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Y. Vapnik V. V. Sharygin V. Samoilov Z. Yudalevich 《International Journal of Earth Sciences》2007,96(4):663-684
The basic and ultrabasic alkaline rocks of western Makhtesh Ramon, Israel crop out in numerous lava flows and subvolcanic
bodies. The rock suite is composed of tephrite, basanite, basanitic nephelinite, analcimite, olivine nephelinite, and melilite-olivine
nephelinite and in many outcrops is represented by glass-bearing varieties. Melt and fluid inclusions have been studied in
olivine, clinopyroxene, and plagioclase phenocrysts. The EP, SIMS and microthermometry methods were used for inclusion study.
The geochemical data obtained on glasses of melt inclusions (major, REE, trace elements, volatiles) are compared with the
data on whole-rock and groundmass glass compositions. The compositions of melt inclusions reflect the different stages of
rock crystallization: the initial products of crystallization are similar to whole-rock compositions whereas final portions
of melts are usually enriched in SiO2, Al2O3, and alkalis, and depleted in mafic components. The data on contemporaneous melt and CO2 inclusions were used for the evaluation of the P–T conditions of rock generation. The following parameters were obtained: tephrite: P = 6.3–7.7 kbar and T = 1,150–1,250°C; basanite: P = 6.6–9.2 kbar and T = 1,150–1,250°C; olivine and analcime-olivine nephelinite: P = 5.6–8.2 kbar and T = 1,150–1,250°C; melilite-olivine nephelinite: 4.0–5.4 kbar and T mainly between 1,150 and 1,200°C. Magma genesis was restricted to P–T conditions of spinel- and plagioclase-lherzolite fields. These data suggest the shallowest depth of magma genesis occurred
in Makhtesh Ramon compared to other occurrences of Early Cretaceous magmatism at the Middle East. Differences in the degree
of batch partial melting of the same source rocks best explain the diversity of the igneous suite in western Makhtesh Ramon. 相似文献
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M. N. Murashko N. V. Chukanov A. A. Mukhanova E. Vapnik S. N. Britvin Yu. S. Polekhovsky Yu. D. Ivakin 《Geology of Ore Deposits》2011,53(7):558-563
A new mineral barioferrite—a natural analogue of synthetic barium ferrite Ba Fe 12 3+ O19—has been identified in the central part of a metamorphosed barite nodule in the rock of the Haturim Formation (Mottled Zone) on the southern slope of Mount Ye’elim in Israel. The mineral is associated with barite, calcite, magnetite, and maghemite and occurs as tiny platy crystals up to 3 × 15 × 15 μm and their irregular aggregates. Barioferrite is black with streaks of brown, and its luster is submetallic. Its Calculated density is 5.31 g/cm3. The mineral is brittle; cleavage is absent. IR absorption bands (cm?1) are observed at 635 (shoulder), 582, 544, 433, and 405 (shoulder). Barioferrite is characterized by ferrimagnetic behavior. Under a microscope in reflected light, barioferrite is grayish white with brownish red internal reflections, the pleochroism is weak (from gray-white on R o to gray-white with a brown tint on R e), and the bireflectance is weak with distinct anisotropy. The reflectance values of R o/R e, % (λ, nm) are 24.51/22.80 (470), 24.17/22.25 (546), 23.65/21.68 (589), and 22.67/20.85 (650). The chemical composition (electron microprobe, wt %; the ranges are given in parentheses) is BaO 13.13 (12.5–13.8), Fe2O3 86.47 (85.5–87.5), and 99.60 in total. The empirical formula is Ba0.95Fe 12.03 3+ O19. Barioferrite is hexagonal with space group P63/mmc, a = 5.875 (3) Å, c = 23.137 (19) Å, V = 691.6 (5) Å3, and Z = 2. The strongest lines of the X-ray powder diffraction pattern [d, Å, (I, 5) (hkl)] are 2.938(46) (110), 2.770(100) (107), 2.624 (84) (114, 200), 2.420(44) (203), 2.225(40) (205), and 1.627(56) (304, 2.0.11). The holotype specimen of barioferrite is deposited at the Mineralogical Museum of St. Petersburg State University; its catalogue number is 1/19436. 相似文献
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Recent changes in the North Atlantic circulation simulated with eddy-permitting and eddy-resolving ocean models 总被引：1，自引：0，他引：1
Robert Marsh Beverly A. de Cuevas Andrew C. Coward Julien Jacquin Joel J.-M. Hirschi Yevgeny Aksenov A.J. George Nurser Simon A. Josey 《Ocean Modelling》2009,28(4):226-239
Three eddy-permitting (1/4°) versions and one eddy-resolving (1/12°) version of the OCCAM ocean model are used to simulate the World Ocean circulation since 1985. The first eddy-permitting simulation has been used extensively in previous studies, and provides a point of reference. A second, improved, eddy-permitting simulation is forced in the same manner as the eddy-resolving simulation, with a dataset based on a blend of NCEP re-analysis and satellite data. The third eddy-permitting simulation is forced with a different dataset, based on the ERA-40 re-analysis data. Inter-comparison of these simulations in the North Atlantic clarifies the relative importance of resolution and choice of forcing dataset, for simulating the mean state and recent variability of the basin-scale circulation in that region. Differences between the first and second eddy-permitting simulations additionally reveal an erroneous influence of sea ice on surface salinity, dense water formation, and the meridional overturning circulation. Simulations are further evaluated in terms of long-term mean ocean heat transport at selected latitudes (for which hydrographic estimates are available) and sea surface temperature errors (relative to observations). By these criteria, closest agreement with observations is obtained for the eddy-resolving simulation. In this simulation, there is also a weak decadal variation in mid-latitudes, with heat transport strongest, by around 0.2 PW, in the mid-1990s. In two of the eddy-permitting simulations, by contrast, heat transport weakens through the study period, by up to 0.4 PW in mid-latitudes. The most notable changes of heat transport in all simulations are linked to a weakening of the subpolar gyre, rather than changes in the meridional overturning circulation. It is concluded that recent changes in the structure of mid-latitude heat transport in the North Atlantic are more accurately represented if eddies are explicitly resolved. 相似文献
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