Jichengite 3CuIr2S4·(Ni, Fe)9S8, a New Mineral, and Its Crystal Structure

A new mineral, jichengite ideally 3CuIr2S4·(Ni,Fe)9S8, was found as a constituent of placer concentrates at a branch of the Luanhe River, about 220 km NNE of Beijing. Its associated minerals are chromite, magnetite, ilmenite, zircon, native gold, iridium, ferrian platinum and osmium. The placer is distributed at places around ultrabasic rock, which hosts chromite orebodies, from which PGM originated. Jichengite occurs commonly as massive or granular aggregates. No perfect morphology of jichengite was observed. It is steel gray and opaque with metallic luster and black streak. It has a Mohs hardness of 5, VHN (d) μm 21.65, Hm 4.465, Hv = 268.1 N/um2. It is brittle and weakly magnetic. Cleavage {010} is rarely observed. No fracture was observed. Density could not be measured because of its too small grain size. Density (calc.) is 7.003 g/cm3. Reflect light is reddish-brown, without internal reflections. Anisotropism is distinct with grayish or yellowish white in crossed nicols and bluish violet-copper red in uncrossed nicols. Jichengite shows weak pleochroism and strong bireflectance. The reflectance values in air at the Standard Commission on Ore Mineralogy wavelengths are: 38.9, 34.3 at 470 nm, 38.9, 34.5 at 546 nm, 39.1, 35.3 at 590 nm, 39.2, 36.8 at 650 nm, parallel-axial extinction. The six strongest lines in the X-ray powder-diffraction pattern [d in ?, (I), (hkl)] are: 3.00 (100) (116), 2.80 (50) (205), 2.48. (50) (208), 1.916 (40) (2, 1, 10), 1.765 (60) (220), 1.753 (50) (2, 0, 16). Five chemical analyses carried out, yielding the following results: S 25.76 (25.49-5.97), Fe 10.03 (9.78-10.31), Co 0.78 (0.75-0.81), Ni 12.48 (12.32-12.85), Cu 4.77 (4.69-4.83), Ir 46.98(46.14-47.89), sum 100.80wt%, which produced a formula (Cu1.556Fe0.976)2.532(Ir5.063S10.126)·(Fe2.7451Ni4.404Co0.273)7.422S6.517. The ideal formula is X10Ir5S17.5, which was calculated by single crystal structure analyses, where X = Cu(II) + Fe(II) + Ni(II) + Co(II). The single crystal data were collected using a diffractometer with Mo Ka radiation and a graphite monochromate. The crystal system is trigonal with space group R3m and unit cell parameters a=7.0745(14) ?, c=34.267(10) ? (The superstructure not found), and the final R Indices [with 564 observed reflections, I>2sigma (I)] are R1=0.0495, wR2=0.1349. The specimens are deposited in the Geological Museum of China.     

Hydroxycalciopyrochlore,A New Mineral Species from Sichuan,China

Hydroxycalciopyrochlore, ideally(Ca,Na,U,□)2(Nb,Ti)2O6(OH), cubic, is a new mineral species(IMA2011-026) within the pyrochlore supergroup that was found occurring at the Maoniuping mine, Mianning County, Xichang prefecture, Sichuan Province, southwest China. The mineral is found in an alkali feldspar granite rare-earth ore deposit(26–27 Ma). Associated minerals include calcite, barite, celestine, albite, aegirine, aegirine-augite, fluorite, parasite-(Ce), thorite, thorianite, zircon, galena, sphalerite, magnetite, and pyrite. Crystals occur mostly as octahedra, and less often as dodecahedra and tetrahexahedra or combinations thereof. Some occur with an allotriomorphic habit with a thick triangular tabular form. Crystals generally range from 0.1 to 1 mm in size. The mineral is brownishblack, greenish-black and black on fresh sections with a brown streak. The crystal is translucent, and has a greasy lustre on fresh sections. It is metamict without any observed parting or cleavage and with a conchoidal fracture. The Vickers microhardness is 572 kg/mm2(5–6 on the Mohs hardness scale). The density measured by hydrostatic weighing is 5.10(3) g/cm3. The strongest four reflections in the X-ray powder-diffraction pattern [d in(I) hkl] are: 2.9657(100) 2 2 2, 1.8142(34) 0 4 4, 1.5463(21) 2 2 6, 2.5688(18) 0 0 4. The unit-cell parameters are a = 10.381(4), V = 1118.7(7)3, Z = 8. The structure was solved and refined in the space group Fd3m with R = 0.09. The empirical formula is(Ca0.74Na0.58U0.40Ce0.05Fe0.02□0.21)2.00(Nb1.15Ti0.80Ta0.03Al0.01Mg0.01)2.00O6.02 [(OH)1.01F0.09]1.10, on the basis of 2 atoms of B pfu; the simplified formula is(Ca,Na,U,□)2(Nb,Ti)2O6(OH). Type material is deposited in the Geological Museum of China, Beijing, People's Republic of China, catalogue number M11800.     

