冈底斯带门巴区晚白垩世花岗岩年代学、地球化学及构造背景

门巴区晚白垩世花岗岩主要分布于冈底斯中段的扎雪、金达和桑巴附近,由黑云母钾长花岗岩、钾长花岗岩和二云母钾长花岗岩及花岗闪长岩等组成。其中花岗闪长岩SHRIMP 锆石U--Pb 年龄为68. 8 ± 1. 6 Ma; 钾长花岗岩黑云母K--Ar 年龄为78. 2 ± 1. 2 Ma 和81. 5 ± 1. 4 Ma; 黑云母钾长花岗岩和二云母钾长花岗岩的黑云母K--Ar 分别为90. 8 ± 1. 81 Ma 和91. 2 ± 1. 8 Ma。岩石学和地球化学分析结果表明,S 型和低Sr 低Yb 特征的黑云母钾长花岗岩和二云母钾长花岗岩形成于拉萨地块与羌塘地块碰撞造山过程中的地壳加厚背景; S 型和总体低Sr、高Yb 特征的钾长花岗岩形成于造山带晚期阶段的伸展背景; I 型花岗闪长岩应是新特提斯洋俯冲作用的结果,形成于岛弧构造环境。     

皖北地区新元古代构造背景的转换:来自碎屑岩地球化学的证据

在对安徽省北部宿州新元古代史家组砂岩地球化学特征分析的基础上,结合前人发表的淮南和凤阳新元古代刘老碑组页岩的地球化学数据,对它们的物源和构造背景进行了对比讨论.结果表明:刘老碑组页岩的地球化学特征表明其来自于中-酸性火成岩高程度的首次风化,而史家组砂岩则来自于经历了再循环的古老地壳物质较低程度的风化.刘老碑组页岩相对史...     

西藏蓬湖西蛇绿岩地球化学及构造背景研究

西藏蓬湖西蛇绿岩隶属于班公湖—怒江缝合带的中段,是藏北湖区较好的堆晶岩剖面之一。形成该堆晶岩时矿物分离结晶顺序为铬铁矿→橄榄石→单斜辉石→斜长石,分离结晶作用具有由富镁质、铁质向富铝质、钙质演化趋势。堆晶岩主量元素组成与世界典型蛇绿堆晶岩成分相似;各种堆晶岩石的微量元素和稀土元素配分曲线总体上基本一致,反映其同源性;岩石Nb和Ta亏损,稀土元素含量很低,分配模式呈LREE微弱亏损的平坦型。该蛇绿岩形成于弧后盆地扩张中心,属SSZ型蛇绿岩。     

大厂锑矿田构造控矿特征及实验构造地球化学初步研究

贵州省晴隆大厂锑矿床严格受地层和构造控制，属构造改造型锑矿床。本从构造与成矿入手，通过野外观测和室内模拟试验，对构造改造和控矿特征、构造热动力作用下锑的地球化学行为、矿田内岩石的应力和应变、物质成分变化等对锑矿成矿作用的影响进行了探讨，对锑矿成矿规律、构造运动及物质运动间的关系有了进一步认识。     

马庄山矿区构造地球化学测量研究

新疆哈密马庄山金矿与构造关系密切，并严格受构造控制。根据马庄山矿区构造地球化学测量的研究，归纳出了构造地球化学测量的基本理论和方法，指出开展构造地球化学测量找矿的路径。概略研究了构造地球化学异常与构造和矿体的关系     

Leveling geochemical data between map sheets

Geochemical surveys are frequently assembled into larger, regional compilations. In some cases a boundary shift in the values for one or more elements may be observed at the join of adjacent surveys. This indicates that data for the affected elements are not consistent between the surveys. Where the same sampling medium has been used, the shift may be due to different crews/organizations, who varied in their sampling techniques. However, most commonly the shift is due to imperfect calibration of the analytical method used for samples from the different surveys. For example, there may have been a lack of proper analytical standardization between survey programs. To carry out leveling, bands are established on either side of the boundary between two surveys that show a shift. It is desirable that the bands have a close match in terms of geology and physiography. A quantitative method is presented to estimate the optimum width for these bands. Quantiles of the data within each band are calculated. The quantile pairs are plotted in X–Y space and a line fitted to express the relationship between the pairs of quantiles. The equation of this line is used to correct the shift between the two surveys. This method is tested on data for Mo in stream sediments, and pH of stream water, from two National Geochemical Reconnaissance Surveys in British Columbia.     

用AutoCAD二次开发系统绘制化探图

将地球化学测量的分析数据按照每条测线上的测点位置以一定的顺序依次输入Microsoft Excel、Microsoft Word或其他数据库软件编制的多元素分析数据表，并对各元素分别建立成纯文本数据文件。根据制图比例尺、测线数目和间距、测线上测点数目和点距、测区的某一角点坐标等已知参数，分别计算出各测点在图纸上的坐标值，将纯文本数据文件中各元素的分析结果标注在图纸上对应的测点位置，以绘制原始数据图并根据如上的参数以及化验数据计算编绘平面剖面图，最后再根据测线方位角使整个图形旋转，从而完成图件的制作。按照上述方法，以VisualLISP为工具，利用AutoCAD2000二次开发技术编制相应的处理程序，从而实现地球化学原始数据图和平面剖面图的微机制图。     

