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1.
Shahid Azam 《Geotechnical and Geological Engineering》2012,30(1):107-118
Knowledge of slurry settling is essential for geotechnical engineering applications such as coastal land reclamation and mine
waste disposal. In the presence of charged solids and ion-rich liquids, complex physicochemical interactions govern the behavior
of slurries. The main objective of this study was to develop a fundamental understanding of self-weight settling of laterite
ore slurries. To capture the influence of geology and the environment, samples were obtained from mining operations in different
parts of the globe. Based on laboratory testing, the investigated ores were found to be either oxide-rich with goethite, gibbsite,
meghamite and hematite making at least 90% of the material or clay-rich with chrysotile, cholritic intergrade, and siliceous
minerals accounting for more than 50% of the sample. The dominance of salt forming ions such as Na+, K+, Ca2+, Mg2+, Cl−, NO3
−, HCO3
− and SO4
2− in the pore waters indicated the influence of seawater on the waters used for slurry preparation. The oxide-rich ores in
low ionic waters resulted in flocculated fabrics whereas the clay-rich ores in high ionic waters led to cardhouse microstructures.
The aggregated fabrics with low tortuousity and fewer dead ends resulted in a high settling rate and amount (k
i
= 10−1 to 10−2 cm/s and SP = 62 to 49%) whereas the cardhouse morphologies with high tortuousity and lower pore connectivity exhibited a
slow and low settling (k
i
= 10−3 to 10−4 cm/s and SP = 37 to 17%). The initial hydraulic conductivity was found to be directly proportional to settling potential. 相似文献
2.
Konstantin D. Litasov Anton Shatskiy Eiji Ohtani Tomoo Katsura 《Physics and Chemistry of Minerals》2011,38(1):75-84
The H2O content of wadsleyite were measured in a wide pressure (13–20 GPa) and temperature range (1,200–1,900°C) using FTIR method.
We confirmed significant decrease of the H2O content of wadsleyite with increasing temperature and reported first systematic data for temperature interval of 1,400–1,900°C.
Wadsleyite contains 0.37–0.55 wt% H2O at 1,600°C, which may be close to its water storage capacity along average mantle geotherm in the transition zone. Accordingly,
water storage capacity of the average mantle in the transition zone may be estimated as 0.2–0.3 wt% H2O. The H2O contents of wadsleyite at 1,800–1,900°C are 0.22–0.39 wt%, indicating that it can store significant amount of water even
under the hot mantle environments. Temperature dependence of the H2O content of wadsleyite can be described by exponential equation
C\textH2 \textO = 6 3 7.0 7 \texte - 0.00 4 8T , C_{{{\text{H}}_{2} {\text{O}}}} = 6 3 7.0 7 {\text{e}}^{ - 0.00 4 8T} , where T is in °C. This equation is valid for temperature range 1,200–2,100°C with the coefficient of determination R
2 = 0.954. Temperature dependence of H2O partition coefficient between wadsleyite and forsterite (D
wd/fo) is complex. According to our data apparent Dwd/fo decreases with increasing temperature from D
wd/fo = 4–5 at 1,200°C, reaches a minimum of D
wd/fo = 2.0 at 1,400–1,500°C, and then again increases to D
wd/fo = 4–6 at 1,700–1,900°C. 相似文献
3.
A set of sheeted quartz veins cutting 380 Ma monzogranite at Sandwich Point, Nova Scotia, Canada, provide an opportunity to
address issues regarding fluid reservoirs and genesis of intrusion-related gold deposits. The quartz veins, locally with arsenopyrite
(≤5%) and elevated Au–(Bi–Sb–Cu–Zn), occur within the reduced South Mountain Batholith, which also has other zones of anomalous
gold enrichment. The host granite intruded (P = 3.5 kbars) Lower Paleozoic metaturbiditic rocks of the Meguma Supergroup, well known for orogenic vein gold mineralization.
Relevant field observations include the following: (1) the granite contains pegmatite segregations and is cut by aplitic dykes
and zones (≤1–2 m) of spaced fracture cleavage; (2) sheeted veins containing coarse, comb-textured quartz extend into a pegmatite
zone; (3) arsenopyrite-bearing greisens dominated by F-rich muscovite occur adjacent the quartz veins; and (4) vein and greisen
formation is consistent with Riedel shear geometry. Although these features suggest a magmatic origin for the vein-forming
fluids, geochemical studies indicate a more complex origin. Vein quartz contains two types of aqueous fluid inclusion assemblages
(FIA). Type 1 is a low-salinity (≤3 wt.% equivalent NaCl) with minor CO2 (≤2 mol%) and has T
h = 280–340°C. In contrast, type 2 is a high-salinity (20–25 wt.% equivalent NaCl), Ca-rich fluid with T
h = 160–200°C. Pressure-corrected fluid inclusion data reflect expulsion of a magmatic fluid near the granite solidus (650°C)
that cooled and mixed with a lower temperature (400°C), wall rock equilibrated, Ca-rich fluid. Evidence for fluid unmixing,
an important process in some intrusion-related gold deposit settings, is lacking. Stable isotopic (O, D, S) analyses for quartz,
muscovite and arsenopyrite samples from vein and greisens indicate the following: (1) δ18Oqtz = +11.7‰ to 17.8‰ and δ18Omusc = +10.7‰ to +11.2‰; (2) δDmusc = −44‰ to−54‰; and (3) δ34Saspy = +7.8‰ to +10.3‰. These data are interpreted, in conjunction with fluid inclusion data, to reflect contamination of a magmatic-derived
fluid (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} ≤ +10‰) by an external fluid (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} ≥ +15‰), the latter having equilibrated with the surrounding metasedimentary rocks. The δ34S data are inconsistent with a direct igneous source based on other studies for the host intrusion (d18OH2O {\delta^{{{18}}}}{{\hbox{O}}_{{{{\rm{H}}_{{2}}}{\rm{O}}}}} = +5‰) and are, instead, consistent with an external reservoir for sulphur based on δ34SH2S data for the surrounding metasedimentary rocks. Divergent fluid reservoirs are also supported by analyses of Pb isotopes
for pegmatitic K-feldspar and vein arsenopyrite. Collectively the data indicate that the vein- and greisen-forming fluids
had a complex origin and reflect both magmatic and non-magmatic reservoirs. Thus, although the geological setting suggests
a magmatic origin, the geochemical data indicate involvement of multiple reservoirs. These results suggest multiple reservoirs
for this intrusion-related gold deposit setting and caution against interpreting the genesis of intrusion-related gold deposit
mineralization in somewhat analogous settings based on a limited geochemical data set. 相似文献
4.
