白银厂中部成矿带稀土元素地球化学特征的研究   总被引：3，自引：0，他引：3       下载免费PDF全文

蒋心明  丛桂新 《地质找矿论丛》1986,(3):68-79

稀土元素在国外已广泛用于岩石学和矿床成因方面的讨论。随着我国测试技术的进步和分析精度的提高,从稀土元素的角度研究岩石和矿床的某些规律,有助于我们对地质现象的认识和解释。众所周知,白银厂是我国老一辈地质学家解放初期发现和勘探成功的大型块状硫化物矿床。地质部和冶金部地质队投入了大量的钻探工程和大比例尺填图。地质科研院、所、大专院校,从不同领域进行较全面的地质研究工作。然而,矿床开采已接近尾声,认识上还不统一。我们为提高对白银厂地区地层、细碧石英角斑岩建造、矿床成因的认识,企图从稀土元素方面提供某些信息,本文是我们对其结果初步研究的成果。  相似文献   

关于郯庐断裂巨大平移问题的商榷     

龙汉春 《华东地质学院学报》1987,(1)

本文以大量地质事实证明郯庐断裂在新生代经历了强烈的水平挤压,中生代则经历了侏罗纪时的水平挤压和白垩纪时的强裂拉张。从古构造和古地理分析,郯庐断裂也未造成过太古界、元古界和古生界地层的明显错移,它们都是受当时的古构造和古地理控制而原地沉积,并非由于郯庐断裂的“巨大平移”才具有现在的布局。郯庐断裂形成于太古代末-元古代初,其后经历了地槽阶段、地台阶段和地洼阶段的漫长演化。不同时期表现出不同的活动特点,但基本上以差异升降和水平挤压及拉张形式为主,未见巨大平移的证据。  相似文献   

The latent and sensible heat fluxes over the western tropical pacific and its relationship to ENSO   总被引：1，自引：0，他引：1  

Long Baosen 《大气科学进展》1989,6(4):467-474

In this paper the Bulk Aerodynamic Formulas are used to compute the latent and sensible heat fluxes over the area 8oS-20oN, 130o-180oE for each month from January 1950 through December 1979 by using the data set of COADS supplied by NOAA of USA. The annual and monthly geographical distributions and the seasonal cycle of heat fluxes are carried out and a seasonal change of heat fluxes for ENSO year is also obtained by compositing individual ENSO year including 1951, 1953, 1957, 1963, 1965, 1969, 1972 and 1976. It is found that during ENSO episodes positive anomalies of heat fluxes appeared during the period of March to July and negative anomalies from August to March of the following year. The time series of sum of heat fluxes for March. April, May, June and July in each year from 1950 through 1979 had a significant link to the eastern tropical Pacific SST index (Wright, 1983). The correlation coefficient was 0.56. As it is found that in the latter half of each ENSO year (August-December) the fre-quency of typhoon formation in the area studied is less than normal, we suggest that the negative anomalies of heat fluxes during the same period be a mechanism for the decreased frequency of typhoon formation.  相似文献   

Chemical differences between minerals from mineralizing and barren intrusions from some North American porphyry copper deposits   总被引：1，自引：0，他引：1  

D. A. F. Hendry  A. R. Chivas  J. V. P. Long  S. J. B. Reed 《Contributions to Mineralogy and Petrology》1985,89(4):317-329

Major-element analyses (by electron microprobe) and copper contents (by ion-probe) are reported for primary biotite, amphibole, magnetite, pyroxene, ilmenite, sphene and secondary biotite from intrusive rocks from mineralizing and barren stocks. The districts studied include Christmas, Globe-Miami, Sierrita and Tombstone, in Arizona; Bingham and Alta, Utah; Ely, Nevada; and Brenda, British Columbia. Amphiboles from barren rocks are relatively iron-rich and display only minor compositional variation. In contrast, amphiboles from mineralizing rocks span the range from magnesio-hornblende to actinolite, commonly even within one grain. Barren intrusions (type B) that are temporally distinct from mineralizing intrusions, and barren intrusions outside areas of known mineralization have higher Cu contents in their constituent minerals than do mineralizing intrusions. Barren intrusions (type A) that are deep-level temporal equivalents of Cu-bearing porphyritic rocks are depleted in copper. This suggests that copper is abstracted from not only the apical portions of porphyries but from parts of the deeper parent intrusions. The Cu contents of biotites (av. 23 ppm) and magnetites (97 ppm) from barren type B intrusions contrast with those from mineralizing intrusions, with biotites containing 7 ppm Cu and magnetites 3 ppm Cu. Primary amphiboles from all intrusive rock types have low copper contents, typically 2 to 5 ppm. In the continental North American deposits, the amount of copper available by liberation from or non-incorporation into amphibole, biotite and magnetite during magmatic crystallization or the early hydrothermal stage is low, perhaps too low to be the sole source of copper mineralization, unless copper is abstracted from large volumes (∼ 100 km³) of rock. These results contrast with a study of the island-arc porphyry copper at Koloula, Guadalcanal, where it was argued that sufficient copper for mineralization could have been abstracted from relatively small volumes of host rocks that originally contained as much Cu as the contemporaneous barren rock types.  相似文献   

