Horizontal homogeneity and vertical extent of new particle formation events   总被引：1，自引：0，他引：1  

BIRGIT WEHNER  HOLGER SIEBERT  FRANK STRATMANN  THOMAS TUCH  ALFRED WIEDENSOHLER  TUUKKA PETÄJÄ  MIIKKA DAL MASO  MARKKU KULMALA 《Tellus. Series B, Chemical and physical meteorology》2007,59(3):362-371

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The lacustrine sediment record of Oberwinkler Maar (Eifel, Germany): Chironomid and macro-remain-based inferences of environmental changes during Oxygen Isotope Stage 3     

STEFAN ENGELS  SJOERD J. P. BOHNCKE  OLIVER HEIRI  KATJA SCHABER  FRANK SIROCKO 《Boreas: An International Journal of Quaternary Research》2008,37(3):414-425

The lacustrine record of Oberwinkler Maar (Eifel, Germany) is the northernmost continuous record documenting the Weichselian Pleniglacial in central Europe – a period characterized by multiple abrupt climate oscillations known as the Dansgaard/Oeschger cycles. Here, the results of a high-resolution study of chironomid remains are presented, with a focus on the earlier part of Oxygen Isotope Stage (OIS) 3 (60–50 kyr BP) covering four stadial/interstadial cycles. During the stadials, the chironomid fauna of the former lake was dominated by many cold-stenothermic chironomid taxa, indicating a cold, oligotrophic lake. The concentrations of chironomid remains were lower during the interstadials, and featured a higher number of warm-indicating taxa. This could have been the result of a higher summer temperature at the study site, but also of bottom-water anoxia, an increase in trophic state or a combination of all these factors. During the stadial intervals, a taxon that is restricted to (sub-)arctic environments is present in our record, suggesting a change in the temperature regime rather than in-lake processes as the driving mechanism for the changes in the chironomid record. Although, consistently, there was a response of the lake ecosystem to climate changes, the amplitude of this response was not constant. This study provides unique and independent evidence of the impact of Dansgaard/Oeschger climate variability on the European continent during the earlier part of OIS-3.  相似文献   

Age, origin and significance of a new middle MIS 3 tephra horizon identified within a long-core sequence from Les Echets, France     

DANIEL VERES  SIWAN M. DAVIES  BARBARA WOHLFARTH  FRANK PREUSSER  STEFAN WASTEGÅRD  LINDA AMPEL  ANNE HORMES  GÖRAN POSSNERT  JEAN-PAUL RAYNAL  GÉRARD VERNET 《Boreas: An International Journal of Quaternary Research》2008,37(3):434-443

A new tephra has been identified within a long core (EC 3) sequence recovered from Les Echets, near Lyon, France. This visible tephra was discovered as part of a high resolution multiproxy re-investigation of the Les Echets sequence. Independent chronological information suggests that the tephra is c . 2 000–45 000 years old, and geochemical analysis indicates that it is of basanitic composition. The latter suggests a possible origin in the Eifel; however, as yet, no other volcanic events or deposits can be correlated to the Les Echets tephra. New sedimentological and chronological data are presented indicating that the tephra falls within an interval that most likely correlates with Dansgaard–Oeschger events 12-9. Thus, this tephra could potentially be an important middle MIS 3 marker horizon in central Europe if it can be traced in other palaeorecords.  相似文献   

Diagenetic formation of gypsum and dolomite in a cold‐water coral mound in the Porcupine Seabight,off Ireland     

HANS PIRLET  LAURA M. WEHRMANN  BENJAMIN BRUNNER  NORBERT FRANK  JAN DEWANCKELE  DAVID VAN ROOIJ  ANNELEEN FOUBERT  RUDY SWENNEN  LIEVEN NAUDTS  MATTHIEU BOONE  VEERLE CNUDDE  JEAN‐PIERRE HENRIET 《Sedimentology》2010,57(3):786-805

Authigenic gypsum was found in a gravity core, retrieved from the top of Mound Perseverance, a giant cold‐water coral mound in the Porcupine Basin, off Ireland. The occurrence of gypsum in such an environment is intriguing, because gypsum, a classic evaporitic mineral, is undersaturated with respect to sea water. Sedimentological, petrographic and isotopic evidence point to diagenetic formation of the gypsum, tied to oxidation of sedimentary sulphide minerals (i.e. pyrite). This oxidation is attributed to a phase of increased bottom currents which caused erosion and enhanced inflow of oxidizing fluids into the mound sediments. The oxidation of pyrite produced acidity, causing carbonate dissolution and subsequently leading to pore‐water oversaturation with respect to gypsum and dolomite. Calculations based on the isotopic compositions of gypsum and pyrite reveal that between 21·6% and 28·6% of the sulphate incorporated into the gypsum derived from pyrite oxidation. The dissolution of carbonate increased the porosity in the affected sediment layer but promoted lithification of the sediments at the sediment‐water interface. Thus, authigenic gypsum can serve as a signature for diagenetic oxidation events in carbonate‐rich sediments. These observations demonstrate that fluid flow, steered by environmental factors, has an important effect on the diagenesis of coral mounds.  相似文献   

