The spread of subducted lithospheric material along the mid-mantle boundary     

Ross C. Kerr  John R. Lister 《Earth and Planetary Science Letters》1987,85(1-3)

Studies of phase transitions in silicate minerals at high temperatures and pressures suggest that the bulk density of subducted lithosphere at the mid-mantle boundary is intermediate between the densities of the upper and lower mantle. We argue that, if this is the case, then the lithospheric material will intrude along the mid-mantle boundary driven by buoyancy forces resulting from the compositional density differences between the intrusion and its surroundings. The rate of spread of the intrusion is given by a balance between these buoyancy forces and the viscous resistance of the mantle to motion. Using results from our recent studies of the fluid mechanics of such viscous gravity currents, we find that lithospheric material can propagate between one thousand and two thoudand kilometres in a hundred million years and can cover the entire boundary in one to six billion years. This spreading may be reflected in the global distribution of the isotopic characteristics of oceanic basalts.  相似文献   

THE PREPARATION OF THREE BASE-METAL REFERENCE MATERIALS: LEAD CONCENTRATE, IGS-42, ZINC CONCENTRATE, IGS-43 AND COPPER MATTE, IGS-44     

Brian Lister 《Geostandards and Geoanalytical Research》1987,11(1):11-34

Three base-metal concentrates, each weighing 25 kg, were ground to -175 mesh (90 μm) and homogenised. They were then sub-sampled into foil-lined envelopes and sealed under argon before being issued to 27 participating laboratories for analysis. Over 4000 analytical results were returned and, after evaluation, a total of 37 elements within the three samples have been given recommended or more cautious probable values. The high standard of precision attained has enabled clear-cut distinctions to be made between methods for the determination of some elements. The most important of these is between titrimetry and electrogravimetry in the determination of copper.  相似文献   

Structural history of high-pressure metamorphic rocks in the southern vanoise massif,french alps,and their relation to alpine tectonic events     

T.P Platt  G.S Lister 《Journal of Structural Geology》1985,7(1):19-35

A nappe of amphibolite-facies metamorphic rocks of pre-Permian age in the southern Vanoise massif (the Arpont schist) has been affected by an Alpine HP/LT metamorphism. The first mesoscopically recognizable deformation (D₁) post-dated the high-pressure peak (jadeitic pyroxene + quartz, glaucophane + ?lawsonite), and was associated with glaucophane + epidote. D₁ produced a flat-lying schistosity and a NW-trending glaucophane lineation, and was probably associated with nappe displacement involving NW-directed subhorizontal shear. D₂ formed small-scale folds and a foliation associated with chlorite + albite. The changing parageneses during the period pre-D₁ to D₁ to D₂ suggest decreasing pressure, so that the deformation appears to have been related to the uplift history, rather than to the process of tectonic burial. D₂ was followed by a static metamorphism (green biotite + chlorite + albite), possibly of Lepontine age. SE-directed backthrusting and folding (D₃), and later differential uplift along steep faults, took place under low-grade conditions.  相似文献   

Late quaternary sediments in Lake Zürich,Switzerland     

G. S. Lister  F. Giovanoli  G. Eberli  P. Finckh  W. Finger  Q. He  C. Heim  K. J. Hsü  K. Kelts  C. Peng  C. Sidler  X. Zhao 《Environmental Geology》1983,5(4):191-205

Lake Zürich occupies a glacially overdeepened perialpine trough in the northern Middlelands of Switzerland. A total of 154.4 m of Quaternary sediments and 47.3 m of Tertiary Molasse bedrock has been cored from the deepest part of the lake, some 10 km south of the city of Zürich. Some 16.8 m of gravels and sands directly overlying the bedrock include basal till and probably earliest subglacial fluvial and lacustrine deposits. These are overlain by 98.6 m of fine-grained, glacial-aged sediments comprising completely deformed proglacial and/or subglacial lacustrine muds, separated by four basal mud tills. The lack of interglacial sediments, fossils, and other datable material, and the presence of severe sediment deformation and unknown amounts of erosion prevent the establishment of an exact chronostratigraphy for sediments older than the upper mud till. Above it some 8.6 m of lacustrine muds were deposited, folded, faulted, and tilted during the final opening of the lake at about 17,500–17,000 years ago. Superimposed are 30.4 m of final Würm and post-glacial sediments comprising (from oldest): cyclic proglacial mud, thick-bedded and laminated mud, a complex transition zone, laminated carbonate, laminated marl, and diatom-calcite varves. These sediments reflect changing catchment and lacustrine conditions including: glacial proximity, catchment stability, lake inflow characteristics, thermal structure, chemistry, and bed stability. Average sedimentation rates ranged from 11 cm yr⁻¹ immediately after glacier withdrawal, to as low as 0.4 mm yr⁻¹ as the environment stabilized. The lack of coarse outwash deposits separating the fine-grained glaciolacustrine sediments from a corresponding underlying basal till suggests that deglaciation of the deep northern basin of Lake Zürich was by stagnation-zone retreat rather than by retreat of an active ice-front.  相似文献   

On the Thermal Balance of a Mid-Ocean Ridge   总被引：12，自引：0，他引：12  

C. R. B. Lister 《Geophysical Journal International》1972,26(5):515-535

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O,p'-DDT induction of vitellogenesis and its inhibition by tamoxifen in Nile tilapia (Oreochromis niloticus)     