A survey of census bureau population projection methods     

Long JF  Mcmillen DB 《Climatic change》1987,11(1-2):141-177

Population projections methods of the U.S. Census Bureau draw upon several different traditions of forecasting: demographic accounting, judgmental, time series, deterministic, and explanatory. This paper reviews each of the forecasting traditions in population projections, describes the U.S. Census Bureau's current methods for national and state population projections, and proposes new hybrid approaches such as demographic-time series methods for national fertility projections and economic-demographic methods for state migration projections. Throughout the article, possible parallels with forecasting in other disciplines are noted.  相似文献   

龙门山断裂带四川北段震源位置的精确修定   总被引：3，自引：0，他引：3  

赵珠  陈农 《四川地震》1995,(4):19-30

本文采用人工地震折射测线和天然地震观测资料，给出了龙门山断裂带四川省境内北段Ｐ波和Ｓ波地壳速度模型，以此模型为基础，采用一种数值性能极好的定位方法和走时与慢度结合确定震源深度的方法，修定了沿龙门山断裂带四川北段及东侧盆地边缘的１１０个地震，给出了震源位置的精确解，讨论了地辰原深度的分布。本文还将定位结果与常规的四川台网地震目录进行了比较，对台网目录的精度进行了评价，并提出了提高台网定位精度的意见和  相似文献   

稀土富铁金刚石增强型硬质合金复合齿的研究     

史晓亮  刘晓阳  汤凤林  段隆臣 《煤田地质与勘探》2004,32(2):60-62

采用稀土La掺杂的添加方式，优选富铁硬质合金基体的配方，通过基体的力学性质测试以及金相分析确定了YGl5富铁硬质合金的基体配方，确定出最佳稀土La添加量为0．5％质量比。单齿抗冲击试验表明，这种复合齿具有良好的抗冲击性能。室内钻进试验说明，适当配方的稀土富铁金刚石增强型硬质合金复合齿具有良好的抗冲击性，较强的研磨能力和对岩样的广谱性。同时，通过野外实际钻进进一步说明，这种复合齿钻头具有高时效性。通过调整金刚石的镀覆方式和物质，金刚石浓度以及烧结工艺，来控制复合齿的性能，从而使稀土富铁金刚石增强型硬质合金复合齿钻头具有高时效、长寿命等特点。  相似文献   

Chemostratigraphy of Flood Basalts in the Garze-Litang Region and Zongza Block: Implications for Western Extension of the Emeishan Large Igneous Province, SW China   总被引：2，自引：0，他引：2  

Pirajno FRANCO 《《地质学报》英文版》2004,78(1):61-67

The Late Permian Emeishan Large Igneous Province (ELIP) is commonly regarded as being located in the western part of the Yangtze craton, SW China, with an asymmetrical shape and a small area. This area, however, is just a maximum estimation because some parts of the ELIP were not recognized or dismembered and destroyed during the Triassic to Cenozoic tectonism. In this paper, the chemostratigraphical data of the Zongza block, the Garze-Litang belt and the Songpan-Garze block suggest that the Late Permian basalts in these areas have remarkable similarities to the ELIP basalts in petrography and geochemistry. Flood basalts in the Sanjiangkou area are composed of the lower part of the low-Ti (LT) tholeiite and the upper part of the high-Ti (HT) tholeiite, which is the same as the flood basalts on the western margin of the Yangtze craton. Flood basalts in the Zongza and Songpan-Garze areas, which are far from the Yangtze craton, consist of HT tholeiite only. This is the same as the flood basalts within the Y  相似文献   

广东省寒潮、强冷空气的气候特征及与ENSO的关系   总被引：3，自引：13，他引：3  

曾琮  谢炯光 《广东气象》2003,(1):7-9

本文对影响广东的寒潮、强冷空气与ENSO的关系进行了分析，结果表明：寒潮和强冷空气活动多的年份一般出现在中等或强的El Nina期间。寒潮和强冷空气活动少的年份容易出现在La Nina期间，而较难出现在El Nina期间。  相似文献   

GIS中DEM产品精度的分析和评价   总被引：8，自引：1，他引：8  

马龙  杜道生 《测绘信息与工程》2003,28(3):4-6

从视觉上和统计上，对3个目前国内主流的GIS软件的DEM产品作了精度分析，给出了其DEM的精度评价结果，对实际生产有一定的参考价值，有助于对软件的DEM产品质量形成一定的认识。  相似文献