Naquite,FeSi, a New Mineral Species from Luobusha,Tibet, Western China

A new mineral species, named naquite(FeSi), is found in the podiform chromitites of the Luobusha ophiolite in Qusong County, Tibet, China. The detailed composition is Fe 65.65, Si 32.57 and Al 1.78 wt%. The mineral is cubic, space group P213. The irregular crystals range from 15 to 50 μm in diameter and form an intergrowth with luobusaite. Naquite is steel grey in color, opaque, with a metallic lustre and gives a grayish-black streak. The mineral is brittle, has a conchoidal fracture and no apparent cleavage. The estimated Mohs hardness is 6.5, and the calculated density is 6.128 g/cm3. Unit-cell parameters are a 4.486 (4) ?, V 90.28 (6) ?3, Z=4. The five strongest powder diffraction lines [d in ? (hkl) (I/I0)] are: 3.1742 (110) (40), 2.5917(111) (43), 2.0076 (210) (100), 1.8307 (211) (65), and 1.1990 (321) (36). Originally called ‘fersilicite’, the species and new name have now been approved by the CNMNC (IMA 2010–010).     

Chengdeite-A New Mineral of Ordered Natural Iron-iridium Alloy

Chengdeite occurs in chromite orebodies in dunite as well as in placers in their neighbourhood. The mineral occurs as granular aggregates in association with inaglyite and in some cases occurs as graphic intergrowths with native iridium. It is opaque with a metallic lustre, colour steel-black, streak black,HM = 5.2, VHN50=452 kg/mm2, cleavage not observed, fracture not observed, strongly magnetic. Its reflection colour is bright white with a yellowish tint. It has no internal reflection, bireflectance or pleochrism, and shows isotropism.Thirteen chemical analyses were carried out by means of the electron microprobe. The mean percentages of the data obtained in the 13 analyses ares S 0.001, Fe 7.9, Ni 0.03, Co 0.03, Cu 0.83, As 0.02, Rh 0.19, Pd 0.00, Os 0.06, Ir 88.5, Ft 2.2 and Pb 0.00. The simplified formula is Ir3Fe, which requires Ir 91.17 and Fe 8.83, the total being 100.00 (% ).Five strongest lines of X-ray powder diffraction (hkl, d, I)are: 111, 2.18 (80);200, 1.89 (60); 220, 1.34 (70);311, 1.142     

Determination of Fe2+/Fe3+ Ratios of Magnetite using Different Methods: A Case Study from the Qimantag Metallogenic Belt

Determination of Fe2+/Fe3+ ratios from metallogenic belts to explore controlling physical and chemical conditions of rock formation is of great significance. In order to explore magnetite Fe2+/Fe3+ ratios of the Qimantag metallogenic belt, part of the Eastern Kunlun orogenic belt in the northeastern margin of the Qinghai–Tibetan plateau, western Central Orogenic Belt of China, and overcome the limitation of the traditional electronic probe, five different measurement methods are proposed and their respective advantages and disadvantages evaluated, with the composition data of the magnetite obtained using electron probe microanalysis (EPMA). The direct oxygen measurement method has a significant impact on the determination results of FeO and Fe2O3, but the accuracy and uniformity of the results are low. The valence method (Flank method) based on the spectral intensity ratio of Lα to Lβ for iron is also unreliable for FeO and Fe2O3 measurements because it is difficult to establish a relationship between Lβ/Lα, the spectral intensity ratio, and the Fe2+/Fe3+ content ratio. In comparison, the charge difference method, the surplus-oxygen method and the M?ssbauer spectrum method are still the most favorable. M?ssbauer spectroscopy, with its isomer movement particularly sensitive to the oxidation state of iron, yields results closer to 0.5, which is relatively reliable. Earlier magnetite deposits are located in intrusions or contact zones and formed by magmatic fluids with high Fe2+/Fe3+ ratios, whereas later magnetite deposits are farther away from intrusions and have low Fe2+/Fe3+ ratios. The transformation mechanism of hematite and magnetite in the Qimantage metallogenic belt is also studied. No large volume changes, such as pore filling and shrinkage fracture, were detected in the metallogenic belt, and the transformation mechanism is more similar to a reoxidation and reduction mechanism.     

