Constraining the Late Mesozoic and Early Tertiary Tectonic Evolution of Southern Mexico: Structure and Deformation History of the Tierra Caliente Region

We analyze the structure and assess the deformation history of the Tierra Caliente Metamorphic Complex (TCMC) of southern Mexico, where Laramide accretion of exotic terranes is in debate. The TCMC consists of a south-plunging antiform fault that is bounded on both its eastern and western flanks. Tierra Caliente Metamorphic Complex rocks show at least two phases of compressional deformation. The first and most prominent records a mean tectonic transport direction of 068 degrees. This phase is responsible for east-verging asymmetrical folding and thrusting of both metamorphic and superjacent sedimentary rocks. The second phase has an average transport direction of 232 degrees and is restricted to the western portion of the TCMC. A third phase is responsible for normal faulting. Lack of discernible deformation before Late Cretaceous time indicates that the main deformation phase is coincident with Laramide orogenesis elsewhere in the North American Cordillera. The stratigraphy, structure, and deformational history of the TCMC do not require accretion of exotic terranes. We explain the Mesozoic tectonostratigraphic evolution of the TCMC in terms of deposition and deformation of Mesozoic volcanic and sedimentary strata over the attenuated continental crust of the North American plate.     

Statistical Properties of SGR 1806-20 Bursts

We present statistics of SGR 1806-20 bursts, combining 290 events detected with the Rossi X-Ray Timing Explorer/Proportional Counter Array, 111 events detected with the Burst and Transient Source Experiment, and 134 events detected with the International Cometary Explorer. We find that the fluence distribution of bursts observed with each instrument are well described by power laws with indices 1.43, 1.76, and 1.67, respectively. The distribution of time intervals between successive bursts from SGR 1806-20 is described by a lognormal function with a peak at 103 s. There is no correlation between the burst intensity and either the waiting times until the next burst or the time elapsed since the previous burst. In all these statistical properties, SGR 1806-20 bursts resemble a self-organized critical system, similar to earthquakes and solar flares. Our results thus support the hypothesis that the energy source for soft gamma repeater bursts is crustquakes due to the evolving, strong magnetic field of the neutron star, rather than any accretion or nuclear power.     

Hard X-Ray Emission from the Galaxy Cluster A2256

After the positive detection by BeppoSAX of hard X-ray radiation up to approximately 80 keV in the Coma Cluster spectrum, we present evidence for nonthermal emission from A2256 in excess of thermal emission at a 4.6 sigma confidence level. In addition to this power-law component, a second nonthermal component already detected by ASCA could be present in the X-ray spectrum of the cluster, which is not surprising given the complex radio morphology of the cluster central region. The spectral index of the hard tail detected by the Phoswich Detection System on board BeppoSAX is marginally consistent with that expected for the inverse Compton model. A value of approximately 0.05 μG is derived for the intracluster magnetic field of the extended radio emission in the northern regions of the cluster, while a higher value of approximately 0.5 μG could be present in the central radio halo, which is likely related to the hard tail detected by ASCA.     

SPME和MCC／UV—IMS的联合应用——地下水和地表水污染的现场快速监测手段

将10．6eV光化电离源离子迁移分光计与多毛细管柱（MCC）的方法联合使用，结合顶空固相微萃取（HS—SPME）和快速色普预分离法，对地下水和地表水污染进行现场的快速监测。在野外条件下，直接检出的污染物的浓度降到上限为lg／L。水中的BTEX、萘、氯烯烃和氯苯的测量方法说明了这种研究方法的潜力。在以前煤气厂的位置调查的污染了的地下水和在金属处理厂位置凋查地下水的实践结果，焦点问题都是污染物为苯、茶和四氯乙烯，这就说明了进行野外测试研究的可行性。     

