Oligocene sequence stratigraphy and basin development in the Danish North Sea sector based on log interpretations     

Mette Danielsen  Olaf Michelsen  Ole Rn Clausen 《Marine and Petroleum Geology》1997,14(7-8)

Five sequences are defined in the Oligocene succession of the Danish North Sea sector. Two of the sequences, 4.1a and 4.3, have been identified onshore Denmark.Two types of prograding lowstand deposits are recognized. Sand-dominated deposits occur proximally, comprising sharp-based forced regressive deposits covered with prograding low-stand deposits. Clay-dominated prograding lowstand deposits occur distally in the sequences. The highstand deposits are proximally represented by thick prograding sandy deposits and distally by thin and condensed intervals.The main sediment input direction was from the north and the northeast. A succession oif lithofacies, from shallow marine facies dominated by sand to outer shelf facies dominated by clay, is mapped in each of the sequences. An overall southward progradation of the shoreline took place during the Oligocene, interrupted only by minor shoreline retreats.  相似文献   

Byproduct Formation During the Reduction of TCE by Zero-Valence Iron and Palladized Iron   总被引：4，自引：0，他引：4  

Liyuan Liang  Nic Korte  J.D. Goodlaxson  Jay Clausen  Quintus Fernando  Rosy Muftikian 《Ground Water Monitoring & Remediation》1997,17(1):122-127

Trichloroethene (TCE) was reduced with zero-valence iron and palladized iron in zero-head-space extractors. Progress of the reaction in these batch studies was monitored with purge-and-trap gas chromatography and a flame ionization detector. When a 5 ppm initial concentration of TCF. reacts with zero-valence iron, approximately 140 ppb of vinyl chloride persists for as long as 73 days. The concentration of vinyl chloride (approximately If) ppb) remaining with palladized iron is approximately an order of magnitude less than when zero-valence iron is the reductant. These data suggest that volatile byproducts may be under-represented in oilier published data regarding reduction with zero-valence metals. These results also demonstrate that the reduction of TCE with palladized iron (0.05 percent palladium) is more than an order of magnitude faster than with zero-valence iron. Wilh a 5:1 solution-to-solid ratio the TCE half-life with zero-valence iron is 7.41 hours. but is only 0.59 hours with the palladized iron.  相似文献   

Energetic Compound False Positives in Ground Water Profile Samples     

Jay Clausen  Elizabeth Wessling  Brad Chirgwin 《Ground Water Monitoring & Remediation》2007,27(3):90-101

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Eclipsing Binaries in Open Clusters     

John Southworth  Jens Viggo Clausen 《Astrophysics and Space Science》2006,304(1-4):199-202

The study of detached eclipsing binaries in open clusters can provide stringent tests of theoretical stellar evolutionary models, which must simultaneously fit the masses, radii, and luminosities of the eclipsing stars and the radiative properties of every other star in the cluster. We review recent progress in such studies and discuss two unusually interesting objects currently under analysis. GV Carinae is an A0 m + A8 m binary in the Southern open cluster NGC 3532; its eclipse depths have changed by 0.1 mag between 1990 and 2001, suggesting that its orbit is being perturbed by a relatively close third body. DW Carinae is a high-mass unevolved B1 V + B1 V binary in the very young open cluster Collinder 228, and displays double-peaked emission in the centre of the Hα line which is characteristic of Be stars. We conclude by pointing out that the great promise of eclipsing binaries in open clusters can only be satisfied when both the binaries and their parent clusters are well-observed, a situation which is less common than we would like.  相似文献   

Reply to comment of E. S. Rasmussen and K. Dybkjær on Patterns of Cenozoic sediment flux from western Scandinavia,by B. Gołędowski,S. B. Nielsen and O. R. Clausen,Basin Research (2012), 24(4), 377–400     

B. Gołędowski  O. R. Clausen  S. B. Nielsen 《Basin Research》2014,26(2):347-350

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No iridium anomaly after the 1908 Tunguska impact: Evidence from a Greenland ice core     

Kaare L. Rasmussen  Henrk B. Clausen  Gregory W. Kallemeyn 《Meteoritics & planetary science》1995,30(6):634-638

Abstract— We have determined the abundances of Ir and other elements by neutron activation analysis on annual dust samples from an ice core from Site B in the Crête region in central Greenland covering the years 1905–1914. Iridium was detected in all samples, but we found no excess Ir above the background in the years following the Tunguska event. The lack of an Ir anomaly in the years after the Tunguska impact combined with the knowledge of the energy released during the impact and our present knowledge about stratospheric transport implies either a very low Ir content of the impactor or an exceptionally high geocentric velocity for the impactor.  相似文献   

Analyses of possible changes in intense and extreme wind speeds over northern Europe under climate change scenarios   总被引：1，自引：0，他引：1  

S. C. Pryor  R. J. Barthelmie  N. E. Clausen  M. Drews  N. MacKellar  E. Kjellstr?m 《Climate Dynamics》2012,38(1-2):189-208

