Low- to medium-grade metamorphism in silicate iron-formations of the Cape Smith Belt, New Quebec

1968 ◽  
Vol 5 (4) ◽  
pp. 881-893 ◽  
Author(s):  
T. Hashimoto ◽  
R. Béland
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Iron Formation ◽  
Chemical Analyses ◽  
Grade Metamorphism ◽  
Isothermal Phase Diagram ◽  
Petrographic Examination ◽  
Mineral Assemblages ◽  
Invariant Points ◽  
Iron Formations

Four different assemblages of iron-rich silicates from the silicate iron-formation of the Cape Smith belt in New Quebec have been investigated. These rocks all contain quartz, magnetite, some calcite, and are composed mostly of two or more of the following silicates: stilpnomelane, minnesotaite, iron chlorite, grunerite, almandite, and biotite.From eight chemical analyses and petrographic examination, using a method developed by J. B. Thompson, an isothermal phase diagram of the system Al2O3–Fe2O3–FeO–MgO–SiO2–H2O has been constructed for the upper part of the greenschist facies of metamorphism.Speculation based on this diagram and on available experimental data is offered on the sequence of reactions leading to the assemblages observed, and on the possibility of finding mineral assemblages representing invariant points in metamorphosed iron-formations.

Solid-Liquid Equilibria for the Quaternary Na2B4O7 - Na2so4 - K2B4O7 - K2so4 - H2O System at 323K

2011 ◽  
Vol 233-235 ◽  
pp. 27-31 ◽  
Author(s):  
Shi Hua Sang ◽  
Xiao Xiao Zeng ◽  
Hui Yin Ning ◽  
Zhen Lei Zhang
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Quaternary System ◽  
Experimental Results ◽  
Invariant Points ◽  
Solid Liquid

Solid - liquid Equilibria for the quaternary system Na2B4O7 - Na2SO4 - K2B4O7 - K2SO4 - H2O at 323K were studied experimentally using the method of isothermal solution saturation. Solubilities and densities of the solution of the system were measured experimentally. On the basis of experimental data, the phase diagram of the quaternary system was constructed. In the equilibrium diagrams of the quaternary system Na2B4O7 - Na2SO4 - K2B4O7 - K2SO4 - H2O at 323 K, there are three invariant points F1, F2 and F3, seven univariant curves E1-F1, E2-F1, E4-F3, E5-F3, E3-F2, F1-F2 and F2-F3, and five fields of crystallization corresponding to Na2B4O7·10H2O，K2B4O7·4H2O，Na2SO4，K2SO4and Na2SO4·3K2SO4. The experimental results show that sulfates have bigger solubilities than borates in the quaternary system Na2B4O7 - Na2SO4 - K2B4O7 - K2SO4 - H2O at 323K.

scholarly journals Iron and Carbon Isotope Constraints on the Formation Pathway of Iron-Rich Carbonates within the Dagushan Iron Formation, North China Craton

Minerals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 94
Author(s):  
Xiaoxue Tong ◽  
Kaarel Mänd ◽  
Yuhao Li ◽  
Lianchang Zhang ◽  
Zidong Peng ◽  
...  
Keyword(s):  
Iron Reduction ◽  
Isotope Composition ◽  
Iron Formation ◽  
Banded Iron Formations ◽  
Organic C ◽  
Formation Pathway ◽  
Wide Range ◽  
Dissimilatory Iron Reduction ◽  
O Isotope ◽  
Iron Formations

Banded iron formations (BIFs) are enigmatic chemical sedimentary rocks that chronicle the geochemical and microbial cycling of iron and carbon in the Precambrian. However, the formation pathways of Fe carbonate, namely siderite, remain disputed. Here, we provide photomicrographs, Fe, C and O isotope of siderite, and organic C isotope of the whole rock from the ~2.52 Ga Dagushan BIF in the Anshan area, China, to discuss the origin of siderite. There are small magnetite grains that occur as inclusions within siderite, suggesting a diagenetic origin of the siderite. Moreover, the siderites have a wide range of iron isotope compositions (δ56FeSd) from −0.180‰ to +0.463‰, and a relatively negative C isotope composition (δ13CSd = −6.20‰ to −1.57‰). These results are compatible with the reduction of an Fe(III)-oxyhydroxide precursor to dissolved Fe(II) through microbial dissimilatory iron reduction (DIR) during early diagenesis. Partial reduction of the precursor and possible mixing with seawater Fe(II) could explain the presence of siderite with negative δ56Fe, while sustained reaction of residual Fe(III)-oxyhydroxide could have produced siderite with positive δ56Fe values. Bicarbonate derived from both DIR and seawater may have provided a C source for siderite formation. Our results suggest that microbial respiration played an important role in the formation of siderite in the late Archean Dagushan BIF.

