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41.
为确定容果地区二长花岗岩的形成时代、成因及其地质意义,对容果地区二长花岗岩进行了岩相学、LA-ICP-MS锆石U-Pb年龄及地球化学研究.结果表明:二长花岗岩中的锆石为岩浆成因,206 Pb/238 U年龄加权平均值为(69±1)Ma,侵入时代属于晚白垩世;二长花岗岩中Al2 O3含量为13.83% ~14.41%,Na2 O含量为3.68% ~3.94%,K2 O含量为4.28% ~4.35%,K2 O/Na2 O为1.08~1.18,相对富钾,铝饱和指数A/CNK平均为1.02,属弱过铝质岩石;微量元素特征表现为相对富集Rb、U、K等大离子亲石元素,亏损Nb、Ta、Ti等高场强元素的特征.结合区域构造演化背景,可得出在80~69 Ma之间,该区的岩浆活动并未停止,仍然持续在发生,所生成的岩体是新特提斯洋壳俯冲的岩浆产物,形成于造山环境下,形成过程贯穿整个造山运动. 相似文献
42.
Stokes polarization profiles of the Mg?b2 5172.68 Å spectral line on two simple sunspots are obtained with the Multi-Channel Solar Telescope (MCST) at the Huairou Solar Observing Station (HSOS). This is done by means of scanning this line over the wavelength interval from 200 mÅ redward of the line center to 200 mÅ blueward, in steps of 10 mÅ. A generalized analytic solution to the transfer equation for polarized radiation is presented. With a nonlinear least-square fitting technique, the linear calibration coefficients for the low-chromospheric longitudinal magnetic field is obtained in the weak-field case. We also discuss the problems in calibrating the transverse field with this line. It is shown that the weak-field approximation is not applicable to the chromospheric Mg?b2 line for the transverse component of the magnetic field. 相似文献
43.
44.
NUMERICAL SIMULATION OF INTERANNUAL AND INTERDECADAL VARIABILITY OF SURFACE WIND OVER THE TROPICAL PACIFIC 总被引:2,自引:0,他引:2
A global atmospheric general circulation model (L9R15 AGCMs) forced by COADS SST was integrated from 1945 to 1993. Interannual and interdecadal variability of the simulated surface wind over the tropical Pacific was analyzed and shown to agree vey well with observation. Simulation of surface wind over the central-western equatorial Pacific was more successful than that over the eastern Pacific. Zonal propagating feature of interannual variability of the tropical Pacific wind anomalies and its decadal difference were also simulated successfully. The close agreement between simulation and observation on the existence of obvious interdecadal variability of tropical Pacific surface wind attested to the high simulation capability of AGCM. 相似文献
45.
Diagenetic control of magnetic susceptibility variation in Core MD98-2172 from the Eastern Timor Sea
Detailed mineral magnetic measurements, integrated with grain-size distribution and X-ray diffraction (XRD) analyses, were
made on the marine sediments of Core MD98-2172, retrieved from the Eastern Timor Sea. Values of magnetic susceptibility in
this core drop sharply down-core from ∼3.85 m deep below sediment/water interface and are very low at ∼5.35 m. However, both
XRD and grain-size distribution results show no sudden change in terrigenous input during sedimentation. Mineral magnetic
results indicate that the depth of ∼3.85 m may be an oxic/anoxic boundary. Therefore, the sediments below ∼3.85 m have been
subjected to intense reductive diagenesis, whereas the sediments above ∼3.85 m are seldom affected. The magnetic properties
of the sediments shallower than 3.85 m are dominated by pseudo-single domain (PSD) magnetite, with little down-core variation
in its content and grain size. Below ∼3.85 m, the magnetic mineral assemblages that have survived in the sediments may record
different stages of the reductive diagenesis: (1) the sediments from the 3.85–5.35 m interval are at the stage of iron oxide
reduction; PSD magnetite is the major magnetic contributor, but it becomes less abundant and coarser down-core; (2) the sediments
below ∼5.35 m are at the stage of sulphate reduction; ferrimagnetic minerals almost vanish and paramagnetic minerals contribute
to down-core susceptibility variations, including pyrite as evidenced by high-temperature magnetic susceptibility measurements.
