RECENT STUDIES IN GEOPHYSICAL HAZARDS edited by M. I. El-Sabh,T. S. Murty,S. Venkatesh,F. Siccardi and K. Andah,Kluwer Academic Publishers,Dordrecht, 1994. No. of pages: 285. ISBN 0-7923-2972-4.     

KEITH SMITH 《地球表面变化过程与地形》1996,21(10):979-979

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COPING WITH FLOODS edited by G. Rossi,N. Harmancioglu and V. Yevjevich,NATO ASI Series,Kluwer Academic Publishers,Dordrecht, 1994. No. of pages: xiii + 776. Price: £193.00. ISBN 0-7923-2706-3.     

KEITH SMITH 《地球表面变化过程与地形》1996,21(8):778-778

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Tailor–made geology 1: General introduction and Salthill Quarry, Lancashire     

KEITH DUFF 《Geology Today》1985,1(2):55-57

The protection and long-term safeguarding of geological localities are fundamental to the continuation of fieldwork, both now and in the future. The responsibility for these lies with the Nature Conservancy Council, the government agency charged with protecting geological and biological sites. Part of the work of the Council's Geology Branch is concerned with creating or re-exposing geological localities which are of value for teaching or collecting; and in the article which follows, Keith Duff explains the background and methods of this work, using the recently established geological trail at Salthill Quarry in Lancashire as as example. This is the first of a series of articles which will give details of British sites developed in this way.  相似文献   

Sheet slides and rotational failures on a convergent margin: the Kidnappers Slide, New Zealand   总被引：1，自引：0，他引：1  

PHILIP M. BARNES  KEITH B. LEWIS 《Sedimentology》1991,38(2):205-221

The Kidnappers Slide, on the upper continental slope of the convergent margin off eastern North Island, New Zealand, has been re-examined using a grid of high-resolution seismic reflection profiles. The slide is not a single feature but a complex of sheet slides and rotational failures ranging from 20 to 140 m thick, and covering a total area of 720 km². Failures occurred in several phases, on slopes of 1–5°, in late Quaternary, muddy, shelf-edge clinoforms that have prograded into an accretionary, trench-slope basin. Piston cores and seismic stratigraphy show that the main failure probably occurred in early Holocene times but that movements ranged from mid last glacial to late Holocene times. The sheet slides exhibit tensional collapse via numerous listric normal faults that sole out on glide planes; there is no clear evidence of compressional structures anywhere within the complex. The glide planes occur at progressively deeper stratigraphic levels towards the northeastern end of the complex, and near the steep slope that defines the seaward edge of the trench-slope basin. There is retrogressive failure at the top of the slope. The surficial slides are being deformed by growth of active tectonic faults and folds associated with the convergent plate margin. This type of slope failure may be partially related to metastable sandy layers within the last glacial age progradational sequence, and possibly to formation of bubble phase gas at shallow depths. Failure was probably triggered by earthquake loading of sediments in this highly seismic region.  相似文献   

The Generation of Oceanic Rhyolites by Crystal Fractionation: the Basalt-Rhyolite Association at Volcn Alcedo, Galpagos Archipelago     

GEIST  DENNIS; HOWARD  KEITH A.; LARSON  PETER 《Journal of Petrology》1995,36(4):965-982

