燕山造山带复杂构造变形型式的新证据及其地质意义   总被引：1，自引：3，他引：1  

汪洋姬广义  夏希凡 《城市地质》2005,17(2):1-13

我们在燕山造山带若干区域的构造填图工作表明，燕山带构造变形型式十分复杂。在华北地区中元古代“标准剖面”所在的天津市蓟县常州村-团山子-杨庄地区，我们的填图工作识别出众多的逆冲构造。在北京市东部密云县丰台顶一带发现了褶皱的推覆体。在北京市西北部延庆县的河口．石槽地区填绘出强烈变形的褶皱冲断构造。但是，前人已发表的地质图并未显示这些构造形迹。根据G A Davis及其合作者的研究和我们的调查工作，我们认为前人对燕山造山带的填图工作在识别区域主要构造特征方面是不成功的，燕山带挤压变形比前人所认为的要更为强烈和复杂。  相似文献   

The phase boundary between wadsleyite and ringwoodite in Mg2SiO4 determined by in situ X-ray diffraction     

T. Inoue  T. Irifune  Y. Higo  T. Sanehira  Y. Sueda  A. Yamada  T. Shinmei  D. Yamazaki  J. Ando  K. Funakoshi  W. Utsumi 《Physics and Chemistry of Minerals》2006,33(2):106-114

The phase boundary between wadsleyite and ringwoodite in Mg₂SiO₄ has been determined in situ using a multi-anvil apparatus and synchrotron X-rays radiation at SPring-8. In spite of the similar X-ray diffraction profiles of these high-pressure phases with closely related structures, we were able to identify the occurrence of the mutual phase transformations based on the change in the difference profile by utilizing a newly introduced press-oscillation system. The boundary was located at ~18.9 GPa and 1,400°C when we used Shim’s gold pressure scale (Shim et al. in Earth Planet Sci Lett 203:729–739, 2002), which was slightly (~0.8 GPa) lower than the pressure as determined from the quench experiments of Katsura and Ito (J Geophys Res 94:15663–15670, 1989). Although it was difficult to constrain the Clapeyron slope based solely on the present data due to the kinetic problem, the phase boundary [P (GPa)=13.1+4.11×10⁻³×T (K)] calculated by a combination of a P–T position well constrained by the present experiment and the calorimetric data of Akaogi et al. (J Geophys Res 94:15671–15685, 1989) reasonably explains all the present data within the experimental error. When we used Anderson’s gold pressure scale (Anderson et al. in J Appl Phys 65:1535–1543, 1989), our phase boundary was located in ~18.1 GPa and 1,400°C, and the extrapolation boundary was consistent with that of Kuroda et al. (Phys Chem Miner 27:523–532, 2000), which was determined at high temperature (1,800–2,000°C) using a calibration based on the same pressure scale. Our new phase boundary is marginally consistent with that of Suzuki et al. (Geophys Res Lett 27:803–806, 2000) based on in situ X-ray experiments at lower temperatures (<1,000°C) using Brown’s and Decker’s NaCl pressure scales.  相似文献   

The stability of primary alluaudites in granitic pegmatites: an experimental investigation of the Na2(Mn2−2x Fe1+2x )(PO4)3 system     

Frédéric Hatert  André-Mathieu Fransolet  Walter V. Maresch 《Contributions to Mineralogy and Petrology》2006,152(4):399-419

In order to assess the geothermometric potential of the Na₂(Mn_2−2x Fe_1+2x )(PO₄)₃ system (x = 0–1), which represents the compositions of natural weakly oxidized alluaudites, we performed hydrothermal experiments between 400 and 800°C, at 1 kbar, under an oxygen fugacity (f(O₂)) controlled by the Ni–NiO (NNO), Fe₂O₃–Fe₃O₄ (HM), Cu₂O–CuO (CT), and Fe–Fe₃O₄ (MI) buffers. When f(O₂) is controlled by NNO, single-phase alluaudites crystallize at 400 and 500°C, whereas the association alluaudite + marićite appears between 500 and 700°C. The limit between these two fields corresponds to the maximum temperature that can be reached by alluaudites in granitic pegmatites, because marićite has never been observed in these geological environments. Because alluaudites are very sensitive to variations of oxygen fugacity, the field of hagendorfite, Na₂MnFe²⁺Fe³⁺(PO₄)₃, has been positioned in the f(O₂)–T diagram, and provides a tool that can be used to estimate the oxygen fugacity conditions that prevailed in granitic pegmatites during the crystallization of this phosphate.  相似文献   

