ISSN:0005-9021    

DOI:10.1002/bbpc.198200001

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe most complex physico‐chemical process “mineral formation in multicomponent system” is discussed in the sense of limiting cases. The following elementary processes are briefly treated: nucleation and formation of new phases, matter transport in one phase multicomponent system, heterogeneous reaction in multicomponent system. In many cases zero, one and two dimensional crystalline defects play an important role for the morphological and kinetical development of minerals. The role of point defect thermodynamics for the transport coefficient and transport theory of crystalline multicomponent systems is pointed out in some d

ISSN:0005-9021    

DOI:10.1002/bbpc.198200002

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe three major units of the earth are the core, the mantle and the crust. The material of the earth's mantle and core originated 4.6 billion years ago from condensation products of solar gases. The continental crust is on the average 40 km thick and varies in composition and age (≤ 3.8 · 109years) while the present oceanic crust is about 7 km thick, composed mainly of basalt and less than 200 million years old. The renewal and the growth of the oceanic crust from partial melting of peridotites in the upper mantle is observable in the basaltic magmatism at mid‐ocean ridges and in the drift of the continents (˜ cm per year). The crustal growth is compensated by subduction of crustal plates into the mantle at some continental margins such as in the Circum‐Pacific. The oceanic basalts gain water through reactions with sea water and lose this during subduction (at about 900°C) to the overlying mantle materials (peridotites). Partial melting of mantle materials (and differentiation of primary melts) results in the formation of basaltic, andesitic or other magmas and contributes substantially to the growth of the continents. This direct or indirect origin of andesitic magmas from water containing peridotites is explained on the base of melting experiments and partition data of trace elements between melts and their potential source rocks. The majority of minerals in magmatic rocks are not stable under earth's surface conditions. They react with the degassing products of the earth's mantle (H2O, CO2, SO2, HCl) and with photochemically produced oxygen to form weathering and sedimentary minerals (OH containing silicates, CaCO3, CaSO4, NaCl etc.). Erosion, water transport and sedimentation control the material balance of elements near the earth's surface. The original sediments which contain water and other specific compounds are buried with time in deeper and warmer crustal levels. Their minerals reequilibrate at increasingly higher temperatures and pressures. Finally at 600–700°C, depending on the availability of water, they partially melt to form granitic magmas. The difference in density between the source rocks and the melts causes the uprise of granitic magmas. This process results in a chemical fractionation between the lower and the upper continental crust over long geologic time. – Summarizing the important observations of this report, water has controlled major processes in the outer shells

ISSN:0005-9021    

DOI:10.1002/bbpc.198200003

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractExamples for the application of five spectroscopic methods to mineralogical problems which exceed a mere characterization are discussed. In addition in some examples results of infrared and optical absorption as classical spectroscopic tools are also used. In many cases the nonideal compositions and structures of the minerals are of decisive influence upon the results, and sometimes they even generate the observed phenomena.

ISSN:0005-9021    

DOI:10.1002/bbpc.198200004

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe stability of complex oxide and silicate phases can be understood in terms of equally important contributions of energy and entropy effects. The change in coordination number at high pressure in silicates has a profound effect on thermodynamic properties. Properties of spinel solid solutions can be systematized using a refined cation distribution model, while those of solid solutions involving no cation redistribution can be correlated with the volume mismatch of the end‐members for a wide variety of structures and compositions. Ordering and exsolution in complex solid solutions is an important featur

ISSN:0005-9021    

DOI:10.1002/bbpc.198200005

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractNatural silicate melts (magmas) are highly polymerized and their structure can essentially be described by the anionic species three‐dimensional network (3D), sheet‐ and chain‐like unit. The concentration of these species depends on the ratio of nonbridging oxygens to tetrahedrally coordinated cations (NBO/T), temperature and electronegativity of the network modifier. Their concentration controls e.g. viscosity, density, solubility of fluids and crystallization of the melts. Melts with a high proportion of 3D units with six‐membered rings (e.g. NaAlSi3O8) exhibit a decrease of viscosity with increasing p

ISSN:0005-9021    

DOI:10.1002/bbpc.198200006

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractA survey is given of recent results on the properties of pure water and binary and ternary mixtures at high temperatures and high pressures with emphasis on the geochemically important systems H2O‐CO2, H2O‐NaCl, and H2O‐CO2‐NaCl. Among the properties discussed are phase diagrams,PVTxdata, thermodynamic and transport properties, dielectric constant, electrical conductivity, and ionic equilibria. Concepts for predictive calculations of thermodynamic properties are briefly de

