Geochemical patterns from local to global   总被引：5，自引：0，他引：5  

Xie Xuejing  Yin Binchuan 《Journal of Geochemical Exploration》1993,47(1-3)

The historical development of geochemical exploration is, in a sense, a process of progressive enlargement of areal coverage by exploration projects and progressive widening of sampling space. Along with this process, a hierarchy of geochemical patterns from small to large is gradually discovered and understood. In this paper, we try to summarize systematically the whole hierarchy of geochemical patterns from local, regional, provincial, megaprovincial to global, using examples obtained in China.Local anomalies (various types of dispersion halos, trains and fans) within areas not exceeding a few km², can be delineated when sampling is done with very close intervals in limited areas. Regional anomalies within areas of tens to hundreds km² and threshold values lower than local anomalies can be identified only when large areas of more than thousands of km² are mapped with wider space sampling. Geochemical provinces with areas of thousands or tens of thousands of km² can be discovered if even larger areas, of more than tens or hundreds of thousands of km², are covered with very low density sampling. More than millions of km² should be covered in order to discover geochemical megaprovinces somewhere in the world. Such megaprovinces are often associated with extraordinarily large mineral resources. If ultra-low density geochemical mapping can be carried out across national boundaries on a continental or global scale, we could find even broader geochemical patterns which will reflect the global tectonic features.The classification of geochemical patterns according to their sizes is necessary because it will be extremely useful in planning sampling layout in order to hit targets of certain size ranges. This in turn is arranged in different geochemical projects for achieving specific aims.  相似文献   

Seawater Intrusion in the Longkou-Laizhou Area, Shandong     

Xue Yuqun  Xie Chunhong  Wu Jichun  Nanjing University Liu Peimin  Wang Jianji  Jiang Qingbo Office of Water Resources of Longkou City Shi Hongwen  Ning Pihai Office of Water Resources of Laizhou City Liu Linqun 《《地质学报》英文版》1993,67(1)

The extensive intrusion (covering an area of 83.7-238.3 km~2 and accounting for 18.6-31.5% of the total area of the plain), the presence of a transitional zone 1.5-6.0 km in width, and the interconnection in distribution between the seawater intrusion district and the region lower than the sea level caused by the strong drop of the groundwater level are major characteristics of the seawater intrusion in the study area. Cation exchange played an important role during the formation of chemical composition of the groundwater in the seawater intrusion district.  相似文献   

福建山地气候生态特征及其宜茶气候带的划分     

谢庆梓 《山地学报》1993,(1)

福建山地分布近海面至海拔2158米,立体气候特征极其明显。本文根据福建山地气候生态特征和茶树的生物学特性,将山地划分为:1.大叶种茶树最适宜、适宜、不适宜种植三个气候带;2.中、小叶种茶树最适宜、适宜、次适宜、不适宜四个气候带。并依此提出科学开发福建山地茶叶生产的五项关键技术措施。  相似文献   

硼酸盐矿物的振动光谱研究：Ⅰ：喇曼光谱特征     

谢先德  查福标 《矿物学报》1993,13(2):130-136

本文利用激光喇曼光谱研究了不同类型的硼酸盐矿物,讨论了它们的谱带特征及其归属。研究结果表明,具简单基团的喇曼光谱可以作出比较明确的归属,且与红外光谱结果一致,而同时具三、四配位硼的矿物,其配阴离子虽很复杂,各种谱带相互叠加,但仍可以对主要谱带作出初步的归属。  相似文献   

用氢氧化物共沉淀法研究热液体系REE（Nb,Ti）2O6型矿物的形成机理     

贡伟亮  赵伟 《矿物学报》1993,13(2):104-108

作者进行了稀土铌钛氢氧化物共沉淀实验,对共沉淀物及其高温灼烧产物进行了XRD、IR、DTA和Raman研究,结合前人高温高压实验结果以及野外地质事实,提出了热液体系复杂氧化物矿物易解石和黑稀金矿的络合物高温水解、氢氧化物共沉淀、脱水去羟、聚合成核和结晶的成因模式。  相似文献   

南京市区降水酸度的初步研究     

莫天麟  谢国梁 《气象学报》1981,39(4):460-464

本文介绍了1979年11月至1980年7月期间南京市区降水酸度的测量结果。结果表明:南京市区降水的pH平均值为5.62,变化范围从4.10—7.93,其中,1980年1月份和7月份出现酸雨,pH的月平均值分别达到5.52和5.26。 测量结果还与日本、英国、美国的观测结果作了比较。  相似文献   

强震记录的采样与插值研究   总被引：2，自引：0，他引：2       下载免费PDF全文

谢礼立  胡成祥 《地震工程学报》1983,5(2):61-71

本文从频域和时域两方面对强震记录的采样和插值过程进行了研究。研究中将采样与插值当作一个信号转换系统,通过数值计算,求得和各种常用的采样和插值过程相对应的传递函数。通过对传递函数的进一步研究表明:采样和插值方式对强震记录数据处理的结果有重要的影响,发现采样过程相当于一个低通滤波器,可以滤除信号中的某些高频信息,而插值过程犹如一个高频噪声源,会在数字记录中引入某些伪高频分量。分析结果还表明:在相同的采样密度下,不等距采样方式具有较高的精度,而等间距采样方式能给出更宽的平坦的频率特性曲线;抛物线插值给出的传递函数结果要比线性插值的结果更精确,这对恢复数字信号中的高频成分具有重要的意义。  相似文献   