Calculated phase equilibria involving minerals and H2O–CO2–NaCl fluid lead to predictions of how infiltration of rock by H2O–NaCl fluids with X
NaCl in the range 0–0.3 (0–58 wt% NaCl) drives the reactions calcite + quartz = wollastonite + CO2 and dolomite = periclase + calcite + CO2. Calculations focus on metamorphism in four aureoles that together are representative of the normal P–T conditions and processes of infiltration-driven contact metamorphic reactions. The effect of salinity on the spatial extent
of oxygen isotope alteration was also computed. The time-integrated input fluid flux (q°) that displaces the mineral reaction front an increment of distance along the flow path always increases with increasing
X
NaCl. For input fluids with salinity up to approximately five times that of seawater (X
NaCl ≤ 0.05), values of q° required to explain the spatial extent of decarbonation reaction are no more than 1.1–1.5 times that computed assuming the
input fluid was pure H2O. For more saline fluids, values of q° may be up to 1.4–7.9 times that for pure H2O. Except for reaction in the presence of halite and vapor (V), infiltration of H2O–NaCl fluids expands the region of oxygen isotope alteration relative to the size of the region of mineral reaction. The
expansion is significant only for saline fluids with X
NaCl ≥ ~0.1. Immiscible fluid phase separation and differential loss of the liquid (L) or V phase from the mineral reaction site increases the amount of reactive fluid required to advance the mineral reaction front
compared to conditions under which equilibration of minerals and fluid is attained with no loss of L or V. Decarbonation reactions driven by infiltration of fluids with even modest seawater-like salinity can explain the occurrence
of salt-saturated fluid and solid halide inclusions in contact metamorphosed carbonate rocks. 相似文献
5.
Mohammed Bouabdellah Georges Beaudoin David L. Leach Fidel Grandia Esteve Cardellach 《Mineralium Deposita》2009,44(6):689-704
The Assif El Mal Zn–Pb (Cu–Ag) vein system, located in the northern flank of the High Atlas of Marrakech (Morocco), is hosted
in a Cambro-Ordovician volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered
with minor tuff and mudstone. Intrusion of synorogenic to postorogenic Late Hercynian peraluminous granitoids has contact
metamorphosed the host rocks giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite,
amphibole, chloritoid, and garnet. The Assif El Mal Zn–Pb (Cu–Ag) mineralization forms subvertical veins with ribbon, fault
breccia, cockade, comb, and crack and seal textures. Two-phase liquid–vapor fluid inclusions that were trapped during several
stages occur in quartz and sphalerite. Primary inclusion fluids exhibit T
h mean values ranging from 104°C to 198°C. Final ice-melting temperatures range from −8.1°C to −12.8°C, corresponding to salinities
of ∼15 wt.% NaCl equiv. Halogen data suggest that the salinity of the ore fluids was largely due to evaporation of seawater.
Late secondary fluid inclusions have either Ca-rich, saline (26 wt.% NaCl equiv.), or very dilute (3.5 wt.% NaCl equiv.) compositions
and homogenization temperatures ranging from 75°C to 150°C. The δ18O and δD fluid values suggest an isotopically heterogeneous fluid source involving mixing between connate seawater and black-shale-derived
organic waters. Low δ13CVPDB values ranging from −7.5‰ to −7.7‰ indicate a homogeneous carbon source, possibly organic matter disseminated in black shale
hosting the Zn–Pb (Cu–Ag) veins. The calculated δ34SH2S values for reduced sulfur (22.5‰ to 24.3‰) are most likely from reduction of SO4
2− in trapped seawater sulfate or evaporite in the host rocks. Reduction of sulfate probably occurred through thermochemical
sulfate reduction in which organic matter was oxidized to produce CO2 which ultimately led to precipitation of saddle dolomite with isotopically light carbon. Lead isotope compositions are consistent
with fluid–rock interaction that leached metals from the immediate Cambro-Ordovician volcaniclastic and metasedimentary sequence
or from the underlying Paleo-Neoproterozoic crustal basement. Geological constraints suggest that the vein system of Assif
El Mal formed during the Jurassic opening of the central Atlantic Ocean. 相似文献
6.
