桑干地区高压麻粒岩中石榴石和斜长石的连续激光探针~(40)Ar~-~(39)Ar等时年龄及其地质意义

采用微区激光探针４０Ａｒ－３９Ａｒ定年方法, 对华北桑干地区高压基性麻粒岩中变质石榴石和斜长石直接进行了原位微区年代测定。石榴石变斑晶是高压麻粒岩相变质作用形成的矿物,石榴石周围后成合晶反应边组合中的斜长石是石榴石减压分解的产物。石榴石斑晶的４０Ａｒ－３９Ａｒ等时线年龄为２５１０ Ｍａ, 证明高压变质作用发生在太古宙末。斜长石４０Ａｒ－３９Ａｒ等时线年龄为１９６８Ｍａ, 代表石榴石在中压麻粒岩相条件下分解的时代。它们之间年龄相差大于５００Ｍａ, 说明高压麻粒岩可能没有经历近等温减压的ＰＴ轨迹。后成合晶组合很可能代表中压麻粒岩相变质作用的叠加。这一结果对探讨华北克拉通桑干地区早期地壳的构造演化具有重要意义。     

Observations of Alfvén Ionospheric Resonances on the Earth's Surface

The paper briefly reviews the preliminary results of observations of Alfvén ionospheric resonances performed in the northern Carpathian Mountains (south-eastern Poland) by the Cracow Schumann Resonances Group. The results confirm the simple models proposed recently by Lysak and Sentman.     

渤、黄海大泷六线鱼耳石微化学特征与群体判别

为探究中国近海大泷六线鱼(Hexagrammosotakii)耳石微化学成分特征及群体分化状况,采集了连云港、青岛、威海、烟台、秦皇岛、大连、丹东7个野生群体和1个威海养殖群体的大泷六线鱼样本。利用LA-ICPMS技术测定耳石中的微量元素,以微量元素与钙的比值进行了分析,结果显示大泷六线鱼耳石中, Na/Ca、Sr/Ca、Fe/Ca、Mg/Ca较高,而Mn/Ca、Ba/Ca、Zn/Ca、Li/Ca较低。耳石1龄前元素比值的组间比较(S-N-K检验)结果显示:Na/Ca、Sr/Ca、Fe/Ca在群体间具显著性差异(P<0.05)。耳石边缘区元素与环境中元素比较发现,Li、Mn元素在耳石中富集程度较大,Sr在耳石的中元素含量远远大于水环境中的浓度,说明耳石中的元素沉积与海水中元素并不是简单的线性关系。判别分析结果显示:耳石1龄前元素指纹的判别分析结果表明,大泷六线鱼群体的判别成功率为63.0%,判别正确范围为30.0%～80.0%,耳石边缘区元素的判别正确率为57.1%,判别正确范围20.0%～80.0%,秦皇岛群体有高的判别成功率80.0%。耳石元素指纹可以用于不同大泷六线鱼群体的...     

两种激光粒度仪测量结果的对比

用两种型号(Cilas 940L和Malvern2000)的激光粒度仪对149个沉积物样品进行了测量,对测量结果作了对比分析。包括各粒级间的对比、各种粒度参数的对比以及相关分析等。找出了两种仪器在不同粒级之间的差异和相关性。分析结果表明,两种仪器的分析数据在13～14pm的粒度区间最为接近,小于此粒级范围时Cilas 940L所测得数据大于同粒级内Malvern2000的观测值,大于此粒级范围的分析结果则相反,即Cilas 940L对细粒样品的敏感性更强一些。     

船基激光法波浪测量仪器的研究

介绍了船基激光法波浪测量仪器研制的可行性。船载激光测波是利用舰船作测量平台,在水面上方设置激光测距装置,以一定的频率测量探头与水面的垂直距离,分析所测距离信号的变化规律,可以得出波浪高度、周期等信息,描述出波浪的形态和变化规律。文章提出了测量原理,分析了可能遇到的测量误差,给出了相应的解决措施,得出了研究开发船基激光法波浪测量仪器的可行性结论。     

Gully morphological characteristics in the loess hilly‐gully region based on 3D laser scanning technique

Gully morphology characteristics can be used effectively to describe the status of gully development. The Chabagou watershed, located in the hilly‐gully region of the Loess Plateau in China, was selected to investigate gully morphological characteristics using a 3D laser scanning technique (LIDAR). Thirty‐one representative gullies located at different watershed locations and gully orders were chosen to quantitatively describe gully morphology and establish empirical equations for estimating gully volume based on gully length and gully surface area. Images and point cloud data for the 31 gullies were collected, and digital elevation models (DEMs) with 10‐cm resolution were generated. ArcGIS 10.1 was then used to extract fundamental gully morphological parameters covering gully length (L), gully width (W_T) and gully depth (D), and some derivative morphological parameters, including gully head curvature (C), gully width–depth ratio (w/d), gully bottom‐to‐top width ratio (W_B/W_T), gully surface area (A_g) and gully volume (V_g). The results indicated that gullies in the upper watershed and the second order were more developed based on their high values of gully head curvature. The potential for gully development increased from the second order to the fourth order. Within the same gully orders, gullies in the lower watershed were more active with more development potential. A method for differentiating between gully head and gully sidewalls based on the gully head curvature value was proposed with a mean relative error of 8.77%. U‐shaped cross‐sections were widely distributed in the upper watershed and upper positions of a gully, while V‐shaped cross‐sections were widely distributed in the lower watershed and lower positions of a gully. V–L and V–A_g empirical equations with acceptable accuracy were established and can be used to estimate gully erosion in the Loess hilly‐gully region. Copyright © 2017 John Wiley & Sons, Ltd.     

两种激光粒度仪测量湖泊沉积物粒度结果的对比

湖泊沉积物粒度参数是湖泊沉积与环境演变研究中常用的环境指标,近年来激光粒度仪的发展和广泛使用更是促进了粒度指标的应用并在很大程度上提高了精度和效率.然而不同的激光粒度仪对于同一样品的测量会得到不同的结果,本文利用两种常见的激光粒度仪测量了西藏纳木错的两支岩芯,并对结果进行了对比分析.从仪器的重现性来看,Mastersizer2000型激光粒度仪要优于LS13320型激光粒度仪,而LS13320型激光粒度仪在对含量较少的细颗粒和粗颗粒的检测效果上优于Mastersizer2000型激光粒度仪;两种仪器得到的粒度参数d(0.1)和d(0.5)无论在变化趋势还是绝对数值上都较为相似,而d(0.9)的差异则较大.对比研究结果为利用湖泊沉积物粒度参数提取古环境信息研究提供了基础依据.     

古建筑保护中新技术的实践应用

随着信息化时代的到来,古建筑保护工作中也逐渐应用了建筑、测绘地理信息行业中的信息化新技术.新技术的实践与应用为古建筑保护与管理工作提供了极大的帮助.本文将三维激光扫描技术、BIM技术、GIS空间分析技术分别应用于不同的古建筑保护项目,对其应用实践进行阐述说明,并就其应用效果进行了简单分析.