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61.
62.
Yi-Sui Sun 《Celestial Mechanics and Dynamical Astronomy》1983,30(1):7-19
In this paper, using two methods: LCN'S (Lyapunov characteristic numbers) method and slice cutting method, we study numerically two mappings with odd dimension: $$T_1 :\left\{ {\begin{array}{*{20}c} {x_{n + 1} = x_n + z_n ,} \\ {y_{n + 1} = y_n + x_{n + 1} , (\bmod 2\pi )} \\ {z_{n + 1} = z_n + A\sin y_{n + 1} ,} \\ \end{array} } \right. T_2 :\left\{ {\begin{array}{*{20}c} {x_{n + 1} = x_n + y_n + B \sin z_n ,} \\ {y_{n + 1} = y_n + A \sin x_{n + 1} , (\bmod 2\pi ),} \\ {z_{n + 1} = z_n + B \sin y_{n + 1} ,} \\ \end{array} } \right.$$ whereA, B are parameters. For the mappingT 1 the whole region is stochastic; however, we find two-dimensional invariant manifolds for the mappingT 2. 相似文献
63.
Chemical structure of Jurassic vitrinites isolated from the coals in basins in NW China have been checked using solid state 13C NMR and flash pyrolysis-GC/MS. Study shows some Jurassic collodetrinites are rich in aliphatic products in pyrolysates, consisting with the high amount of methylene carbon in 13C NMR spectra. In contrast, pyrolysates of Jurassic collotelinites are rich in phenols and alkylbenzenes. Also one Pennsylvanian and one Permian vitrinite selected from the Ordos basin, NW China have been checked for comparison. The proportion of aliphatics is low in pyrolysates, and aliphatic carbon peak in 13C NMR spectrum of Permian vitrinite is mostly composed of gas-prone carbons compared with collodetrinites in those Jurassic basins. But both pyrolysis and 13C NMR data shows the Pennsylvanian vitrinite is not only gas-prone but also oil-prone. Relatively high proportion of long chain aliphatic structure of some Jurassic vitrinite in Junggar, Turpan-Hami basins may be due to the contribution of liptodetrinites, which may be included during the formation of vitrinites. And it seems that suberinite is the most possible precursor of long chain aliphatics in the structure of Jurassic collodetrinite. 相似文献
64.
华南寒武系年代地层系统的修订及相关问题 总被引:10,自引:3,他引:7
将早先提出的华南寒武系4统9阶的年代地层系统,修订成4统10阶,除王村阶的底界略高于全球鼓山阶(Drumian Stage)的底界外,其余界线都与目前的全球4统10阶的年代地层界线一致。新系统采纳了在我国华南建立的全球芙蓉统、排碧阶和古丈阶,在原桃源阶的上部另建"牛车河阶"。原王村阶和桃源阶的时限因这一修订有所缩减。全球鼓山阶的底界与台江阶上部的Ptychagnostus atavus带底界可以精确对比。滇东统包含晋宁阶和梅树村阶(狭义)两个年代地层单位,晋宁阶的底界采用全球寒武系的底界,梅树村阶的底界采用罗惠麟等1994年正式修订后的定义,即位于梅树村剖面的"B"点。梅树村阶的原始定义仅指梅树村剖面的磷块岩层(即现今的中谊村段),它的底界高于现在的以Tricophycus pedum首现定义的全球寒武系底界。 相似文献
65.
Chang-Guk Sun Sung-Ho Chun Tae-Gyun Ha Choong-Ki Chung Dong-Soo Kim 《Computers and Geotechnics》2008,35(3):436-449
An integrated GIS-based tool (GTIS) was constructed to estimate site effects related to the earthquake hazards in the Gyeongju area of Korea. To build the GTIS for the study area, intensive site investigations and geotechnical data collections were performed and a walk-over site survey was additionally carried out to acquire surface geo-knowledge data in accordance with the procedure developed to build the GTIS. For practical applications of the GTIS used to estimate the site effects associated with the amplification of ground motion, seismic microzoning maps of the characteristic site period and the mean shear wave velocity to a depth of 30 m were created and presented as a regional synthetic strategy addressing earthquake-induced hazards. Additionally, based on one-dimensional site response analyses, various seismic microzoning maps for short- and mid-period amplification potentials were created for the study area. Case studies of seismic microzonations in the Gyeongju area verified the usefulness of the GTIS for predicting seismic hazards in the region. 相似文献
66.
Min Sun Chao Yuan Wenjiao Xiao Xiaoping Long Xiaoping Xia Guochun Zhao Shoufa Lin Fuyuan Wu A. Kröner 《Chemical Geology》2008,247(3-4):352-383
Gneissic rocks in the Chinese Altai Mountains have been interpreted as either Paleozoic metasedimentary rocks or Precambrian basement. This study reports geochemical and geochronological data for banded paragneisses and associated gneissic granitoids collected along a NE–SW traverse in the northwestern Chinese Altai. Petrological and geochemical data suggest that the protoliths of the banded gneisses were possibly immature sediments with significant volcanic input and that the gneissic granitoids were derived from I-type granites formed in a subduction environment. Three types of morphological features can be recognized in zircons from the banded gneisses and are interpreted to correlate with different sources. Zircons from five samples of banded paragneiss cluster predominantly between 466 and 528 Ma, some give Neoproterozoic ages, and a few yield discordant Paleoproterozoic to Archean ages. Zircon Hf isotopic compositions indicate that both juvenile/mantle and crust materials were involved in the generation of the source rocks from which these zircons were derived. In contrast, zircons occur ubiquitously as elongated euhedral prismatic crystals in the four samples of the gneissic granitoids, and define single populations for each sample with mean ages between 380 and 453 Ma. The general absence of Precambrian inheritance and positive zircon ?Hf values for these granitoids suggest insignificant crustal contribution to the generation of the precursor magmas. Our data can be interpreted in terms of a progressive accretionary history in early to middle Palaeozoic times, and the Chinese Altai may possibly represent a magmatic arc built on a continental margin dominated by Neoproterozoic rocks. 相似文献
67.
