Poor fen succession over ombrotrophic peat related to late Holocene increased surface wetness in subarctic Quebec,Canada     

MICHELLE GARNEAU  ALEXANDRE LAMARRE  ÉLISABETH C. ROBERT  GABRIEL MAGNAN  HANS ASNONG  STEVE PRATTE 《第四纪科学杂志》2013,28(8):748-760

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Changes in the winter precipitation in Romania and its relation to the large-scale circulation   总被引：1，自引：0，他引：1  

ARISTITA BUSUIOC  HANS VON STORCH 《地球，A辑:动力气象学与海洋学》1996,48(4):538-552

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NUMERICAL INTERPRETATION OF RESISTIVITY SOUNDINGS OVER HORIZONTAL BEDS*     

HANS A. MEINARDUS 《Geophysical Prospecting》1970,18(3):415-433

The digital computer technique described for interpreting resistivity soundings over a horizontally stratified earth requires two steps. First, the kernel function is evaluated numerically from the inverse Hankel transform of the observed apparent resistivity curve. Special attention is given to the inversion of resistivity data recorded over a section with a resistant basement. The second step consists in the least-squares estimation of layer resistivities and thicknesses from the kernel function. For the case of S or T-equivalent beds only one layer-parameter can be obtained, either the longitudinal conductance, or the transverse resistance respectively. Two examples given in the paper show that a wide tolerance is permitted for Choosing the starting values of the layering parameters in the successive approximation procedure. Another important feature for practical applications is good convergence of the iterations. The method is probably best suited for interpreting profiles of electrical soundings with the purpose of mapping approximately horizontal interfaces at depth.  相似文献   

Central Scandinavian winter precipitation variability during the past five centuries reconstructed from Pinus sylvestris tree rings     

HANS W. LINDERHOLM  DELIANG CHEN 《Boreas: An International Journal of Quaternary Research》2005,34(1):43-52

Using Scots pine ( Pinus sylvestris L.) tree-ring data, winter (September-April) precipitation variability in west central Scandinavia was reconstructed for the past five centuries. The main growth-limiting factor for pine growing in the studied area is summer temperature, but there is an additional influence of precipitation. Using principal components analysis on three tree-ring-width chronologies, a time series was yielded that contained information on winter precipitation (P_w). Using tree rings, only a small part (20%) of the interannual P_w variability could be explained. However, better agreement between the modelled and measured P_w data on semi-decadal time scales (45% variance explained) suggests that tree-ring data from the west-central part of Scandinavia contain useful information on those time scales. The driest winters, disregarding the absolute beginning of the record, were found at the beginning of the 18th century; the last half of the 20th century seems to be the wettest, at least for the past 400 years. Since our precipitation reconstruction agrees fairly well with previously published precipitation proxies, it is suggested that tree rings may add useful information to future multi-proxy reconstructions.  相似文献   

CO₂ measurements from polar ice cores: more data from different sites     

THOMAS STAFFELBACH  BERNHARD STAUFFER  REAS SIGG  HANS OESCHGER 《Tellus. Series B, Chemical and physical meteorology》1991,43(2):91-96

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Moscovian (Carboniferous) microfossils (Bryozoa, Conodonta, and Fusulinida) from Novaya Zemlya, Arctic U.S.S.R.     

HANS A. NAKREM  INGER NILSSON  BJØRN T. SIMONSEN 《Polar research》1991,9(1):45-64

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DIFFERENT SOURCES CONTRIBUTING TO A BEACH SAND, SOUTHEASTERN BORNHOLM (DENMARK)     

HANS FÜCHTBAUER and  JOHN M. ELROD 《Sedimentology》1971,17(1-2):69-79

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Lateglacial landform associations at Jæren (SW Norway) and their glaci-dynamic implications     

STÅLE RAUNHOLM  HANS PETTER SEJRUP  EILIV LARSEN 《Boreas: An International Journal of Quaternary Research》2003,32(3):462-475

