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91.
Postsedimentation alteration and structural assemblies of the Triassic sedimentary complexes of West Chukotka are discussed.
Zoning of the alteration is based on examination of newly formed structural and mineral assemblages, the chemical composition,
and the polytypes of clay minerals. Three zones of postsedimentation transformation of sandstones are distinguished: (1) the
zone of chlorite, illite, and mixed-layer disordered chlorite-smectite; (2) the zone of illite and chlorite; and (3) the zone
of phengite and ferroan chlorite. The grade of postsedimentation transformation and the composition of the newly formed micas
are correlated with the cleavage type. The development of two-three types of cleavage leads to the highest degree of rock
transformation. The assemblages of clay minerals and the crystal chemistry of the authigenic phengite show that the grade
of postsedimentation transformation of the Triassic rocks attains the stage of greenschistfacies metamorphism in the zone
of development of two cleavage types. Where the second cleavage is not documented or poorly developed, the rocks remain unmetamorphosed.
Evidence is given that postsedimentation transformation of terrigenous rocks in the foldbelt is controlled largely by deformation. 相似文献
92.
The detailed investigation of conditions of the durational stabilization of subtropical anticyclone in the unusual region of the temperate zone is carried out and the reasons for its multiple regeneration are revealed. Separated are five periods of the subtropical anticyclone regeneration associated with the entering of active and relatively anticyclones of middle and high latitudes developed at the rear of cyclonic series into its circulation. All invasions were divided into three types depending on the trajectories of the movement of active anticyclones: the polar invasion from the north and northwest, the ultrapolar invasion from the east and northeast, and the western invasion from the Atlantic Ocean and Baltic Sea. The instability index introduced by V.P. Dymnikov was used for the quantitative estimation of the blocking process lifetime. It is demonstrated that this index is informative enough and could be used for the lifetime forecast of concrete quasistationary regimes of atmospheric circulation. 相似文献
93.
Surface energy balance measurements at a tropical site in West Africa during the transition from dry to wet season 总被引:1,自引:0,他引:1
M. Mauder O. O. Jegede E. C. Okogbue F. Wimmer T. Foken 《Theoretical and Applied Climatology》2007,89(3-4):171-183
Summary In one of the first micrometeorological experiments at a tropical site in West Africa, direct measurements of all surface
energy balance components were carried out. The experiment NIMEX-1 in Ile-Ife, Nigeria (7°33′ N, 4°33′ E), was conducted from
February 19, 2004 to March 9, 2004, during the transition from the dry to the wet season. Three typical weather situations
could be observed: firstly, monsoonal winds from the southwest blew over desiccated soils. Almost 100% of the available energy
at the surface was transformed into sensible heat flux. Secondly, after several thundershowers, monsoonal winds swept over
soils of increased water content, which led to a partitioning of the available energy corresponding to Bowen ratios between
0.3 and 0.5. Thirdly, harmattan winds advected dry dusty air from northern directions, which reduced the incoming shortwave
radiation. Again, Bowen ratios range from 0.3 to 0.5 during daytime, whereas latent heat fluxes are still high during the
night due to the advection of very dry air. No systematic non-closure of the surface energy balance could be found for the
NIMEX-1 dataset. Unlike other experiments in Europe, most of the ogives for the sensible and latent heat flux were found to
be convergent during NIMEX-1 in Ile-Ife. This can be attributed to the homogeneity of the surrounding bush, which lacks the
defined borders found in agriculturally cultivated landscapes. 相似文献
94.
95.
96.
P. R. Isaac R. Leuning J. M. Hacker H. A. Cleugh P. A. Coppin O. T. Denmead M. R. Raupach 《Boundary-Layer Meteorology》2004,110(1):69-98
Two methods are examined for combining measurements from instrumented aircraftand towers to estimate regional scale evapotranspiration. Aircraft data provided spatially averaged values of properties of the surface, the evaporative fraction and maximum stomatal conductance. These quantities are less sensitive to meteorological conditions than the turbulent fluxes of heat and water vapour themselves. The methods allowed aircraft data collected over several days to be averaged and thus to reduce the random error associated with the temporal under-sampling inherent in aircraft measurements. Evaporative fraction is estimated directly from the aircraft data, while maximum stomatal conductance is estimated by coupling the Penman–Monteith equation to a simple model relating surface conductance to the incoming shortwave radiation and specific humidity saturation deficit. The spatial averages of evaporative fraction and maximum stomatal conductance can then be used with routine tower data to estimate the regional scale evapotranspiration. Data from aircraft flights and six ground based sites during the OASIS field campaign in south–east New South Wales in 1995 have been used to check the methods. Both the evaporative fraction and the maximum stomatal conductance derived from the aircraft data give information on the spatial variability of the surface energy budget at scales from 10 to 100 km. Daily averaged latent heat fluxes estimated using these methods for the OASIS study region agree with the available observations in quasi-stationary conditions or in weakly non-stationary conditions when the data from several aircraft flights are averaged to reduce the impact of short term imbalances in the surface energy budget. 相似文献
97.
Full-Scale Spectrum of Boundary-Layer Winds 总被引:1,自引:1,他引:0
98.
N. M. Sushchevskaya O. V. Levchenko E. P. Dubinin B. V. Belyatsky 《Geochemistry International》2016,54(3):237-256
The study of magmatism and tectonic structure of the East Indian or Ninetyeast Ridge (NER) reveals the geochemical similarity of mantle sources for the NER and Kerguelen Plateau melts. Magmas related to the Kerguelen plume were derived from an enriched mantle source, whereas the NER tholeiitic basalts originated from a source contaminated by a depleted material. While, depleted basalt varieties were not found within the NER basalts. It was shown that magmatic rocks forming the NER were generated by high degrees (30%) of partial melting within the ancient Wharton spreading ridge due to the activity of the Kerguelen plume, which was located at this time in the vicinity of the ridge. The most significant impact of the plume on the NER structures was recorded at 70–50 Ma ago. 相似文献
99.
The purpose of the study was to examine the extent to which royalties generated from forest resources contributed to community development in Boki Local Government area of Cross River State, Nigeria. The study used questionnaire survey of house-hold heads and Interview with focus groups to obtain data for this study. A total of 224 household heads representing 20 % of the available house-hold heads in the area was used for the study. The data collected were presented using tables and charts while an inferential statistics (Pearson’s Product Moment correlation) was employed to test the hypothesis of the study. The result of the analysis revealed that there exist a positive correlation coefficient of 0.911 which indicates a strong and positive relationship between royalties collected from forest resources and the number of developmental projects in the study area. Based on the findings of this study, it was recommended that more efforts be directed towards the monitoring and regulation of forest resource exploration activities in the area to ensure that royalties collected are directed towards the establishment of more developmental projects in the area so as to impact more positively on the living standard of the people. 相似文献