scholarly journals Thermodynamic reassessment of the Mn-Ni-Si system

2015 ◽  
Vol 51 (2) ◽  
pp. 125-132 ◽  
Author(s):  
B. Hu ◽  
Y. Du ◽  
J.J. Yuan ◽  
Z.F. Liu ◽  
Q.P. Wang
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Phase Diagrams ◽  
Thermodynamic Parameters ◽  
Ternary Phase ◽  
Sublattice Model ◽  
Diagram Approach ◽  
Measured Phase

Iased on the new experimental data available in the literature, the Mn-Ni-Si system has been reassessed using the CALPHAD (CALculation of PHAse Diagram) approach. Compared with the previous modeling, the ?8 and ?12 ternary phases were treated as the same phase according to the new experimental data. The Mn3Si phase was described with two sublattice model (Mn, Ni)3(Si)1. The reported new ternary phase ? was not considered in the present work. Comprehensive comparisons between the calculated and measured phase diagrams showed that a set of thermodynamic parameters of the Mn-Ni-Si system obtained in this work was more accurate than the previous one.

Occurrence and genetic implications of hyalophane in manganese-rich iron-formation, Cuyuna Iron Range, Minnesota, USA

1994 ◽  
Vol 58 (392) ◽  
pp. 387-399 ◽  
Author(s):  
Peter L. McSwiggen ◽  
G. B. Morey ◽  
Jane M. Cleland
Keyword(s):  
Depositional Environment ◽  
Iron Formation ◽  
East Central ◽  
Early Proterozoic ◽  
Iron Range ◽  
The North ◽  
History Of ◽  
Ferromanganese Deposits ◽  
Iron Formations ◽  
Chemical Sediments

AbstractThe recent discovery of hyalophane [(K,Ba)Al1−2Si3−2O8] on the North range segment of the Early Proterozoic Cuyuna Iron Range of east-central Minnesota has shed new light on the depositional environment of these rocks. This Ba-feldspar occurs in a 10 m thick interval within the main iron-formation and typically contains between 8 and 26 mol.% celsian (BaAl2Si2O8). Its occurrence in several textural settings suggests that barium was being deposited at various stages in the paragenetic history of the iron-formation. Some of the hyalophane grains occur as the cores of micronodules, which are structurally similar to oolites or oncolites, but mineralogically are very complex. The hyalophane also occurs as rims on core grains of diverse mineral composition and as discrete phases in late crosscutting veins.Hyalophane, like other Ba-silicates, has a very restricted paragenesis. They are associated typically either with sedimentary manganese and ferromanganese deposits, or with Cu-Pb-Zn-Ba deposits. The presence of hyalophane in the Early Proterozoic manganiferous iron ores of east-central Minnesota casts doubt on the historic interpretation of these deposits as typical Superior-type sedimentary iron-formations and instead supports the view that these deposits, at least in part, consist of chemical sediments from a hydrothermal fumarolic system. The suggested involvement of a hydrothermal system is also supported by the occurrence of aegirine within the hyalophane-rich layer, and the occurrence of tourmalinites and Sr-rich baryte veins elsewhere in the Cuyuna North range.

