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1.
METTE BJØRNSEN LARS B. CLEMMENSEN REW MURRAY KARSTEN PEDERSEN 《Boreas: An International Journal of Quaternary Research》2008,37(1):157-168
Recent geomorphological and sedimentological investigation of the raised beach ridge plain on Anholt in the Kattegat Sea, Denmark, has demonstrated how these deposits, when combined with Optically Stimulated Luminescence (OSL) dating, can provide information about past changes in relative sea level. The southwest–northeast trending plain is divided into three topographic levels, one of which has been surveyed using Ground-Penetrating Radar (GPR). Samples retrieved from the survey line indicate that the initial part of the beach ridge plain formed about 7700 years ago in response to a mid-Holocene Littorina transgression. The raised marine deposits document a subsequent rise in relative sea level of about 9 m, and OSL dates indicate that this transgression took place about 6650 years ago. The flooding of the Kattegat Sea 7700 years ago might possibly be related to a rapid global sea-level rise peaking around 7500 years ago. 相似文献
2.
Petrogenesis of Tertiary Continental Intra-plate Lavas from the Westerwald Region, Germany 总被引：2，自引：2，他引：2
HAASE KARSTEN M.; GOLDSCHMIDT BJORN; GARBE-SCHONBERG C.-DIETER 《Journal of Petrology》2004,45(5):883-905
Tertiary volcanic rocks from the Westerwald region range frombasanites and alkali basalts to trachytes, whereas lavas fromthe margin of the Vogelsberg volcanic field consist of morealkaline basanites and alkali basalts. Heavy rare earth elementfractionation indicates that the primitive Westerwald magmasprobably represent melts of garnet peridotite. The Vogelsbergmelts formed in the spinel–garnet peridotite transitionregion with residual amphibole for some magmas suggesting meltingof relatively cold mantle. Assimilation of lower-crustal rocksand fractional crystallization altered the composition of lavasfrom the Westerwald and Vogelsberg region significantly. Thecontaminating lower crust beneath the Rhenish Massif has a differentisotopic composition from the lower continental crust beneaththe Hessian Depression and Vogelsberg, implying a compositionalboundary between the two crustal domains. The mantle sourceof the lavas from the Rhenish Massif has higher 206Pb/204Pband 87Sr/86Sr than the mantle source beneath the Vogelsbergand Hessian Depression. The 30–20 Ma volcanism of theWesterwald apparently had the same mantle source as the QuaternaryEifel lavas, suggesting that the magmas probably formed in apulsing mantle plume with a maximum excess temperature of 100°Cbeneath the Rhenish Massif. The relatively shallow melting ofamphibole-bearing peridotite beneath the Vogelsberg and HessianDepression may indicate an origin from a metasomatized portionof the thermal boundary layer. KEY WORDS: continental rift volcanism; basanites; trachytes; assimilation; fractional crystallization; partial melting 相似文献
3.
Total field anomalies as defined from normal aeromagnetic surveys give good approximations of the anomalous components along the direction of the main geomagnetic field, which is generally much larger than the anomalous field. Using the relations between vertical and horizontal components of the field, the total field anomaly is related to any vertical or horizontal component and the corresponding horizontal and vertical derivatives. An example from the Siljan impact structure indicates that such directional filters may be applied to extract useful information from magnetic maps. 相似文献
4.
H. PEDERSEN R. E. SPALDING E. TAGLIAFERRI Z. CEPLECHA T. RISBO H. HAACK 《Meteoritics & planetary science》2001,36(4):549-558
Abstract— Data on the trajectory and orbit of an extremely bright bolide (superbolide) over Greenland on 1997 December 9 are given, and circumstances of the phenomenon and its observations are described. A surveillance video camera and satellite‐based records enabled computing the trajectory and orbit independently of visual sightings of casual observers. The superbolide body of about 36 000 kg penetrated the atmosphere with an initial velocity of 30.5 ± 1.7 km s?1. Its orbit was a long‐period orbit and seems to be at variance with the low value of ablation coefficient (0.017 kg MJ?1) derived from modeling the atmospheric trajectory. However, such an event has been documented previously. Also the intensity and brevity of the satellite‐detected light flares are highly unusual. The impact area of the main hypothetical remnant of the body is given. Search for meteorites was performed. No meteorites were recovered. Also analysis of snow samples gave no hint of meteoritic dust. 相似文献
5.
