Low melt fraction connectivity of granitic and tonalitic melts in a mafic crustal rock at 800 °C and 1 GPa     

Afina Lupulescu  E. Bruce Watson 《Contributions to Mineralogy and Petrology》1999,134(2-3):202-216

In the absence of an externally applied stress, the segregation of small amounts of granitic or tonalitic melts from their residual mafic crystals is possible only if the melt forms an interconnected network phase. Accordingly, this research focuses on melt connectivity at low melt fraction (<4 wt% or 5 vol.%). Connectivity of granitic and tonalitic melts in amphibole-rich rock was assessed by performing two types of piston-cylinder experiments at 1 GPa and 800 °C. The first involved annealing samples that consisted of either alternating layers or homogeneous mixtures of calcic amphibole and metaluminous obsidian powder. The second type of experiment involved creating diffusion couples. Here, an upper cylinder of amphibole-saturated granitic or tonalitic melt was placed against a lower cylinder consisting of an amphibole-rich rock containing zero or a small melt (granitic or tonalitic) fraction. The upper part of the diffusion couple was doped with β emitter (¹⁵¹Sm or ¹⁴C) and functioned as an infinite melt reservoir. The lower part of the diffusion couple was considered to be the host rock. The experiments approached textural equilibrium which allowed us to characterize the wetting behaviour of the calcic amphibole by the hydrous silicic melt (granitic or tonalitic). These particular experiments also provided information concerning diffusive transport, because the β emitter could diffuse through the connected melt (liquid) in the amphibole-rich rock. The dihedral angle measurements show that melt connectivity was achieved. This conclusion is based on the fact that the dihedral angles, θ, consistently yielded median apparent values of 53°<θ<58° for an amphibole-rich rock/granitic melt system, and 46°<θ<48° for an amphibole-rich rock/tonalitic melt system. However, the frequency distribution of θ angles is found to be relatively broad. The results of the diffusion-couple experiments, assessed using the β radiographic technique, complement the dihedral (wetting) angle measurements by showing that melt connectivity is achieved at a melt fraction less than 4wt% (5 vol.%). Received: 15 April 1997 / Accepted: 23 September 1998  相似文献   

The Impact of the Anomalous Weather of 1995 on the U.K. Economy     

S. Subak  J. P. Palutikof  M. D. Agnew  S. J. Watson  C. G. Bentham  M. G. R. Cannell  M. Hulme  S. McNally  J. E. Thornes  D. Waughray  J. C. Woods 《Climatic change》2000,44(1-2):1-26

This study assesses selected impacts on tertiary activities of the anomalously hot summer of 1995 and warm period from November 1994 through October 1995 in the U.K. Over this period, the mean Central England temperature was 1.6 °C above the 1961–1990 normal, representing the highest mean 12-month temperature since the start of the Central England temperature record in 1659. The study is distinguished by its breadth of coverage, for it includes tertiary sectors and activities. Although impacts in tertiary activities are often not included in assessments of the potential impacts of climatic change, many of these activities are very important to the U.K. economy, and therefore even a small perturbation in output due to a weather extreme can have significant implications for the economy as a whole. The activities and sectors studied include energy consumption, retailing and manufacturing, construction and buildings, tourism, health, human behaviour, and fires. Both negative and positive impacts were incurred within most sectors. Net positive impacts (to the general public) were found convincingly for energy consumption and health, and clear negative impacts for buildings insurance and fires. Sectors which show clear differences in their response to winter and summer warm anomalies are energy consumption, tourism and health (greater sensitivity to winter anomalies) and buildings insurance and fires (greater sensitivity to summer anomalies). Changes in sensitivity to climate extremes may have occurred over time, and a comparison of impacts of the 1995 anomalous weather with the unusually warm dry period of 1975–1976 is approached for several series.  相似文献   

Imaging the cool stars in the interacting binaries AE Aqr,BV Cen and V426 Oph     

C.A. Watson  D. Steeghs  V.S. Dhillon  T. Shahbaz 《Astronomische Nachrichten》2007,328(8):813-816

It is well known that magnetic activity in late‐type stars increases with increasing rotation rate. Using inversion techniques akin to medical imaging, the rotationally broadened profiles from such stars can be used to reconstruct ‘Doppler images’ of the distribution of cool, dark starspots on their stellar surfaces. Interacting binaries, however, contain some of the most rapidly rotating late‐type stars known and thus provide important tests of stellar dynamo models. Furthermore, magnetic activity is thought to play a key role in their evolution, behaviour and accretion dynamics. Despite this, we know comparatively little about the magnetic activity and its influence on such binaries. In this review we summarise the concepts behind indirect imaging of these systems, and present movies of the starspot distributions on the cool stars in some interacting binaries. We conclude with a look at the future opportunities that such studies may provide. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Geomathematics,Mathematical Background and Geo-Science Applications, F.P. Agterberg (Ed.), Elsevier, Amsterdam (1974), xvi + 596 pp., U.S. $51.90     

G.S. Watson 《Engineering Geology》1975,9(3):267-268

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The regulation of carbon dioxide and climate: Gaia or geochemistry     

J.E. Lovelock  A.J. Watson 《Planetary and Space Science》1982,30(8):795-802

This is a review of the Gaia hypothesis which postulates a condition of planetary homeostasis affecting chemical composition and climate. Some criticisms are answered and a new model is introduced for the long term regulation of the mean surface temperature through the biological control of CO₂ partial pressure.  相似文献   