Mineral-specific IR absorption coefficients were calculated for natural and synthetic olivine, SiO2 polymorphs, and GeO2 with specific isolated OH point defects using quantitative data from independent techniques such as proton–proton scattering,
confocal Raman spectroscopy, and secondary ion mass spectrometry. Moreover, we present a routine to detect OH traces in anisotropic
minerals using Raman spectroscopy combined with the “Comparator Technique”. In case of olivine and the SiO2 system, it turns out that the magnitude of ε for one structure is independent of the type of OH point defect and therewith
the peak position (quartz ε = 89,000 ± 15,000
\textl \textmol\textH2\textO-1 \textcm-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}), but it varies as a function of structure (coesite ε = 214,000 ± 14,000
\textl \textmol\textH2\textO-1 \textcm-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}; stishovite ε = 485,000 ± 109,000
\textl \textmol\textH2\textO-1 \textcm-2\text{l}\,\text{mol}_{{\text{H}_2}\text{O}}^{-1}\,\text{cm}^{-2}). Evaluation of data from this study confirms that not using mineral-specific IR calibrations for the OH quantification in
nominally anhydrous minerals leads to inaccurate estimations of OH concentrations, which constitute the basis for modeling
the Earth’s deep water cycle. 相似文献
7.
Sivajini Gilchrist Alexander E. Gates Matthew Gorring Evert Jan Elzinga 《Environmental Earth Sciences》2011,63(5):1029-1041
Organic material in metal contaminated soils around an abandoned magnetite mine–smelter complex in the critical Highlands
watershed protects the groundwater and surface water from contamination. Metals in these waters were consistently below local
and national water standards. Two groups of soil types cover the area: (1) Group A disturbed metal-rich soils, and (2) Group
B undisturbed organic soils. Chromium and nickel were more elevated than other metals with Cr more widespread than Ni. In
Group A, Cr correlated strongly with sesquioxides in the lower horizons (Fe2O3: r = 0.74, p < 0.025; Al2O3: r = 0.92, p < 0.005). In Group B, Cr correlated strongly (r = 0.96, p < 0.005) with soil organic matter (SOM) in the O-horizons. Ni–Cr (Group A: 52 and 70% in O- and lower horizons, respectively;
Group B: ~100% in both horizons) and V–Cr correlations (78% only in Group A lower horizons) suggest similar retention mechanisms
for these elements. Average soil
\textpH\textCaCl2 {\text{pH}}_{{{\text{CaCl}}_{2} }} for both groups ranged between 3.65 and 5.91, suggesting that soil acidity is determined by organic acids and solubility
of Al3+ releasing H+ ions. SOM and sesquioxides contribute significantly to creating naturally occurring filtration systems, removing metals,
and protecting water quality. High Ca, Fe, and Ti in Group A soils suggest slag and ash were mixed into the soils. Some low-Cr
sources include magnetite, slag, and ash (100, 100 and 200 mg/kg, respectively). Constant ZrO
2
:TiO
2
ratios in the lower soils indicate soil formation from breakdown of underlying tailing rocks, contributing Cr to these layers. 相似文献
8.
Dariusz Dobrzyński 《Aquatic Geochemistry》2007,13(3):197-210
A wide set of aqueous chemistry data (574 water analyses) from natural environments has been used to testify and validate
of the solubility of synthetic hydroxyaluminosilicate (HASB), Al2Si2O5(OH)4. The ground and surface waters represent regolith and/or fissure aquifers in various (magmatic, sedimentary and metamorphic)
bedrocks in the Sudetes Mts. (SW Poland). The solubility of HASB in natural waters was calculated using the method proposed by Schneider et al. (Polyhedron 23:3185–3191, 2004). Results confirm
usefulness and validity of this method. The HASB solubility obtained from the field data (logKsp = −44.7 ± 0.58) is lower than it was estimated (logKsp = −40.6 ± 0.15) experimentally (Schneider et al. Polyhedron 23:3185–3191, 2004). In the waters studied the equilibrium with
HASB is maintained at pH above 6.7 and at [Al3+] ≤ 10−10. Silicon activity (log[H4SiO4]) ranges between −4.2 and −3.4. Due to the calculation method used, the Ksp mentioned above cannot be considered as a classical solubility constant. However, it can be used in the interpretation of
aluminium solubility in natural waters. The HASB has solubility lower than amorphous Al(OH)3, and higher than proto-imogolite. From water samples that are in equilibrium with respect to HASB, the solubility product described by the reaction,
is calculated to be logKsp = 14.0 (±0.7) at 7°C. 相似文献
9.
