The pinning of Lyme Regis     

Tony Waltham 《Geology Today》2001,17(5):175-176

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Editors' Foreword: Population, Environment, Societies and Health: Elucidating “Sustainability”     

Tony McMichael 《Global Change & Human Health》2002,3(1):3-3

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Unloading joints and rockfalls in Norway's fiordlands   总被引：1，自引：0，他引：1  

Tony Waltham 《Geology Today》2002,18(6):220-225

When overburden is removed by erosion, rock relaxes towards the surface and develops new fractures. These are then the focus of slope failures that are common and sometimes disastrous in Norway's mountain regions.  相似文献   

Andean geodynamics: main issues and contributions from the 4th ISAG, Göttingen     

Etienne Jaillard  Grard Hrail  Tony Monfret  Gerhard Wrner 《Tectonophysics》2002,345(1-4)

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Critical factors for the formation of a nickel–copper deposit in an evolved magma system: lessons from a comparison of the Pants Lake and Voisey's Bay sulfide occurrences in Labrador, Canada     

Chusi Li  Anthony J. Naldrett  Edward M. Ripley 《Mineralium Deposita》2001,36(1):85-92

The Voisey's Bay nickel–copper deposit and the Pants Lake sulfide occurrences are the most important mineral systems discovered to date within the Nain Plutonic Suite in northern Labrador. There are many intriguing similarities at both locations. Both are hosted by relatively small troctolite/gabbro bodies that intrude the sulfide-bearing paragneiss of the Churchill Province, and these intrusions contain inclusions of the paragneiss. Similar chemical reactions of the gneissic inclusions with the host magmas are observed at both locations. The reactions resulted in the addition of SiO₂, K₂O, Na₂O and sulfur to the magmas, and are responsible for sulfide-saturation and resultant segregation of immiscible sulfide liquids from the magmas. The initial sulfide liquids in both cases were relatively poor in metals, containing <2.5 wt% Ni and 2 wt% Cu. The sulfides at Pants Lake remained poor in metals because of a lack of subsequent interaction with new, chalcophile-undepleted magma. At Voisey's Bay, the initial sulfides segregated in a dynamic conduit, and were subsequently upgraded in metals to ∼6 wt% Ni and 3 wt% Cu by a new surge of undepleted magma using the same conduit. These sulfides were then concentrated to form large sulfide bodies in the wider parts of the conduit and its entry to an upper chamber in response to a sudden change of liquid velocity in these environments. This study confirms three of the most important factors for the formation of magmatic sulfide deposits in an evolved magma system: (1) contamination of magma with sulfide-bearing country rock to achieve sulfide saturation; (2) a dynamic magmatic system such as a magma conduit to transport large volume of sulfide liquid and to concentrate them in limited localities, and (3) upgrading of metals in the sulfide by new, chalcophile-undepleted magma. Received: 20 February 2000 / Accepted: 14 September 2000  相似文献   

Book reviews     

Marie-José Gaillard  André F. Lotter  Norman D. Yan  Tony Stevenson  H. E. Wright 《Journal of Paleolimnology》1993,8(1):85-95

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Contrasting platinum-group element concentration patterns in cumulates of the Bushveld complex   总被引：4，自引：0，他引：4  

G. von Gruenewaldt  L. J. Hulbert  A. J. Naldrett 《Mineralium Deposita》1989,24(3):219-229

Chromite-rich lithologies in both the lower and the critical zones of the Bushveld Complex in the Potgietersrus area display flat, chondrite-normalized, platinum-group-element (PGE) concentration patterns, whereas those of associated sulphide-bearing, but chromite-poor rocks are considerably steeper. The low (Pt+Pd)/(Os+Ir+Ru) ratio in the chromite-bearing rocks is maintained irrespective of the amount of sulphide or chromite in the rock. This feature suggests that the partitioning of the individual PGE into PGE-bearing phases during conditions in the magma under which crystallization of chromite in excess of the normal cotectic amounts was favoured differed from conditions under which an immiscible sulphide liquid separated from the same magma in the absence of enhanced chromite crystallization. These changes in the partitioning coefficients of the individual PGE are considered to reflect changes in the solubility of these elements in response to variations in the intensive parameters in the magma necessary to bring about the enhanced crystallization of chromite.  相似文献   

Peralkaline nephelinites     

Tony D. Peterson 《Contributions to Mineralogy and Petrology》1989,102(3):336-346

Two fractionation trends in sodic alkaline ultramafic liquids have been predicted from experiments in subsystems of the join Di-Ak-Ne-Lc-Qz. The products of these trends are equated with contrasting suites of peralkaline nephelinites from two nephelinite-carbonatite volcanos of the south Gregory Rift, Shombole (southern Kenya) and Oldoinyo L'engai (northern Tanzania). In both trends, peralkalinity is interpreted to result from fractional crystallization of aluminous clinopyroxene. The Shombole trend has olivine nephelinite as its parental magma, and the differentiation products are mildly peralkaline [(Na+K)/Al1.15] nephelinites. It is the most common lineage observed in nephelinite-carbonatite centres. The Oldoinyo L'engai trend has melilitite or olivine-melilite nephelinite as its parental magma, and produces extremely peralkaline [(Na+K)/Al=1.4–2.3] wollastonite- and combeite- (Na₂ Ca₂Si₃O₉) bearing nephelinites. The presence of a reaction relation between wollastonite and liquid to produce combeite, indicated by corroded wollastonite phenocrysts armoured by combeite in some nephelinites from Oldoinyo L'engai, is confirmed by melting experiments. Combeite nephelinites from Oldoinyo L'engai were erupted simultaneously with natrocarbonatite ash, and are very similar in composition to silicate liquids that have been shown by experiment to be immiscible with natrocarbonatite. Because the L'engai trend is rarely expressed at extrusive centres (combeite has been recorded at only three localities), and combeite nephelinites are highly evolved magmas, it is unlikely that natrocarbonatite is primary to other carbonatite types. It is proposed that carbonatite liquid is exsolved at crustal pressures from a wide range of nephelinitic liquids: Mg-rich carbonatite from primitive, olivine-bearing alkaline ultramafic liquids, Ca-rich carbonatite from olivine-free nephelinites of low peralkalinity, and natrocarbonatite from strongly peralkaline combeite nephelinites.  相似文献   

Editorial     

Cavazzani  Ada  Fuller  Tony 《GeoJournal》1982,6(4):283-286

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Climates throughout geologic time: L.A. Frakes. Elsevier,Amsterdam, 1979, 310 pp., U.S. $ 58.50/Df. 120.00     

Tony J. Chandler 《Sedimentary Geology》1980,27(4):317-318

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