甚长基线干涉测量天线参考点和轴线偏差监测方法探讨

高精度监测VLBI天线参考点和轴线偏差等参数,对提高VLBI台站坐标测定精度及天测、测地VLBI资料解析精度等具有重要意义.常规监测方式占用望远镜工作时间,监测效率低,所得参数精度较差.文章提出通过参数化VLBI天线的旋转运动建立天线固连合作目标在局域网中坐标数学模型的方法,有望实现全天候、全自动监测;考察了代表性数学模型,在观测方程构建、解算参数设置和约束条件选取等方面提出了新的见解.最后通过仿真分析,验证了对方程与参数所做调整的有效性,初步结论可供参考.     

古人利用节理面开凿遂昌唐代金矿巷道的发现及论证

在对遂昌金矿唐代古金矿4号古洞的考察中,发现分布在矿中的巷道两侧的围岩都是坚硬的变质岩。通过现场研究,作者有4点发现：（1）发现发育于围岩中的节理面具有密度大、倾角陡和间距小的特点;（2）古巷道轴线的走向与节理面的走向基本一致;（3）古巷道的横截面被古人设计成高宽比很大的洞形;（4）巷道的走向都被设计成某种弧形。据此,可以作出以下判断：在一千多年前的唐代,古人很可能已发现这些发育于围岩中的陡倾角节理面之间的结合力很低,使用铁凿就可撬下来,并据此来开挖古巷道的。这也表明唐代的古人已经掌握了相当多的地质知识,并能够将之成功地应用于工程实践中。     

阿尔金南缘阿克提山岩体锆石U- Pb定年、Hf同位素特征及构造意义

阿克提山花岗岩体位于阿尔金断裂南缘,其形成时代与区域内其他花岗岩体差异较大,该岩体走向明显地受阿尔金断裂带分支断裂控制。锆石LA-ICP-MS U-Pb年代学分析表明,该岩体结晶年龄约为262Ma,其形成可能与南阿尔金地区在华力西期-印支期发生的大规模线性构造运动有关。岩体的岩性主要为石英闪长岩、花岗闪长岩,其暗色矿物以角闪石、黑云母为主,岩石A/CNK值均小于1.1,显示准铝质—弱过铝质特征,属于高钾钙碱性系列;大离子亲石元素Rb、Th、K相对富集,高场强元素Nb、Ta、P、Sr、Ti明显呈负异常;稀土元素配分曲线具有中等负Eu异常,δEu的平均值为0.73,(La/Yb)_N平均值为14.57,说明该花岗岩体岩浆部分熔融程度较高。根据岩石学及地球化学特征可判断该岩体为I型花岗岩。锆石Lu-Hf同位素分析表明,锆石ε_(Hf)(t)值为+1.46～+9.14,均为正值,二阶段模式年龄的峰值平均为943Ma,表明其源岩主要为新元古代新生地壳物质的部分熔融。阿尔金断裂在印支期的走滑运动是从地壳深部的韧性变形开始的,随后在浅地表发生脆性断裂形成大规模走滑断裂带。阿克提山岩体的形成与地壳深部减压熔融有关。     

Selenium content in soils from Murcia Region (SE,Spain)

The objective of this study was to determine the selenium content in soils from the Region of Murcia (SE, Spain) and to study the possible relationship between mineralogical composition, soil properties and selenium content. In addition, generic reference level (GRL) for selenium was determined according to Spanish legislation. For this study, 490 samples were selected in areas subjected to agricultural activity or abandoned agricultural soils with natural vegetation. Five different zones were established in order to study selenium variability. Four different mineralogical groups were established, based on significant relationship with the mineralogical composition, and each sample was included in one mineralogical group. The results showed that the concentration of selenium is correlated with the electrical conductivity, sulphate content and with the mineralogical composition, particularly positively with quartz and in a negative way with calcite percentage. In addition, selenium level was positively correlated with the phyllosilicate content. Established GRL for selenium varies with the mineralogical group, having a great transcendence from the legal and economic points of view.     

1948年川西理塘M7.3地震地表破裂特征及Riedel剪切构造分析

1948年川西理塘M 7.3地震是川滇菱形块体内部近一个世纪以来发生的震级最大的走滑型地震。在对此次同震地表破裂进行详细调查基础上,利用差分GPS对同震地表破裂带进行了精确测量与统计分析。结果揭示该地表破裂的现存长度为36 km,北端始于无量河以北,往东南沿藏坝盆地北东缘、德巫盆地东南缘,延伸至德巫乡北,分为南、北两段,而在交德附近存在约3 km长的地表破裂空区。对同震地表破裂的线密度和同震水平位错量进行分段统计后揭示,此次地震的宏观震中应位于德巫盆地中部交德东南约4～5 km处。对理塘同震地表破裂的Riedel剪切分析结果指示,该破裂带主要由R剪切组成,以发育雁列状排列的挤压鼓包(Push-up)为主要特征,伴有少量R′剪切与T裂缝,缺少P型与X型剪切。其中R剪切占95%以上,其在藏坝段(北段)的优势方向为318°,德巫段(南段)为315°,整条地表破裂带的R剪切平均方向为316°。同时发现,此次地震形成的雁列状挤压鼓包主要以平缓的"弧形"为主,这与1981年道孚M_S 6.9地震和2010年玉树M_S 7.1地震地表破裂带中出现大量反"S"形...     