The onset of hydrous partial melting in the mantle above the transition zone is dictated by the H2O storage capacity of peridotite, which is defined as the maximum concentration that the solid assemblage can store at P and T without stabilizing a hydrous fluid or melt. H2O storage capacities of minerals in simple systems do not adequately constrain the peridotite water storage capacity because
simpler systems do not account for enhanced hydrous melt stability and reduced H2O activity facilitated by the additional components of multiply saturated peridotite. In this study, we determine peridotite-saturated
olivine and pyroxene water storage capacities at 10–13 GPa and 1,350–1,450°C by employing layered experiments, in which the
bottom ~2/3 of the capsule consists of hydrated KLB-1 oxide analog peridotite and the top ~1/3 of the capsule is a nearly
monomineralic layer of hydrated Mg# 89.6 olivine. This method facilitates the growth of ~200-μm olivine crystals, as well
as accessory low-Ca pyroxenes up to ~50 μm in diameter. The presence of small amounts of hydrous melt ensures that crystalline
phases have maximal H2O contents possible, while in equilibrium with the full peridotite assemblage (melt + ol + pyx + gt). At 12 GPa, olivine and
pyroxene water storage capacities decrease from ~1,000 to 650 ppm, and ~1,400 to 1,100 ppm, respectively, as temperature increases
from 1,350 to 1,450°C. Combining our results with those from a companion study at 5–8 GPa (Ardia et al., in prep.) at 1,450°C,
the olivine water storage capacity increases linearly with increasing pressure and is defined by the relation
C\textH2 \textO\textolivine ( \textppm ) = 57.6( ±16 ) ×P( \textGPa ) - 169( ±18 ). C_{{{\text{H}}_{2} {\text{O}}}}^{\text{olivine}} \left( {\text{ppm}} \right) = 57.6\left( { \pm 16} \right) \times P\left( {\text{GPa}} \right) - 169\left( { \pm 18} \right). Adjustment of this trend for small increases in temperature along the mantle geotherm, combined with experimental determinations
of
D\textH2 \textO\textpyx/olivine D_{{{\text{H}}_{2} {\text{O}}}}^{\text{pyx/olivine}} from this study and estimates of
D\textH2 \textO\textgt/\textolivine D_{{{\text{H}}_{2} {\text{O}}}}^{{{\text{gt}}/{\text{olivine}}}} , allows for estimation of peridotite H2O storage capacity, which is 440 ± 200 ppm at 400 km. This suggests that MORB source upper mantle, which contains 50–200 ppm
bulk H2O, is not wet enough to incite a global melt layer above the 410-km discontinuity. However, OIB source mantle and residues
of subducted slabs, which contain 300–1,000 ppm bulk H2O, can exceed the peridotite H2O storage capacity and incite localized hydrous partial melting in the deep upper mantle. Experimentally determined values
of
D\textH2 \textO\textpyx/\textolivine D_{{{\text{H}}_{2} {\text{O}}}}^{{{\text{pyx}}/{\text{olivine}}}} at 10–13 GPa have a narrow range of 1.35 ± 0.13, meaning that olivine is probably the most important host of H2O in the deep upper mantle. The increase in hydration of olivine with depth in the upper mantle may have significant influence
on viscosity and other transport properties. 相似文献
10.
Zhiyuan Ma Juan Yu Yan Su Juan Xie Xubing Jia Yang Hu 《Environmental Earth Sciences》2010,59(5):995-1008
The thermal-waters resources in Weihe Basin of Shaanxi province, NW China are historically classified as middle- to low- temperature
thermal-waters in China. Recent exploitation of the deep thermal reservoir in the centre part of the basin (i.e. Xi’an and
Xianyang) had observed plentiful supply of thermal fluid with higher measured maximum temperature (120°C) and higher hydraulic
pressure (80.50 MPa) in the deeper (more than 4,000 m deep) sedimentary basin. A recent isotope study shows that deep geothermal
waters in the cities of Xi’an and Xianyang are characterized by an observable horizontal oxygen-18 (δ18O) shift and minor deuterium (2H) enrichment. The considerable oxygen shift is possibly due to the following four reasons: water–rock interaction at high
temperature, slow circulation rate of water, low water-to-rock ratio, and old age. On the end number of the δ18O shift, minor δ2H enrichment occur when there is higher concentrations of H2S, CH4, I and Br with lower rate of rSO4
2−/rCl− and r
Na+/r
Cl− suggesting relatively isolated geological environment. In a few thermal waters points,
r\textNa\text+ \text/r\textCl-r{\text{Na}}^{{\text{+}}} {\text{/}}r{\text{Cl}}^{-} < 0.85. This shows possible presence of formation waters. Combining the results from isotopic study and chemical analysis,
we can classify the types of geothermal waters into three groups, the shallow and fast circulating system, the semi-circulating
system and the deep and slow circulating system. 相似文献
11.
Dirk Frei Axel Liebscher Gerhard Franz Bernd Wunder Stephan Klemme Jon Blundy 《Contributions to Mineralogy and Petrology》2009,157(4):473-490
We determined experimentally the Nernst distribution coefficient between orthopyroxene and anhydrous silicate melt for trace elements i in the system Na2O–CaO–MgO–Al2O3–SiO2 (NCMAS) along the dry model lherzolite solidus from 1.1 GPa/1,230°C up to 3.2 GPa/1,535°C in a piston cylinder apparatus.