Book review     

D. F. Watson 《Mathematical Geology》1993,25(5):637-639

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Structures in the Great Attractor region     

D. J. Radburn-Smith  J. R. Lucey  P. A. Woudt  R. C. Kraan-Korteweg  F. G. Watson 《Monthly notices of the Royal Astronomical Society》2006,369(3):1131-1142

To further our understanding of the Great Attractor (GA), we have undertaken a redshift survey using the 2-degree Field (2dF) instrument on the Anglo-Australian Telescope (AAT). Clusters and filaments in the GA region were targeted with 25 separate pointings resulting in approximately 2600 new redshifts. Targets included poorly studied X-ray clusters from the Clusters in the Zone of Avoidance (CIZA) Catalogue as well as the Cen–Crux and PKS 1343−601 clusters, both of which lie close to the classic GA centre. For nine clusters in the region, we report velocity distributions as well as virial and projected mass estimates. The virial mass of CIZA J1324.7−5736, now identified as a separate structure from the Cen–Crux cluster, is found to be  ∼3 × 10¹⁴ M_⊙  , in good agreement with the X-ray inferred mass. In the PKS 1343−601 field, five redshifts are measured of which four are new. An analysis of redshifts from this survey, in combination with those from the literature, reveals the dominant structure in the GA region to be a large filament, which appears to extend from Abell S0639  ( l = 281°, b =+11°)  to  ( l ∼ 5°, b ∼−50°)  , encompassing the Cen–Crux, CIZA J1324.7−5736, Norma and Pavo II clusters. Behind the Norma cluster at   cz ∼ 15 000 km s⁻¹  , the masses of four rich clusters are calculated. These clusters (Triangulum Australis, Ara, CIZA J1514.6−4558 and CIZA J1410.4−4246) may contribute to a continued large-scale flow beyond the GA. The results of these observations will be incorporated into a subsequent analysis of the GA flow.  相似文献   

Matheronian geostatistics—Quo vadis?     

G. M. Philip  D. F. Watson 《Mathematical Geosciences》1986,18(1):93-117

Components of geostatistical estimation, developed as a method for ore deposit assessment, are discussed in detail. The assumption that spatial observations can be treated as a stochastic process is judged to be an inappropriate model for natural data. Problems of semivariogram formulation are reviewed, and this method is considered to be inadequate for estimating the function being sought. Characteristics of bivariate interpolation are summarized, highlighting kriging limitations as an interpolation method. Limitations are similar to those of inverse distance weighted observations interpolation. Attention is drawn to the local bias of kriging and misplaced claims that it is an “optimal” interpolation method. The so-called “estimation variance,” interpreted as providing confidence limits for estimation of mining blocks, is shown to be meaningless as an index of local variation. The claim that geostatistics constitutes a “new science” is examined in detail. Such novelties as exist in the method are shown to transgress accepted principles of scientific inference. Stochastic modeling in general is discussed, and purposes of the approach emphasized. For the purpose of detailed quantitative assessment it can provide only prediction qualified by hypothesis at best. Such an approach should play no part in ore deposit assessment where the need is for local detailed inventories; these can only be achieved properly through local deterministic methods, where prediction is purely deductive.  相似文献   

Book review     

D. F. Watson  A. G. Journel  C. John Mann 《Mathematical Geosciences》1986,18(1):147-152

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Kinetics of zircon dissolution and zirconium diffusion in granitic melts of variable water content   总被引：2，自引：0，他引：2  

T. Mark Harrison  E. Bruce Watson 《Contributions to Mineralogy and Petrology》1983,84(1):66-72

The experimental dissolution of zircon into a zircon-undersaturated felsic melt of variable water content at high pressure in the temperature range 1,020° to 1,500° C provides information related to 1) the solubility of zircon, 2) the diffusion kinetics of Zr in an obsidian melt, and 3) the rate of zircon dissolution. Zirconium concentration profiles observed by electron microprobe in the obsidian glass adjacent to a large, polished zircon face provide sufficient information to calculate model diffusion coefficients. Results of dissolution experiments conducted in the virtual absence of water (<0.2% H₂O) yield an activation energy (E) for Zr transport in a melt ofM=1.3 [whereM is the cation ratio (Na+K+2Ca)/(Al·Si)] of 97.7±2.8 kcal-mol^?1, and a frequency factor (D ₀) of 980 _?580 ^+1,390 cm²-sec^?1. Hydrothermal experiments provide an E=47.3±1.9 kcal-mol^?1 andD ₀=0.030 _?0.015 ^+0.030 cm²-sec^?1. Both of these results plot close to a previously defined diffusion compensation line for cations in obsidian. The diffusivity of Zr at 1,200° C increases by a factor of 100 over the first 2% of water introduced into the melt, but subsequently rises by only a factor of five to an apparent plateau value of ～2×10^?9 cm²-sec^?1 by ～6% total water content. The remarkable contrast between the wet and dry diffusivities, which limits the rate of zircon dissolution into granitic melt, indicates that a 50 μm diameter zircon crystal would dissolve in a 3 to 6% water-bearing melt at 750° C in about 100 years, but would require in excess of 200 Ma to dissolve in an equivalent dry system. From this calculation we conclude that zircon dissolution proceeds geologically instantaneously in an undersaturated, water-bearing granite. Estimates of zircon solubility in the obsidian melt in the temperature range of 1,020° C to 1,500° C confirm and extend an existing model of zircon solubility to these higher temperatures in hydrous melts. However, this model does not well describe zircon saturation behavior in systems with less than about 2% water.  相似文献