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81.
东海陆架盆地位于欧亚板块的东南缘和西太平洋活动大陆边缘,本文选取了东海陆架盆地主要凹陷的17条地震剖面,采用平衡剖面技术,计算了主要凹陷新生代不同演化阶段的伸展率和压缩率。分析表明,东海陆架盆地构造演化总体由西向东跃迁。晚白垩世至晚古新世东海陆架盆地裂陷中心在西部坳陷带,始新世东迁至东部坳陷带,上新世东迁至东海陆架盆地东侧的冲绳海槽盆地。古新世中后期东海陆架盆地西部坳陷带北侧昆山凹陷反转; 中新世东部坳陷带的西湖凹陷反转。东海陆架盆地西部坳陷带与东部坳陷带构造演化不同,证明了东海陆架盆地的东西分带。西部坳陷带北部的长江坳陷和南部的台北坳陷构造演化不同,东部坳陷带北部的西湖凹陷和南部的钓北凹陷构造演化不同,证明了东海陆架盆地的南北分块. 相似文献
82.
83.
Fluid sources for the La Guitarra epithermal deposit (Temascaltepec district, Mexico): Volatile and helium isotope analyses in fluid inclusions 总被引:1,自引:0,他引:1
Antoni Camprubí Beverly A. Chomiak Ruth E. Villanueva-Estrada David I. Norman Martin Stute 《Chemical Geology》2006,231(3):252-284
The La Guitarra deposit (Temascaltepec district, South-Central Mexico), belongs to the low/intermediate sulfidation epithermal type, has a polymetallic character although it is currently being mined for Ag and Au. The mineralization shows a polyphasic character and formed through several stages and sub-stages (named I, IIA, IIB, IIC, IID, and III). The previous structural, mineralogical, fluid inclusion and stable isotope studies were used to constrain the selection of samples for volatile and helium isotope analyses portrayed in this study. The N2/Ar overall range obtained from analytical runs on fluid inclusion volatiles, by means of Quadrupole Mass Spectrometry (QMS), is 0 to 2526, and it ranges 0 to 2526 for stage I, 0 to 1264 for stage IIA, 0 to 1369 for stage IIB, 11 to 2401 for stage IIC, 19 to 324 for stage IID, and 0 to 2526 for stage III. These values, combined with the CO2/CH4 ratios, and N2-He-Ar and N2-CH4-Ar relationships, suggest the occurrence of fluids from magmatic, crustal, and shallow meteoric sources in the forming epithermal vein deposit. The helium isotope analyses, obtained by means of Noble Gas Mass Spectrometry, display R/Ra average values between 0.5 and 2, pointing to the occurrence of mantle-derived helium that was relatively diluted or “contaminated” by crustal helium. These volatile analyses, when correlated with the stable isotope data from previous works and He isotope data, show the same distribution of data concerning sources for mineralizing fluids, especially those corresponding to magmatic and crustal sources. Thus, the overall geochemical data from mineralizing fluids are revealed as intrinsically consistent when compared to each other.The three main sources for mineralizing fluids (magmatic, and both deep and shallow meteoric fluids) are accountable at any scale, from stages of mineralization down to specific mineral associations. The volatile and helium isotope data obtained in this paper suggest that the precious metal-bearing mineral associations formed after hydrothermal pulses of predominantly oxidized magmatic fluids, and thus it is likely that precious metals were carried by fluids with such origin. Minerals from base-metal sulfide associations record both crustal and magmatic sources for mineralizing fluids, thus suggesting that base metals could be derived from deep leaching of crustal rocks. At the La Guitarra epithermal deposit there is no evidence for an evolution of mineralizing fluids towards any dominant source. Rather than that, volatile analyses in fluid inclusions suggest that this deposit formed as a pulsing hydrothermal system where each pulse or set of pulses accounts for different compositions of mineralizing fluids.The positive correlation between the relative content of magmatic fluids (high N2/Ar ratios) and H2S suggests that the necessary sulfur to carry mostly gold as bisulfide complexes came essentially from magmatic sources. Chlorine necessary to carry silver and base metals was found to be abundant in inclusion fluids and although there is no evidence about its source, it is plausible that it may come from magmatic sources as well. 相似文献
84.
江陵凹陷北部高速玄武岩下二维广角地震初探 总被引:2,自引:0,他引:2
江汉油田江陵凹陷北部高速玄武岩发育,利用常规地震资料很难得到高速玄武岩下的地震反射。分析研究表明,广角地震有利于玄武岩下的地震成像。通过综合正演和实际地震数据完成了广角地震资料的处理,获得了江陵凹陷北部高速玄武岩下的反射地震信息。在开展广角地震波场的识别和利用研究过程中,从正演模型出发,探讨了在不同地质条件下高速层对地震波场的影响,并针对靶区资料讨论了如何识别广角地震信息。在上述基础上,通过对实际地震资料做精细的分析和处理,最终完成了高速玄武岩下地震资料的成像。 相似文献
85.
