A mixed-phase cloud scheme based on a single prognostic equation     

ANDRÉ TREMBLAY  ANNA GLAZER  WEI YU  ROBERT BENOIT 《地球，A辑:动力气象学与海洋学》1996,48(4):483-500

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On a mechanism for orographic triggering of tropical cyclones in the Eastern North Pacific     

JOSEPH A. ZEHNDER  ROBERT L. GALL 《地球，A辑:动力气象学与海洋学》1991,43(1):25-36

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Residual currents in tidally dominated, well-mixed estuaries     

ROBERT K. MCCARTHY   《地球，A辑:动力气象学与海洋学》1993,45(4):325-340

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The Earth Galleries: an inside view     

Head of Exhibition Research  Design  ROBERT M. BLOOMFIELD 《Geology Today》1997,13(3):96-96

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Responsible Geographies: Co-oreating Knowledge in Aotearoa     

ROBERT MCCLEAN  LAWRENCE D. BERG  MICHAEL M. ROCHE 《New Zealand geographer》1997,53(2):9-15

We examine in this paper the potential for (reforming the relations of social scientific research in Aotearoa. Drawing upon our experience of undertaking historical geographical research with and for Ngati-Toa Rangatira, we argue for the need to develop responsible geographies in Aotearoa. We suggest that the metaphors of ‘crossing borders’ and ‘building structures’ might offer one route into the development of such a responsible geography.  相似文献   

Cross-stratified calcarenites from New Zealand: subaqueous dunes in a cool-water, Oligo-Miocene seaway   总被引：2，自引：0，他引：2  

ALEXIS S. ANASTAS  ROBERT W. DALRYMPLE  NOEL P. JAMES  CAMPBELL S. NELSON† 《Sedimentology》1997,44(5):869-891

Cross-bedded, cool-water, bioclastic limestones of the Te Kuiti Group on the North Island of New Zealand are composed primarily of bryozoans, echinoderms, and benthic foraminifers. Their prominent, large-scale, unidirectional cross-stratification is interpreted as produced by migrating subaqueous dunes on the floor of a 50–100 km wide, north-east-trending seaway in water depths of 40–60 m. These dunes are thought to have developed in response to strong, seaway-parallel, tidal currents combined with a north-east-directed, set-up or oceanic current. Cross-stratification is organized into four hierarchical levels: (1) cross-lamination; (2) first-order sets; (3) second-order sets; and (4) cross-stratified successions. The levels are based on increasing degrees of internal complexity. Distinct attributes such as internal organization, cross-set thickness, foreset shape, and lower bounding-surface shape are used to describe and interpret the cross-stratification. All these attributes are here integrated in a new and expanded classification of unidirectional cross-stratification that emphasizes flow and bedform dynamics rather than overall set shape. Individual cross-stratified successions are interpreted to have formed by dunes with varying sinuosity, superposition, and flow history, under conditions of different current strength but constant sediment production. Horizontally bedded successions are the result of robust, active dune fields that grew during times of vigorous sediment transport. Formset successions were produced from large compound dunes and are the expression of languid and decaying dune fields that developed during times of decreasing sediment transport. These decaying dunes were gradually smothered by continuously and locally produced bioclastic sediment. Formset cross-stratified successions are most likely to develop in carbonates, where the sediment is produced in place, than in terrigenous clastics where the sediment is imported.  相似文献   

Microbial micritic carbonates in uppermost Permian reefs, Sichuan Basin, southern China: some similarities with Recent travertines     

LI GUO  ROBERT RIDING 《Sedimentology》1992,39(1):37-53

The uppermost Permian Chuenmuping reef formed on the western side of a carbonate platform situated in the eastern Sichuan Basin, southern China. Contrasts exist between this western patch reef and the better known Jiantianba barrier reef complex on the eastern platform margin in western Hubei Province, 250 km to the east. Microbial micritic carbonates form significant components of the Chuenmuping reef limestones. Three types of fabric can be identified: irregular, clotted and scalloped-laminated. An additional, cuneiform fabric has been found only in fore-reef facies at Jiantianba. Irregular fabric is comparable with the surface of presently forming travertines at Rapolano Terme, central Italy, which are produced by calcification of cyanobacteria. Clotted fabric shows indistinct peloids which tend to lack rims, and are amalgamated into irregular masses, some of which exhibit bush-like arrangements where traces of filaments can be seen. Traces of filaments are observed in both dark and light layers in the scalloped-laminated fabric, again suggesting a microbial origin. Cuneiform fabric consists of peloids and filaments, and closely resembles deposits in Quaternary travertines which may have been caused by bacterial action. Chuenmuping reef shows a shallowing sequence in normal marine conditions. The micritic fabrics interpreted here as microbial occur more commonly in the upper part of the reef. This indicates that microbial micrites, with a cementing role, formed coevally with reef growth within the upper part of the photic zone.  相似文献   

