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1.
Olaf?Brockamp Norbert?Clauer Michael?ZutherEmail author 《International Journal of Earth Sciences》2003,92(6):843-851
A fossil geothermal area is hosted by the Carboniferous, Permian and Bunter sandstones of the Offenburg intramontane trough in the central Black Forest. The hydrothermal alteration is identified on the basis of newly formed sericites, which appear as pseudomorphs after feldspar and filling of pore spaces. According to K–Ar dating of sericite, serititization occurred about 145 Ma ago (Jurassic). On the basis of 18O analyses of sericite, sericite composition and vitrinite reflectance, the hydrothermal fluids had temperatures of 150–210 °C. Because their electrolyte content was low, these fluids are assumed to have derived from meteoric water. A second pulse of electrolyte-rich hydrothermal fluids resulted in quartz overgrowths. Fluid mobilization seems to be linked to the disintegration of Pangaea and to reactivated fault systems extending from the crystalline basement into the intramontane sediments. 相似文献
2.
40Ar/39Ar method is a high precision dating means, of which the age is obtained by contrasting the un- known sample with those of standards. Usually the age of standard is determined by K-Ar method in which the 38Ar spike should be added for measurement. However, the absolute concentration of 38Ar spike is measured through the calibrated standards in turn, al- though occasionally the concentration of 38Ar spike is determined by other dating methods, such as Rb-Sr, U-Pb methods, which is kn… 相似文献
3.
Wang Fei He Huaiyu Zhu Rixiang Sang Haiqing Wang Yinglan Yang Liekun 《中国科学D辑(英文版)》2006,49(5):461-470
Four international standards, Ga1550, MMhb-1, Lp-6, Bem 4M, and one domestic standard BT-1 have been intercalibrated. The
repeated measurements on MMhb-1 with different mass demonstrate that MMhb-1 is inhomogeneous in age and its average age is
519.8 Ma. The results of Bern 4M and Lp-6 reflect that they have an invariable value of 40Ar*/39Ark (F) and the ages we obtained are consensus with their K-Ar age: Lp-6=127.7Ma; Bern 4M=18.2 Ma. Analyses of BT-1 age spectra,
Ca/K and Cl/K spectra as well as inverse isochrons indicate that the sample is homogeneous and invariable and keeps close
chemically, with its trapped argon isotope composition close to the atmosphere. The dating results show that age values are
reproducible and steady, total fusion age, step-heating age, plateau age and isochron age are in accord with each other within
the error range (2σ). Therefore, we recommend 28.7 Ma as the calibrated age of BT-1.
We also discuss the variation in neutron flux gradients of Beijing 49-2 reactor. It was found that the neutron flux gradient
varies considerably, and more monitors (standard samples) are needed to fix the trend of variation. The coefficient of the
49-2 reactor that transfers the ratio of production rate of 37ArCa/39ArK into Ca/K ratio is 1.78. This is different from that reported earlier, 2.0, which may be caused by the reconstruction of
the reactor. 相似文献
4.
Morphological and spectral studies of the galaxies Kaz 69 and Kaz 460 are reported. The observations were made on the 2.6-m
telescope at the Byurakan Observatory using the VAGR multiaperture spectrograph. Isophotes of monochromatic images of the
Hα, [NII] λ6584, and [SII] λ6717 lines are constructed. Densifications I and II are found to rotate with north-south oriented
axes of rotation. The two densifications (“knots”) have all the kinematic and spectral properties of individual galaxies.
It is assumed that Kaz 139 and the densifications I and II were ejected from the nucleus of Kaz 460 at different times, with
Kaz 139 probably having been ejected first, although they may all have been ejected simultaneously with different velocities.
Along with Kaz 460, these objects form a physical group of galaxies and, at the same time, are a consequence of the activity
of the nucleus of Kaz 460.
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Translated from Astrofizika, Vol. 50, No. 3, pp. 415–426 (August 2007). 相似文献
5.