燕山中、新元古代沉积盆地构造演化   总被引：1，自引：0，他引：1  

黄学光 《华北地质》2006,29(4):263-270

燕山中、新元古代沉积盆地是一个经历了十亿年演化的长寿盆地。在漫长的地质历史时期中,受华北地台北缘构造环境变化的制约,该盆地经历了三个阶段的演变。裂陷槽阶段(1800Ma～1600Ma)形成一个北东向半地堑式的楔形槽地,团山子-大红峪期火山活动是裂陷作用顶峰的标志。之后,华北地台北侧古大洋板块发生第一次消减作用,裂陷槽迅速消亡,成为一支废弃的裂谷。裂陷槽消亡后盆地向克拉通盆地过渡的阶段(1600Ma～1200Ma),其构造特点是一方面盆地日趋稳定,另一方面还残留了某些裂陷特征。克拉通盆地阶段(1200Ma～800Ma),沉积了典型的地台盖层沉积,沉积物厚度小,厚度变化小,相变也小,盆地表现出整体同升同降的特点,形成数个区域性的间断面。此时,华北地台北侧的古亚洲洋已经封闭消失,沉积盆地古地理格局发生了根本性的变化,转而向东与大洋沟通。  相似文献   

燕山西段及北京西山晚中生代逆冲构造格局及其地质意义   总被引：18，自引：0，他引：18  

张长厚  张勇  李海龙  吴淦国  王根厚  徐德斌  肖伟峰  戴凛 《地学前缘》2006,13(2):165-183

燕山西段及北京西山晚中生代逆冲构造集中分布于三个NE向带状区域中,三个带状区域的间隔约为60km,延伸长度自东向西依次减小,呈现出明显的逆冲构造发育的三角形区域。三角形区域的北界为“内蒙地轴”南缘断裂西段,南西界与中元古代早期古盆地构造边界一致,东南部边界则与华北克拉通基底新太古代-古元古代中部碰撞造山带的东部边界大致吻合。逆冲构造具有基底卷入的厚皮构造与盖层内部的薄皮构造共存的构造属性,上盘运动方向总体指向NW,逆冲构造变形主要发生在140~130Ma。逆冲后伸展构造变形以发育在主要逆冲构造后侧为主,并利用先存构造薄弱带。先存构造薄弱带在有利区域构造应力和其他影响因素的作用下导致的构造活化,可能是燕山板内构造变形的重要机制之一。主要逆冲变形前后均有大规模岩浆活动的构造-岩浆时空组合表明,收缩构造造成地壳加厚及由此引发的深部地壳重熔,难以作为统一的机制对这些特征进行合理阐释,需要有其他方式的深部热物质与能量的参与。北京西山霞云岭—长操、教军场—大安山以及马兰—胡林等逆冲断层,是一个统一的大规模的逆冲构造的不同组成部分,具典型、连续的断坪-断坡结构,它形成于髫髻山组(148~146Ma)之后、南窖闪长岩(128Ma)侵入之前,而不是“印支期(或更早)”,它与南大寨—八宝山逆冲构造构成北京西山晚中生代逆冲构造格局。区域性的NW-SE向收缩构造作用及南大寨—八宝山逆冲构造上覆岩席的构造加载,可能是北京西山的蓝晶石带和硬绿泥石带为代表的高压动力变质作用的基本构造原因。  相似文献   

Development and testing of a new ray-tracing approach to GNSS carrier-phase multipath modelling     

Lawrence Lau  Paul Cross 《Journal of Geodesy》2007,81(11):713-732

Multipath is one of the most important error sources in Global Navigation Satellite System (GNSS) carrier-phase-based precise relative positioning. Its theoretical maximum is a quarter of the carrier wavelength (about 4.8 cm for the Global Positioning System (GPS) L1 carrier) and, although it rarely reaches this size, it must clearly be mitigated if millimetre-accuracy positioning is to be achieved. In most static applications, this may be accomplished by averaging over a sufficiently long period of observation, but in kinematic applications, a modelling approach must be used. This paper is concerned with one such approach: the use of ray-tracing to reconstruct the error and therefore remove it. In order to apply such an approach, it is necessary to have a detailed understanding of the signal transmitted from the satellite, the reflection process, the antenna characteristics and the way that the reflected and direct signal are processed within the receiver. This paper reviews all of these and introduces a formal ray-tracing method for multipath estimation based on precise knowledge of the satellite–reflector–antenna geometry and of the reflector material and antenna characteristics. It is validated experimentally using GPS signals reflected from metal, water and a brick building, and is shown to be able to model most of the main multipath characteristics. The method will have important practical applications for correcting for multipath in well-constrained environments (such as at base stations for local area GPS networks, at International GNSS Service (IGS) reference stations, and on spacecraft), and it can be used to simulate realistic multipath errors for various performance analyses in high-precision positioning.  相似文献   

