南秦岭增生杂岩带马道地区变泥质岩的变质作用     

王东升  王宗起  张英利  宫江华  王涛  林健飞 《现代地质》2016,30(6):1254-1266

摘要：南秦岭构造带出露于勉略断裂和虞关—留坝断裂之间,是一条复杂的增生杂岩带,也是秦岭造山带的重要组成部分。增生杂岩带内马道地区发育一套由黑云母片麻岩、片岩组成的变泥质岩,内部包含有石英岩、大理岩及超基性岩等岩块,构成了典型的“block in matrix”结构。选取了含石榴子石黑云母片麻岩样品进行详细的岩石学研究。结果显示,北部变质岩样品中的石榴子石具有弱退变质成分环带,利用岩石矿物组合中的石榴子石-黑云母温度计、石榴子石-黑云母-斜长石-石英组合温度-压力计,估算峰期压力为078~079 GPa,温度为705~707 ℃,退变质时期压力为064~076 GPa,温度为602~650 ℃,揭示出岩石峰期高角闪岩相变质后,经历降温减压过程。南部岩石样品中含有特征的十字石+蓝晶石组合,样品中的石榴子石具有进变质成分环带,其峰期压力为049~057 GPa,温度为553~562 ℃,相当于低角闪岩相。通过与其他典型增生杂岩带变质岩的剥露机制对比,认为马道变泥质岩的变质作用演化与南秦岭地区碰撞作用有关,而其剥露过程则主要受到双重逆冲构造控制。  相似文献   

Estimation of the Source Time Function Based on Blind Deconvolution with Gaussian Mixtures     

Boi-Yee?Liao  Huey-Chu?HuangEmail author 《Pure and Applied Geophysics》2005,162(3):479-494

It is demonstrated that the blind deconvolution method is fully capable of recovering the unknown Greenp9v5g0/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s function and of estimating the source time functions from observed seismic data of small earthquakes. Based on the assumption of the Gaussian-mixture model of the Greenp9v5g0/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s function, the newly-formulated algorithm is evaluated using synthetic seismic data along with those of the May 8, 1996 Mexico earthquake (M_c = 4.6). Since the estimated results closely match the theoretical input very well, the method is then employed to analyze the source time functions of the July 7, 1995 Pu-Li, Taiwan earthquake (M_L = 5.3). The stations triggered by this event were azimuthally well covered. Using the estimated source time functions, information pertaining to the directivity effect is readily obtained, and the actual fault plane of this event is identified, thus clearly indicating that this method provides a most efficient way to estimate the source time function of a small earthquake.Acknowledgment The authors would like to express their thanks to two anonymous reviewers for their valuable suggestions and Dr. I. Santamariap9v5g0/xxlarge8217.gif" alt="rsquo" align="BASELINE" BORDER="0">s courteous assistance. They also appreciate the efforts of Drs. H.C. Chiu and R.J. Rau, who provided the seismic data and the fault plane solutions. The National Science Council, Taiwan, has supported this research (NSC 91-2119-M-194-011).  相似文献   

近代四川气候特征初步分析及展望     

陈效孟 《成都信息工程学院学报》1993,(4)

本文分析了近代四川气温、旱涝变化的基本特征,并对未来变化趋势进行展望。  相似文献   

立体定向^32P腔内放射治疗囊性颅咽管瘤的一例随访报告     

任自强  李安敏 《CT理论与应用研究》1996,5(3):49-50

本文报导一例多次复发的囊性颅咽管瘤，应用＾３２Ｐ腔内放射治疗成功，随访４．５年无复发，生活自理，视力维持术前状态，复查ＣＴ囊腔缩小５０％以上，可以认为立体定向腔内离疗是一种安全有效的方法，对于孤立的或多发的囊性颅咽管瘤病例应作为外科手术首选方法，但仍需进行深入的临床研究，以观察和确定疗效。  相似文献   

金沙江下游及三峡段水文气象因子演变与响应的分析          下载免费PDF全文

杨璐  梅亚东  叶琰  林玉茹 《水文》2016,36(1):37-45

对金沙江下游及三峡段3个水文站1954~2008年径流序列和2个气象站1951~2008年降雨、气温序列运用滑动平均法和Mann-Kendall法进行趋势性检验,利用有序聚类法、均值检验法分析突变性及小波分析法进行周期性诊断,并应用Pearson法对径流、降雨和气温的相关关系进行研究。研究表明:(1)研究区径流量的年内分配不均匀性和年际变化不显著。(2)金沙江下游段屏山站的径流量呈上升趋势,并在1997年发生突变,但该区域宜宾站的降雨量呈下降趋势并在1991年发生突变;三峡段寸滩站和宜昌站的径流量呈下降趋势,分别在1968年和2005年发生突变,同时该区域沙坪坝站的降雨量呈上升趋势并在1961年和1995年发生突变。(3)径流和降雨时间序列都存在小于10a的主周期以及20a以上的次周期。(4)各水文站夏季径流量受同期降雨量和同期气温的共同影响,而秋季径流量受前期气温的影响最大。  相似文献   

A novel insight into vertical ground motion modelling in earthquake engineering     

Luca Prakash Argani  Alessandro Gajo 《国际地质力学数值与分析法杂志》2022,46(1):164-186

Recent observations of failure and damage of buildings and structures under seismic action has led to an increasing interest for an in-depth analysis of the vertical component of site ground motion. In particular, when dealing with saturated soils, the current engineering practice does not usually go beyond the simplified phic/nag3295-math-0005.png"> u–phic/nag3295-math-0006.png"> p formulation of the Biot's equations describing the coupled hydro-mechanical behaviour, thus neglecting some terms of fluid inertial forces, despite the presence of more refined formulations, for example, the phic/nag3295-math-0007.png"> u–phic/nag3295-math-0008.png"> U formulation. Therefore, a theoretical and numerical validation of the phic/nag3295-math-0009.png"> u–phic/nag3295-math-0010.png"> p formulation as compared with the phic/nag3295-math-0011.png"> u–phic/nag3295-math-0012.png"> U formulation is proposed in this work, where the numerical simulations are compared with the analytical solution for the phic/nag3295-math-0013.png"> u–phic/nag3295-math-0014.png"> p formulation, which is also derived and illustrated in this text. The comparison between the two formulations and the analytical solution is provided for different levels of permeability and dynamic actions, which are representative of a wide scenario of site ground properties and seismic hazard in the vertical direction. In particular, the soil response is analysed in terms of acceleration and pore pressure time history, frequency content, acceleration response spectrum, and amplification ratio of acceleration. This study extends the discussion of the limits of applicability of the phic/nag3295-math-0015.png"> u–phic/nag3295-math-0016.png"> p formulation with respect to the rigorous solution of Biot's equations (obtained here with phic/nag3295-math-0017.png"> u–phic/nag3295-math-0018.png"> U formulation) to the context of a complex dynamic regime provided by the vertical components of real earthquake records, and paves the way for further investigations.  相似文献