ANTIDUNE CROSS-STRATIFICATION IN A TURBIDITE SEQUENCE, CLORIDORME FORMATION, GASPÉ, QUEBEC     

KEITH SKIPPER 《Sedimentology》1971,17(1-2):51-68

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Nocturnal carbon efflux: reconciliation of eddy covariance and chamber measurements using an alternative to the u_*-threshold filtering technique     

EVA VAN GORSEL  RAY LEUNING  HELEN A. CLEUGH  HEATHER KEITH  TANJA SUNI 《Tellus. Series B, Chemical and physical meteorology》2007,59(3):397-403

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The earth's radiocarbon budget     

KEITH R. LASSEY  IAN G. ENTING  CATHY M. TRUDINGER 《Tellus. Series B, Chemical and physical meteorology》1996,48(4):487-501

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Algebraic approach to spatial reasoning     

TERENCE R. SMITH  KEITH K. PARK 《International journal of geographical information science》2013,27(3):177-192

Abstract

A simple, exemplary system is described that performs reasoning about the spatial relationships between members of a set of spatial objects. The main problem of interest is to make sound and complete inferences about the set of all spatial relationships that hold between the objects, given prior information about a subset of the relationships. The spatial inferences are formalized within the framework of relation algebra and procedurally implemented in terms of constraint satisfaction procedures. Although the approach is general, the particular example employs a new ‘complete’ set of topological relationships that have been published elsewhere. In particular, a relation algebra for these topological relations is developed and a computational implementation of this algebra is described. Systems with such reasoning capabilities have many applications in geographical analysis and could be usefully incorporated into geographical information systems and related systems.  相似文献   

Influences on formation and dissipation of high arctic fogs during summer and autumn and their interaction with aerosol   总被引：1，自引：0，他引：1  

E. DOUGLAS NILSSON  E. KEITH BIGG 《Tellus. Series B, Chemical and physical meteorology》1996,48(2):234-253

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An undulatory discontinuity surface on a gently inclined muddy ramp: possible evidence of secondary helical flow from the geological record     

KEITH B. MILLER 《Sedimentology》1991,38(6):1097-1112

An unusual, somewhat cryptic, undulatory discontinuity has been recognized near the basal contact of the Wanakah Shale Member of the Middle Devonian Ludlowville Formation in western New York. It is in part marked by undulating diagenetic limestone beds and concretionary horizons, but can be traced continuously by subtle surfaces of fossil and pyritic lags. This surface marks the top of parallel, elongate mud ridges trending approximately N-S, perpendicular to the inferred E-W depositional strike of the Appalachian Basin in western New York. These ridges are observed in the field as irregularly spaced mud swells which have up to 1.5 m of relief, and vary from 30 to 50 m or more in width. The intervening, broad, flat‘channel floors’ are characterized by dense concentrations of diminutive brachiopods with gastropods and styliolinids, which are gradually replaced by thin styliolinid horizons with abundant pyrite nodules and pyritized burrows over the tops of the swells. Traceable shelly horizons are observed to pinch out over the swells, suggesting a period of relatively undisturbed sediment-filling following the formation of the channellized surface. The interval of nearly barren shale below this irregular surface, however, contains concretionary horizons and rare styliolinid pavements which are themselves irregular, possibly indicating a changing topography for this surface through time. Previous taphonomic and palaeoecological studies of the lower Wanakah Shale Member have disclosed a well-defined regressive-transgressive cycle with more subtle superimposed subcycles. The undulatory surface described here occurs within the early regressive part of this cycle, and appears to record an accentuated regressive kick of a lower-order subcycle. The formation of this surface is therefore interpreted to be a consequence of regressive submarine erosion and sediment bypass, together with redeposition from suspension. The development of the‘channels’ and parallel longitudinal mud ridges was probably controlled by helical flow cells within offshore-directed bottom currents. They may be the first recorded instance of sedimentary furrows described from the geological record. Taphonomic and biofacies data indicate relative depths below average storm wave-base, suggesting that sediment winnowing and redeposition occurred at depths only rarely affected by the direct impact of storm wave agitation.  相似文献   

A Chemical Study of Serpentinization--Burro Mountain, California   总被引：7，自引：0，他引：7  

COLEMAN  R. G.; KEITH  T. E. 《Journal of Petrology》1971,12(2):311-328

Serpentinized dunites and harzburgites from the Burro Mountainperidotite show no change in the ratio of iron and magnesiato silica when compared with the same ratio for the unserpentinizedequivalents. The mineral assemblage resulting from serpentinizationconsists of lizardite-chrysotile, brucite, and magnetite andis determined by the original bulk composition of the peridotite.The chemical and mineralogical data indicate that serpentinizationproceeded under isochemical conditions except for the introductionof water into the peridotite. Expansion accompanies serpentinizationbecause the serpentine products occupy a greater volume thanthe peridotite protolith. Tectonic emplacement of the BurroMountain peridotite was facilitated by serpentinization andthe attendant expansion.  相似文献   

Petrogenesis of Mesozoic, Peraluminous Granites in the Lamoille Canyon Area, Ruby Mountains, Nevada, USA   总被引：5，自引：0，他引：5  

LEE  SANG-YUN; BARNES  CALVIN G.; SNOKE  ARTHUR W.; HOWARD  KEITH A.; FROST  CAROL D. 《Journal of Petrology》2003,44(4):713-732

Two groups of closely associated, peraluminous, two-mica graniticgneiss were identified in the area. The older, sparsely distributedunit is equigranular (EG) with initial  相似文献   

Late Holocene climatic history of northern Germany and Denmark: peat macrofossil investigations at Dosenmoor, Schleswig-Holstein, and Svanemose, Jutland   总被引：3，自引：0，他引：3  

KEITH E. BARBER  FRANK M. CHAMBERS  DARREL MADDY 《Boreas: An International Journal of Quaternary Research》2004,33(2):132-144

Plant macrofossil remains have been analysed from two raised peat bogs in northern Germany and Denmark. The quantified vegetation reconstructions of each profile were subjected to multivariate analyses to extract records of changing bog surface wetness (BSW), which are interpreted in these rain-fed bogs as being proxy climate signals. Age/depth models were constructed using radiocarbon dates and a number of drier and wetter phases were defined. The records both register cooler/wetter conditions around 2700, 1800 and 1400 cal. yr BP, and at the beginning of the Little Ice Age around AD 1250–1350. These rising bog water tables must have been reflected in poorer conditions for agriculture, and in particular near Dosenmoor where the profile records a catastrophic change to such conditions culminating at 2750–2600 cal. yr BP.  相似文献   

Analytical compensation between DTM grid resolution and effective values of staurated hydraulic conductivity within the TOPMODEL framework     

GEORGES-MARIE SAULNIER  CHARLES OBLED  KEITH BEVEN 《水文研究》1997,11(9):1331-1346

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