Major and trace element composition of melt and orthopyroxene were determined with a combination of electron microprobe and
ion probe analyses. We provide partitioning data for trace elements Li, Be, B, K, Sc, Ti, V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb,
Cs, Ba, La, Ce, Sm, Nd, Yb, Lu, Hf, Ta, Pb, U, and Th. The melts were chosen to be boninitic at 1.1 and 2.0 GPa, picritic
at 2.3 GPa and komatiitic at 2.7 and 3.2 GPa. Orthopyroxene is Tschermakitic with 8 mol% Mg-Tschermaks MgAl[AlSiO6] at 1.1 GPa while at higher pressure it has 18–20 mol%. The rare earth elements show a continuous, significant increase in
compatibility with decreasing ionic radius from D
Laopx−melt ∼ 0.0008 to D
Luopx−melt ∼ 0.15. For the high-field-strength elements compatibility increases from D
Thopx−melt ∼ 0.001 through D
Nbopx−melt ∼ 0.0015, D
Uopx−melt ∼ 0.002, D
Taopx−melt ∼ 0.005, D
Zropx−melt ∼ 0.02 and D
Hfopx−melt ∼ 0.04 to D
Tiopx−melt ∼ 0.14. From mathematical and graphical fits we determined best-fit values for D
0M1, D
0M2, r
0M1, r
0M2, E
0M1, and E
0M2 for the two different M sites in orthopyroxene according to the lattice strain model and calculated the intracrystalline
distribution between M1 and M2. Our data indicate extreme intracrystalline fractionation for most elements in orthopyroxene;
for the divalent cations D
i
M2−M1 varies by three orders of magnitude between D
CoM2−M1 = 0.00098–0.00919 and D
BaM2−M1 = 2.3–28. Trivalent cations Al and Cr almost exclusively substitute on M1 while the other trivalent cations substitute on
M2; D
LaM2−M1 reaches extreme values between 6.5 × 107 and 1.4 × 1016. Tetravalent cations Ti, Hf, and Zr almost exclusively substitute on M1 while U and Th exclusively substitute on M2. Our
new comprehensive data set can be used for polybaric-polythermal melting models along the Earth’s mantle solidus.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
12.
The Samgwang mine is located in the Cheongyang gold district (Cheonan Metallogenic Province) of the Republic of Korea. It
consists of eight massive, gold-bearing quartz veins that filled NE- and NW-striking fractures along fault zones in Precambrian
granitic gneiss of the Gyeonggi massif. Their mineralogy and paragenesis allow two separate vein-forming episodes to be recognized,
temporally separated by a major faulting event. The ore minerals occur in quartz and calcite of stage I, associated with fracturing
and healing of veins. Hydrothermal wall-rock alteration minerals of stage I include Fe-rich chlorite (Fe/(Fe+Mg) ratios 0.74-0.81),
muscovite, illite, K-feldspar, and minor arsenopyrite, pyrite, and carbonates. Sulfide minerals deposited along with electrum
during this stage include arsenopyrite, pyrite, pyrrhotite, sphalerite, marcasite, chalcopyrite, galena, argentite, pyrargyrite,
and argentian tetrahedrite. Only calcite was deposited during stage II. Fluid inclusions in quartz contain three main types
of C–O–H fluids: CO2-rich, CO2–H2O, and aqueous inclusions. Quartz veins related to early sulfides in stage I were deposited from H2O–NaCl–CO2 fluids (1,500–5,000 bar, average 3,200) with T
htotal values of 200°C to 383°C and salinities less than about 7 wt.% NaCl equiv. Late sulfide deposition was related to H2O–NaCl fluids (140–1,300 bar, average 700) with T
htotal values of 110°C to 385°C and salinities less than about 11 wt.% NaCl equiv. These fluids either evolved through immiscibility
of H2O–NaCl–CO2 fluids as a result of a decrease in fluid pressure, or through mixing with deeply circulated meteoric waters as a result
of uplift or unloading during mineralization, or both. Measured and calculated sulfur isotope compositions (δ34SH2S = 1.5 to 4.8‰) of hydrothermal fluids from the stage I quartz veins indicate that ore sulfur was derived mainly from a magmatic
source. The calculated and measured oxygen and hydrogen isotope compositions (δ18OH2O = −5.9‰ to 10.9‰, δD = −102‰ to −87‰) of the ore-forming fluids indicate that the fluids were derived from magmatic sources
and evolved by mixing with local meteoric water by limited water–rock exchange and by partly degassing in uplift zones during
mineralization. While most features of the Samgwang mine are consistent with classification as an orogenic gold deposit, isotopic
and fluid chemistry indicate that the veins were genetically related to intrusions emplaced during the Jurassic to Cretaceous
Daebo orogeny. 相似文献
13.