Crystal Structure and Chemical Composition of Ludwigite from Vranovac Ore Deposit (Boranja Mountain,Serbia)

The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) ?; b=12.3109(2) ?; c=3.03712(7) ?; and V=345.91(1) ?3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-Al3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01(Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.     

Titanium,Ti, A New Mineral Species from Luobusha,Tibet, China

We describe the new mineral species titanium,ideally Ti,found in the podiform chromitites of the Luobusha ophiolite in Tibet,People’s Republic of China.The irregular crystals range from 0.1 to 0.6 mm in diameter and form an intergrowth with coesite and kyanite.Titanium is silver grey in colour,the luster is metallic,it is opaque,the streak is grayish black,and it is non-fluorescent.The mineral is malleable,has a rough to hackly fracture and has no apparent cleavage.The estimated Mohs hardness is 4,and the calculated density is 4.503 g/cm3.The composition is Ti 99.23-100.00 wt%.The mineral is hexagonal,space group P63 /mmc.Unit-cell parameters are a 2.950(2),c 4.686(1),V 35.32(5) 3,Z = 2.The five strongest powder diffraction lines [d in(hkl)(I/I0)] are: 2.569(010)(32),2.254(011)(100),1.730(012)(16),1.478(110)(21),and 0.9464(121)(8).The species and name were approved by the CNMNC(IMA 2010–044).     

Geochemical Constraints of Sediments on the Provenance, Depositional Environment and Tectonic Setting of the Songliao Prototype Basin

The geochemistry of sediments is primarily controlled by their provenances, and different tectonic settings have distinctive provenance characteristics and sedimentary processes. So, it is possible to discriminate provenances, depositional environments and tectonic settings in the development of a sedimentary basin with the geochemistry of the clastic rocks. The analytical results of the present paper demonstrate that sediments in the Songliao prototype basin are enriched in silica (SiO2=66.48-80.51 %), and their ΣREE are 30-130 dmes of that of chondrite with remarkable Eu anomalies. In discriminating diagrams of Eu/Eu vs eeeeeREE and (La/Yb)N vs ΣREE, most samples locate above the line Eu/ Eu=l, on the right of the line Eu/Eu/ΣREE=1 and under the line La/Yb)N/eeeeeREE=1/8, which indicates that the depositional environment of sediments in the basin was oxidizing. In addition, variations of MgO, TiO2, A12O3, FeO+Fe2O3, Na2O and CaO vs SiO2 reflect a tendency of increasing mineral maturity of sediments     

Malanite——A New Cupric Platinum (Pt~(3+)) and Iridium (Ir~(3+)) Sulphide

Malanite was first found in veinlets of disseminated copper-nickel ores inZunhua County, Hebei Province, and then in platinum-bearing chromite ores in ShuangfengVillage, Yanshan. In the former case, malanite appears as octahedrons or dodecahedrons asso-ciated with pyrrhotite, pentlandite, sperrylite and cooperite; while in the latter case, it is massiveor present in anhedral glomerocrysts, filling in cracks of iridisite and associated with osmiride,ferrian platinum and iridisite. Malanite is steel-grey in colour, opaque with metallic lustre andblack streaks and brittle with no magnetism. H_M=5.0, VHN_(20)=417kg/mm~2, cleavage {111}sometimes observed. The calculated density is 7.57g/cm~3. The reflective colour is white with alight green tint. Internal reflections are not observed. This mineral is isotropic, showing nobireflection or reflection pleochroism in air. By means of electron microprobe analysis, the em-pirical formula (based on 7 atoms) is expressed as (Cu_(0.93)Fe_(0.06))_(∑0.99)(Pt_(1.03)Ir_(0.66)Rh_(0.04)Pd_(0.03)Co_(0.20)Ni_(0.03))_(1.99)S_(4.03) or (Cu_(0.95)Fe_(0.07))_(∑1.02)(Pt_(1.37)Ir_(0.45)Co_(0.11)Rh_(0.08))_(∑2.01)S_(3.97). Five strongestlines (hkl, d, I) of X-ray powder diffraction data of malanite are 311,2.98(6); 400,2.48(5);333, 1.90(7); 440, 1.75(10); 731, 1.29(5). It was known on the basis of X-ray powder diffractiondata that malanite is cubic, and the space group is Fd3m with α=0.9940nm, V=0.9821(3)nm~3 and Z=4. The type material of malanite is deposited at the Geological Museum of China(GMC)s     