Leaños-Castañeda O  Van Der Kraak G  Lister A  Simá-Alvarez R  Gold-Bouchot G 《Marine environmental research》2002,54(3-5):703-707

In order to investigate the mechanism by which o,p'-DDT disrupts endocrine functioning of Nile tilapia in vivo, the estrogenicity of o,p'-DDT was investigated in conjunction with 17beta-estradiol (E2) and tamoxifen. Mature, male tilapia were treated intraperitoneally with o,p'-DDT (60 mg/kg, one dose) or E2 (5 mg/kg, four doses) in the presence or absence of tamoxifen (5 mg/kg, six doses) for 12 days and then plasma vitellogenin (Vtg) (measured as alkaline-labile phosphorous), E2, and testosterone (T) were measured. Vtg levels were increased dramatically by E2 (1,744 +/- 171 microg/ml) and moderately by o,p'-DDT (82 +/- 15 microg/ml) compared with controls (23 +/- 3.5 microg/ml). Tamoxifen alone had no effect on Vtg production, but inhibited both E2 and o,p'-DDT stimulated vitellogenesis. T levels were reduced with E2 administration (1,688 +/- 383 pg/ml) and declined further with the combined treatment of E2 and tamoxifen (281 +/- 70 pg/ml), compared with controls (6,558 +/- 1,438 pg/ml). Tamoxifen or o,p'-DDT alone did not affect T levels, but their combined treatment did (2,069 +/- 647 pg/ml). The results of this study suggest that o,p'-DDT is weakly estrogenic in male tilapia, and that this activity may be mediated through the estrogen receptor.  相似文献   

An aromatase inhibitor and tamoxifen decrease plasma levels of o,p-DDT and its metabolites in Nile tilapia (Oreochromis niloticus)     

Olga Leaos-Castaeda  Gerardo Gold-Bouchot  Glen Van Der Kraak  Andrea Lister  Victor Ceja-Moreno  Raul Sim-Alvarez 《Marine environmental research》2004,58(2-5):337

The objective of this study was to determine if tamoxifen or an aromatase inhibitor (4-hydroxyandrostenedione; 4-OHA) affected plasma concentrations of o,p^′-DDT and its metabolites, o,p^′-DDD and o,p^′-DDE, in mature tilapia. Male and female tilapia were injected 6 times intraperitoneally with o,p^′-DDT (40 mg/kg) alone or in combination with 4-OHA (2 mg/kg) over a 12 day period. An additional group of male fish was injected with tamoxifen (5 mg/kg) plus o,p^′-DDT. At the end of the treatment period, plasma samples were extracted and analyzed by GC/ECD. Females injected only with o,p^′-DDT had significantly higher levels of o,p^′-DDT compared with males. Interestingly, females and males treated concomitantly with o,p^′-DDT and 4-OHA or tamoxifen had significantly lower concentrations of plasma o,p^′-DDT (about 50%) compared with fish treated with only o,p^′-DDT. These initial results suggest that an interaction between endocrine-active compounds occurs in vivo in tilapia and may involve alterations in metabolism of o,p^′-DDT.  相似文献   

Climate change,ecosystems and smallholder agriculture in Central America: an introduction to the special issue     

Pablo Imbach  Megan Beardsley  Claudia Bouroncle  Claudia Medellin  Peter Läderach  Hugo Hidalgo  Eric Alfaro  Jacob Van Etten  Robert Allan  Debbie Hemming  Roger Stone  Lee Hannah  Camila I. Donatti 《Climatic change》2017,140(1):1-4

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GEOGRAPHIC NOTEBOOK     

Kenneth B.  Cumberland  James W.  Fox  Murray  McCaskill  R. G. Lister  R. P. Hargreaves 《New Zealand geographer》1966,22(1):80-80

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An early-time infrared and optical study of the Type Ia Supernova 1998bu in M96     

M. Hernandez  W. P. S. Meikle  A. Aparicio  C. R. Benn  M. R. Burleigh  A. C. Chrysostomou  A. J. L. Fernandes  T. R. Geballe  P. L. Hammersley  J. Iglesias-Paramo  D. J. James  P. A. James  S. N. Kemp  T. A. Lister  D. Martinez-Delgado  A. Oscoz  D. L. Pollacco  M. Rozas  S. J. Smartt  P. Sorensen  R. A. Swaters  J. H. Telting  W. D. Vacca  N. A. Walton  M. R. Zapatero-Osorio 《Monthly notices of the Royal Astronomical Society》2000,319(1):223-234

We present first-season infrared (IR) and optical photometry and spectroscopy of the Type Ia Supernova 1998bu in M96. We also report optical polarimetry of this event. SN 1998bu is one of the closest type Ia supernovae of modern times, and the distance of its host galaxy is well determined. We find that SN 1998bu is both photometrically and spectroscopically normal. However, the extinction to this event is unusually high, with     We find that SN 1998bu peaked at an intrinsic     Adopting a distance modulus of 30.25 (Tanvir et al.) and using Phillips et al.'s relations for the Hubble constant, we obtain     Combination of our IR photometry with those of Jha et al. provides one of the most complete early-phase IR light curves for a SN Ia published so far. In particular, SN 1998bu is the first normal SN Ia for which good pre- t _{B max} IR coverage has been obtained. It reveals that the J , H and K light curves peak about 5 days earlier than the flux in the B -band curve.  相似文献