Water and Iron effect on the P-T-x coordinates of the 410-km discontinuity in the Earth upper mantle
Fiorenza Deon Monika Koch-Müller Dieter Rhede Richard Wirth 《Contributions to Mineralogy and Petrology》2011,161(4):653-666
We performed multi-anvil experiments in the system MgO-SiO2 ± H2O at 13.0–13.7 GPa and 1,025–1,300°C and in the system MgO-FeO-SiO2 ± H2O, under reducing conditions, at 11.0–12.7 GPa and 1,200°C, to depict the effect of H2O on the P-T-x coordinates of the 410-km discontinuity, i.e. the olivine–wadsleyite phase boundary. The charges were investigated
with Electron Microprobe (EMP), Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Secondary Ion Mass Spectrometry
(SIMS) and Electron Energy Loss Spectroscopy (EELS). We observe in the MgO-SiO2-H2O system at 1,200°C a 0.6 GPa shift of the phase boundary to lower pressure compared to dry conditions, due to the stronger
water fractionation into wadsleyite (wad) rather than in olivine (ol). In the MgO-FeO-SiO2-H2O system, we reproduced the triple point, i.e. observed coexisting hydrous ol, wad and ringwoodite (ring). SIMS H quantifications
provided partitioning coefficients for water:
D\textwad/ol\textwater D_{\text{wad/ol}}^{\text{water}} ~ 3.7(5) and
D\textring/ol\textwater D_{\text{ring/ol}}^{\text{water}} ~ 1.5(2) and
D\textwad/ring\textwater D_{\text{wad/ring}}^{\text{water}} ~ 2.5(5). For a bulk composition of x
Fe = 0.1, our data indicate only a slight difference in the width of the loop of the two phase field ol–wad under hydrous conditions
compared to dry conditions, i.e. no broadening with respect to composition but a shift to lower pressures. For bulk compositions
of x
Fe > 0.2, i.e. in regions where wad–ring and ol–ring coexist, we observe, however, an unexpected broadening of the loops with
a shift to higher iron contents. In total, the stability field of hydrous wad expands in both directions, to lower and higher
pressures. Fe3+ concentrations as determined by EELS are very low and are expected to play no role in the broadening of the loops. 相似文献
14.
The melting reaction: albite(solid)+ H2O(fluid) =albite-H2O(melt) has been determined in the presence of H2O–NaCl fluids at 5 and 9.2 kbar, and results compared with those obtained in presence of H2O–CO2 fluids. To a good approximation, albite melts congruently at 9 kbar, indicating that the melting temperature at constant
pressure is principally determined by water activity. At 5 kbar, the temperature (T)- mole fraction (X
(H2O) ) melting relations in the two systems are almost coincident. By contrast, H2O–NaCl mixing at 9 kbar is quite non-ideal; albite melts ∼70 °C higher in H2O–NaCl brines than in H2O–CO2 fluids for X
(H2O) =0.8 and ∼100 °C higher for X
(H2O) =0.5. The melting temperature of albite in H2O–NaCl fluids of X
(H2O)=0.8 is ∼100 °C higher than in pure water. The P–T curves for albite melting at constant H2O–NaCl show a temperature minimum at about 5 kbar. Water activities in H2O–NaCl fluids calculated from these results, from new experimental data on the dehydration of brucite in presence of H2O–NaCl fluid at 9 kbar, and from previously published experimental data, indicate a large decrease with increasing fluid pressure
at pressures up to 10 kbar. Aqueous brines with dissolved chloride salt contents comparable to those of real crustal fluids
provide a mechanism for reducing water activities, buffering and limiting crustal melting, and generating anhydrous mineral
assemblages during deep crustal metamorphism in the granulite facies and in subduction-related metamorphism. Low water activity
in high pressure-temperature metamorphic mineral assemblages is not necessarily a criterion of fluid absence or melting, but
may be due to the presence of low a
(H2O) brines.
Received: 17 March 1995/Accepted: 9 April 1996 相似文献
15.
Rodney Grapes Sophia Korzhova Ella Sokol Yurii Seryotkin 《Contributions to Mineralogy and Petrology》2011,162(2):253-273
Sekaninaite (XFe > 0.5)-bearing paralava and clinker are the products of ancient combustion metamorphism in the western part of the Kuznetsk
coal basin, Siberia. The combustion metamorphic rocks typically occur as clinker beds and breccias consisting of vitrified
sandstone–siltstone clinker fragments cemented by paralava, resulting from hanging-wall collapse above burning coal seams
and quenching. Sekaninaite–Fe-cordierite (XFe = 95–45) is associated with tridymite, fayalite, magnetite, ± clinoferrosilite and ±mullite in paralava and with tridymite
and mullite in clinker. Unmelted grains of detrital quartz occur in both rocks (<3 vol% in paralavas and up to 30 vol% in
some clinkers). Compositionally variable siliceous, K-rich peraluminous glass is <30% in paralavas and up to 85% in clinkers.
The paralavas resulted from extensive fusion of sandstone–siltstone (clinker), and sideritic/Fe-hydroxide material contained
within them, with the proportion of clastic sediments ≫ ferruginous component. Calculated dry liquidus temperatures of the
paralavas are 1,120–1,050°C and 920–1,050°C for clinkers, with calculated viscosities at liquidus temperatures of 101.6–7.0 and 107.0–9.8 Pa s, respectively. Dry liquidus temperatures of glass compositions range between 920 and 1,120°C (paralava) and 920–960°C
(clinker), and viscosities at these temperatures are 109.7–5.5 and 108.8–9.7 Pa s, respectively. Compared with worldwide occurrences of cordierite–sekaninaite in pyrometamorphic rocks, sekaninaite occurs
in rocks with XFe (mol% FeO/(FeO + MgO)) > 0.8; sekaninaite and Fe-cordierite occur in rocks with XFe 0.6–0.8, and cordierite (XFe < 0.5) is restricted to rocks with XFe < 0.6. The crystal-chemical formula of an anhydrous sekaninaite based on the refined structure is
| \textK0.02 |(\textFe1.542 + \textMg0.40 \textMn0.06 )\Upsigma 2.00M [(\textAl1.98 \textFe0.022 + \textSi1.00 )\Upsigma 3.00T1 (\textSi3.94 \textAl2.04 \textFe0.022 + )\Upsigma 6.00T2 \textO18 ]. \left| {{\text{K}}_{0.02} } \right|({\text{Fe}}_{1.54}^{2 + } {\text{Mg}}_{0.40} {\text{Mn}}_{0.06} )_{\Upsigma 2.00}^{M} [({\text{Al}}_{1.98} {\text{Fe}}_{0.02}^{2 + } {\text{Si}}_{1.00} )_{\Upsigma 3.00}^{T1} ({\text{Si}}_{3.94} {\text{Al}}_{2.04} {\text{Fe}}_{0.02}^{2 + } )_{\Upsigma 6.00}^{T2} {\text{O}}_{18} ]. 相似文献
16.