Control of Melt Structures on Cu-Au Mineralization in Basic-Ultrabasic Complexes of Northern China

Based on systematic analyses of 72 samples of different basic-ultrabasic rocks, the present paper discusses the relationship between melt structure and Cu and Au mineralization. It is found that if the NBO/T, NBO, M2+, FeO and MgO values are relatively high and the T, M3+, Fe2O3 and CaO values are low the basic-ultrabasic melt will be favourable to Cu (Ni) mineralization, but if the former are low and the latter are high it is favourable to Au metallization. Cu ions occupy dominantly octahedra in basic-ultrabasic melt and the higher the NBO/T, NBO and M2+ values, the more the octahedra in the melt. Au element mainly takes the form of Au+ ions in basic-ultrabasic melt and the Au+ ions constitute tetrahedral sites together with Fe3+ ions. Therefore, low M2+ and high Fe3+, i.e. high oxygen fu-gacity, can promote the enrichment of Au+ ions and Au mineralization. Components NT (other than Au+), Al2O3 and SiO2 in basic-ultrabasic melt have no effect on metallogenetic species. As mentioned above, in relevant d     

Opaque Mineralogy as a Tracer of Magmatic History of Volcanic Rocks:an Example from the Neogene-Quaternary Harrat Rahat Intercontinental Volcanic Field, North Western Saudi Arabia

The Neogene-Quaternary Harrat Rahat volcanic field is part of the major intercontinental Harrat fields in western Saudi Arabia.It comprises lava flows of olivine basalt and hawaiite,in addition to mugearite,benmorite,and trachyte that occur mainly as domes,tuff cones and lava flows.Based on opaque mineralogy and mineral chemistry,the Harrat Rahat volcanic varieties are distinguished into Group I(olivine basalt and hawaiite) and Group II(mugearite,benmorite and trachyte).The maximum forsterite content(~85) is encountered in zoned forsteritic olivine of Group I,whereas olivine of Group II is characterized by intermediate(Fo=50),fayalitic(Fo=25) and pure fayalite in the mugearite,benmorite and trachyte,respectively.The more evolved varieties of Group II contain minerals that show enrichment of Fe2+,Mn2+and Na+that indicates normal fractional crystallization.The common occurrence of coarse apatite with titanomagnetite in the benmorite indicates that P5+becomes saturated in this rock variety and drops again in trachyte.Cr-spinel is recorded in Group I varieties only and the Cr#(0.5) suggests lherzolite as a possible restite of the Harrat Rahat volcanics.The plots of Cr# vs.the forsterite content(Fo) suggest two distinct trends,which are typical of mixing of two basaltic magmas of different sources and different degrees of partial melting.The bimodality of Harrat Rahat Cr-spinel suggests possible derivation from recycled MORB slab in the mantle as indicated by the presence of high-Al spinel.It is believed that the subcontinental lithospheric mantle was modified by pervious subduction process and played the leading role in the genesis of the Harrat Rahat intraplate volcanics.The trachytes of the Harrat Rahat volcanic field were formed most probably by melting of a lower crust at the mantle-crust boundary.The increase in fO2 causes a decrease in Cr2 O3,and Al2 O3,and a strong increase in the proportion of Fe3+and Mg# of spinel crystallizing from the basaltic melt at T ~1200°C.The olivine-pyroxene and olivine-spinel geothermometers yielded equilibrium temperature in the range of 935-1025°C,whereas the range of <500-850°C from single-pyroxene thermometry indicates either post crystallization reequilibrium of the clinopyroxene,or the mineral is xenocrystic and re-equilibrated in a cooling basaltic magma.     

