IMPACTS OF FUTURE SEA LEVEL RISE ON SALT WATER INTRUSION IN THE CHANGJIANG RIVER ESTUARY   总被引：1，自引：0，他引：1  

杨桂山 《中国地理科学(英文版)》1992,2(1):30-41

Sea level rise could increase the salinity of an estuary by altering the balance between fresh water and salt water. The implications of sea level rise for increasing salinity have been examined in the Changjiang (Yangtze) River estuary. By correlative analysis of chlorinity, discharge and tidal level and calculation of two-dimensional chlorinity, distribution of the Changjiang River estuary, the changes of the intensity and lasting hours of salt water intrusion at Wusong Station and the changes of chlorinity distribution in the South Branch of the Changjiang River estuary have been estimated when future sea level rises 50-100 cm. The intensity of salt water intrusion in the future will be far more serious than current trend.  相似文献   

Fluid infiltration during contact metamorphism of interbedded marble and calc-silicate hornfels, Twin Lakes area, central Sierra Nevada, California     

S. R. DAVIS  J. M. FERRY 《Journal of Metamorphic Geology》1993,11(1):71-88

Abstract In the Twin Lakes area, central Sierra Nevada, California, most contact metamorphosed marbles contain calcite + dolomite + forsterite ± diopside ± phlogopite ± tremolite, and most calc-silicate hornfelses contain calcite + diopside + wollastonite + quartz ± anorthite ± K-feldspar ± grossular ± titanite. Mineral-fluid equilibria involving calcite + dolomite + tremolite + diopside + forsterite in two marble samples and wollastonite + anorthite + quartz + grossular in three hornfels samples record P± 3 kbar and T± 630° C. Various isobaric univariant assemblages record CO₂-H₂O fluid compositions of χCO₂= 0.61–0.74 in the marbles and χCO₂= 0.11 in the hornfelses. Assuming a siliceous dolomitic limestone protolith consisting of dolomite + quartz ° Calcite ± K-feldspar ± muscovite ± rutile, all plausible prograde reaction pathways were deduced for marble and hornfels on isobaric T-XCO₂ diagrams in the model system K₂O-CaO-MgO-Al₂O₃-SiO₂-H₂O-CO₂. Progress of the prograde reactions was estimated from measured modes and mass-balance calculations. Time-integrated fluxes of reactive fluid which infiltrated samples were computed for a temperature gradient of 150 °C/km along the fluid flow path, calculated fluid compositions, and estimated reaction progress using the mass-continuity equation. Marbles and hornfelses record values in the range 0.1–3.6 × 10⁴ cm³/cm² and 4.8–12.9 × 10⁴ cm³/cm², respectively. For an estimated duration of metamorphism of 10⁵ years, average in situ metamorphic rock permeabilities, calculated from Darcy's Law, are 0.1–8 × 10^?6 D in the marbles and 10–27 × 10^?6 D in the hornfelses. Reactive metamorphic fluids flowed up-temperature, and were preferentially channellized in hornfelses relative to the marbles. These results appear to give a general characterization of hydrothermal activity during contact metamorphism of small pendants and screens (dimensions ± 1 km or less) associated with emplacement of the Sierra Nevada batholith.  相似文献   

