古吉黑造山带的演化与陆壳的增生

当把全球性洋陆结构体制用于区域性地质构造、特别是大陆古造山带研究时 ,我们发现还存在着一种“块带结构体制”区。本文所讨论的东北亚古吉黑造山带即是其中一例。古吉黑造山带 ,在空间上指松辽平原及其以东的吉林和黑龙江二省的东部山区。在时间上是指新元古代—早、中三叠世的造山演化历史。该区从新元古代起 ,就存在着晚太古宙所形成的松嫩、佳木斯、兴凯和龙岗等地块 ,及挟持其间的陆缘活动带 ,它是由古、中元古宙变质岩花岗岩系为结晶基底所形成的过渡型陆壳 ,从而构成了一个典型的块带结构体制区。通过阿森特兴凯期的弱造山 ,加里东期的次弱造山 ,早华力西期的次强造山和晚华力西期—早印支的强造山 ,使过渡型陆壳在造山作用的岩石圈深部动力学过程中 ,实现了壳幔能量和物质的交换 ;通过地幔物质的添加、陆壳物质的再循环 ,以英云闪长质深成岩垂直增生的模式 ,得到增长的同时成熟度不断提高 ,最终实现了向成熟陆壳的转化 ,并和诸地块实现了一体化 ,成为东北亚复合大陆的重要组成部分。这一过程 ,在陆壳物质成分的演化上表现尤为明显。无论是沉积物还是火山和侵入体的物质组成 ,总体上都向着富硅、富碱、特别是富钾的方向发展。作为造山带演化结束、成熟陆壳形成、复合大陆诞生的物质成分标志—     

卸荷工程岩体非线性模型的研究与应用

卸荷工程岩体与传统的加载岩体的力学条件有着本质的区别，其非线性特征更为明显，卸荷工程岩体的研究是一个崭新的领域，对卸荷岩体的工程地质特征、力学参数的确定、本构关系及卸荷岩体释放荷载的计算方面进行了初步的探讨。     

Application of Laser Ablation ICP-MS to U-Th-Pb Dating of Monazite

Recent advances in laser ablation ICP-MS techniques allow accurate U-Th-Pb age dating of monazites that are as young as several tens of million years to a precision better than 2%. Accuracy of the age determinations has been improved by true real-time mass bias correction via nebulisation of a solution containing enriched ²³³U and natural Tl isotopes. The Tl-U tracer solution eliminates possible effects of variable sample matrices on the precision and accuracy of measured isotopic ratios. Mass bias corrections based on measured ²⁰⁵Tl/²³³U ratios in the tracer solution allow direct measurement of ²³⁵U in monazite. Combined with high-sensitivity laser ablation ICP-MS measurements, direct measurement of ²³⁵U particularly improves the precision of U-Pb dating of young monazites. Correction for laser-induced Pb/U and Pb/Th elemental fractionation is based on a mathematical treatment of time resolved count-rate data that is independent of laser ablation characteristics, does not require external standardisation and allows variable laser pit size or raster patterns for each measurement. The new procedures make the LA ICP-MS technique more flexible for in situ U-Th-Pb analysis.     

Alteration Patterns Related to Hydrothermal Gold Mineralizaition in Meta-andesites at Dungash Area, Eastern Desert, Egypt

Abstract: The hydrothermal alteration patterns associating with the gold prospect hosted by metavolcanics in the Dungash area, Eastern Desert of Egypt, were investigated in order to assign their relationship to mineralization. The metavolcanics of andesitic composition are generated by regional metamorphism of greenschist facies superimposed by hydrothermal activity. Epidote and chlorite are metamorphic minerals, whereas sericite, carbonates, and chlorite are hydrothermal alteration minerals. The auriferous quartz vein is of NEE‐SWW trend and cuts mainly the andesitic metavolcanics, but sometimes extends to the neighbouring metapyroclastics and metasediments. Quartz‐sericite, sericite, carbonate‐sericite, and chlorite‐sericite constitute four distinctive alteration zones which extend outwards from the mineralized quartz vein. The quartz‐sericite and sericite zones are characterized by high contents of SiO₂, K₂O, Rb, and As, the carbonate‐sericite zone is by high contents of CaO, Au, Cu, Cr, Ni, and Y, and the chlorite‐sericite zone is by high contents of MgO, Na₂O, Zn, Ba, and Co. Gold and sulphide minerals are relatively more abundant in the carbonate‐sericite zone followed by the sericite one. The geochemistry of the alteration system was investigated using volume‐composition and mass balance calculations. The volume factors obtained for the different alteration zones, mentioned above (being 1.64, 1.19, 1.17, and 1.07, respectively), indicate that replacement had taken place with a volume gain. The mass balance calculations revealed addition of SiO₂, K₂O, As, Cu, Rb, Ba, Ni, and Y to the system as a whole and subtraction of Fe2O3 from the system. Initial high aK+ and aH+ for the invading fluids is suggested. As the fluids migrated into wallrocks, they became more concentrated in Mg, Ca, and Na with increasing activities of CO₂ and S. The calculated loss‐gain data are in agreement with the microscopic observations. Breakdown of ferromagnesian minerals and feldspars in the quartz‐sericite, sericite, and chlorite‐sericite zones accompanied by loss in Mg, Fe, Ca, and Na under acidic conditions and low CO2/H2O ratio may obstruct the formation of carbonates and sulphides, and the precipitation of gold in these zones. The role of metamorphic fluids in the area is expected to be restricted to the liberation of Au and some associated elements from their hosts.     