Hong-Fu Zhang Steven L. Goldstein Xin-Hua Zhou Min Sun Jian-Ping Zheng Yue Cai 《Contributions to Mineralogy and Petrology》2008,155(3):271-293
The ages of subcontinental lithospheric mantle beneath the North China and South China cratons are less well-constrained than
the overlying crust. We report Re–Os isotope systematics of mantle xenoliths entrained in Paleozoic kimberlites and Mesozoic
basalts from eastern China. Peridotite xenoliths from the Fuxian and Mengyin Paleozoic diamondiferous kimberlites in the North
China Craton give Archean Re depletion ages of 2.6–3.2 Ga and melt depletion ages of 2.9–3.4 Ga. No obvious differences in
Re and Os abundances, Os isotopic ratios and model ages are observed between spinel-facies and garnet-facies peridotites from
both kimberlite localities. The Re–Os isotopic data, together with the PGE concentrations, demonstrate that beneath the Archean
continental crust of the eastern North China Craton, Archean lithospheric mantle of spinel- to diamond-facies existed without
apparent compositional stratification during the Paleozoic. The Mesozoic and Cenozoic basalt-borne peridotite and pyroxenite
xenoliths, on the other hand, show geochemical features indicating metasomatic enrichment, along with a large range of the
Re–Os isotopic model ages from Proterozoic to Phanerozoic. These features indicate that lithospheric transformation or refertilization
through melt-peridotite interaction could be the primary mechanism for compositional changes during the Phanerozoic, rather
than delamination or thermal-mechanical erosion, despite the potential of these latter processes to play an important role
for the loss of garnet-facies mantle. A fresh garnet lherzolite xenolith from the Yangtze Block has a Re depletion age of
∼1.04 Ga, much younger than overlying Archean crustal rocks but the same Re depletion ages as spinel lherzolite xenoliths
from adjacent Mesozoic basalts, indicating Neoproterozoic resetting of the Re–Os system in the South China Craton. 相似文献
68.
The altitude effect on the isotopic composition of precipitation and its application to paleoelevation reconstruction using authigenic or pedogenic minerals have been intensively studied. However, there are still no studies on variations in biomarker δD along altitude transects to investigate its potential as a paleoelevation indicator, although it has been observed that δD of higher plant lipid may record changes in precipitation δD (δDp). Here, we present δD values of higher plant-derived C27, C29, and C31n-alkanes from surface soil along the eastern slope of Mount Gongga, China with great changes in physical variables and vegetation over a range from 1000 to 4000 m above sea level. The weighted-mean δD values of these n-alkanes (δDwax) show significant linear correlations with predicted δDp values (R2 = 0.76) with an apparent isotopic enrichment (εwax-p) of −137 ± 9‰, indicating that soil δDwax values track overall δDp variation along the entire altitudinal transect. Leaf δDwax is also highly correlated with mountain altitude by a significant quadratic relationship (R2 = 0.80). Evapotranspiration is found declining with altitude, potentially lowering δDwax values at higher elevations. However, this evapotranspiration effect is believed to be largely compensated by the opposing effect of vegetation changes, resulting in less varied εwax-p values over the slope transect. This study therefore confirms the potential of using leaf δDwax to infer paleoelevations, and more generally, to infer the δD of precipitation. 相似文献
69.
Identification of sources and causes of leakage on a zoned earth dam in northern Taiwan: Hydrological and isotopic evidence 总被引:3,自引:0,他引:3
Seepage through an earth dam body must be regulated as a well–planned process, if it is not properly managed, the abnormal seepage may cause dam failure. This study employed stable isotopic and statistical methods to identify the source and cause of an abnormal leakage on the zoned earth dam of the Xin–Shan reservoir located in northern Taiwan. Water samples from the dam area over a 2-a period were collected and analyzed for their stable O and H isotope compositions. In addition, a 4-a period of hydrological data, including rainfall, reservoir level, well level, seepage of filter drainage and leakage, were statistically analyzed with a stepwise multiple regression approach. Both the stable isotopic and hydrological results indicate that the abnormal leakage on the dam shell comes from the filter drainage in the dam. The reason for abnormal leakage is due to unexpected and significant precipitation–sourced water flowing into the dam’s body. The dam filter fails to drain out the incoming water sufficiently, thus generating the abnormal seepage. In addition, the defect in the dam filter may also cause the drainage filter to drain off reservoir seepage inadequately. Therefore, it is suggested that checking the filter function and preventing excessive precipitation–sourced water from flowing into the dam are the two top priorities for the follow-up remedial strategy of the dam. 相似文献
70.
This paper explores the links between a strategic policy, urban consolidation, and house prices by examining the changes in
the mix of housing and in house price for the period 1991–2004. We contend that urban consolidation could be seen as a source
of additional supply, (which might be expected to be felt in lower prices and so contribute to a local policy objective) but
also as a stimulus to demand (by developers who could bid up the price of lots where it was understood more housing could
be built). Analyses were carried out at the metropolitan and sub-regional scales using correlation tests. The research finds
very weak statistical connections, and concludes that this policy has not been associated with price changes. 相似文献