应用MAPGIS地形库管理整合1∶200000区域化探数据

利用1∶200 000地球化学数据,从整个成矿地球化学环境的角度出发,最大限度地开发、挖掘三十九种化学元素中每个元素以及元素组合所蕴含的矿化信息,为成矿远景区预测提供更加翔实的地球化学依据,是地球化学工作者的研究任务之一。MAPGIS功能强大,其地图库管理模块为多幅1∶200 000地球化学异常图的拼接提供了技术支持。这里论述了1∶200 000地球化学数据的特征和MAPGIS的地图库管理的功能,并记述了在实际工作中应用MAPGIS的地图库管理对多幅1∶200 000地球化学异常图的拼接,实现了对1∶200 000地球化学数据的另一种应用方式。     

新疆东昆仑喀拉曲哈铜矿地球化学特征

喀拉曲哈铜矿是东昆仑西段古尔嘎金铜成矿远景区中的一个受断裂构造控制的蚀变岩型矿床，本文重点介绍了喀拉曲哈铜矿床的地球化学特征及矿床地质特征。     

第四系覆盖区元素地球化学制图方法新探讨

受分析误差、成图方法以及众多人为因素的影响,根据分析测试数据制作的元素地球化学图有时并不能客观真实地反映元素区域分布起伏特征.笔者以浙北地区土壤元素资料为基础,探讨了成图处理方法对地球化学图的影响,旨在更好地利用计算机制图技术,有效削减分析误差及成图处理方法的畸变干扰,以绘制出更加准确可靠的元素地球化学图.     

化探综合异常图定量编制方法及应用

现阶段以单元素异常图为基础编制的综合异常图,只能定性地圈定出综合异常范围,并没有考虑异常点元素彼此之间的叠加贡献,不能定量评价综合异常。研究发现,该类图件不论在图面表达形式还是在应用效果中均存在诸多不足。明确了"平均衬度法"的概念,提出利用平均衬度法编制综合异常图的思路和方法,即以原始分析数据为基础,利用平均衬度定量表达综合异常范围,编制形成平均衬度综合异常图。对比结果表明,平均衬度法对综合异常的圈定效果优于累加衬度法和综合衬度法。平均衬度综合异常图特别适合1:5万化探普查资料的开发研究,由于圈定的范围小、浓集中心明显,适合准确布置地表探矿工程,并可以节约勘查成本,提高找矿命中率。     

A preliminary geochemical map for arsenic in surficial materials of Canada and the United States

Over the past 30 a, regional and national solid-phase geochemical surveys have been conducted by the United States Geological Survey and the Geological Survey of Canada. In the present paper the authors have examined the distribution of As in stream-sediment and soil samples of the US and Canada in terms of geologic and anthropogenic components. The results of the compilations indicate that the distribution of As in stream sediments, lake sediments, and soils in Canada and the US shows that most of the variability is controlled by the bed rock characteristics.     

An environmental risk assessment map of the Slovak Republic: application of data from geochemical atlases

A water budget analysis for the Cedar River watershed in northeastern Iowa was conducted to determine the water balance during the summer months of 2000. The watershed has eight major tributaries that comprise a drainage area of 20,242 km², of which 81% is agricultural land. Water budgets are essential when examining the movement of agricultural chemicals as well as nutrients within the system. The water budget was determined using the hydrologic mass-balance equation, which states that [inflow = outflow - storage]. The inflow components were measured individually and included precipitation, tributary and Cedar River baseflow. The outflow components included evaporation, transpiration, tributary and Cedar River discharge. The results of this study indicate a slightly larger volume of water leaving the watershed (6.24᎒⁹ m³) than entering (6.21᎒⁹ m³). The surplus of the outgoing water (0.5%) is most likely due to an overestimation of transpiration, or the contribution of water from the intermittent streams not measured during the study. Calculations of nutrient flux showed that approximately 2.99᎒⁶ kg of nitrogen and 2.39᎒⁵ kg of phosphorus were lost from the watershed during the study.     

Application of the geochemical prospecting to improve oilfield structure models

Background： Complicated structure of surveyed area has minor efficiency of seismic surveys-the main method for petroleum and gas prospecting and interpretation of subsurface structure of the Earth. This paper gives an example that in certain cases geochemical surveys can be used as additional tool to establish suitable geological model of the trap. This paper presents geochemical studies in the southeastern part of European territory of Russia-Nagumanovskoe oilfield. Complicated geological structure causes difficulties to create suitable geological model of the trap itself. There are two models of geological structure for the Nagumanovskoe oilfield： Variant A： Researchers assume the presence of gas condensate accumulation and perspective for exploration traps. Variant B： Researchers assume presence of 2 local structures. Method and results： Geochemical data came from over than 2000 shallow probes （2 meters, 6.6 feet） of soil gas samples collected every 200 meters over more than 7 different long profiles. The adsorbed soil gases were analyzed for hydrocarbones. All samples were decomposed into geochemical populations. According to geochemical data the Nagumanovskoe oilfield was well defined on all geochemical profiles. Examination and comparison of hydrocarbon ratio plots and magnitude graphs for each of the two models indicate that the more anomalous magnitude sites agree with the disposition of structures according to model B. The geochemical oil/gas data exhibit clearly defined compositional sub-populations which match the composition of the underlying reservoirs, difference in standard deviation of hydrocarbon values at background and Cretaceous structure （model B） leads to the deduction that variant B is more suitable geological structure model of the Nagumanovskoe oilfield.     

印度尼西亚Buti铜矿的土壤地球化学特征与成矿预测

文章通过分析印度尼西亚Buti铜矿的地质地球化学特征,圈定出5个矿致综合异常,并对可能富集成矿的异常进行成矿潜力评价,最后认定3个综合异常BT2,BT4和BT5具有寻找斑岩型和低温热液型铜-金矿的潜力。