基于MERIS影像空间、光谱及时间维信息提取亚像元级的土地覆盖组分

及时获取有效的土地覆盖信息是地球系统模拟的基础。因此,中等空间分辨率传感器如MODIS或MERIS空前的通道设置与观测能力,使其具有快速更新土地覆盖图的能力。本文说明了如何结合MERIS的空间维（像元大小为300m）、光谱维（可见光与近红外范围内15个通道）和时间维（重返周期2—3d）,用于获取不同区域土地覆被组分的亚像元级组成权重。利用4月、7月和8月三期MERIS FR1b级数据得到荷兰主要土地覆被类型的组成权重。单一时相和多时相的数据都使用单个像元最优化的端元数进行线性光谱分解。利用一种形态偏离指数得到MERIS的空间维并用于端元的选择。应用荷兰土地利用数据库（LGN5）25m分辨率的栅格数据作为本文的参考数据。基于这种数据的高分辨率,因此可以从像元和亚像元的水平同时评价的分类精度。结果显示,结合4月和7月的影像可以获得最优的分类结果,精度约为58%。总的说来,亚像元和像元级的分类精度相似。通过几种组分类别和日期的光谱融合表明,物候状况对于数据获取时相最佳结合的选择以及正确识别土地覆盖类型的重要性。     

考虑地下水入侵导致土壤强度变化的沿海建筑地基韧性模型

海平面上升导致的地下水入侵沿海地区的建筑地基造成显著风险。提出了一个考虑地下水侵入导致土壤强度退化的沿海建筑地基韧性模型。该模型由地基的性能函数在服役期内的积分得到。考虑条形基础的韧性,其极限承载力由Terzaghi公式描述。韧性模型考虑气候变化背景下地下水位的上升对土壤强度的影响。通过一个算例,展示了所提出的韧性模型的适用性。结果表明,如果不考虑气候变化影响下地下水位的上升,则会得到不保守的结构韧性评估结果。结构全寿命周期内的韧性也取决于所采用的维护措施（即,修复受损的结构性能）。未来的研究中,还应考虑其他因素（如锈蚀）对沿海建筑地基性能退化的联合影响。     

“一带一路”沿线部分国家测绘地理信息标准组织及其标准化工作概况

我国与"一带一路"沿线国家的合作由来已久,"一带一路"倡议的提出更是为我国与沿线国家的深层合作、交流、互惠互利以及推广实施"创新、协调、绿色、开放、共享"的发展理念提供了机遇。对国防地理空间信息工作组、北大西洋公约组织下设的标准组织、欧洲标准化组织地理信息技术委员会等国际和区域测绘地理信息标准化组织以及"一带一路"沿线国家印度尼西亚、马来西亚、阿曼苏丹国和土耳其的标准化工作概况进行介绍,再结合其他资料总结"一带一路"沿线国家的测绘地理信息标准化工作的主要特点,为分析我国与沿线国家测绘地理信息标准共建、共享的可能性以及国内标准的制修订和研究提供参考。     

浅谈“一带一路”对测绘标准化建设的新要求

"一带一路"沿线国家大部分是与我国有共同利益的发展中国家,基于"一带一路"倡议背景,发展经济,改善民生,应对危机,实现各国和各地区互联互通,急需解决信息覆盖问题及对测绘技术的新要求问题。在分析"一带一路"建设对测绘标准化需求的基础上,探究测绘标准化建设的新思路,为沿线国家社会、经济建设提供有效的信息支持。     

Petro Gram: An excel-based petrology program for modeling of magmatic processes

Petro Gram is an Excel?based magmatic petrology program that generates numerical and graphical models.Petro Gram can model the magmatic processes such as melting,crystallization,assimilation and magma mixing based on the trace element and isotopic data.The program can produce both inverse and forward geochemical models for melting processes(e.g.forward model for batch,fractional and dynamic melting,and inverse model for batch and dynamic melting).However,the program uses a forward modeling approach for magma differentiation processes such as crystallization(EC:Equilibruim Crystallization,FC:Fractional Crystallization,IFC:Imperfect Fractional Crystallization and In-situ Crystallization),assimilation(AFC:Assimilation Fractional Crystallization,Decoupled FC-A:Decoupled Fractional Crystallization and Assimillation,A-IFC:Assimilation and Imperfect Fractional Crystallization)and magma mixing.One of the most important advantages of the program is that the melt composition obtained from any partial melting model can be used as a starting composition of the crystallization,assimilation and magma mixing.In addition,Petro Gram is able to carry out the classification,tectonic setting,multi-element(spider)and isotope correlation diagrams,and basic calculations including Mg^#,Eu/Eu^*,εSrandεNdwidely used in magmatic petrology.