The Jæren lowland is located on the southwestern coast of Norway between a mountainous region in the east and the offshore Norwegian Channel in the west. During the Last Glacial Maximum, Jæren was in an intermediate position between an ice stream following the Norwegian Channel northwards, and westward flowing inland ice. The dynamic behaviour of the inland ice and the interaction with the ice stream are examined by means of geomorphological analysis of digital terrain models and sedimentological investigations. SW-trending drumlins were formed at Jæren below tributary ice from the inland, feeding into the Norwegian Channel Ice Stream. The presence of Rogen moraine in the central part of Jæren indicates a frozen substratum prior to their formation, and this suggests a transition to cold-based ice between the tributaries. The deglaciation of the Norwegian Channel at about 15 ka BP resulted in an unstable ice front for the inland ice sheet. The formation of Rogen moraine may be explained by a dynamic advance resulting in extensional flow and fracturing of the frozen substratum between the tributaries. The dynamic advance was followed by an early deglaciation of the coastal areas as evidenced by shallow marine sediments. Deformation of the shallow marine sand indicates a glacial readvance through the valleys formerly acting as tributaries to the ice stream.  相似文献   

SEDIMENT TRANSPORT, DELTA GROWTH AND SEDIMENTATION IN LAKE NIGARDSVATN, NORWAY     

GUNNAR ØSTREM  NILS HAAKENSEN  HANS CHR. OLSEN 《Geografiska Annaler: Series A, Physical Geography》2005,87(1):243-258

ABSTRACT. The retreat of Nigardsbreen, an outlet glacier from the ice-cap Jostedalsbreen in south-central Norway, from its largest extent during the Little Ice Age, uncovered a proglacial lake during 1936–1967. This lake, Nigardsvatn, has been studied since 1968 in order to obtain data on solid material carried by the meltwater stream from the glacier, both in suspension and as bottom load. Between 70 and 85% of the suspended sediment has been deposited on the lake bottom, forming annual varves. The coarse material has been deposited in a delta, the formation of which started in 1968. Its growth, and hence the volume of total annual bottom load, has been surveyed annually for the past 36 years. In 1969 the entire bottom load was collected by building a fence-like net across the river. Material >3 cm was caught by this net, and formed approximately half the amount of suspended sediment transport during the same three-week period. Annual average deposition on the delta was 11800×10³ kg for the period 1968–2003. This is almost the same amount as carried in suspension from the glacier on an annual mean basis for the 36-year period. If conditions remain constant, the lake will be completely filled in about 500 years. The glacier erosion is calculated to be 0.3 mm/a.  相似文献   

Ferroan calcite replacement indicates former magnesian calcite skeletons     

DETLEV K. RICHTER  HANS FÜCHTBAUER 《Sedimentology》1978,25(6):843-860

The replacement by ferroan calcite with preservation of the original structures can be used as a new criterion for identifying skeletons originally composed of high-magnesian calcite. This applies to bryozoa, rugose corals, echinoderms, many foraminifera, most ostracods, red algae, and serpulids. On the other hand, skeletons originally composed of low-magnesian calcite were never replaced by ferroan calcite, as shown by belemnites, brachiopods, and most of the pelecypods. Using this criterion, an original low-magnesian calcite composition is inferred for Tentaculites and some ostracods and foraminifera, whereas a previous high-magnesian calcite composition is inferred for trilobites, oligostegina and certain ooids. Chemical instability of high-magnesian calcite is suggested to be the driving force of the replacement by ferroan calcite. In most of the thirty-seven samples investigated, of Oligocene to Devonian age, the ferrous iron concentration of the interstitial fluid increased during diagenesis, as shown by well established sequences of cement A and B and fissure fill. This offers a relative time scale for diagenetic processes. Ferroan calcites contain up to 6 mol % FeCO₃ and up to 5 mol % MgCO₃. In this range of concentration, the distribution coefficients for Fe and Mg between calcite and solution at about 25°C are about 1 to 0-03, respectively, according to experiments. Possible sources of iron are iron oxides and hydroxides as well as clay minerals including glauconite. Though a submarine origin below the sediment surface is conceivable for ferroan calcite, there are serious limiting conditions such as low Eh and, at the same time, lack in sulphate-reducing bacteria. On the other hand, ferroan ‘dedolomite’, compositional zonality in individual ferroan calcite overgrowths, low δ¹⁸C and δ¹⁸O values, and low Mg concentrations point more to a meteoric-phreatic origin of many ferroan calcite occurrences.  相似文献