Diagenesis-very low-grade metamorphism of clastic Cambrian and Ordovician sedimentary rocks in the Iberian Range (Spain)

Clay Minerals ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 373-393 ◽  
Author(s):  
B. Bauluz ◽  
C. Fernandez-Nieto ◽  
J. M. Gonzalez Lopez
Keyword(s):  
Chemical Equilibrium ◽  
Sedimentary Rocks ◽  
Low Grade ◽  
Evolutionary Trend ◽  
Compositional Heterogeneity ◽  
Chemical Analyses ◽  
Grade Metamorphism ◽  
Iberian Range ◽  
Mixed Layering

AbstractCambrian and Ordovician pelites and greywakes from the Iberian Range were studied using XRD, EMPA and AEM/TEM techniques, lllite and chlorite are the main phases in Cambrian <2 µm fractions. Illites show crystallinities (IC) from 0.28 to 0.23°2θ the 2M1 is almost the only polytype; they do not have expandable layers, and they are heterogeneous in composition. Chlorites show two compositional types, both containing variable proportions of smectite-like layers. Clinochtores growing over bedding surfaces are also present. An evolutionary trend from anchizone to near the anchizone-epizone limit has been proposed for Cambrian samples.In the Ordovician <2 µm fractions, illites are associated with minor chlorites and kaolinites. The ICs range from 0.68-0.28°2θ the 2M1 polytype dominates over 1M, and it is associated with illitesmectite mixed-layering (R3 ordering). An evolutionary trend from diagenesis to low grade anchizone has been inferred.Chemical analyses of coarser detrital micas indicate muscovite and phengite compositions. The compositional heterogeneity exhibited by authigenic and detrital phases suggests that chemical equilibrium was not attained.

scholarly journals Clay diagenesis and low-grade metamorphism of Tithonian and Berriasian sediments in the Cameros Basin (Spain)

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 325-333 ◽  
Author(s):  
J. F. Barrenechea ◽  
M. Rodas ◽  
M. Frey ◽  
J. Alonso-Azcárate ◽  
J. R. Mas
Keyword(s):  
Clay Mineral ◽  
Mixed Layer ◽  
Sedimentary Facies ◽  
Metamorphic Grade ◽  
Metamorphic Event ◽  
Low Grade ◽  
Grade Metamorphism ◽  
Mineral Assemblages ◽  
Cameros Basin ◽  
Southern Border

AbstractThe clay mineral assemblages of the Tithonian and Berriasian sediments (Tera and Oncala Groups) in the eastern part of the Cameros basin are investigated at seven localities. The lowest-grade assemblage, located on the southern border of the basin, contains calcite + quartz + hematite + kaolinite + mixed-layer illite-smectite (R = 1, 65 85% illite layers) + discrete illite (IC = 0.5 0.65Δ°2θ). Systematic increases in the illite and chlorite crystallinities suggest increasing metamorphic grade from the northwest part of the basin to the southeast. This trend does not follow the pattern previously described for the overlying late Berriasian–early Aptian sediments (Urbión and Enciso Groups), which exhibit a higher metamorphic grade. This may result from local variations in sedimentary facies, as well as the circulation of hot migratory fluids. Tertiary compression occurring long after the main metamorphic event is considered to be responsible for the enhanced illite and chlorite crystallinities measured in the SE extreme of the basin.

Cold-Set Whey Protein Isolate Gels Prepared with Mg2+: Denaturing Conditions and Phase Diagram

2009 ◽  
Vol 283-286 ◽  
pp. 559-564 ◽  
Author(s):  
M. Vázquez da Silva ◽  
João M.P.Q. Delgado
Keyword(s):  
Experimental Data ◽  
Phase Diagram ◽  
Young’S Modulus ◽  
Whey Protein ◽  
Elastic Properties ◽  
Magnesium Chloride ◽  
Whey Protein Isolate ◽  
Protein Isolate ◽  
Viscoelastic Behaviour ◽  
Made In

Cold-set gels of whey protein isolate (WPI) were produced. The cold gelation was induced through the addition of magnesium chloride whose cation is an alternative to the most common cations used in this kind of gelation. A phase diagram for denatured WPI in magnesium was determined by varying protein and salt concentrations. In this diagram the protein and cation concentrations varied from 0.3 to 8.0 wt % and 1 to 75 mM, respectively. The viscoelastic behaviour of the WPI was analysed, whereas gels elastic properties were measured by means of texture tests. Mathematical manipulation of the experimental data relative to the puncture tests was made in order to obtain the Young’s modulus for each cold-set gel.

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