G. Diego Gatta Marco Merlini Hanns-Peter Liermann André Rothkirch Mauro Gemmi Alessandro Pavese 《Physics and Chemistry of Minerals》2012,39(5):385-397
The thermoelastic behavior of a natural clintonite-1M [with composition: Ca1.01(Mg2.29Al0.59Fe0.12)Σ3.00(Si1.20Al2.80)Σ4.00O10(OH)2] has been investigated up to 10 GPa (at room temperature) and up to 960°C (at room pressure) by means of in situ synchrotron
single-crystal and powder diffraction, respectively. No evidence of phase transition has been observed within the pressure
and temperature range investigated. P–V data fitted with an isothermal third-order Birch–Murnaghan equation of state (BM-EoS) give V
0 = 457.1(2) ?3, K
T0 = 76(3)GPa, and K′ = 10.6(15). The evolution of the “Eulerian finite strain” versus “normalized stress” shows a linear positive trend. The
linear regression yields Fe(0) = 76(3) GPa as intercept value, and the slope of the regression line leads to a K′ value of 10.6(8). The evolution of the lattice parameters with pressure is significantly anisotropic [β(a) = 1/3K
T0(a) = 0.0023(1) GPa−1; β(b) = 1/3K
T0(b) = 0.0018(1) GPa−1; β(c) = 1/K
T0(c) = 0.0072(3) GPa−1]. The β-angle increases in response to the applied P, with: βP = β0 + 0.033(4)P (P in GPa). The structure refinements of clintonite up to 10.1 GPa show that, under hydrostatic pressure, the structure rearranges
by compressing mainly isotropically the inter-layer Ca-polyhedron. The bulk modulus of the Ca-polyhedron, described using
a second-order BM-EoS, is K
T0(Ca-polyhedron) = 41(2) GPa. The compression of the bond distances between calcium and the basal oxygens of the tetrahedral
sheet leads, in turn, to an increase in the ditrigonal distortion of the tetrahedral ring, with ∂α/∂P ≈ 0.1°/GPa within the P-range investigated. The Mg-rich octahedra appear to compress in response to the applied pressure, whereas the tetrahedron
appears to behave as a rigid unit. The evolution of axial and volume thermal expansion coefficient α with temperature was
described by the polynomial α(T) = α0 + α1
T
−1/2. The refined parameters for clintonite are as follows: α0 = 2.78(4) 10−5°C−1 and α1 = −4.4(6) 10−5°C1/2 for the unit-cell volume; α0(a) = 1.01(2) 10−5°C−1 and α1(a) = −1.8(3) 10−5°C1/2 for the a-axis; α0(b) = 1.07(1) 10−5°C−1 and α1(b) = −2.3(2) 10−5°C1/2 for the b-axis; and α0(c) = 0.64(2) 10−5°C−1 and α1(c) = −7.3(30) 10−6°C1/2for the c-axis. The β-angle appears to be almost constant within the given T-range. No structure collapsing in response to the T-induced dehydroxylation was found up to 960°C. The HP- and HT-data of this study show that in clintonite, the most and the less expandable directions do not correspond to the most and
the less compressible directions, respectively. A comparison between the thermoelastic parameters of clintonite and those
of true micas was carried out. 相似文献
17.
Virender K. Sharma Ria A. Yngard Zoltan Homonnay Abhishek Dey Chun He 《Aquatic Geochemistry》2010,16(3):483-490
The kinetics of the formation of the purple-colored species between FeIII-EDTA and peroxynitrite were studied as a function of pH (10.4–12.3) at 22°C in aqueous solutions using a stopped-flow technique.
A purple-colored species was immediately formed upon mixing, which had an absorbance maximum at 520 nm. The increase in absorbance
with time could be fit empirically by a power function with two parameters a and b. The power equation determined was absorbance = a*t
b
, where a increased linearly with pH and the concentration of peroxynitrite, while b almost remained constant with a value of ~0.25. The molar extinction coefficient ε520 nm for the colored species was determined as 13 M−1cm−1, which is much lower than ε520 nm = 520 M−1 cm−1 for the [FeIII(EDTA)O2]3−, a purple species observed in the FeIII–EDTA–H2O2 system. The results of kinetics and spectral measurements of the present study are briefly discussed and compared with those
of the reaction between Fe(III)-EDTA and hydrogen peroxide. 相似文献
18.
