Evolution and REE geochemistry of Huangsha-Tieshanlong ore-bearing granite     

Xia Hongyuan  Liang Shuyi 《中国地球化学学报》1988,7(3):207-219

Our studies show that the granite bodies (γ ₅ ^{2 − 1} and γ ₅ ³ ) which constitute the Huangsha-Tieshanlong composite granitic intrusion in Jiangxi are characterized by their similarities in mineral assemblage, petrochemistry, trace element and REE distribution pattern. The values of ΣREE, ΣLREE, ΣHREE, ΣCe/ΣY, δEu and La/Yb apparently decrease from γ ₅ ^{2 − 1a} to γ ₅ ^{2 − 1b} , γ ₅ ³ and γ ₅ ³ . It is shown that the early Yenshanian W(Ta, Nb)-bearing granite (γ ₅ ^{2 − 1} ) and late Yenshanian Ta, Nb-bearing granite (γ ₅ ³ ) may have been derived from the differentiation and evolution of granitic magmas due to repeated remelting of the crust and their earlier and later intrusion. Although the earlier (γ ₅ ^{2 − 1b} and later (γ ₅ ³ ) albitized Ta, Nb-bearing granites show some obvious differences in REE content, their δEu values and La/Yb ratios are similar to each other. Therefore, it may be concluded that the early and late Ta, Nb-bearing granites were derived from a congenetic magma.  相似文献   

REE compositional characteristics of Hannuoba basalts     

Li Shaobing  Liu Delin  Zhang Zhenjiang  Xu Jianen 《中国地球化学学报》1988,7(3):243-251

The Hannuoba basalts are a suite of associated rocks consisting of alkali basalts and tholeiites. The alkali basalts can be divided into the K-rich type and the Na-rich type, while the tholeiites are almost solely of the Na-rich type. These two types of basalt are characterized as being obviously rich in light rare earth elements, as is shown in the chondrite-normalized REE patterns exhibiting positive Eu anomalies. However, significant differences in (La / Yb)_N and Eu / Eu* ratios are noticed between these two types of basalt. They seem to have been derived from varying-degree partial melting of mantle rocks.  相似文献   

Decollements in slate belts,examples from the European variscides and the Qin Ling Belt of Central China     

Dr. Ph. Matte  Q. Xu Zhi 《International Journal of Earth Sciences》1988,77(1):227-238

Decollements are conspicuous features of collision belts as a result of shortening and shearing of rocks of different competencies in response to intracontinental subduction and crustal stacking. When these decollements occur at upper levels, the classical thin skin tectonics of the foredeeps without important internal strain results; at mid crustal levels slaty cleavage and foliation development occurs. In the more internal parts of the chains, in the lower crust, near the crust mantle boundary, the more severe conditions (granulitic metamorphism) result in ductile deformation in the deepest parts of the mountain belts. Examples of middle and lower crust are well documented in Central China and the Variscan Belt of Europe from field evidence and deep seismic profiling.From these examples it appears more and more likely that most of the mid-crustal slate belts showing vertical slaty cleavage at the erosion surface overly flat decollements.At greater depth large decollements must occur as well in the lower continental crust and at crust-mantle boundary. Typical features of the deep seismic vertical profiles such as the strongly layered lower crust may represent the image of such deep decollements.

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Zusammenfassung Abscherungen sind charakteristische Strukturen von Kollisions-Orogenen. Sie sind das Ergebnis von Verkürzung und Scherung verschieden kompetenter Gesteine infolge intrakontinentaler Subduktion und Krustenüberlagerung. Zu unterscheiden sind Überschiebungen oberer Zonen, wie in den Randgebirgsbereichen ohne bedeutende innere Deformation, von internen metamorphen Zonen mit Schieferung und Plättung. In den tiefen Krustenzonen und im Krusten-Mantelbereich gehen sie einher mit hochgradiger Metamorphose, allgemein in der Granulitfazies.Beispiele der mittleren und tiefen Zonen sind gut erschlossen im paleozoischen Orogen Zentralchinas und im Variszikum Europas und belegt sowohl durch die Geologie wie tiefenseismische Profile. Diese Beispiele zeigen mehr und mehr, daß geschieferte Gebirgsstockwerke mit an der Oberfläche steilstehender Schieferung von flachen Abscherungen unterlagert werden.Die typische Erscheinung einer seismisch gut geschichteten Strukturierung der Unterkruste könnte in dieser Hinsicht als Deckenbahnen interpretiert werden.