Luobusaite： A New Mineral

A group of mantle minerals including about 70-80 subtypes of minerals are discovered from a podiform chromitite in Tibet, China. Recovered minerals include diamond, coesite, moissanite, wustite, Fe-silides and a new mineral, luobusaite. All of these minerals were hand-picked from heavymineral separates of the podiform chromitite in the mantle peridotite of an ophiolite. The grains of luobusaite are as host mineral with inclusions of native silicon or as an intergrowth with native silicon and Fe-Si phase. Luobusaite occurs as irregular grains, with 0.1-0.2 mm in size, consisting of very finegrained aggregates. The mineral is steel-grey in color, metallic luster, and opaque. The empirical formula （based on 2 for Si） is Fe0.83Si2, according to the chemical compositions of luobusaite. X-ray powder-diffraction data： orthorhombic system, space group Cmca, a = 9.874 （14） A, b = 7.784 （5） A, c= 7.829（7） A, Z=16.     

Zircon Geochronology and Trace Element Geochemistry from the Xiaozhen Copper Deposit, North Daba Mountain: Constraints on Albitites Petrogenesis

Albitite often accompanies with various metal and gem mineral deposits and a large number of occurrences have been reported globally, including the South Qinling orogen, China. The Xiaozhen copper deposit is a typical deposit in the North Daba Mountain area of the South Qinling orogen whose distribution is controlled by albitite veins and fractures. As there are few studies on the petrogenesis of albitite in Xiaozhen copper deposit, this paper focuses on the petrogenesis of albitite and its mineralization age. Detailed fieldwork and mineral microscopic observations initially suggest that albitite from the Xiaozhen copper deposit is igneous in origin. Further zircon trace element geochemistry studies indicate that these zircons have high Th/U ratios(0.5), low La content, high(Sm/La)N and Ce/Ce*values, and a strong negative Eu anomaly, which are commonly seen in magmatic zircons. The chondrite–normalized rare earth element(REE) patterns are consistent with magmatic zircons from throughout the world, and they fall within or near the field of magmatic zircons on discriminant diagrams. The calculated average apparent Ti–in–zircon temperature for young zircons is 780°C, consistent with magmatic zircon crystallization temperatures. Therefore, zircon geochemistry indicates that the albitite origin is magmatic. SIMS U–Pb dating on nine magmatic zircons yielded a concordia age of 154.8±2.2 Ma, which represents the formation of albitite and the metallogenic age. More importantly, it is consistent with the ages of Yanshanian magmatism and metallogenesis in the South Qinling orogen, so formation of the Xiaozhen copper deposit may be a closely related geological event.     

The Discovery of Magnesioferrite from Au (Fe, Cu) Magnesian Skarn Deposits and Study of the Magnesioferrite-Magnesiomagnetite Series

Magnesioferrite, a rare metasomatic mineral, was discovered for the first time in China from the Qinlou Au (Fe, Cu) magnesian skarn deposit, Sanpu, Huaibei, Auhui Province, and the Mulonggou Fe (Mo, Cu) magnesian skarn deposit, Luonan County, Shaanxi Province. In this paper, the geological setting, mineral associations, chemical composition, some physical properties, X-ray powder diffraction data and infrared spectroscopy of magnesioferrite and magnesiomagnetite are discussed. Magnesioferrite contains 17.66%-13.48% of MgO. Its main associated minerals are clinohumite, chondrodite, serpentine,, calcite and magnesiomagnetite. The density of magnesioferrite is 4.537-4.720, reflectances in percent are: 17.8-18.1, hardness is 838-900 kg/mm2, and the cell parameter a0 = 8.371-8.379 A. A systematic study of the magnesioferrite-magnesiomagnetite-magnetite series suggests that along with the increase of magnesioferrite molecules in the mineral, the density, reflectances and cell parameters decrease corresponding     