浅谈地勘单位如何实施群众性经济技术创新工程

本文论述了地勘单位实施群众性经济技术创新工程的重要性和必要性，指出实施群众性经济技术创新工程，有利于推动地勘单位的技术进步和产业升级；有利于充分发挥工人阶级在两个文明建设中的主力军作用，提出推动群众性经济技术创新工程的实施，必须贯彻落实党的全心全意依靠工人阶级的方针；必须立足基层、注重实效，必须营造一个良好的氛围和环境，通过实施群众性经济技术创新工程的，从而不断加快地勘经济的发展。     

正热电离质谱同时测定硝酸盐中氮和氧同位素组成

初步研究了一种硝酸盐中氮和氧同位素质谱测定的新方法。该法利用石墨的非还原热离子发射特性 ,建立了以测定 Cs2 NO2 + 离子的正热电离质谱测定硝酸盐中氮和氧同位素组成的过程 ,对方法的可行性、特点和存在的问题进行了讨论 ,并对几种测定氮和氧同位素的方法进行了比较。运用正热电离质谱法对几种不同厂家生产的硝酸盐试剂的氮和氧同位素组成进行了测定 ,发现氮和氧同位素组成存在较大的差异     

Clast Fabric in Relict Periglacial Colluvium, Salamanca Re-Entrant, Southwestern New York, USA

Samples of macrofabric data obtained from colluvial deposits near the late-Wisconsinan glacial margin display widely divergent characteristics. Those from highly weathered and jointed sandstone plot as girdle distributions. Samples from red colluvium of early-Wisconsinan age form moderately strong clusters. Fabrics from shallow depth in medium-textured brown colluvium of late-Wisconsinan age generally have modes aligned with the local slope but are weak, and appear to have been modified by frost heaving. Clasts in the basal layers of an overlying loess unit were emplaced by frost heaving from the brown colluvium and have very weak or uniform fabrics. Particle shape exerts an influence on fabric strength in the brown colluvium, with samples composed of more elongated clasts displaying stronger fabrics. Fabrics from near-surface deposits show generally weaker shape and strength characteristics and higher inclinations than those at depth. Calculated seasonal frost penetration is consistent with the depth to which weaker, more steeply inclined fabrics are found. Sampling in relict periglacial deposits should be performed only below the level of disturbance by seasonal frost.     

岩体变形监测时序分析与动态建模

基于时序ARMA模型, 分析了岩体变形监测数据的动态建模及其预测的基本方法, 并用ARMA模型对板岩山危岩体监测数据进行建模及预测, 取得了较好的效果。     

共轭平移断层中各序次应力场和断裂等构造形迹相互关系的力学分析

从数学、力学的角度定量分析了各类构造结构面之间的空间组合规律, 并推导出相关的公式。本文首次提出了预测或预报对区域稳定性或岩体稳定性具有重大影响的断裂构造的产状要素和派生构造应力场的方位、大小的方法。     

Influential input classification in probabilistic multimedia models

 Monte Carlo analysis is a statistical simulation method that is often used to assess and quantify the outcome variance in complex environmental fate and effects models. Total outcome variance of these models is a function of (1) the variance (uncertainty and/or variability) associated with each model input and (2) the sensitivity of the model outcome to changes in the inputs. To propagate variance through a model using Monte Carlo techniques, each variable must be assigned a probability distribution. The validity of these distributions directly influences the accuracy and reliability of the model outcome. To efficiently allocate resources for constructing distributions one should first identify the most influential set of variables in the model. Although existing sensitivity and uncertainty analysis methods can provide a relative ranking of the importance of model inputs, they fail to identify the minimum set of stochastic inputs necessary to sufficiently characterize the outcome variance. In this paper, we describe and demonstrate a novel sensitivity/uncertainty analysis method for assessing the importance of each variable in a multimedia environmental fate model. Our analyses show that for a given scenario, a relatively small number of input variables influence the central tendency of the model and an even smaller set determines the spread of the outcome distribution. For each input, the level of influence depends on the scenario under consideration. This information is useful for developing site specific models and improving our understanding of the processes that have the greatest influence on the variance in outcomes from multimedia models.