The tangent linear model for semi-Lagrangian schemes: linearizing the process of interpolation     

SAROJA POLAVARAPU  MONIQUE TANGUAY  RICHARD MÉNARD  ANDREW STANIFORTH 《地球，A辑:动力气象学与海洋学》1996,48(1):74-95

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Basin architecture and thermal maturation in the strike-slip Deer Lake Basin, Carboniferous of Newfoundland     

RICHARD S. Hyde  HUGH G. Miller  RICHARD N. Hiscott  JAMES A. Wright 《Basin Research》1988,1(2):85-105

Abstract The Deer Lake Basin is an entirely non-marine basin associated with the Cabot fault zone. Structural and stratigraphic evidence strongly suggest dextral strike-slip movements along the fault zone during Tournaisian-Visean time. Two elongated, end-on structural blocks (probable positive flower structures) contain fold axes and second-order faults oriented obliquely to fault traces bounding the blocks, in a manner implying dextral movements. In one part of the basin, the stratigraphic thickness of a long homoclinal section of later basin-fill sediment (Deer Lake Group) greatly exceeds the suggested depth to basement based on gravity measurements, a situation common to strike-slip basins. Formations representing basin fill can be arranged into megasequences (from oldest to youngest: Anguille Group, Wetstone Point and Wigwam Brook Formations, Deer Lake Group, Howley Formation) corresponding to lateral growth stages of the basin. Gravity, magnetic, and seismic data show that depths to basement on either side of the end-on flower structures are comparable, so that the youngest strata in the basin (Howley Formation) are not underlain by earlier basin fill. These geophysical data, therefore, corroborate the geological conclusion of onlapping stratigraphic relations. The geophysical data suggest participation of basement in Carboniferous gravity faulting and show the location of the subsurface extension of the Taylors Brook Fault in the western part of the Deer Lake Basin. Thermal maturation of the Anguille and Deer Lake Groups, as measured by vitrinite reflectance, clay mineral assemblages, illite crystallinity, and Rock-Eval pyrolysis, indicate a much higher level of maturation for the Anguille than for the Deer Lake Group. Palaeotemperatures for the Anguille and Deer Lake Groups are estimated to be around 200 and 100^oC, respectively, suggesting that Anguille Group rocks are overmature whereas Deer Lake Group strata are within the oil-generating window. Onlapping stratigraphic relations and areally homogeneous time/temperature effects, however, have created a situation in which the Deer Lake Group and Howley Formation have similar maturation levels.  相似文献   

A comparison of grain‐size analysis methods for sand‐dominated fluvial sediments     

MICHAEL D. CHEETHAM  ANNABELLE F. KEENE  RICHARD T. BUSH  LEIGH A. SULLIVAN  WAYNE D. ERSKINE 《Sedimentology》2008,55(6):1905-1913

Grain‐size distribution is a fundamental tool for interpreting sedimentary units within depositional systems. The techniques assessed in this study are commonly used to determine grain‐size distributions for sand‐dominated sediments. However, the degree of consistency and differences in interpretation when using a combination of grain‐size methods have not yet been assessed systematically for sand‐dominated fluvial sediments. Results obtained from laser diffraction, X‐ray attenuation and scanning electron microscopy grain‐size analysis techniques were compared with those obtained from the traditional sieve/hydrometer method. Scanning electron microscopy was shown to provide an inaccurate quantitative analysis of grain‐size distributions because of difficulties in obtaining representative samples for examination. The X‐ray attenuation method is unsuitable for sand‐dominated sediments because of its upper size range of only 300 μm. The consistently strong correlation between the laser diffraction results and the sieve/hydrometer results shows that these methods are comparable for sand‐dominated fluvial sediments. Provided that sample preparation is consistent, the latter two methods can be used together within a study of such sediments while maintaining a high degree of accuracy. These results indicate that data for sand‐dominated fluvial sediments gained from the long‐established sieve/hydrometer method can be compared with confidence to those obtained by modern studies using laser diffraction techniques.  相似文献   

Estimates of Slope Retreat Around the Ivory Glacier Catchment, South Island, New Zealand     

RICHARD V. BIRNIE 《New Zealand geographer》1992,48(1):37-42

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Shallow-water gravity-flow deposits, Chapel Island Formation, southeast Newfoundland, Canada   总被引：3，自引：0，他引：3  