Cathodoluminescence imaging and titanium thermometry in metamorphic quartz     

F. S. SPEAR  D. A. WARK 《Journal of Metamorphic Geology》2009,27(3):187-205

Cathodoluminescence (CL) of quartz from metamorphic rocks representing a range of conditions from the garnet grade to the migmatite grade reveals a variety of textures, that is, a function of metamorphic grade and deformation history. Ti concentrations, determined by electron microprobe and ion microprobe, generally correlate with CL intensity (blue wavelengths), and application of the Ti‐in‐quartz thermometer (TitaniQ) reflects the temperature of quartz growth or recrystallization, and, in some settings, modification by diffusion. Quartz from garnet grade samples is not visibly zoned, records temperatures of 425–475 °C, and is interpreted to have recrystallized during fabric formation. Quartz grains from staurolite grade samples are zoned in CL with markedly darker cores and brighter rims, some of which are interpreted to have been produced by the dominant staurolite‐producing reaction, whereas others are interpreted as having formed by diffusion of Ti into quartz rims. Quartz from the matrix of kyanite and sillimanite grade samples are generally unzoned, although locally displays slightly brighter rims (higher Ti); quartz inclusions within garnet and staurolite have distinctly brighter rims, which are interpreted as having been produced by diffusive exchange with the host mineral. Quartz from migmatite grade samples displays highly variable CL intensity, which is dependent on the location of the grain. Matrix grains in melanosomes are largely unzoned or rarely zoned with darker cores. Leucosome quartz is strongly zoned with bright cores and dark rims and is interpreted as having formed during crystallization of the melt. Locally within the leucosome is observed oscillatory‐zoned quartz, which is interpreted as a subsolidus recrystallization to achieve strain relaxation. Quartz inclusions within garnet or plagioclase crystals often show bright domains separated by zones of dark CL. These enigmatic textures possibly reflect local melting fluxed by fluid inclusions. Temperatures calculated from the Ti–in–quartz thermometer are a function of the metamorphic grade of the sample, the textural setting of the quartz, the reaction history and the deformation history of the rock. The TitaniQ temperatures can be used to constrain the conditions at which various metamorphic processes have occurred.  相似文献   

Galaxy merging, the fundamental plane of elliptical galaxies and the  M_BH−σ₀  relation     

C. Nipoti  P. Londrillo  L. Ciotti 《Monthly notices of the Royal Astronomical Society》2003,342(2):501-512

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Black hole winds     

A. R. King  K. A. Pounds 《Monthly notices of the Royal Astronomical Society》2003,345(2):657-659

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A comparison of the acceleration mechanisms in young stellar objects and active galactic nuclei jets     

D. J. Price  J. E. Pringle  A. R. King 《Monthly notices of the Royal Astronomical Society》2003,339(4):1223-1236

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Dynamical response to supernova-induced gas removal in two-component spherical galaxies     

Masahiro Nagashima &#;  Yuzuru Yoshii 《Monthly notices of the Royal Astronomical Society》2003,340(2):509-518

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A universal radio–X-ray correlation in low/hard state black hole binaries     

E. Gallo  R. P. Fender  G. G. Pooley 《Monthly notices of the Royal Astronomical Society》2003,344(1):60-72

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Three-dimensional calculations of high- and low-mass planets embedded in protoplanetary discs     

M. R. Bate  S. H. Lubow  G. I. Ogilvie  K. A. Miller 《Monthly notices of the Royal Astronomical Society》2003,341(1):213-229

We analyse the non-linear, three-dimensional response of a gaseous, viscous protoplanetary disc to the presence of a planet of mass ranging from 1 Earth mass (1 M_⊕) to 1 Jupiter mass (1 M_J) by using the zeus hydrodynamics code. We determine the gas flow pattern, and the accretion and migration rates of the planet. The planet is assumed to be in a fixed circular orbit about the central star. It is also assumed to be able to accrete gas without expansion on the scale of its Roche radius. Only planets with masses   M _p≳ 0.1 M_J  produce significant perturbations in the surface density of the disc. The flow within the Roche lobe of the planet is fully three-dimensional. Gas streams generally enter the Roche lobe close to the disc mid-plane, but produce much weaker shocks than the streams in two-dimensional models. The streams supply material to a circumplanetary disc that rotates in the same sense as the orbit of the planet. Much of the mass supply to the circumplanetary disc comes from non-coplanar flow. The accretion rate peaks with a planet mass of approximately 0.1 M_J and is highly efficient, occurring at the local viscous rate. The migration time-scales for planets of mass less than 0.1 M_J, based on torques from disc material outside the Roche lobes of the planets, are in excellent agreement with the linear theory of type I (non-gap) migration for three-dimensional discs. The transition from type I to type II (gap) migration is smooth, with changes in migration times of about a factor of 2. Starting with a core which can undergo runaway growth, a planet can gain up to a few M_J with little migration. Planets with final masses of the order of 10 M_J would undergo large migration, which makes formation and survival difficult.  相似文献   

Dust formation in early galaxies     

H. L. Morgan  M. G. Edmunds 《Monthly notices of the Royal Astronomical Society》2003,343(2):427-442

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