Dynamical downscaling of ECHAM5 using HIRHAM5 and RCA3 for a northern European domain focused on Scandinavia indicates sustained extreme wind speeds with long recurrence intervals (50?years) and intense winds are not likely to evolve out of the historical envelope of variability until the end of C21st. Even then, significant changes are indicated only in the SW of the domain and across the central Baltic Sea where there is some evidence for relatively small magnitude increases in the 50?year return period wind speed (of up to 15%). There are marked differences in results based on the two Regional Climate Models. Additionally, internal (inherent) variability and initial conditions exert a strong impact on projected wind climates throughout the twenty-first century. Simulations of wind gusts by one of the RCMs (RCA3) indicate some evidence for increased magnitudes (of up to +10%) in the southwest of the domain and across the central Baltic Sea by the end of the current century. As in prior downscaling of ECHAM4, dynamical downscaling of ECHAM5 indicates a tendency towards increased energy density and thus wind power generation potential over the course of the C21st. However, caution should be used in interpreting this inference given the high degree of wind climate projection spread that derives from the specific AOGCM and RCM used in the downscaling.  相似文献   

Lithofacies and cyclicity of Mohilla evaporite basins on the rifted margin of the Levant in the Late Triassic,Makhtesh Ramon,southern Israel     

OR M. BIALIK  DORIT KORNGREEN  CHAIM BENJAMINI 《Sedimentology》2012,59(7):2097-2124

Marine‐connected basins with evaporites occur beneath most extensional continental margins that originated at low‐latitudes and often are of major economic significance. Cyclicity in the evaporite lithofacies reflects the degree of restriction of the basin, overprinted by sea‐level changes, and caused by structural movements in the barrier region, whether by fault‐block rotation, footwall uplift or hanging wall subsidence, in both extensional and compressional basins. The Upper Triassic evaporites of the Ramon section in southern Israel model cyclic sedimentation in such environments. The Mohilla Formation is a carbonate–evaporate–siliciclastic succession of Carnian age that fills a chain of basins extending along the Levant margin from southern Israel to Jordan and Syria. The basins developed in half‐grabens adjacent to normal faults that formed during a period of regional extension. Evaporites of this formation are well‐exposed in outcrops at Makhtesh Ramon, the southernmost of these basins. The M2 Member of the Mohilla Formation is composed of 42 sub‐metre cycles of alternating dolostone, gypsum and calcareous shales. Field and microfacies analysis showed these cycles to conform mostly to restricted shallow and marginal marine environments, spatially limited by the uplifted shoulders of the half‐graben systems. A total of 10 facies types belonging to six depositional environments have been identified. From stacking patterns and analysis of bed to bed change, cycles can be categorized into three groupings: (i) low frequency exposure to exposure cycles that developed under eustatic or climate control; (ii) high frequency deepening/shallowing‐upward cycles, characterized by gradual transitions due to short‐term sea‐level or runoff‐event oscillations possibly referable to orbital forcing; and (iii) high frequency shallowing‐upward cycles, characterized by abrupt transitions, attributable to sporadic tectonic events affecting accommodation space or barrier effectiveness. The way facies and cycling of the sedimentary environments was deciphered in the Mohilla evaporite basin can be used to unravel the genesis of many other evaporite basins with barriers of tectonic origin.  相似文献   

Filter-feeding ascidians (Ciona intestinalis) in a shallow cove: Implications of hydrodynamics for grazing impact     

Hans Ulrik Riisgård  Carsten Jürgensen  Torben Clausen 《Journal of Sea Research》1996,35(4):293-300

The grazing impact by a dense population of filter-feeding ascidians Ciona intestinalis on horizontally flowing water (driven by density circulation) in a shallow cove (Kertinge Nor, Denmark) has been described and quantified by means of a simple one-dimensional numerical model. The agreement between observations and modelled predictions was satisfactory. The applied numerical model has the following analytical solution in the idealized case: Cx = C₀e^−(fx/Y₂), where C_x = algal concentration at a downstream distance x, C₀ = initial concentration, f = F/v_c; F = area specific population filtration rate; v_c = current velocity; Y₂ = depth of mixed layer below halocline. The numerical model quantifies the actual grazing impact while the analytical model illustrates the governing physics in well-known terms. To describe situations with no current (i.e. stagnant water), we performed simulation studies in the laboratory and measured vertical profiles of algal cells over filter-feeding C. intestinalis. The results showed that phytoplankton became reduced in a near-bottom water layer of 20–30 cm thickness. Such water layers may develop in stagnant water (calm days and no advective currents), thus uncoupling the pelagic food and the filter feeders which within a short time will experience extremely meagre food conditions.  相似文献   

Frequency of swimming and energy cost of byssus production in Chlamys islandica (O. F. Muller)     

Vahl  O.; Clausen  B. 《ICES Journal of Marine Science》1980,39(1):101-103

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