PAUL M. MYROW  RICHARD N. HISCOTT† 《Sedimentology》1991,38(5):935-959

A remarkable suite of shallow-water, gravity-flow deposits are found within very thinly-bedded siltstones and storm-generated sandstones of member 2 of the Chapel Island Formation in southeast Newfoundland. Medium to thick siltstone beds, termed unifites, range from non-graded and structureless (Type 1) to slightly graded with poorly developed lamination (Type 2) to well graded with lamination similar to that described for fine-grained turbidites (Type 3). Unifite beds record deposition from a continuum of flow types from liquefied flows (Type 1) to turbidity currents (Type 3). Calculations of time for pore-fluid pressure dissipation support the feasibility of such transitions. Raft-bearing beds consist of siltstone with large blocks or‘rafts’ of thinly bedded strata derived from the underlying and adjacent substrate. Characteristics suggest deposition from debris flows of variable strength. Estimates of debris strength and depositional slope are calculated for a pebbly mudstone bed using measurable and assumed parameters. An assumed density of 2.0 g cm^-1 and a compaction estimate of 50% gives a strength estimate of 79.7 dyn cm^-2 and a depositional slope estimate of 0.77°. The lithologies and sedimentary structures in member 2 indicate an overall grain-size distribution susceptible to liquefaction. Inferred high sediment accumulation rates created underconsolidated sediments (metastable packing). Types of sediment failure included in situ liquefaction (‘disturbed bedding’), sliding and slumping. Raft-bearing debrites resulted from sliding and incorporation of water. Locally, hummocky cross-stratified sandstone directly overlies slide deposits and raft-bearing beds, linking sediment failure to the cyclical wave loading associated with large storms. The gravity flows of the Chapel Island Formation closely resemble those described from the surfaces of modern, mud-rich, marine deltas. Details of deltaic gravity-flow deposition from this and other outcrop studies further our understanding of modern deposits by adding a third dimension to studies primarily carried out with side-scan sonar.  相似文献   

Transverse and linear dunes in an Upper Pleistocene marine sequence, Corinth Basin, Greece     

RICHARD E. LL. COLLIER  JILL THOMPSON† 《Sedimentology》1991,38(6):1021-1040

A range of large-scale dunes of oolitic calcarenite composition are exposed in the Corinth Basin of central Greece. These transverse dunes and a very large linear dune (> 15 m high) lie within an Upper Pleistocene, transgressive marine sequence. Tidal flow, accelerated by constriction through a narrow, fault-bounded seaway, is interpreted to have generated the current velocities necessary to produce the dunes. Marine facies in the Upper Pleistocene sequence include beach to offshore conglomerates and sandstones with wave-modified sedimentary structures and herringbone cross-stratification. An offshore facies association comprises variably bioturbated siltstones and sandstones with a varied marine fauna that includes thermophile species such as scleractinian corals and Strombus bubonius. Oolitic sandstone facies also occur. Oolitic sands were apparently produced in shoal environments subject to tidal (and wave) action, and transported by dominant southerly currents over the southern part of the basin. Oolites accumulated in a linear dune 2.7 km long and 15–20 m high and in three-dimensional transverse dunes up to 10 m high having a variety of compound and simple internal geometries. The isolated, WSW-ENE-trending linear form exhibits angle of repose sedimentary dips (up to 35°) of avalanche sets on its SE flank and sets typically with dips of 15–20° to the NW. Internal high-angle discontinuities are developed in the SE-dipping lee face. It is proposed that a dominant north-to-south flow crossed over the crest obliquely, resulting in both net erosional and depositional processes on the lee flank. A subordinate (?tidal) current may have locally and or periodically crossed the dune crest in a westwards direction. A string of transverse dunes, which were located adjacent to a fault/marine terrace scarp, is interpreted to have originally coalesced to form the linear dune. The distribution of transverse and linear dunes together with the palaeogeographical reconstruction suggest that a marine connection periodically existed across the Corinth Isthmus during the Late Pleistocene due to a combination of active faulting and glacio-eustatic highstands of sea level.  相似文献   