Circulation regime fluctuations and their effect on intraseasonal variability in the ECHAM climate model     

MICHAEL PONATER  WINFRIED KÖNIG  ROBERT SAUSEN  FRANK SIELMANN 《地球，A辑:动力气象学与海洋学》1994,46(3):265-285

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The early days of the 100 kyr cycle     

FRANK SIROCKO 《Boreas: An International Journal of Quaternary Research》2006,35(4):694-694

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Environmental change modelling for Central and High Asia: Pleistocene, present and future scenarios     

JÜRGEN BÖHNER  FRANK LEHMKUHL 《Boreas: An International Journal of Quaternary Research》2005,34(2):220-231

A regional modelling concept was developed for late Quaternary climate reconstructions and future climate impact assessments. Based on estimates of different climate parameters covering the entire Central and High Asia in a grid-cell spacing of 1 km², climatic determinants of the recent spatial distribution of climate-sensitive environments (glacial and periglacial environments, forest) were explored. Simple climatic threshold functions were established, defining critical climate values for modelling the spatial extension of environments considered. Using palaeogeomorphological indicators as a basis, late Quaternary climatic conditions were modelled in a Last Glacial Maximum (LGM) scenario consistent with palaeogeomorphological and palaeoclimatological data. The results enabled a validation of LGM palaeoclimate simulations performed by the ECHAM GCM. To assess the magnitude of possible future climatic impacts on the spatial distribution of glaciers, permafrost and potential forest stands, two GCM-based IPCC-SRES climate change scenarios (IPCC special report on emission scenarios) for the time period 2070-2099 were considered. Assuming future climates to be perturbed for long enough to affect the environments, a distinct loss of glaciated areas and permafrost must be expected.  相似文献   

REGIONAL DEVELOPMENT IN DENMARK     

ROLF GUTTESEN M.Sc.  FRANK HANSEN M.Sc.  BUE NIELSEN M.Sc. 《Geografisk tidskrift / udgivet af Bestyrelsen for Det Kongelige danske geografiske selskab》2013,113(1):74-87

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Hydrogeochemical analysis for Tasuj plain aquifer, Iran   总被引：1，自引：0，他引：1  

ATA ALLAH NADIRI  ASGHAR ASGHARI MOGHADDAM  FRANK T-C TSAI  ELHAM FIJANI 《Journal of Earth System Science》2013,122(4):1091-1105

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Metamorphic P–T Paths from pelitic schists and greenstones from the south-west Tauern Window, Eastern Alps     

JANE SELVERSTONE  FRANK S. SPEAR 《Journal of Metamorphic Geology》1985,3(4):439-465

Abstract Petrological data from intercalated pelitic schists and greenstones are used to construct a pressure–temperature path followed by the Upper Schieferhülle (USH) series during progressive metamorphism and uplift in the south-west Tauern Window, Italy. Pseudomorphs of Al–epidote + Fe-epidote + albite + oligoclase + chlorite after lawsonite and data on amphibole crystal chemistry indicate early metamorphism in the lawsonite-albite-chlorite subfacies of the blueschist facies at P ± 7–8 kbar. Geothermometry and geobarometry yield conditions of final equilibration of the matrix assemblage of 475±25°C, 5–6 kbar; calculations with plagioclase and phengite inclusions in garnet indicate early garnet growth at pressures of ∼ 7.5 kbar. Garnet zoning patterns are complex and reversals in zoning can be correlated between samples. Thermodynamic modelling of these zoning profiles implies garnet growth in response to four distinct phases of tectonic activity. Fluid inclusion data from coexisting immiscible H₂O–CO₂–NaCl fluids constrain the uplift path to have passed through temperatures of 380 + 30°C at 1.3 + 0.2 kbar.
There is no evidence for metamorphism of USH at pressures greater than ∼ 7.5 kbar in this area of the Tauern Window. This is in contrast to pressures of ± 10 kbar recorded in the Lower Schieferhülle only 2–3 km across strike. A history of differential uplift and thinning of the intervening section during metamorphism is necessary to reconcile the P–T data obtained from these adjacent tectonic units.  相似文献