ISSN:0005-9021    

DOI:10.1002/bbpc.198200007

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe part played by the fluid phase(s) in most geological processes is of primary importance. These fluids have been often trapped in usually microscopic “fluid inclusions” which are considered as good samples of the natural solutions that once “wet” the rocks, with a few exceptions that can be easily detected. Once it has been trapped, the bulk composition and the bulk density of the inclusion fluid remain constant. – The major purpose of a fluid inclusion study is to determine the nature and the physical and chemical properties of the trapped fluids, and then to fit these properties with relevant geochemical processes. This is largely obtained by microthermometry, which consists in measuring the temperature of all the phase transitions observed in the inclusions when heated from −150°C to 700°C or more. Because fluid inclusions are assumed to be isochemical‐isochore univariant systems in theTPVXspace, the microthermometry data can be interpreted in terms of chemical composition and molar volume. These data can be completed by other analytical techniques, such as bulk chemical analyses and Raman Microprobe analyses. – The first example presented in this paper deals with the postmagmatic hydrothermal alteration of a pegmatite. Because of the density‐composition constraints derived from fluid inclusions study, theTPcooling path of the fluid can be estimated with a fairly good accuracy between 500 and 200°C. Taking into account this result and the bulk chemical analyses (Cl, Na, K, Mg, Ca), it is possible to calculate the whole mass transfer and the water/rock ratio all over the evolution. – The second example, very briefly summarized, concerns fluid unmixing in porphyry copper type deposits. Such a process yields highly saline brines of moderate density and diluted vapour with low density. It is responsible of part of the mineral deposition, as a consequence of the supersaturation of the “boiling” liquid with respect to chalcopyrite. – The last example is related to the fluid evolution in a tin and tungsten deposit associated with a shallow granitic intrusion from Central Morocco. It is shown, mainly from fluid inclusion study, that the original fluid composition (70% water, 24% CO2, 5% N2, 1% CH4, traces of C2H6and H2S) is changed by mixing with a slightly saline (5 wt% NaCl) aqueous solution. The composition of the volatile part (relative amounts of CO2, N2, CH4) has been analyzed by Raman spectroscopy. – Ore deposition occurred during this mixing process. Because of the lack of accurate experimental data on the system H2O – CO2– N2– (CH4) – NaCl, theTPconditions of the evolution cannot be accurately estimated, and using the system H2O – CO2– NaCl as an approximation yields irrelevant results. This last example clearly shows why the availability of relevant experimental data on the C – O – H – N electrolytes systems is crucial for geochem

ISSN:0005-9021    

DOI:10.1002/bbpc.198200008

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractA high pressure piezometer is described with whichpVT‐measurements on solutions of gases in liquids like oils can be performed at pressures and temperatures up to 2000 bar and 440 K, respectively. The present investigations deal mainly with the system squalane/CO2at different mole fractions, but also with squalane/N2. – The high accuracy of the measurements reveals a pronounced structure of thepV‐curves in dependence on temperature and mole fraction. At larger mole fractions is the unequivocal assignment of the phases ambiguous, and the representation of the experimental data in terms of an equation of state not possible for the whole pressure and temperature range. However, for solutions with lower mole fractions could be determined the saturation pressures and the isothermal compressibility in the unsaturated region. Furthermore, the molar excess volumes of the mixtures have been calculated and the phase behaviour has been discussed br

ISSN:0005-9021    

DOI:10.1002/bbpc.198200010

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY

摘要:

AbstractThe investigation of suitable mineral equilibria (e.g. decarbonation reactions) allows to deduce the mixing properties of supercritical gas mixtures. The data obtained are best ascertained in an intermediate range of fluid composition and where ideal mixing occurs. The mixing properties of CO2in CO2– H2O mixtures are deduced from the equilibrium conditions of the reaction CaCO3+ SiO2= CaSiO3+ CO2at 4 kbar and 870 – 1070 K. The “close‐to‐Nature” high pressure experiments yield considerable larger positive deviation from ideal mixing than results deduced fromP‐V‐Tmeasurements or thermodynam

ISSN:0005-9021    

DOI:10.1002/bbpc.198200011

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA    

年代:1982

数据来源: WILEY