Preliminary investigation of mineralogy,petrology and chemical composition of Qingzhen enstatite chondrite     

Daode Wang  Xiande Xie 《中国地球化学学报》1982,1(1):69-81

On September 13, 1976, the Qingzhen enstatite chondrite fell near Qingzhen County, Guizhou Province (26°32′N, 106°28′E). The total mass recovered was 2.6 kg. Phenomena of the meteorite fall were recorded as well. In the present paper some of the significant observations are described. X-ray diffraction analyses and petrologic studies revealed that it is mainly composed of enstatite/clinoenstatite, plagioclase, troilite, kamacite, taenite, quartz and oldhamite. X-ray electron microprobe analyses were performed on orthoenstatite and clinoenstatite. Chemical analysis gave: SiO₂-36.48; Al₂O₃-1.64; TiO₂-0.08; Cr₂O₃-0.28; FeO-0.30; MnO-0.25; MgO-18.19; CaO-1.14; Na₂O-1.06; K₂O-0.11; H₂O⁺-0.47; H₂O^?-0.10; P₂O₅-0.39; FeS-13.35; FeO-22.94; Ni-1.81; Co-0.093; C-0.37; Cu-0.022; Zn-0.027; CaS-0.60; total-99.70 (wt.%). This meteorite has been extremely reduced; all iron is present as FeS and metallic Fe-Ni. The Qingzhen enstatite chondrite is characterized by high ratio, Si/Mg as compared with ordinary chondrites, scarcity of olivine, and enrichment in sulfur and iron. In thin sections, it is observed that round chondrules approximately account for 10–15 per cent, being porphyritic, radial, excentroradial, or excentric fan-shaped. Devitrified chondrules composed of pyroxene were also identified. It is postulated from its mineralogy, chemistry and textural characteristics that the Qingzhen meteorite should be assigned toE ₄ orEH chondrites.  相似文献   

Recent advances in geochemical exploration in China     

Xie Xuejing  Zheng Kangle 《Journal of Geochemical Exploration》1983,19(1-3)

This paper outlines the recent advances in geochemical exploration in China.The Regional Geochemistry—National Reconnaissance (RGNR) Project first proposed in 1978, continues to be the focus of geochemical exploration activities in China. Several rapid quantitative multi-element analysis systems using conventional equipment available in most Chinese geological laboratories, have been developed. Eight Geochemical Standard Reference Samples of Drainage Sediments were prepared. Large-scale orientation or pilot surveys are being carried out by nearly 2/3 of the provincial geological bureaus in China. Methods of regional and follow up surveys for high and cold mountainous terrain have been worked out.Special attention has been given to the improvement and application of mercury vapour detection techniques. A new sampler was used to enhance anomalous values. A new Zeeman effect mercury detector was constructed and tested in routine analysis of mercury. Experiments of the application of soil gas mercury survey in petroleum and uranium prospecting are briefly described.Some examples of recent geochemical success in China are given.  相似文献   

塔里木克拉通北缘库鲁克塔格地块太古宙基底组成与地壳演化     

朱文斌  林和丰  葛荣峰  董春艳  颉颃强  刘守竭  万渝生 《地质学报》2022,96(9):3084-3101

塔里木克拉通太古宙岩石主要出露在库鲁克塔格、北阿尔金、铁克里克和敦煌等四个边缘基底隆起带。库鲁克塔格地块位于塔里木克拉通东北缘，其中有可靠年代学报道的太古宙岩石主要出露在库尔勒、辛格尔、兴地和帕尔岗塔格四个地区。库鲁克塔格地块的太古宙岩石主要由长英质正片麻岩(含TTG片麻岩)和少量以包体产出的斜长角闪岩组成，真正的太古宙表壳岩较少见。本次研究在库尔勒地区对长英质正片麻岩和石英岩开展锆石SHRIMP U- Pb测年分析，2个长英质正片麻岩样品的年龄分别为2695±9 Ma和2705±8 Ma；石英岩样品中的碎屑锆石核最小年龄峰为2513 Ma，石英岩有可能是太古宙沉积岩；上述岩石样品都经历了古元古代早期 (1. 9~1. 8 Ga)高级变质作用。地球化学分析发现，库鲁克塔格地块新太古代长英质片麻岩的原岩有多种岩石类型，这些长英质岩石都形成于与俯冲作用有关的岛弧构造背景。基性的斜长角闪岩和变质辉长岩可能产出于不同的背景，一部分来源于岛弧地幔楔的部分熔融，另一部分则可能来自于大洋板内，以洋脊玄武岩为主。库鲁克塔格地块太古宙岩石具有2. 7 Ga和2. 5 Ga两个年龄峰值，2. 7 Ga岩浆事件主要发生在库鲁克塔格西部地区，锆石的εHf(t)值既有正值也有负值，表明这一时期地壳生长和改造同时并存；~2. 5 Ga的岩浆活动分布范围较为广泛，全岩εNd(t)和锆石εHf(t)值以正值为主，暗示这一时期可能存在显著的大陆地壳生长。  相似文献