Karem Azmy Evan Edinger Joyce Lundberg Wilfredo Diegor 《International Journal of Earth Sciences》2010,99(1):231-244
Mid-Holocene age fossil-fringing reefs occur along the tectonically stable north coast of Java, Indonesia, presenting an opportunity
for sea level and paleoclimate reconstruction. The fossil reef at Point Teluk Awur, near Jepara, Central Java, contains two
directly superposed horizons of Porites lobata microatolls. Corals in the lower horizon, 80 cm above modern sea level, yielded Uranium series dates of 7090 ± 90 year BP,
while corals in the upper horizon at 1.5 m grew at 6960 ± 60 year BP. These dates match the transgressive phase of regional
sea-level curves, but suggest a mid-Holocene highstand somewhat older than that recorded on mid-Pacific islands. Paleotemperature
was calibrated using Sr/Ca and δ18O values of a modern P. lobata coral and the locally measured sea surface temperature (SST), yielding SST–Sr/Ca and SST–δ18O calibration equations [T
Sr/Ca = 91.03–7.35(Sr/Ca) and
Td18 \textO T_{{\delta^{18} {\text{O}}}} = −3.77 to −5.52(δ18O)]. The application of the local equations to Sr/Ca and δ18O measurements on these corals yielded a range of temperatures of 28.8 ± 1.7°C, comparable to that of the modern Java Sea
(28.4 ± 0.7°C). A paleo-salinometer [Δδ18O = ∂δ18O/∂T (
Td18 \textO T_{{\delta^{18} {\text{O}}}} − T
Sr/Ca)], re-calculated using the local parameters, also suggests Java Sea mid-Holocene paleosalinity similar to modern values. 相似文献
19.
Jiang-Feng Qin Shao-Cong Lai Chun-Rong Diwu Yin-Juan Ju Yong-Fei Li 《Contributions to Mineralogy and Petrology》2010,159(3):389-409
Petrogenesis of high Mg# adakitic rocks in intracontinental settings is still a matter of debate. This paper reports major
and trace element, whole-rock Sr–Nd isotope, zircon U–Pb and Hf isotope data for a suite of adakitic monzogranite and its
mafic microgranular enclaves (MMEs) at Yangba in the northwestern margin of the South China Block. These geochemical data
suggest that magma mixing between felsic adakitic magma derived from thickened lower continental crust and mafic magma derived
from subcontinental lithospheric mantle (SCLM) may account for the origin of high Mg# adakitic rocks in the intracontinental
setting. The host monzogranite and MMEs from the Yangba pluton have zircon U–Pb ages of 207 ± 2 and 208 ± 2 Ma, respectively.
The MMEs show igneous textures and contain abundant acicular apatite that suggests quenching process. Their trace element
and evolved Sr–Nd isotopic compositions [(87Sr/86Sr)i = 0.707069–0.707138, and εNd(t) = −6.5] indicate an origin from SCLM. Some zircon grains from the MMEs have positive εHf(t) values of 2.3–8.2 with single-stage Hf model ages of 531–764 Ma. Thus, the MMEs would be derived from partial melts of the
Neoproterozoic SCLM that formed during rift magmatism in response to breakup of supercontinent Rodinia, and experience subsequent
fractional crystallization and magma mixing process. The host monzogranite exhibits typical geochemical characteristics of
adakite, i.e., high La/Yb and Sr/Y ratios, low contents of Y (9.5–14.5 ppm) and Yb, no significant Eu anomalies (Eu/Eu* = 0.81–0.90),
suggesting that garnet was stable in their source during partial melting. Its evolved Sr–Nd isotopic compositions [(87Sr/86Sr)i = 0.7041–0.7061, and εNd(t) = −3.1 to −4.3] and high contents of K2O (3.22–3.84%) and Th (13.7–19.0 ppm) clearly indicate an origin from the continental crust. In addition, its high Mg# (51–55),
Cr and Ni contents may result from mixing with the SCLM-derived mafic magma. Most of the zircon grains from the adakitic monzogranite
show negative εHf(t) values of −9.4 to −0.1 with two-stage Hf model ages of 1,043–1,517 Ma; some zircon grains display positive εHf(t) of 0.1–3.9 with single-stage Hf ages of 704–856 Ma. These indicate that the source region of adakitic monzogranite contains
the Neoproterozoic juvenile crust that has the positive εHf(t) values in the Triassic. Thus, the high-Mg adakitic granites in the intracontinental setting would form by mixing between
the crustal-derived adakitic magma and the SCLM-derived mafic magma. The mafic and adakitic magmas were generated coevally
at Late Triassic, temporally consistent with the exhumation of deeply subducted continental crust in the northern margin of
the South China Block. This bimodal magmatism postdates slab breakoff at mantle depths and therefore is suggested as a geodynamic
response to lithospheric extension subsequent to the continental collision between the South China and North China Blocks. 相似文献
20.
Let {Z(s):s∈D⊆ℝ
d
} be a zero mean stationary random field observed at a finite number of locations. Lahiri (Sankhya Ser. A 65:356–388, 2003) proved spatial central limit theorems (CLT) for ∑
i=1
n
Z(s
i
) assuming a ‘nearly infill domain sampling’. Applications of his results depended on the underlying spatial sampling region
and the design in a complicated fashion. The main objective of this paper is to provide CLTs that could be applied easily
in practice. We present two main results assuming a ‘nearly infill domain sampling’ defined mainly in terms of dependence.
Theorem 1 establishes a CLT for ∑
i=1
n
Z(s
i
) and Theorem 2 is obtained mainly for applications to density estimates. We report on a simulation study for illustrating
a way of applying our results in practice. 相似文献