SCHMIDT‐HAMMER EXPOSURE AGES FROM PERIGLACIAL PATTERNED GROUND (SORTED CIRCLES) IN JOTUNHEIMEN,NORWAY, AND THEIR INTERPRETATIVE PROBLEMS          下载免费PDF全文

STEFAN WINKLER  JOHN A. MATTHEWS  RICHARD W. MOURNE  PETER WILSON 《Geografiska Annaler: Series A, Physical Geography》2016,98(3):265-285

Periglacial patterned ground (sorted circles and polygons) along an altitudinal profile at Juvflya in central Jotunheimen, southern Norway, is investigated using Schmidt‐hammer exposure‐age dating (SHD). The patterned ground surfaces exhibit R‐value distributions with platycurtic modes, broad plateaus, narrow tails, and a negative skew. Sample sites located between 1500 and 1925 m a.s.l. indicate a distinct altitudinal gradient of increasing mean R‐values towards higher altitudes interpreted as a chronological function. An established regional SHD calibration curve for Jotunheimen yielded mean boulder exposure ages in the range 6910 ± 510 to 8240 ± 495 years ago. These SHD ages are indicative of the timing of patterned ground formation, representing minimum ages for active boulder upfreezing and maximum ages for the stabilization of boulders in the encircling gutters. Despite uncertainties associated with the calibration curve and the age distribution of the boulders, the early‐Holocene age of the patterned ground surfaces, the apparent cessation of major activity during the Holocene Thermal Maximum (HTM) and continuing lack of late‐Holocene activity clarify existing understanding of the process dynamics and palaeoclimatic significance of large‐scale sorted patterned ground as an indicator of a permafrost environment. The interpretation of SHD ages from patterned ground surfaces remains challenging, however, owing to their diachronous nature, the potential for a complex history of formation, and the influence of local, non‐climatic factors.  相似文献   

THE EFFECT OF EVAPOTRANSPIRATION ON STREAMFLOW RECESSION / L'effet de l'évapotranspiration sur l'écoulement en décrue     

RICHARD N. WEISMAN 《水文科学杂志》2013,58(3):371-377

Abstract

The effect that evapotranspiration has on recession curves during low flow periods is explored. Recession constants are obtained from flow data and plotted against the average daily pan evaporation occurring during the recession. The results for the three study basins are similar, showing a decrease in recession constant with an increase in average daily pan evaporation. For low values of average daily pan evaporation, the recession constant approaches a constant value.  相似文献   

Comparative assessment of water use and environmental implications of coal slurry pipelines / Evaluation comparative de l'utilisation de l'eau et des implications pour l'environnement des pipelines de bouillie de charbon     

RICHARD N. PALMER  IVAN C. JAMES II  ROBERT M. HIRSCH 《水文科学杂志》2013,58(4):455-469

Abstract

One of the most talked about issues with respect to development, transportation, and conversion of the energy resources of the Western United States is the water requirement and its consequent impacts upon the ambience of that part of the country. In conjunction with other studies conducted by the US Geological Survey of water use in the conversion and transportation of the West's coal, an analysis of water use and environmental implications of coal slurry pipeline transport is presented.

Simulations of a hypothetical slurry pipeline of 1000 mile length transporting 12.5 million tons per year indicate that pipeline costs and energy requirements are quite sensitive to the coal-to-water ratio. For realistic water prices, the optimal ratio will not vary far from the 50/50 ratio by weight. In comparison to other methods of energy conversion and transport, coal slurry pipelines utilize about a third of the amount of water required for coal gasification, and about a fifth of the amount required for onsite electrical generation.

An analysis of net energy output from operating alternative energy transportation systems for the assumed conditions indicates that both slurry pipeline and rail shipment require approximately 4.5 per cent of the potential electrical energy output of the coal transported and high-voltage, direct-current transportation requires approximately 6.5 per cent. The environmental impacts of the different transport options are so substantially different that a common basis for comparison does not exist.  相似文献   

Influence of tidal‐range change and sediment compaction on Holocene relative sea‐level change in New Jersey,USA     

BENJAMIN P. HORTON  SIMON E. ENGELHART  DAVID F. HILL  ANDREW C. KEMP  DARIA NIKITINA  KENNETH G. MILLER  W. RICHARD PELTIER 《第四纪科学杂志》2013,28(4):403-411

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