排序方式： 共有16条查询结果，搜索用时 109 毫秒
1.
A. Lindh 《Contributions to Mineralogy and Petrology》1973,39(3):219-230
The distribution of elements among silicate- and oxide minerals is investigated in a metamorphosed gabbro. The silicate minerals are found to be rather insensitive to the metamorphic process and to retain their initial high temperature character. The oxide minerals are completely altered and only show low temperature characteristics. A former high temperature origin is discussed from textural evidence. 相似文献
2.
3.
Anders Lindh 《Lithos》1975,8(2):151-161
A population of 117 coexisting nonalkaline pyroxene pairs has been studied statistically to evaluate compositional and thermal effects on the element distribution. KDMgopx-cpx is influenced by the Fe/Mg-ratio, by the Ca content—especially of clinopyroxene—and by the content of tetrahedral Al. Fe and tetrahedral Al are found to be negatively correlated. A principal component analysis based on the variation of Si, AlIV, AlVI, Fe, Mg, Mn, Ca is performed. Dropping of highly correlated variables does not affect the result significantly. The first principal component reflects the major chemical variation in Fe and Mg. When using ferrous and ferric iron as separate entries of the analysis, either the second or the third component demonstrates a temperature dependence. It is, however, not possible to obtain pure temperature and chemical components due to the composition not being uncorrelated to temperature of formation. From these components a graph reflecting temperature of formation has been constructed. 相似文献
4.
Anders Lindh 《Lithos》1974,7(4):197-205
A population of 117 coexisting nonalkaline pyroxene pairs has been studied statistically to evaluate compositional and thermal effects on the element distribution. KDMgopx−cpx is influenced by the Fe/Mg-ratio, by the Ca content—especially of clinopyroxene—and by the content of tetrahedral Al. Fe and tetrahedral Al are found to be negatively correlated. A principal component analysis based on the variation of Si, AlIV, AlIV, Fe, Mg, Mn, Ca is performed. Dropping of highly correlated variables does not affect the result significantly. The first principal component reflects the major chemical variation in Fe and Mg. When using Ferrous and ferric iron as separate entries of the analysis, either the second or the third component demonstrates a temperature dependence. It is, however, not possible to obtain pure temperature and chemical components due to the composition not being uncorrelated to temperature of formation. From these components a graph reflecting temperature of formation has been constructed. 相似文献
5.
6.
A dolerite sill cutting slightly older basalt in west-central Sweden shows a strong chemical variation (54% < SiO2 < 73%) within a restricted area (< 100 × 100 m2). The linear correlation among almost all elements is extremely high; in addition, NdT is strongly correlated with the SiO2 content. Least-square hyperbolic-ratio and three-element ratio modelling (common denominator) suggests that most of the chemical variation is explained by mixing and/or micro-mingling. In all, we test 407 hyperbolas, of which 402 are fitted. The five ratio pairs, which could not be fitted to a hyperbola using a least-square fitting procedure, have the ratio Th / Eu in common. Testing the goodness of fit is problematic for hyperbolic distributions; for comparing purposes we sum the distances to chords approximating the hyperbola. Mobile and immobile elements behave similarly, suggesting that no elements are lost or added from outside the system. The data suggests that already the most mafic of the analysed rocks is a mixture of the ‘normal’ dolerite and a siliceous crustal rock. A mafic magma intruded into the base of the crust, where it fractionated resulting in a decreased Mg number. The magma was then contaminated with country rocks in an intermediate magma chamber due to country rock melting; during mixing/mingling almost no fractionation took place. The contaminated rock suggests the presence of a fluid phase. This was probably a prerequisite for country-rock melting. Enrichment in some incompatible elements suggests that besides major mixing/mingling a thermochemical separation process has affected the most felsic rock enriching it in light rare earths and Zr. 相似文献
7.
Anders Lindh 《Lithos》1972,5(4):325-343
Phase relations in the system FeO---Fe2O3---TiO2, at temperatures ranging between 300°C and 700°C, have been investigated experimentally with special refference to the reaction Fe3O4 + TiO2 = Fe2O3 + FeTiO3. Pressure was varied between 500 and 2000 bars but its effect was negligible. Magnetite and rutile are the stable assemblage at temperatures above 550 dgC, and hematite and ilmenite are stable for lower temperatures. The equilibrium oxygen fugacity is estimated to be 10−17.5 bars at equilibrium temperature. It is suggested that intermediate hematite-ilmenite solid solutions are inhomogeneous, consisting of ‘domains’ of hematite and ilmenite. The ‘domains’ are too small to be resolved by X-ray diffraction techniques. The top of the solvus curve in the hematite-ilmenite solution corresponds to a temperature of 660°C. Regular solution theory is not applicable to the solid solution. 相似文献
8.