A New Three–Dimensional Superstructure in Bafertisite

A new superstructure was found in bafertisite [(Ba0.98Na0.02)1.00(Fe1.71Mn0.26Mg0.01)1.98 TiO[(Si1.82Ti0.04Al0.03Cr0.01)1.90O7](OH1.40F0.53Cl0.03)1.96] from Donghai County, Jiangsu Province, China. The occurrence of the superstructure reflections were observed by single crystal diffraction using a SMAR APEX CCD. The a*, b*and c* axis directions revealed extra weak reflection spots of the superstructure. The apparent 2a, 2b and 2c superstructure is monoclinic with unit cell a＝10.6502(15)?, b＝13.7233(19)?, c＝21.6897(3)?, α＝90o, β＝94.698(3)o, γ＝90o,space group Cm,Z=16. If c* extra weak reflections are ignored, the secondary supercell gave a cell a＝10.6548(15)?, b＝13.7284(19)?, c＝11.6900(17)?, α＝90o, β＝112.322(28)o, γ＝90o,space group Cm,Z=8. The basic subcell was obtained by ignoring all extra weak reflection spots and gave: a＝5.3249(17)?, b＝6.8669(22)?, c＝10.8709(36)?, α＝90o, β＝94.740(62)o, γ＝90o,space P21/m,Z=2. The superstructure has been refined to R = 0.063 for 7805 [R(int) = 0.0266] unique reflections I>2δ(I). The structure consists of an octahedra (O) sheet sandwiched between two heteropolyhedral (H) sheets. These sheets consist of Ti–octahedra and twin tetrahedral disilicate groups [Si2O7]. The O sheet comprises (Fe,Mg)O4 octahedra. The large Ba cation is located in the interlayer area. The refined structure shows Fe, Mg are partly ordered. The shifting of the TiO6 octahedron and SiO4 tetrahedron sites in the sheet may be a consequence of the superstructure.     

Study on the Crystal of Daomanite

It was not possible to carry out a complete analyses of crystal, as the experiment by Ding and Shi et al.. It's analysis precision R=0.25 or more big than this, which value are not satisfied for single crystal study, but we through many test and found the best: [R(int)=14.5%]. The final fullmatix least-squares refinement on F2 converged to R1=0.0791 and wR2=0.1864 for 704 observed reflections [I 3 2s(I)]. Daomanite is orthorhombic system, space group Cmc21, a=3.7520(8))?, b=15.844(4) ?, c=5.8516(12) ?, α=β=γ=90°. V=347.86(14)?3, Z=4. Daomanite chemical formula is Cu Pt AsS 2. Idealized composition Me+M2+M2+S2=CuS ·PtA s S. There is no other similar mineral in the world.     

Shale Gas Reservoir Evaluation by Geophysical Measurements: A Case Study of the Upper Ordovician–Lower Silurian in the Fenggang Block, Northern Guizhou Province

With the aid of geophysical measurements, including seventeen two-dimensional(2 D) seismic lines and the well logging curves of well FGY1, the structure and reservoir characteristics of the Upper Ordovician–Lower Silurian strata in the Fenggang block, northern Guizhou Province, were analyzed thoroughly to identify desert areas and favorable intervals. The results show that Longmaxi-Wufeng is the most prospect-rich formation, consisting of a thick succession of overmature black shale, this formation remaining partially in the Suiyang, Fenggang and Jianchaxi synclines. The Longmaxi-Wufeng shale, especially the lower member, was deposited in a reducing low-energy environment with relatively high U content and a low Th/U value. In this shale, the organic matter type(sapropelic and humic-sapropelic), total organic carbon(TOC) content, gas content, gas adsorption capacity, vitrinite reflectance and brittle mineral content are profitable for shale gas preservation and development. The fractures of this shale were closed because of its high overburden pressure. The gas adsorption capacity of this shale increases with increasing TOC content and Ro. In the Longmaxi-Wufeng Formation at well FGY1, the most favorable intervals are in the depth ranges of 2312.4–2325.1 m and 2325.8–2331.1 m.     

Discovery and Genetic Mechanism of Basic Granulite in the Altay Orogenic Belt, Xinjiang, NW China

Altay granulite (AG), which represents the product of high-grade metamorphism in the lower crust, was newly found in the Wuqiagou area, Fuyun County in the Altay orogenic belt, Northwest China. It is composed mainly of hypersthene, augite, basic plagioclase, amphibole and brown biotite. Its mineral compositions of amphibole and biotite are rich in Mg/(Mg+Fe2+) and Ti. Geochemically, the AG is enriched in Mg/(Mg+Fe2+) and A12O3, and poor in CaO, with depletion of U, Th, K and Rb contents. Furthermore, geochemical data reflect that the protolith of the AG is igneous-genetic calc-alkaline basalt formed under an island arc environment. The AG has ZREE of 92.38-96.58 ppm and enriched LREE model with weak positive Eu anomaly of 1.09-1.15. In the MORB normalized spider diagram, the AG shows tri-doming pattern with a strong negative Nb anomaly and medium negative P and Ti anomalies, reflecting that the AG has tectonic relation with subduction or subduction-related materials. The P-T conditions of peak metamorphi     