Fabien Gibert Juan Cuesta Jun-Ichi Yano Nicolas Arnault Pierre H. Flamant 《Boundary-Layer Meteorology》2007,125(3):553-573
We question the correlation between vertical velocity (w) on the one hand and the occurrence of convective plumes in lidar reflectivity (i.e. range corrected backscatter signal Pz
2) and depolarization ratio (Δ) on the other hand in the convective boundary layer (CBL). Thermal vertical motion is directly
investigated using vertical velocities measured by a ground-based Doppler lidar operating at 2 μm. This lidar provides also
simultaneous measurements of lidar reflectivity. In addition, a second lidar 200 m away provides reflectivities at 0.53 and
1 μm and depolarization ratio at 0.53 μm. The time series from the two lidars are analyzed in terms of linear correlation
coefficient (ρ). The main result is that the plume-like structures provided by lidar reflectivity within the CBL as well as the CBL height
are not a clear signature of updrafts. It is shown that the lidar reflectivity within the CBL is frequently anti-correlated
(ρ (w, Pz
2 )) with the vertical velocity. On the contrary, the correlation coefficient between the depolarization ratio and the vertical
velocity ρ (w, Δ ) is always positive, showing that the depolarization ratio is a fair tracer of updrafts. The importance of relative humidity
on the correlation coefficient is discussed.
An erratum to this article can be found at 相似文献
86.
This paper presents the changes of crust thickness and Poissons ratios distribution in the Binchuan region,where the first air-gun transmitting station and its a small dense array were deployed.From September 2011 to January 2014,more than 239 teleseismic events of M≥6.0 were recorded in 16 stations in the Binchuan region.Their P-wave receiver functions were analyzed respectively.The high spatial resolution result shows that the average crust thickness of Binchuan region is 45.3km,it follows the rule of"deeper in the north and east part,shallower in the south and west part."The deepest region is in Xiaoyindian Station;the crust thickness is 47.9km;the shallowest region is in Paiying Station,it has the thickness of 42.1km.It shows that the deeper Moho surface nearby the Chenghai fault and shallower nearby the Honghe fault;the isoline distribution of thickness changes greatly nearby the Chenghai fault and slowly nearby the Honghe fault.From the distribution of Poissons ratios,it is unevenly in the study area with a great difference from the north part to the south part,which shows a characteristic of"lower in the north,higher in the south".The Poissons ratio nearby the Honghe fault is medium too high(0.26≤σ≤0.29);lower nearby the Chenghai fault(σ≤0.26).This paper concludes the possible reason of different characteristic between Poissons ratio and crust thickness is thicker in the upper crust in the Binchuan region. 相似文献
87.
固结试验是研究软土动力特性的重要环节,固结时间是影响软土动力特征参数的重要因素。围绕岩土工程及科研工作中对动三轴试验中固结时间影响规律的认识较为模糊的问题,拟对天津滨海软土开展动三轴平行试验,分别采用8h、12h、24h、48h进行固结,针对软土的最大动剪切模量Gmax、最大阻尼比λmax及动剪切模量比Gd/Gmax和阻尼比λ随动剪切应变γd的变化规律,分析固结时间对软土动力特性参数的影响。试验结果表明:Gmax、λmax、Gd/Gmax-γd曲线、λ-γd曲线受固结时间的影响较为显著。Gd/Gmax-γd曲线随着固结时间的增加而减小。阻尼比试验结果表明动剪切应变存在明显的分界点,分界点以下,中长期固结时间所得阻尼比较大,而分界点以上,短期固结时间所得阻尼比较大。 相似文献
88.
89.
根据2014年1月及2017年2月杭州湾大、小潮水沙资料,计算了流速、含沙量、单宽潮量、单宽输沙量,进而分析了潮周期断面净潮量、净输沙量和区域冲淤分布。研究发现杭州湾涨、落潮平均流速比值整体较20世纪八九十年代增大,绝大部分区域大于1.0,涨潮流相对增强,澉浦南岸和金山北岸尤为显著。含沙量平面上分布澉浦、杭州湾南岸两个高值区(大潮大于3 kg/m3,小潮大于1.3 kg/m3)以及北岸湾口至乍浦之间的低值区(大潮小于2 kg/m3,小潮小于0.9 kg/m3),随潮汛变化显著,最大含沙量浓度通常滞后于急流时刻。各测站涨、落潮量和输沙量呈现“大涨大落”和“大进大出”的特征,造成杭州湾短时间尺度内的“大冲大淤”。大潮两涨两落金山与乍浦、乍浦与澉浦之间区域净输沙量可达几千万吨,净冲淤则在几百万吨。 相似文献
90.
为研究pH值对单环刺螠(Urechis unicinctus)呼吸排泄的影响,采用静水密封法,研究了不同pH值(5、6、7、8、9)对体质量5.65±1.06g单环刺螠耗氧率、排氨率、能量代谢率、O/N值的影响.结果表明,pH值对单环刺螠耗氧率、排氨率、能量代谢率、O/N值均有显著影响(p0.05).单环刺螠耗氧率随pH值的升高而增大,pH值为8时达到最大值,之后随pH值的升高而减小.单环刺螠耗氧率与pH值之间的拟合方程为:OR=-2.977X2+55.188X-176.380,R2=0.937.单环刺螠排氨率的变化与耗氧率相似,在pH值为7时排氨率达到最大值;pH值为9时排氨率最小,与pH值为8的组差异不显著(p0.05).排氨率与pH值之间的拟合方程为:NR=-0.350X2+4.442X-6.822,R2=0.724.单环刺螠能量代谢率、O/N值均随pH值的升高呈先增大后减小的趋势,拟合方程分别为:M=-0.040X2+0.424X-0.044,R2=0.937;A=0.053X2+1.879X-7.470,R2=0.901.pH值为8的环境中,单环刺螠体内蛋白质代谢水平最低,有利于蛋白质的积累.研究表明,单环刺螠在一定pH值范围内可以通过调整生理代谢水平适应水体pH值,其适宜生活在弱碱性水中,生存最适pH值为8. 相似文献