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21.
方解石和白云石溶蚀实验热力学模型及地质意义 总被引:15,自引:0,他引:15
通过碳酸盐(方解石、白云石)溶蚀作用实验室模拟研究,建立了溶蚀作用的热力学模型方程,对埋藏成岩的3种不同温压条件下(348.15K,Mpa ,373.15K,25Mpa,403.15K,30MPa)碳酸盐溶蚀作用进行了定量研究。提出随着温度和压力的升高,碳酸盐溶解反应的吉布春播由能降低,因而溶解反应增强;在相同温度和压力的地质条件下,白云石较方解石更易溶蚀并形成次生孔隙,这为油气生成运移提供了有利的地下空间和通道。 相似文献
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The Quadrantids, one of the more active of the annual meteor showers, is unusual for its strong but brief maximum within a broader background of activity. It is also notable for its recent onset, the first observation having been likely made in 1835. Until recently, no parent with a similar orbit had been observed and previous investigators concluded that the stream was quite old, with the stream's recent appearance and sharp peak attributed to a fortuitous convergence of meteoroid orbits. The discovery of the near-Earth Asteroid 2003 EH1 on an orbit very similar to that of the Quadrantids has probably unveiled the parent body of this stream [Jenniskens and Marsden, 2003. 2003 EH1 and the Quadrantids. IAU Circ. 8252]. From simulations of the orbit of this body and of meteoroids released from it at different intervals in the past, we find that both the sharp peak and recent appearance of the Quadrantids can most easily be explained by a release of meteoroids from 2003 EH1 near 1800 AD. This is supported by three lines of evidence. First, the evolution of the observed solar longitude of the Quadrantids over time is consistent with release from 2003 EH1 approximately 200 years ago. Second, numerical simulations of meteoroids released from this parent body at this time match the basic orbital characteristics of the Quadrantid stream well. Finally, these simulations also reveal that the Quadrantid core is well reproduced by a single outburst at perihelion circa 1800, whereas earlier releases result in the shower's appearance in our skies significantly prior to 1835. These results apply to the concentrated central core of the stream: the extended background was likely produced at earlier times. In fact, we find that 2003 EH1 is in a state of Kozai circulation along with a number of other comets and NEAs which may form a larger Quadrantid complex. Using the current total duration of the broader background Quadrantid activity compared to our simulations, we suggest a minimum age of ∼3500 years for the stream as a whole. This also represents the approximate lower limit for the age of the complex. We have further identified five comets as well as nine additional NEAs which may be part of the aforementioned complex, the latter all having Tisserand parameters less than three, further suggesting that the are extinct comet nuclei. 相似文献
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刘沛 《测绘与空间地理信息》2011,34(3):239-241
在对自动全站仪自由设站观测原理进行认真分析研究后,利用TC 2003高精度自动全站仪的自由设站加极坐标法对某高层建筑的一级基坑进行变形监测,通过监测结果精度分析,验证了自动全站仪在建筑物变形监测中的快速、准确性. 相似文献
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震后桥梁结构震害快速评估能够为地震应急救援提供重要参考信息,对减灾工作具有重要价值。为了快速准确地评估遭受地震影响梁式桥的破坏状态,使梁式桥震害评估方法在地震应急中发挥更大作用,基于统计回归模型、神经网络模型和推断模型等三种梁式桥震害评估模型,采用VC++6.0及Access2003数据库软件开发了有关评估软件,并以桥梁震害资料为算例验证了软件的可靠性。 相似文献
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Mount Etna volcano erupted almost simultaneously on its northeastern and southern flanks between October 27 and November 3,
2002. The eruption on the northeastern flank lasted for 8 days, while on the southern flank it continued for 3 months. The
northeastern flank eruption was characterized by the opening of a long eruptive fracture system between 2,900 and 1,900 m.a.s.l.