Alcedo volcano is one of six shield volcanoes on Isabela Islandin the western Galpagos Islands. Although Alcedo is dominantiybasaltic, it is unusual in that it also has erupted 1 km³ ofrhyolite. The rhyolitic phase marked a 10-fold decrease in themass-eruption rate of the volcano, and the volcano has returnedto erupting basalt. The basalts are tholeiitic and range fromstrongly to sparsely porphyritic. Olivine and plagiodase arethe liquidus phases in the most primitive basalts. The MgO andNi concentrations in the most primitive basalts indicate thatthey have undergone substantial differentiation since extractionfrom the mantle. The rhyolites contain the assemblage oligoclase-augite-titanomagnetite-fayalite-apatiteand sparse xenoliths of quenched basalt and cumulate gabbros.Intermediate rocks are very rare, but some are apparently basaltrhyolitehybrids, and others resulted from differentiation of tholeiiticmagma. Several modeling approaches and Sr-, Nd-, and O-isotopicdata indicate that the rhyolites resulted from 90% fractionation(by weight) of plagiodase, augite, titanomagnetite, olivine,and apatite from the most primitive olivine tholeiite. The dataare inconsistent with the rhyolites originating by crustal anatexis.The extreme Daly gap may be caused by the large increase inviscosity as the basaltic magma differentiates to intermediateand siliceous compositions; highly evolved magmas are eruptibleonly after they become saturated with volatiles by second boiling.The close association of the hybrid intermediate magmas andmagmatic inclusions with the climactic plinian eruption indicatesmixing between mafic and silicic magmas immediately before eruption.Rhyolite production was favored by the decrease in supply ofbasaltic magma as Alcedo was carried away from the focus ofthe Galpagos hotspot. A three-stage model for the magmaticevolution of a Galpagos volcano is proposed. In the first stage,the supply of basaltic magma is large. Basaltic magma continuallyintrudes the subcaldera magma chamber, buffering the magmas'compositional and thermal evolution. As the volcano is carriedaway from the basaltic source, the magma chamber is allowedto cool and differentiate, as exemplified by Alcedo's rhyoliticphase. Finally, the volcano receives even smaller influx ofbasalt, so a large magma chamber cannot be sustained, and thevolcano shifts to isolated basaltic eruptions. KEY WORDS: Galpagos; oceanic rhyolites; fractional crystallization; Isabela Island ^*Corresponding author, e-mail: Geist{at}IDUI1.csrv.uidaho.edu. Telephone: 208-885-6491. Fax: 208-885-5724  相似文献   

WEATHERING AND ROUNDNESS OF QUARTZ SAND GRAINS     

KEITH A. W. CROOK 《Sedimentology》1968,11(3-4):171-182

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‘The methodological basis for fine‐resolution,multi‐proxy reconstructions of ombrotrophic peat bog surface wetness’: Reply to comments     

MATTHEW J. AMESBURY  KEITH E. BARBER  PAUL D. M. HUGHES 《Boreas: An International Journal of Quaternary Research》2011,40(2):382-383

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The Turiy Massif, Kola Peninsula, Russia: Isotopic and Geochemical Evidence for Multi-source Evolution   总被引：6，自引：1，他引：6  

DUNWORTH  ELIZABETH ANN; BELL  KEITH 《Journal of Petrology》2001,42(2):377-405

The Turiy Massif, lying within the Kandalaksha Graben, and onthe southern coast of the Kola Peninsula, contains carbonatites,phoscorites, melilitolites, ijolites and pyroxenites withinone central and four surrounding satellite complexes. Sr–Ndisotopic data from the central complex phoscorites and carbonatites,and the nearby Terskii Coast kimberlites, combined with otherrecently published data on the Devonian Kola Alkaline Province,allow us to redefine the position of the Kola Carbonatite Line(KCL) of Kramm (European Journal of Mineralogy 5, 985–989,1993). We propose that the revised-KCL mantle sources includea lower-mantle plume, and a second enriched source, which alsocontributed to the Terskii Coast and Archangelsk kimberlites.The Turiy Massif silicate rocks and northern complex carbonatiteshave more enriched isotopic signatures than the distinct, anddepleted signatures of the central complex phoscorites and carbonatites,particularly with respect to  相似文献   

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

BRYCE M. HAND  GERARD V. MIDDLETON  KEITH SKIPPER 《Sedimentology》1972,18(1-2):135-138

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Fluvial herring-bone cross-stratification in a modern tributary mouth bar, Coonamble, New South Wales, Australia   总被引：2，自引：0，他引：2  

M. MUSTAFA ALAM  KEITH A. W. CROOK  GRAHAM TAYLOR 《Sedimentology》1985,32(2):235-244

Herring-bone cross-stratification occurs in tributary mouth bar sediments less than 150 yr old in Warrena Creek near its confluence with the Castlereagh River some 2000 river kilometres from the sea in northern New South Wales. These streams have low gradients, with straight to anastomosing channels which become sinuous and distributive downstream. Channel beds are sand but banks are almost exclusively mud which is burrowed and extensively penetrated by roots. Herring-bone cross-stratification results from flow reversals in Warrena Creek during flood events. Flow direction depends upon discharge and stage in the creek relative to that in the adjacent river. The lithofacies resemble inter-tidal deposits and could easily be misidentified on the basis of herring-bone cross-stratification in an ancient sedimentary sequence. Herringbone cross-stratification should be regarded as diagnostic of depositional environments in which current directions are principally determined by reversals of water surface gradient, rather than by regional slope. Flow reversal phenomena may be a characteristic of very low gradient fluvial systems.  相似文献