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Résumé Les décollements sont des structures typiques des chaînes de collision. Ils résultent du raccourcissement et du cisaillement de roches de différentes compétences en réponse à la subduction continentale et à l'empilement crustal. On peut distinguer des décollements superficiels surtout dans les bassins d'avant chaîne où les roches charriées ont subi une déformation interne faible à nulle (plis et chevauchements sans schistosité). Des décollements plus profonds dans le tiers supérieur de la croûte accompagnés de schistosité et de foliation, dans les parties plus internes métamorphiques des chaînes. Enfin des décollements très profonds à la base de la croûte ou entre croûte et manteau, accompagnés ou suivis d'un métamorphisme de haut degré, généralement granulitique.Ces deux derniers types de décollement sont clairement exprimés dans la chaîne Varisque d'Europe et dans la chaîne Paléozoïque Qin Ling de Chine Centrale. Il apparaît ainsi de plus en plus évident que la plupart des zones plissées à schistosité verticale, non liées à des décrochements, passent en profondeur à de grands décollements plats. On les met en évidence sur le terrain ou/et grâce à des profils de sismique réflexion écoute longue. Des aspects caractéristiques de ces profils comme par exemple la croûte inférieure litée pourraient représenter l'image sismique de tels décollements profonds.

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Quasi-hydrostatic compression of ruby to 500 Kbar     

Pascal Richet  Ji-An Xu  Ho-Kwang Mao 《Physics and Chemistry of Minerals》1988,16(3):207-211

Measurements of the cell parameters of ruby to 500 Kbar under quasi-hydrostatic conditions in a diamond-anvil cell show a practically isotropic compression, the ratio c/a of the hexagonal cell parameters remaining constant. These results are consistent with previous single-crystal measurements below 100 Kbar as well as with ultrasonic elastic-constant measurements. There is no evidence for significant differences between the bulk moduli of ruby and corundum, and a review of compression and ultrasonic data yield Ko = 2.53±0.01 Mbar and Ko = 5.0 ± 0.4. Good agreement with the experimental values is found for compressions calculated from empirically or theoretically determined elastic properties.  相似文献   

离子色谱法测定矿物包裹体中阴离子     

许银焕  蒋桂玉 《铀矿地质》1988,(5)

本文介绍了用离子色谱法同时测定矿物包裹体中F~-、Cl~-、PO_4~(3-)、Br~-、NO_3~-、SO_4~(2-)6种阴离子的新方法。研究了流动相浓度对保留时间的影响以及消除负峰干扰的方法。  相似文献   

内蒙古狼山地区的层控铀矿及其控制因素的卫片影象模式     

曹宏经  许定远  高淑惠 《铀矿地质》1988,(6)

狼山地区广泛分布着花岗岩型铀矿化和砂岩型铀矿化。本文通过对该区的遥感地质综合解译,重点研究了几个含铀盆地的砂岩型铀矿化成矿特点及其通感图象的影象特征,发现广布于早白垩世断陷盆地的砂岩型铀矿化是一典型的层控型铀矿。并通过区域构造型式的研究,强调了弧形构造的断块活动特征及其对含铀盆地和含矿层分布的控制作用;揭示了弧形构造的后期活动和环形构造、北北东向线性构造与铀矿化的再造关系。从而得出砂岩铀矿化是受地层岩相和弧、环、线构造“四位一体”条件控制的新认识。该矿化在MSS图象上呈现一定的影象特征,据此,本文概括出本区层控铀矿的影象模式。  相似文献   

Application of Hydro-Electric Effect Method to NDI of Piles     

Liang Zhian 《岩土力学》1988,9(2):59-64

This paper presents briefly the essential principle and measurement process of hydro-electric effect method for NDI of piles. In the past three years, more than three hundred piles from twenty project sites inspected with method. Coring piles and comparing dynamic with static tests have proved that hydro-electric effect method is available for engineering with easy operation, quick inspection, and low costs.  相似文献   

Seepage and Deformation of Fissured Rock Mass     

Liang Yaochi 《岩土力学》1988,9(3):51-56

Seepage law of fissured rock masses is presented in this paper. The Navier-stokes equation is demonstrated available to describe seepage law of rock masses by testing study. The dynamical seepage pressure in rock masses makes great effect on deformation of rock masses, results in opining of fissure and deformation of rock masses. The seepage and deformation of rock mass and dynamical seepage pressure is studied. The experimental results are checked with Bossiness formula, and are closed to the computing data.  相似文献   

Dynamic Effect of Mudstone Strength Properties     

Zhang Huaifang  Xu Xin 《岩土力学》1988,9(4):31-40

This paper, comparing the dynamic test results of mudstone (silty clay) with the static ones, verifies influence of cyclic loading and loading rates on the strength of mudstone. It is found that the dynamic strength is higher than the static strength. In the case of rapid loading (rising time of pressure is 10ms ), the unconfined compressive strength for this type of soil in dynamic test is 2.3 to 2.9 times as high as that in static tests, and the strength index, Cd , is about 2.8 times as great as Cs , but ∅ values are approximately equal to each other. Repeat loading (up to 3600 cycles) has no great influence on the strength of mudstone, and under the condition of unconfined loading, the fatigue strength of mudstone is somewhat lower than its statically strength.  相似文献   

某矿区断裂带含矿糜棱岩形成时物理条件的初步研究     

梁良  钟芝筠 《华东地质学院学报》1989,12(1):1-6

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