An impact frequency of one per 10 Ma corresponds to projectiles of at least 2–4 km in diameter for Vesta and of 60–300 m for the 100× smaller Vesta-derived “vestoids.” Based on the HED exposure-age distribution, the size distribution of the main-belt asteroids and the difference in size between Vesta and the kilometer size vestoids, we favor Vesta as the major source of HED meteorites, although some of the meteorites may have been ejected from the vestoids rather than directly from Vesta.  相似文献