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101.
南京地区分布着一套新近纪的松散砂砾沉积,曾被统称为雨花台砾石层。依据岩性、层序、沉积构造等特征,我们解译了4个地点砂砾层的沉积环境。研究发现,洞玄观组的沉积环境类似于曲流河沉积,六合组类似于砂质辫状河沉积,雨花台组则属于砾质辫状河沉积。沉积环境的不同印证了前人的观点,即这些砂砾层是不同时期形成。古流向显示,从中新世到更新世早期本区的流域格局与目前的大体一致。而河流沉积环境的演化,却指示河道的坡降具有不断增大的趋势。我们认为这可能是全球海平面不断下降导致侵蚀基准面降低所引起的,而差异性的构造运动似乎不是主要的驱动因素。 相似文献
102.
Lü Fuliang 《中国地质大学学报(英文版)》2009,20(1)
The northern South China Sea margin has experienced a rifting stage and a post-rifting stage during the Cenozoic.In the rifting stage,the margin received lacustrine and shallow marine facies sediments.In the post-rifting thermal subsidence,the margin accumulated shallow marine facies and hemipelagic deposits,and the decpwater basins formed.Petroleum systems of deepwater setting have been imaged from seismic data and drill wells.Two kinds of source rocks including Paleogene lacustrine black shale and Oligocene-Early Miocene mudstone were developed in the deepwater basin of the South China Sea.The deepwater reservoirs are characterized by the deep sea channel fill,mass flow complexes and drowned reef carbonate platform.Profitable capping rocks on the top are mudstoues with huge thickness in the post-rifting stage.Meanwhile,the faults developed during the rifting stage provide a migration path favournble for the formation of reservoirs.The analysis of seismic and drilling data suggests that the joint structural and stratigraphic traps could form giant hydrocarbon fields and hydrocarbon reservoirs including syn-rifting graben subaqueous delta,decpwater submarine fan sandstone and reef carbonate reservoirs. 相似文献
103.
We performed 2D numerical simulations of oscillatory tidal flexing to study the interrelationship between tidal dissipation (calculated using the Maxwell model) and a heterogeneous temperature structure in Europa’s ice shell. Our 2D simulations show that, if the temperature is spatially uniform, the tidal dissipation rate peaks when the Maxwell time is close to the tidal period, consistent with previous studies. The tidal dissipation rate in a convective plume encased in a different background temperature depends on both the plume and background temperature. At a fixed background temperature, the dissipation increases strongly with plume temperature at low temperatures, peaks, and then decreases with temperature near the melting point when a melting-temperature viscosity of 1013 Pa s is used; however, the peak occurs at significantly higher temperature in this heterogeneous case than in a homogeneous medium for equivalent rheology. For constant plume temperature, the dissipation rate in a plume decreases as the surrounding temperature increases; plumes that are warmer than their surroundings can exhibit enhanced heating not only relative to their surroundings but relative to the Maxwell-model prediction for a homogeneous medium at the plume temperature. These results have important implications for thermal feedbacks in Europa’s ice shell.To self-consistently determine how convection interacts with tidal heating that is correctly calculated from the time-evolving heterogeneous temperature field, we coupled viscoelastic simulations of oscillatory tidal flexing (using Tekton) to long-term simulations of the convective evolution (using ConMan). Our simulations show that the tidal dissipation rate resulting from heterogeneous temperature can have a strong impact on thermal convection in Europa’s ice shell. Temperatures within upwelling plumes are greatly enhanced and can reach the melting temperature under plausible tidal-flexing amplitude for Europa. A pre-existing fracture zone (at least 6 km deep) promotes the concentration of tidal dissipation (up to ∼20 times more than that in the surroundings), leading to lithospheric thinning. This supports the idea that spatially variable tidal dissipation could lead locally to high temperatures, partial melting, and play an important role in the formation of ridges, chaos, or other features. 相似文献
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Jinzhong Liu Yu Zhang Zhanwen Han Fenghui Zhang 《Astrophysics and Space Science》2010,329(1-2):297-303
This paper provides new detailed specifics and characteristics of the close double white dwarfs (CDWDs) LISA foreground noise floor using the newest information on the astrophysics with binary population algorithms, which were judged to satisfy the observations. We use the binary population synthesis approach of CDWDs in combination with the latest findings of synthesis models from Han (Mon. Not. R. Astron. Soc. 296:1019, 1998), here, specifically formation by the three evolutionary channels of (a) stable Roche lobe overflow plus common envelope (RLOF?+?CE), (b) CE plus CE, (c) exposed core plus CE. We collect resulting CDWDs in the frequency range of 10?8 Hz to 10?2 Hz and compare strength and number statistics per resolvable frequency bin to derive the properties of the noise floor and the nature of possible outliers that may become individually resolvable. We find resolvable outliers to be solely produced by CE?+?CE evolution; the other two channels contribute only to the unresolvable foreground noise. Within the CE?+?CE evolution a detailed look into the chemical buildup of the stars reveals dominantly double helium (He?+?He) WDs or carbon-oxygen CO?+?He WDs. 相似文献
106.
Yu Zhang Fenghui Zhang Zhanwen Han Jinzhong Liu 《Astrophysics and Space Science》2010,329(1-2):255-260
Spectra synthesis is entering a new era with the availability of large and high-quality spectroscopic data and full spectrum fitting methods. Establishing the reliability whether the STARLIGHT code (a full spectrum fitting code, Cid Fernandes et al. (Mon. Not. R. Astron. Soc. 358:363, 2005)) is suitable to study the properties of various types of galaxies is vital to galaxy study. In testing this possibility, Galactic globular clusters (GCs) provide an excellent medium. Taking the 40 Galactic GCs as an example in our work, we analyze their integrated spectra from Schiavon et al. (Astrophys. J. Suppl. 160:163, 2005) and obtain their mixtures of stellar populations that best represents their composite nature. Through analyzing the distributions of stellar ages and metallicities respectively, we find that the stellar metallicity distribution is centered at a low value and the stellar age distribution is very scattered. To compare with the literature, we also calculate the light-weighted ages and metallicities of GCs, and we find that the light-weighted metallicities agree with the literature, while the light-weighted ages are lower than those of the literature. This demonstrates that STARLIGHT can be used to obtain the metallicities of GCs. 相似文献
107.
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109.
1 INTRODUCTION Active oxygen free radicals can damage cell structure, even kill the cells, causing aging and cer- tain serious diseases (Bors et al., 1989). Usually, the production and scavenging of active oxygen free radicals are in balance in healthy hu… 相似文献
110.
HAN Liang LI Bo SONG Tao TONG Lian-jun 《中国地理科学(英文版)》2006,16(2):148-153
1INTRODUCTION The circular-economyisan efficient resources metabolic process, based on principles of ecology and system engi- neering.Withcoupledstructure andthe complex ecolo- gical and economic evolution, it has the characteristics of overall integrity, coordination, and circulation (WANG, 2005). Compared with the traditionalecono- mic model, the circular-economy requires the technical model of production process to be changed from the opening flow pattern that is "resourcesconsumption… 相似文献