A general treatment of end corrections in gravity and magnetic modeling is presented. The well-known 2-D formulae of Talwani and Talwani and Heirtzler become slightly changed to represent a 2 1/2–D body, i.e. a body of polygonal cross section with the tails In the strike direction cut off. 相似文献
6.
L. B
RSTING PEDERSEN 《Geophysical Prospecting》1977,25(2):199-230
The interpretation of potential field data from two-dimensional structures with a single interface of density or susceptibility contrasts is solved in terms of generalized matrix inversion. The model equations are derived, and important features of generalized matrix inversion are treated. The method is subsequently used to solve two gravity problems, an artificial one where the solution is known, and a geophysical one related to the crust-mantle interface. The solution is shown to compare well with the FFT results of Oldenburg. The method is also used to solve two magnetic problems, an artificial one with the solution known, and a geophysical one from the continental shelf of Greenland. The advantages and limitations of the method are finally discussed. 相似文献
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8.
JAN-PETTER PEDERSEN 《Polar research》1990,8(1):3-9
This paper introduces satellite remote sensing of sea-surface temperatures and ocean colour studies. The basic radiative transfer equations and available satellite sensor systems are presented. The final part of the paper focuses on temperature applications. Sea surface temperature data derived from available satellite data are presented and discussed. 相似文献
9.
KARSTEN ALBÆK JENSEN KAREN LUISE KNUDSEN 《Boreas: An International Journal of Quaternary Research》1988,17(3):273-287
A 140.2 m deep boring (BH 81/29) from the central North Sea (British sector) has been investigated for its foraminiferal content. Fourteen assemblage zones are identified, and these are correlated with other records from the North Sea region. The stratigraphical interpretation of BH 81/29 is supported by palaeomagnetic data and by amino acid dates and thermoluminescence dates from the same boring. Foraminiferal zones 14 to 8, from the bottom of the core, have been referred to the Early Pleistocene. Zones 7 to 4, which occur above the Bruhnes/Matuyama boundary, seem to belonged in the Middle Pleistocene, and zones 3 to 1 are referred to the Late Pleistocene. A characteristic feature of the present sequence is that a major part of the Quaternary record seems to be missing. As is also known from other areas of the North Sea, interglacial deposits are especially badly represented. 相似文献
10.
Excellent exposures of thick, multistorey, fluvial deposits from the deltaic Atane Formation on south‐east Nuussuaq, central West Greenland, show the architecture of up to 100 m thick continuously aggrading fluvial depositional complexes. The succession comprises vertically stacked channel belt sandstones separated by thin floodplain deposits, with little to no incision between storeys. Architectural elements and palaeocurrent patterns of channel deposits indicate deposition in large, relatively stable, low‐sinuosity rivers, probably located within an incised valley. Gradual transitions from channel to floodplain deposits accompanied by a gradual change from floodplain to spillover sand suggest avulsion on the floodplain as a possible mechanism for the vertically alternating channel and floodplain deposits. Despite its relative proximity to contemporaneous sea‐level (ca 35 km upstream from the palaeo‐shoreline) the depositional complex is entirely non‐marine. The aggrading nature of the deposits suggests a continuously rising base level coupled with a high and steady sediment supply. Vertical alternations between floodplain and channel deposits may be forced by subtle interruptions in this balance or autocyclic mechanisms on the floodplain. This study provides an example of aggrading lowstand/non‐marine transgressive systems tract deposits. 相似文献