Preparation of a New Geological Survey of Japan Geochemical Reference Material: Coral JCp-1

A new geochemical reference material, coral Porites sp. JCp-1 has been prepared by the Geological Survey of Japan (GSJ). Provisional values for twenty one major, minor and trace elements are presented. The homogeneity tests showed that all elements studied are considered to be homogeneously distributed.     

Magnitude of lateral displacement on the Crevillente Fault Zone (Betic Cordillera,SE Spain): stratigraphical and sedimentological considerations

The Crevillente Fault Zone (CFZ) comprises a system of northeast to southwest oriented dextral faults that extend for some 600 km in the External Zones of the Betic Cordillera (SE Spain). The magnitude of lateral displacement related to this fault zone is not well constrained, and it is considered to be between 20 and 400 km. The stratigraphical and sedimentological criteria used in this work have proven effective in quantifying the magnitude of the displacement along this structure. We have analysed an oolitic turbidite facies in the Middle Jurassic of the Sierra de Ricote (Median Subbetic of Murcia Province). A detailed revision of ooidal limestone outcrops has revealed that the source area of these deposits was to the Internal Subbetic zone, north of Vélez Rubio (Almería Province). These two tectonic units, the Median and Internal Subbetic, are currently 75 km from each other and separated by the CFZ. The conclusions arising from our stratigraphical, petrological and sedimentological studies favour interpretation of a 75–100 km lateral displacement. After restoring the Late Jurassic–Cretaceous anticlockwise rotation of Iberia, the CFZ appears to belong to the E–W palaeofault system that is related to the extension of the South Iberian Continental Margin (SICM). Copyright © 2004 John Wiley & Sons, Ltd.     

Fault dimensions,displacements and growth

Maximum total displacement (D) is plotted against fault or thrust width(W) for 65 faults, thrusts, and groups of faults from a variety of geological environments. Displacements range from 0.4 m to 40 km and widths from 150 m to 630 km, and there is a near linear relationship betweenD andW ². The required compatibility strains (e _s) in rocks adjacent to these faults increases linearly withW and with and ranges frome _s=2×10^–4 toe _s=3×10^–1. These are permanent ductile strains, which compare with values ofe _s=2×10^–5 for the elastic strains imposed during single slip earthquake events, which are characterised by a linear relationship between slip (u) andW.The data are consisten with a simple growth model for faults and thrusts, in which the slip in successive events increases by increments of constant size, and which predicts a relationship between displacement and width of the formD=cW ². Incorporation of constant ductile strain rate into the model shows that the repreat time for slip events remains constant throughout the life of a fault, while the displacement rate increases with time. An internally consistent model withe _s=2×10^–5, giving repeat times of 160 years and instantaneous displacement rates of 0.02 cm/yr, 0.2 cm/yr, and 2.0 cm/yr when total displacement is 1 m, 100 m, and 10 km, and slip increasing by 0.5 mm with each event, gives a good approximation of the data. The model is also applicable to stable sliding, the slip rate varying with ductile strain rate and withW ².     

Structural style and tectono-stratigraphic evolution of the Neogene–Quaternary Siderno Basin,southern Calabrian Arc,Italy

The Neogene–Quaternary Siderno Basin is located in the southern Calabrian Arc, along an E–W transect including the Ionian side and part of the Tyrrhenian margin. The orogenic belt was generated by ongoing northward subduction of Ionian oceanic lithosphere beginning in the Early Cretaceous. Since the Oligocene, the area has experienced complex tectonics, including NW–SE-oriented pull-apart basins. The forearc region contains >2000 m of Oligocene-to-Quaternary strata that cover pre-Tertiary rocks. The succession forms an E-dipping monocline, with tectonic growth structures increasing upward. Erosional truncations and thickness variations suggest a different evolution for the Siderno Basin, which in comparison with northern and southern parts of the Ionian accretionary wedge, evolved differently during the Serravallian–Tortonian stages. NW–SE and NE–SW fault systems are dominant, the first exhibiting strike–slip and normal kinematics in the Nicotera–Gioiosa and Molochio–Antonimina fault zones. These structures were active during infilling of the Neogene basin, and represent a complex transfer zone.

The NE–SW system shows two types of tectonic kinematics: (1) a compressive stage, with NW–SE-orientated shortening, responsible for inversion tectonics documented by east-verging folds, thrusts, and back-thrusts, and (2) emplacement of the variegated clay during the Langhian, which is related to back-thrust propagation. The strike–slip accommodated stress generated in the accretionary prism in response to subduction of Ionian lithosphere and progradation of the accretionary front of the Calabrian forearc.