Study on Composition of Inclusions in Minerals and Simulation Experiment on Hydrothermal Metasomatic Process of the Bayan Obo Iron Deposit

On the basis of the mechanism of formation of mineral inclusions, it may be assumed that a certain relation exists between the compositions of fluid inclusions in various minerals formed at the same stage of hydrothermal activity. In order to study the genetic relationships between different minerals in the Bayan Obo iron deposit, the compositions(K~+, Na~+, Ca~+, Mg~+, F~+, Cl~+, CO_2~(2-), ΣSO_4~(2-) and pH) of inclusions in fluorite(23), hematite(13), magnetite(3), sodium pyroxene(2) and dolomite(5) from the main mine and the eastern mine were determined by using the vacuum decrepitation and leaching methods, and cluster analyses of the data on the compostions were made. The Q-mode cluster analysis indicates that some iron oxide minerals in the deposit are related to dolomite of sedimentary origin, while others are related to fluorite and sodium pyroxene--products of hydrothermal activity. The R-mode cluster analysis shows that the components of the leaching solution may be divided into two groups: one includes CO_2~(2-), Mg~(2+) and H~+(pH), which are obviously associated with dolomite; the other comprises Na~+, K~+, Ca~+, F~+, Cl~+ and SO_4~(2-), which may possibly represent the composition of hydrothermal solutions.The reaction of the Na-F-Cl solution(pH 4.72) with hematite dolomite at 300℃ and 5 × 10~7 Pa and under alternately"static and dynamic" conditions produced large amounts of hematite and fluorite and small amounts of smectite and Na(Fe) silicates, and the hematite-fluorite assemblage accords with the actual geological conditions in the deposit. From a comparison between the compositions of"static" and"dynamic" solution samples, it may be known that the flow reaction facilitates the migration of Fe, F, Ca and other components as well as Na-metasomatism(Na and Si are fixed in a solid phase).The study of the compositions of mineral inclusions and simulation experiments on hydrothermal metasomatism have provided new evidence for the hypothesis of metamorphosed-sedimentary and hydrothermal-remoulding origin of the Bayan Obo deposit, and pointed out emphatically that hydrothermal metasomatism plays an important role in the formation of the mineral deposit, particularly in the main and the east mine.     

Modeling transport of arsenic through modified granular natural siderite filters for arsenic removal

Groundwater arsenic(As)contamination is a hot issue,which is severe health concern worldwide.Recently,many Fe-based adsorbents have been used for As removal from solutions.Modified granular natural siderite(MGNS),a special hybrid Fe(II)/Fe(III)system,had higher adsorption capacity for As(III)than As(V),but the feasibility of its application in treating high-As groundwater is still unclear.In combination with transport modeling,laboratory column studies and field pilot tests were performed to reveal both mechanisms and factors controlling As removal by MGNS-filled filters.Results show that weakly acid pH and discontinuous treatment enhanced As(Ⅲ)removal,with a throughput of 8700 bed volumes(BV)of 1.0 mg/L As(Ⅲ)water at breakthrough of 10 μg/L As at pH 6.Influent HCO_3~-inhibited As removal by the filters.Iron mineral species,SEM and XRD patterns of As-loading MGNS show that the important process contributing to high As(Ⅲ)removal was the mineral transformation from siderite to goethite in the filter.The homogeneous surface diffusion modeling(HSDM)shows that competition between As(III)and HCO_3~-with adsorption sites on MGNS was negligible.The inhibition of HCO_3~-on As(Ⅲ)removal was connected to inhibition of siderite dissolution and mineral transformation.Arsenic loadings were lower in field pilot tests than those in the laboratory experiments,showing that high concentrations of coexisting anions(especially HCO_3~-and SiO_4~(4-)),high pH,low EBCT,and low groundwater temperature decreased As removal.It was suggested that acidification and aeration of highAs groundwater and discontinuous treatment would improve the MGNS filter performance of As removal from real high-As groundwater.