Test of a northwards-decreasing ²²²Rn source term by comparison of modelled and observed atmospheric ²²²Rn concentrations     

LYNETTE B. ROBERTSON  DAVID S. STEVENSON  FRANZ CONEN 《Tellus. Series B, Chemical and physical meteorology》2005,57(2):116-123

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Microstructure,chemistry, and origin of grain rims on ilmenite from the lunar soil finest fraction     

Roy CHRISTOFFERSEN  DAVID S. McKay  Lindsay P. KELLER 《Meteoritics & planetary science》1996,31(6):835-848

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ENSO prediction experiments using a simple ocean-atmosphere model     

DENG-HUA WU  DAVID L. T. ANDERSON  MICHAEL K. DAVEY 《地球，A辑:动力气象学与海洋学》1994,46(4):465-480

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Remote sensing     

DAVID A. ROTHERY 《Geology Today》1985,1(4):105-108

Pictures in digital form taken from space or aircraft can be processed to reveal useful structural and compositional information on geology. Widespread, uniform coverage enhances our understanding of large areas of this and other planets. Continuing improvements in technology suggest that remote sensing will play an increasingly important role in geological research and exploration.  相似文献   

Modelling the seasonal course of the upper ocean pCO₂ (II). Validation of the model and sensitivity studies     

DAVID ANTOINE  ANDRÉ MOREL 《Tellus. Series B, Chemical and physical meteorology》1995,47(1-2):122-144

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A geological excursion in the Wadi Fatima area, near Jiddah, Saudi Arabia     

DAVID J. GRAINGER 《Geology Today》1992,8(6):215-219

Wadi Fatima, east of jiddah on the Red Sea coast of Saudi Arabia, is a microcosm of the geology of the jiddah area. Rocks ranging in age from 800-million-year-old metamorphic rocks to Tertiary lava flows are exposed, and illustrate the geological richness of western Saudi Arabia. The valley is a major south-west-trending fault zone that has been active since Precambrian times. A major Tertiary dyke swarm in the vicinity of Wadi Fatima is related to the opening of the Red Sea as the African-Arabian landmass split apart.  相似文献   

Quantifying sample bias in clast fabric measurements     

DAVID M. CHANDLER  BRYN HUBBARD 《Sedimentology》2008,55(4):925-938

Sampling elongate clasts that protrude from a planar face for clast macro‐fabric analysis introduces a bias into reconstructed fabrics because clasts aligned perpendicular to the sampling face are over‐represented relative to those aligned parallel to the face. This study develops a probability‐based mathematical analysis to quantify sample bias for a variety of clast shapes and population fabrics, including isotropic, clustered and girdled fabric styles. Bias is expressed in terms of sample eigenvalues and eigenvectors relative to those of the parent population. Results indicate that sampling always has the effect of artificially drawing fabrics towards perpendicularity to the sampling face relative to the populations from which they are drawn. This rotation generally has the effect of artificially strengthening population fabrics, by up to 30% in the case of very weakly clustered or girdled populations. However, fabric strengthening is by no means universal and sampling alters different parent populations in different, sometimes complex, ways: the analysis in this paper identifies situations where sampling can strengthen or weaken parent fabrics, where it can rotate parent fabrics (by up to 90° in the case of a very weak population fabric), and where it can even change the style of a population fabric. For example, near‐isotropic population fabrics can appear clustered; weakly clustered and weakly girdled population fabrics can appear isotropic; weakly clustered population fabrics can appear weakly girdled; and girdled population fabrics can appear clustered. Overall, this analysis indicates that weakly orientated population fabrics are most susceptible to bias. Thus, a weakly clustered population fabric aligned parallel to a sample face is particularly susceptible to major sample bias in both fabric strength (artificially overestimated) and orientation (artificially rotated perpendicular to the face). Bias can be reduced either by sampling all the clasts from a cube‐shaped block of sediment excavated from the face, or by sampling equal numbers of clasts from the three orthogonal faces of the same sedimentary unit.  相似文献   

Dimensions and architecture of late Pleistocene submarine lobes off the northern margin of East Corsica   总被引：2，自引：0，他引：2  

MARK E. DEPTUCK  DAVID J. W. PIPER  BRUNO SAVOYE  ANNE GERVAIS‡ 《Sedimentology》2008,55(4):869-898

Sandy lobe deposits on submarine fans are sensitive recorders of the types of sediment gravity flows supplied to a basin and are economically important as hydrocarbon reservoirs. This study investigates the causes of variability in 20 lobes in small late Pleistocene submarine fans off East Corsica. These lobes were imaged using ultra‐high resolution boomer seismic profiles (<1 m vertical resolution) and sediment type was ground truthed using piston cores published in previous studies. Repeated crossings of the same depositional bodies were used to measure spatial changes in their dimensions and architecture. Most lobes increase abruptly down‐slope to a peak thickness of 8 to 42 m, beyond which they show a progressive, typically more gradual, decrease in thickness until they thin to below seismic resolution or pass into draping facies of the basin plain. Lobe areas range from 3 to 70 km² and total lengths from 2 to 14 km, with the locus of maximum sediment accumulation from 3 to 28 km from the shelf‐break. Based on their location, dimensions, internal architecture and nature of the feeder channel, the lobes are divided into two end‐member types. The first are small depositional bodies located in proximal settings, clustered near the toe‐of‐slope and fed by slope gullies or erosive channels lacking or with poorly developed levées (referred to as ‘proximal isolated lobes’). The second are larger architecturally more complex depositional bodies deposited in more distal settings, outboard more stable and longer‐lived levéed fan valleys (referred to as ‘composite mid‐fan lobes’). Hybrid lobe types are also observed. At least three hierarchical levels of compensation stacking are recognized. Individual beds and bed‐sets stack to form lobe‐elements; lobe‐elements stack to form composite lobes; and composite lobes stack to form lobe complexes. Differences in the size, shape and architectural complexity of lobe deposits reflect several inter‐related factors including: (i) flow properties (volume, duration, grain‐size, concentration and velocity); (ii) the number and frequency of flows, and their degree of variation through time; (iii) gradient change and sea floor morphology at the mouth of the feeder conduit; (iv) lobe lifespan prior to avulsion or abandonment; and (v) feeder channel geometry and stability. In general, lobes outboard stable fan valleys that are connected to shelf‐incised canyons are wider, longer and thicker, accumulate in more basinal locations and are architecturally more complex.  相似文献   

Breeding distribution and abundance of the great cormorant Phalacrocorax carbo carbo in Greenland     

DAVID BOERTMANN  ERS MOSBECH 《Polar research》1997,16(2):93-100

The Greenland population of the great cormorant Phalacrocorax carbo carbo numbers 2000–3000 pairs which breed in about 110 colonies distributed along a 1000 km long coastline in central and northern West Greenland. The number of colonies has increased and the breeding range has expanded in recent decades. These trends are believed to be related to a reduced hunting pressure. The number of nests per colony is smaller than in European colonies. The population is of particular conservation concern to Greenland because of its small size and presumed discrete status.  相似文献   

Lateral migration of sand-bed rivers: examples from the Devonian Glashabeg Formation, SW Ireland and the Cambrian Alderney Sandstone Formation, Channel Islands   总被引：1，自引：0，他引：1  

SIMON P. TODD  DAVID J. WENT† 《Sedimentology》1991,38(6):997-1020

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