利用乌兰乌苏镇1964～2012年的气象资料,选取逐年平均气温、极端最高气温、极端最低气温、大风、雷暴、沙尘暴、沙尘天气及大雾、轻雾天气出现的天数作为分析对象,运用3年移动平均法、回归分析法、非参数检验方法的Mann-Kendall趋势检验和突变检验法以及小波分析法,进行了多种天气事件的年纪变化趋势分析.结果表明：（1）大雾天气的发生日数呈增加趋势,沙尘天气、沙尘暴天气、轻雾天气、大风天气和雷暴天气的发生日数都呈减少趋势,其中大风天气发生日数减少趋势最为明显.（2）平均气温、年极端最高气温、年极端最低气温、大雾天气、轻雾天气、沙尘暴天气、雷暴天气和沙尘天气在研究时段都出现了突变,且平均气温、轻雾天气、沙尘天气和雷暴天气在突变之后不久都达到了极显著的上升或者下降变化趋势.（3）平均气温、年极端最低气温、年极端最高气温、大雾天气、雷暴天气和大风天气有明显的周期性,但是不同的气象要素周期性长短是不同的,沙尘、沙尘暴和轻雾天气则没有明显的周期性. 相似文献
6.
Results from a spectral study of the quasar Kaz 102 are presented. It is shown that its spectrum varies as a whole; that is,
the parameters of both the lines and the continuum change. Based on a comparison of results presented previously and in this
paper, it is concluded that over a time of approximately 27.5 years the equivalent widths and relative intensities of the
lines have increased, while their half widths have decreased. The spectral composition of Kaz 102 has also changed: new lines,
HeII λ4686, [OIII] λ4363, and others, appear in spectra of 2000 and 2001 which were not observed in spectra taken in 1973.
The electron density, and the mass and effective radius of the gas component are determined to be 2·107 cm-3, 2·104 M⊙, and 0.2 pc.
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Translated from Astrofizika, Vol. 50, No. 2, pp. 161–170 (May 2007). 相似文献
7.
M.?ZhangEmail author H.?Xu E. K. H.?Salje P. J.?Heaney 《Physics and Chemistry of Minerals》2003,30(8):457-462
The structural behavior of -eucryptite (LiAlSiO4) has been investigated using infrared (IR) spectroscopy over a temperature range of 20 to 900 K and FT-Raman spectroscopy at room temperature. IR reflectance measurements show that -eucryptite possesses high reflectivity in the far-IR region, as is consistent with its reported superionic conductivity along the c-axis. On heating, the Li-related IR bands near 246 and 300 cm–1 (with A2 symmetry) broadened and weakened dramatically, presumably as a result of Li+ positional disordering along the structural channels parallel to c. The disordering process appears to induce a framework distortion, as is evidenced by the broadening of some vibrations of Si(Al)–O with increasing temperature. A change in slope in the temperature dependence of the phonon frequency near 300 cm–1 and the linewidth of the 760 cm–1 band at 715 K indicates that Li becomes completely disordered above this temperature. In addition, the temperature dependence of the linewidth for the 760 cm–1 band exhibits an additional change in slope at 780 K, implying the existence of an intermediate state within this temperature range. The detailed structure of this intermediate phase, however, needs further study. Our IR data provide no indication of structural changes between room temperature and 20 K. 相似文献
8.
The partial pressure of CO2 (pCO2) and dissolved inorganic carbon (DIC) were monitored in shallow coastal waters located inside and outside giant kelp beds (Macrocystis pyrifera) located in the Kerguelen Archipelago (Southern Ocean). Photosynthesis and respiration by microplankton and kelp lead to marked pCO2 and DIC diel cycles. Daily variations of pCO2 and DIC are significant in the spring and summer, but absent in the winter, reflecting the seasonal cycle of biological activity in the kelp beds. If the kelp beds seem to favour the onset of phytoplankton blooms, most of the primary production inside the kelp beds is due to the kelp itself. The primary production of Macrocystis kelp beds in the Sub-Antarctic high-nutrient, low-chlorophyll (HNLC) waters off the Kerguelen Archipelago is elevated and closely linked to light availability. This production is significant from October to March and reaches its climax in December at the solar radiation maximum. 相似文献
9.
10.
PETER S. MORRIS 《Geographical review》1999,89(4):469-490
ABSTRACT. The borderland concept is not often applied to the U.S. West's northern boundary, but the northwestern Great Plains have been the subject of at least two border-straddling regional conceptions: Whoop-Up Country, based on a shared regional history; and Chinook Country, based on a shared natural environment. Both ideas can be found to varying degrees in northern Montana and southern Alberta, but as expressions of regional distinction, their significance and meaning differ sharply north and south of the international boundary. In borderlands such as these, nationalism and regionalism intersect. 相似文献