八宝井田地质构造特征及成因分析     

何保  ;李茂丰  ;洪常久 《中国煤炭地质》2008,(7):7-9

通过对八宝井田勘探资料及野外地质资料进行分析,探讨了八宝井田地质构造特征及其成因,认为八宝井田位于老房子-砟子向斜东段,由一轴向NE倒转向斜构造、一组与向斜轴向大致平行的逆掩断层和NNW向的断裂（F1、F15）构成井田的主要构造格局。印支运动、燕山运动的多期活动使前晚侏罗世地层受到强烈改造,形成NE－近EW向的褶皱和断裂。井田内断层发育,给煤炭生产带来一定困难,但在NE向逆掩断层倾向与煤层倾向一致的地方,有可能找到储量可观的煤炭资源。  相似文献   

Li-Na-K-Mg-Ca-Sr-Cl-H₂O七元体系多温相平衡性质的热力学模拟研究   总被引：1，自引：1，他引：0       下载免费PDF全文

雷锦顺  李东东  庄子宇  曾德文  李武  高丹丹 《盐湖研究》2021,29(3):17-37

地下卤水中普遍存在较高浓度的锶(1 g/L),研究该类卤水中锶的成盐规律对于资源综合利用具有重要的指导意义。采用Pitzer-Simonson-Clegg超额Gibbs自由能方程和CALPHAD方法构建了Li-Na-K-Mg-Ca-Sr-Cl-H_2O体系的多温相平衡热力学模型,确定了5个含氯化锶三元子体系的多温混合参数。在广泛的温度范围内(273.15 K～373.15 K),模型计算结果与大多数实验结果基本一致,但对于一些体系,模型预测的平衡固相和相区大小仍与实验结果之间存在显著差异;实验数据的离散和匮乏成为全面检验模型预测结果的最大障碍。将模型用于我国三种典型含锶卤水(青海南翼山油田水、四川宣汉川25井卤水和四川平落坝地下卤水)结晶行为的模拟表明:这三种卤水蒸发后期均会有锶盐形成,温度较低时形成SrCl_2·6H_2O,温度较高时形成SrCl_2·2H_2O;温度对青海南翼山油田水和四川宣汉川25井卤水中锶富集最大程度的影响较大,温度升高均有利于锶在卤水中的富集;相比之下,四川平落坝地下卤水中锶的最大富集程度受温度影响较小,当高温析出SrCl_2·2H_2O时卤水中锶的最高浓度几乎不受温度影响。  相似文献   

Multiphase flow modeling with general boundary conditions and automatic phase-configuration changes using a fractional-flow approach     

Heejun Suk  Gour-Tsyh Yeh 《Computational Geosciences》2008,12(4):541-571

The multiphase flow simulator moving particle semi-implicit (MPS) method is developed based on the fractional-flow approach, originated in the petroleum engineering literature, considering the fully three-phase flow with general boundary conditions. The fractional flow approach employs water saturation, total liquid saturation, and total pressure as primary variables. Most existing models based upon fractional flow are limited to two-phase flow and specific boundary conditions. Although there appear a number of three-phase flow models, they were mostly developed using pressure-based approaches, which require variable-switch techniques to deal with phase appearance and disappearance. The use of fractional flow-based approaches in MPS makes it unnecessary to use variable-switching to handle the change of phase configurations because the water saturation, total liquid saturation, and total pressure exist throughout the solution domain regardless of whether certain phases are present or not. Furthermore, most existing fractional flow-based models consider only specific boundary conditions, usually Dirichlet-type pressure for water phase and flux-type boundary for nonaqueous phase liquid or particular combinations for individual phase. However, the present model considers general boundary conditions of ten most possible and plausible cases. The first eight cases are the combinations of the phase pressure or the phase flux of each of the three individual phases. The other two cases are the variable boundary conditions: one for water-medium interface and the other for the air-medium interface when the directions of fluxes are not known a priori. Thus, the model’s capabilities of handling general boundary conditions extend the simulators’ usefulness in the field system.  相似文献   

A hybrid method for optimization of the adaptive Goldstein filter     

《ISPRS Journal of Photogrammetry and Remote Sensing》2014

The Goldstein filter is a well-known filter for interferometric filtering in the frequency domain. The main parameter of this filter, alpha, is set as a power of the filtering function. Depending on it, considered areas are strongly or weakly filtered. Several variants have been developed to adaptively determine alpha using different indicators such as the coherence, and phase standard deviation. The common objective of these methods is to prevent areas with low noise from being over filtered while simultaneously allowing stronger filtering over areas with high noise. However, the estimators of these indicators are biased in the real world and the optimal model to accurately determine the functional relationship between the indicators and alpha is also not clear. As a result, the filter always under- or over-filters and is rarely correct. The study presented in this paper aims to achieve accurate alpha estimation by correcting the biased estimator using homogeneous pixel selection and bootstrapping algorithms, and by developing an optimal nonlinear model to determine alpha. In addition, an iteration is also merged into the filtering procedure to suppress the high noise over incoherent areas. The experimental results from synthetic and real data show that the new filter works well under a variety of conditions and offers better and more reliable performance when compared to existing approaches.  相似文献