However, the susceptibility variations below ∼5.35 m of Core MD98-2172 show obvious periodicity, despite the intense effect
of reductive diagenesis. Furthermore, the down-core susceptibility variations are coincident with fluctuations in the quantity
of fine detrital particles (<8 μm), which may come mainly from the advection of the Indonesia Throughflow (ITF) and/or river
input from Timor. Therefore, for Core MD98-2172, susceptibility variation below ∼5.35 m, which potentially correspond to fluctuations
in the quantity of fine particles, may record the histories of the development of the ITF and precipitation on Timor. 相似文献
46.
Climate affects Picea crassifolia growth and climate change will lead to changes in the climate–growth relationship (i.e., the “divergence” phenomenon). However, standardization methods can also change the understanding of such a relationship. We tested the stability of this relationship by considering several variables: 1) two periods (1952–1980 and 1981–2009), 2) three elevations (2700, 3000, and 3300 m), and 3) chronologies detrended using cubic splines with two different flexibilities. With increasing elevation, the climatic factor limiting the radial growth of Picea crassifolia shifted from precipitation to temperature. At the elevation of 2700 m, the relationship between radial growth and mean temperature of the previous December changed so that the more flexible spline had a greater precipitation signal. At the elevation of 3000 m, positive correlation of radial growth with mean temperature and precipitation in September of the previous year became more significant. At the elevation of 3300 m, positive correlation between radial growth and precipitation of the current summer and the previous spring and autumn was no longer significant, whereas the positive correlation between radial growth and temperature of the current spring and summer strengthened. The detrending with the most flexible spline enhanced the precipitation signal at 2700 m, while that with the least flexible spline enhanced the temperature signal at 3300 m. All results indicated that the divergence phenomenon was affected by the climatic signals in the chronologies and that it was most dependent on the detrending method. This suggests it is necessary to select a suitable spline bootstrap for studies of growth divergence phenomena. 相似文献
47.
【目次】了解方斑东风螺中响应LPS刺激的SNP位点及SNP所在基因SNP-Unigenes的功能。【方法】使用SOAPsnp软件分析不同时间条件下转录组数据中的SNP位点,使用GO、COG和KEGG数据库进行功能注释。【结果】转录组数据中共挖掘到673 782个SNP位点,分布在110 869条SNP-unigenes序列上。SNP类型分析表明,转换位点发生的频率远高于颠换位点,且6种单碱基变异类型中以A/G转换发生概率最大。有5866条SNP-unigenes富集到298个KEGG子集中,其中以"内吞作用"子集中富集的SNP-Unigenes最多,共富集182条。 相似文献
48.
提出了一种用于垂直形变分析的附有标高刻度的三维立体剖面图的全新模型方法 ,介绍了用这一模型方法建立国家复测水准网三维立体剖面图模型的过程。使用表明 ,这一模型方法与目前常用的三维空间表示方法相比 ,在定量、定位分析水准点的沉降变化时具有直观、快速等优点。 相似文献
49.
石大明 《成都信息工程学院学报》1998,(4)
以知识经济的特点为背景,论述了知识经济与科技发展的关系,探讨了面对知识经济科技编辑如何处理好基础研究类学术著作、高科技图书与实用普及类图书的出版,以及编辑自身提高等问题。 相似文献
50.
在土地利用变化及相关研究中,地形图已成为重要的信息源.本文以1∶ 100000地形图为基础信息源,根据地图制图原理并结合专家知识与规则,进行了没有影像时期的土地利用信息提取的尝试.并选取典型区,以系列影像数据作为背景数据,以耕地为例,将提取结果与同期统计数据及所推算的影像数据进行了对比分析和精度的验证.如以推算的影像数据为标准,则验证误差<5%.研究表明,按照一定的知识规则,基于地形图进行历史时期土地利用信息重建是可行的,完全可以满足相同比例尺及较小比例尺上土地利用制图及分析的需要. 相似文献