Changes in velocity profiles at roughness transitions in coarse grained channels   总被引：2，自引：0，他引：2  

ANDRE ROBERT  RE G. ROY†  BERNARD DE  SERRES† 《Sedimentology》1992,39(5):725-735

Heterogeneous coarse grained channels are often characterized by local transitions in bed surface roughness. Distinct spatial zones in terms of grain size have been reported, for example sand ribbons and bedload sheets. The transition from areas of finer to coarser grained surface sediment is often abrupt. However, the effects of these transitions on the shape of the velocity profile and associated shear velocity and roughness length estimates have not been investigated in detail in coarse grained channels. This paper therefore examines the combined effects of a sudden change in surface roughness and of superimposed scales of resistancé on the structure of the turbulent boundary layer. Measurements along roughness transitions from smooth to rough beds were conducted in a flume using artificial roughness features and in a natural gravel bed river. Immediately at the transition from a zone of close packed roughness to a rougher section dominated by obstacles superimposed on the more or less uniform roughness surface, boundary shear stress and roughness length increase considerably. Downstream from this transition, velocity profiles become concave upwards. Downstream and upstream sections show significant differences in terms of near bed velocities (deceleration downstream of the transition), velocity gradient and turbulence intensity of the streamwise velocity component. Comparing the mean velocity profiles corresponding to these two different roughness surfaces gives some indication of the proportion of total shear velocity (or shear stress) associated with the pressure drag produced by large and isolated obstacles.  相似文献   

1000 years of explosive volcanism recorded at the South Pole   总被引：5，自引：0，他引：5  

ROBERT J. DELMAS  SEVERINE KIRCHNER  JULIE M. PALAIS  JEAN-ROBERT PETIT 《Tellus. Series B, Chemical and physical meteorology》1992,44(4):335-350

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Dolomitization of the Devonian Swan Hills Formation, Rosevear Field, Alberta, Canada     

JONATHAN KAUFMAN  GILBERT N. HANSON  WILLIAM J. MEYERS 《Sedimentology》1991,38(1):41-66

The Swan Hills Formation (Middle-Upper Devonian) of the Western Canada Basin is host to several NW-SE-trending gas fields developed in massive replacement dolostone. One of these, the Rosevear Field, contains two major dolostone trends along opposing margins of a marine channel that penetrates into a platform-reef complex. Dolostones consist predominantly of branching and bulbous strdmatoporoid floatstones and rudstones with well-developed moldic and vuggy porosity. Replacement dolomite is coarsely crystalline (100-600 μm), inclusion-rich, composed of euhedral through anhedral crystals and has a blotchy to homogeneous red cathodoluminescence. Geochemically, replacement dolomite is characterized by (i) nearly stoichiometric composition (50.1-51.1 mol% CaCO₃), (ii) negative δ¹⁸O values (mean=-7.5‰, PDB) and (iii) variable ⁸⁷Sr/⁸⁶Sr ratios ranging from values similar to Late Devonian-Early Mississippian seawater (～0.7082) to radiogenic compositions comparable to saddle dolomite cements (>0.7100). Dolomitization began after widespread precipitation of early, equant calcite spar and after the onset of pressure solution, implying that replacement dolomite formed in a burial environment. Oxygen isotope data suggest that dolomite formed at 35-75°C, temperatures reached during burial in Late Devonian through Jurassic time, at minimum depths of 450 m. The linear NW-SE orientation of most dolomite fields in the Swan Hills Formation is suggestive of fault control on fluid circulation. Two models are proposed for fault-controlled circulation of dolomitizing fluids at the Rosevear Field. In the first, compaction-driven, updip fluid migration occurred in response to basin tilting commencing in the Late Palaeozoic. Deep basinal fluids migrating updip were focused into channel-margin sediments along fault conduits. The second model calls upon fault-controlled convective circulation of (i) warm Devonian-Mississippian seawater or (ii) Middle Devonian residual evaporitic brines. The overlap in ⁸⁷Sr/⁸⁶Sr and δ¹⁸O compositions, and similar cathodoluminescence properties between replacement and saddle dolomites provide evidence for neomorphism of some replacement dolomite. Quantitative modelling of Sr and O isotopes and Sr abundances suggests partial equilibration of some replacement dolomite with hot radiogenic brines derived during deep burial of the Swan Hills Formation in the Late Cretaceous-Palaeocene. Interaction of replacement dolomite with deep brines led to enrichment in ⁸⁷Sr while leaving δ¹⁸O similar to pre-neomorphism values.  相似文献