Summary ¶The lithology, age, geological setting, structural and metamorphic history of the granitic mylonites from the Mylonite Zone (MZ) in southwestern Sweden have been studied extensively. The deformation history, growth of microstructures, intensity of deformation, changes in mineral compositions, and pressure-temperature conditions of deformation have, however, not been addressed. In this study, powder X-ray diffraction, optical microscopy, electron microprobe analysis and transmission electron microscopy of micas, chlorite, and plagioclase are combined to understand the physical and textural changes experienced by the rocks during mylonitization. It is shown that the occurrence of foliated micas in shear bands, recrystallization of quartz and biotite, and undulatory extinction in quartz grains were not uniform throughout the samples studied. Occurrence of dislocations and low-angle grain boundaries confirm that deformation occurred largely by glide dislocations. The low-angle grain boundaries observed are formed by the re-arrangement of these dislocations during grain size reduction processes. The micas show a high degree of spatial stacking order, but spatial stacking disorder in micas and chlorites has also been found.Ordered stacking faults are formed during low strain while disordered stacking faults are formed under high strain conditions. Occurrence of both ordered and disordered stacking faults indicates that the intensity of deformation was not uniform through the entire MZ. Moreover, the chemical composition of plagioclase shows that the exsolution lamellae observed with optical and electron microscopy are due to Ca-subsolidus reactions during low temperature deformation. Several substitution reactions occurring in the micas indicate that deformation took place between 0.3 and 0.4GPa, at a temperature higher than 500°C.Received October 15, 2001; revised version accepted December 25, 2002
Published online June 2, 2003 相似文献
9.
Anders Lindh 《International Journal of Earth Sciences》1982,71(1):130-140
The Postsvecokarelian development of the Baltic Shield shows a parallel development with tension and dolerite intrusions in the core zone and granite intrusions, compression and crustal shortening in the south-western margin. A crustforming event with calk-alkalic granitoid intrusions which with time moves westwards is followed by remelting and intrusion of alkali-intermediate granites and metamorphism. The south-western margin of the Shield probably was a stable ocean/continent border zone for a very long time. In spite of several attempts, no conclusive testable model for the development can be put forward today.
Zusammenfassung Die postsvekokarelische Entwicklung des Baltischen Schildes ist von einer zeitgemäßen Parallelität mit Tension und Diabasintrusionen in der östlichen Kernzone und Granitintrusionen, Kompression und Krustenverkürzung in der südwestlichen Marginalzone gekennzeichnet. Eine Phase mit Krustenbildung, die mit der Zeit nach Westen rückt, und wo kalkalkalische Granitoide als wesentlichstes neugebildetes Gestein auftreten, wird von Metamorphose und erneutem Aufschmelzen und Intrusionen alkaliintermediärer Granite gefolgt. Die südwestliche Marginalzone des Schildes war ein stabiler Ozean/Kontinent-Grenzbereich während einer langen Zeitperiode. Ein testbares endgültiges Modell der Entwicklung kann heute trotz mehrerer Versuche nicht aufgestellt werden.
Résumé Le développement postsvécokarélien du bouclier baltique est caractérisé par un parallélisme dans le temps entre l'extension et l'intrusion de diabases dans la zone centrale de l'Est et par des intrusions granitiques, une compression et un rétrécissement crustal dans la zone marginale du Sud-ouest. Une phase avec formation d'une croûte, qui se propage vers l'ouest, et au cours de laquelle les nouvelles roches formées sont essentiellement des granitoïdes calco-alcalins, est suivie d'un métamorphisme et d'une palingenèse avec intrusions de granites alcalins intermédiaires. La zone marginale du Sud-ouest du bouclier était un domaine-limite océan-continent »stable«, pendant une longue période de temps. Une modélisation controlable du développement ne peut être avancée aujourd'hui malgré plusieurs tentatives.
- , . , , - , . - /. .相似文献
10.
Origin of chemically distinct granites in a composite intrusion in east-central Sweden: geochemical and geothermal constraints 总被引：1，自引：0，他引：1
Anders Lindh 《Lithos》2005,80(1-4):249-266
A few tens of millions of years after the intrusion of the Early Svecofennian (1.87–1.85 Ma) granitoids in central Sweden, a renewed magmatic activity resulted in the emplacement of the Late Svecofennian granites, the tectonic setting of which remains obscure. S-type granites dominate this group, but both I-type and transitional granites are common. This study deals with one of these intrusions in east-central Sweden; a composite pluton that is insignificantly deformed and hosts both I- and S-type granites. One of the I-type granites shows a compositional trend from granodiorite to granite, which is uncommon among the Late Svecofennian granites. Major element and incompatible trace element compositions and Nd data show that two different sources, one igneous and one sedimentary, were involved. An important conclusion is that nearly coeval granites derived from different sources are found in close connection. The granites are suggested to have formed by partial melting in a thickened continental crust that was formed in an early stage of the Svecofennian event. Thermal models suggest that the slightly older, high-temperature I-type granite (granodiorite) was formed deeper in the crust than the S-type granite. The coexistence of essentially pure I- and S-type granites, rather than transitional mixtures, reflects the relative depths of the proposed sources and the varying thermal parameters of the lithologic units in the Svecofennian crust. 相似文献