A detailed survey indicates that the fractures’ direction shifted during the opening from N10W (at the NE Crater, 2,900 m)
to N45E (at its lowest portion, 1,900 m) and that distinct magma groups were erupted at distinct fracture segments. Based
on their petrological features, three distinct groups of rocks have been identified. The first group, high-potassium porphyritic
(HKP), is made up of porphyritic lavas with a Porphyritic Index (P.I.) of 20–32 and K2O content higher than 2 wt%. The second group is represented by lavas and tephra with low modal phenocryst abundance (P.I. < 20)
named here oligo-phyric (low-phyric), and K2O content higher than 2 wt% (HKO, high-potassium oligophyric). The third group, low-potassium oligophyric (LKO), consists
of tephra with oligophyric texture (P.I. < 20) but K2O content < 2 wt%. K-rich magmas (HKP and HKO) are similar to the magma erupted on the southern flank, and geochemical variations
within these groups can be accounted for by a variable degree of fractionation from a single parent magma. The K-poor magma
(LKO), erupted only in the upper segment of the fracture, cannot be placed on the same liquid line of descent of the HK groups,
and it is similar to the magmas that fed the activity of Etna volcano prior to the eruption of 1971. This is the first time
since then that a magma of this composition has been documented at Mt. Etna, thus providing a strong indication for the existence
of distinct batches of magma whose rise and differentiation are independent from the main conduit system. The evolution of
this eruption provides evidence that the NE Rift plays a very active role in the activity of Mt. Etna volcano, and that its
extensional tectonics allows the intrusion and residence of magma bodies at various depths, which can therefore differentiate
independently from the main open conduit system. 相似文献
28.
We study characteristics of long-period ground motions from the 2003 Tokachi-oki earthquake (Mj 8.0), a large interplate earthquake,
based on spatial distribution maps and attenuation relationships for four kinds of peak ground velocity (PGV) value. The first
kind (PGV(WB)) is obtained from a maximal value of vector sum of the three-component, wide-band velocity seismograms, and
the other three kinds (PGV(BP10), PGV(BP20), and PGV(BP30)) are obtained from a maximal value of vector sum of the three-component,
narrow band-pass filtered velocity seismograms (the central periods are 10, 20, and 30 s). The spatial distribution maps for
all kinds of PGV value show azimuth dependence; the PGV values in Hokkaido, northern side of the epicenter are larger than
those in Tohoku, southwestern side of the epicenter, when compared at a comparable distance. We find that the features result
from the radiation pattern of long-period surface waves, that is, the source effect. The attenuation relationships show the
following trends: The PGV(WB) values are larger than the sum of the PGV(BP10), PGV(BP20), and PGV(BP30) at distances (D) less than 200 km, while the PGV(WB) values are comparable to the sum of the PGV(BP20) and PGV(BP30) at D > 200 km. This indicates that the PGV(WB) values at D < 200 km are affected by ground motions with periods less than 10 s, while long-period surface waves mainly contribute to
the PGV(WB) values at D > 200 km. The basin site effects generate a patchy pattern in the spatial distribution maps and a large scattering in the
attenuation relationships for the PGV(WB) and PGV(BP10) values. Finally, we conclude that the PGV(WB) values from the 2003
Tokachi-oki earthquake are controlled by the radiation pattern of long-period S and surface waves and various basin site effects. 相似文献
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Frank Beyrich Jens-Peter Leps Matthias Mauder Jens Bange Thomas Foken Sven Huneke Horst Lohse Andreas Lüdi Wouter M. L. Meijninger Dmitrii Mironov Ulrich Weisensee Peter Zittel 《Boundary-Layer Meteorology》2006,121(1):33-65
Micrometeorological measurements (including eddy-covariance measurements of the surface fluxes of sensible and latent heat) were performed during the LITFASS-2003 experiment at 13 field sites over different types of land use (forest, lake, grassland, various agricultural crops) in a 20 × 20 km2 area around the Meteorological Observatory Lindenberg (MOL) of the German Meteorological Service (Deutscher Wetterdienst, DWD). Significant differences in the energy fluxes could be found between the major land surface types (forest, farmland, water), but also between the different agricultural crops (cereals, rape, maize). Flux ratios between the different surfaces changed during the course of the experiment as a result of increased water temperature of the lake, changing soil moisture, and of the vegetation development at the farmland sites. The measurements over grass performed at the boundary-layer field site Falkenberg of the MOL were shown to be quite representative for the farmland part of the area. Measurements from the 13 sites were composed into a time series of the area-averaged surface flux by taking into account the data quality of the single flux values from the different sites and the relative occurrence of each surface type in the area. Such composite fluxes could be determined for about 80% of the whole measurement time during the LITFASS-2003 experiment. Comparison of these aggregated surface fluxes with area-averaged fluxes from long-range scintillometer measurements and from airborne measurements showed good agreement. 相似文献