scholarly journals Petrogenesis, Ore Mineralogy, and Fluid Inclusion Studies of the Tagu Sn–W Deposit, Myeik, Southern Myanmar

Minerals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 654
Author(s):  
Kyaw Thu Htun ◽  
Kotaro Yonezu ◽  
Aung Zaw Myint ◽  
Thomas Tindell ◽  
Koichiro Watanabe

Most of the granite-related Sn–W deposits in Myanmar are located in the Western Granitoid Province (WGP) of Southeast Asia. The Tagu deposit in the southern part of the WGP is a granite related Sn–W deposit. The biotite granite is composed of quartz, feldspars (plagioclase, orthoclase, and microcline), and micas (muscovite and biotite) and belongs to S-type peraluminous granite. Abundances of large-ion lithophile elements (LILEs), such as Rb, K, and Pb, coupled with the deficiency of high-field-strength elements (HFSEs), such as Nb, P, and Ti, indicate that the parental magma for the Tagu granite was derived from the lower continental crust at syn-collisional setting. Mineralized veins consist of early-formed oxide ore minerals, such as cassiterite and wolframite, which were followed by the formation of sulfide minerals. Three main types of fluid inclusions were distinguished from the mineralized quartz veins hosted by granite and metasedimentary rocks: Type-A—two phases, liquid (L) + vapor (V) aqueous inclusions; Type-B—two phases, vapor (V) + liquid (L) vapor-rich inclusions; And type-C—three phases, liquid + CO2-liquid + CO2-vapor inclusions. Quartz in the veins hosted in granite corresponding with earlier deposition contains type-A, type-B, and type-C fluid inclusions, whereas that in the veins hosted in metasedimentary rocks corresponding with later deposition contains only type-A fluid inclusions. The homogenization temperatures of type-A inclusions range from 140 °C to 330 °C (mode at 230 °C), with corresponding salinities from 1.1 wt.% to 8.9 wt.% NaCl equivalent for quartz veins hosted in metasedimentary rocks, and from 230 °C to 370 °C (mode at 280 °C), with corresponding salinities from 2.9 wt.% to 10.6 wt.% NaCl equivalents for quartz veins hosted in granite. The homogenization temperatures of type-B vapor-rich inclusions in quartz veins in granite range from 310 °C to 390 °C (mode at 350 °C), with corresponding salinities from 6.7 wt.% to 12.2 wt.% NaCl equivalent. The homogenization temperatures of type-C H2O–CO2–NaCl inclusions vary from 270 °C to 405 °C (mode at 330 °C), with corresponding salinities from 1.8 wt.% to 5.6 wt.% NaCl equivalent. The original ascending ore fluid was probably CO2-bearing fluid which evolved into two phase fluid by immiscibility due to pressure drop in the mineralization channels. Furthermore, the temperature and salinities of two-phase aqueous fluids were later most likely decreased by the mixing with meteoric water. The salinities of the type-B vapor-rich inclusions are higher than those of the type-C CO2-rich inclusions, which may have resulted from CO2 separation from the fluids. The escape of gases can lead to an increase in the salinity of the residual fluids. Therefore, the main ore-forming mechanisms of the Tagu Sn–W deposit are characterized by fluid immiscibility during an early stage, and fluid mixing with meteoric water in the late stage at a lower temperature.

Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-21
Author(s):  
Xinglin Chen ◽  
Yongjun Shao ◽  
Chunkit Lai ◽  
Cheng Wang

The Longmendian Ag–Pb–Zn deposit is located in the southern margin of the North China Craton, and the mineralization occurs mainly in quartz veins, altered gneissic wallrocks, and minor fault breccias in the Taihua Group. Based on vein crosscutting relations, mineral assemblages, and paragenesis, the mineralization can be divided into three stages: (1) quartz–pyrite, (2) quartz–polymetallic sulfides, and (3) quartz–carbonate–polymetallic sulfides. Wallrock alteration can be divided into three zones, i.e., chlorite–sericite, quartz–carbonate–sericite, and silicate. Fluid inclusions in all Stage 1 to 3 quartz are dominated by vapor-liquid two-phase aqueous type (W-type). Petrographic and microthermometric analyses of the fluid inclusions indicate that the homogenization temperatures of Stages 1, 2, and 3 are 198–332°C, 132–260°C, and 97–166°C, with salinities of 4.0–13.3, 1.1–13.1, and 1.9–7.6 wt% NaCleqv, respectively. The vapor comprises primarily H2O, with some CO2, H2, CO, N2, and CH4. The liquid phase contains Ca2+, Na+, K+, SO42−, Cl−, and F−. The sulfides have δ34S=–1.42 to +2.35‰ and 208Pb/204Pb=37.771 to 38.795, 207Pb/204Pb=15.388 to 15.686, and 206Pb/204Pb=17.660 to 18.101. The H–C–O–S–Pb isotope compositions indicate that the ore-forming materials may have been derived from the Taihua Group and the granitic magma. The fluid boiling and cooling and mixing with meteoric water may have been critical for the Ag–Pb–Zn ore precipitation. Geological and geochemical characteristics of the Longmendian deposit indicate that the deposit is best classified as medium- to low-temperature intermediate-sulfidation (LS/IS) epithermal-type, related to Cretaceous crustal-extension-related granitic magmatism.


2021 ◽  
Vol 21 (4) ◽  
pp. 13-30
Author(s):  
Laécio Cunha de Souza ◽  
Regina Celia de Oliveira Brasil Delgado ◽  
Heitor Neves Maia

Micaschists that host the Acari batholith (Ediacaran age, 572 to 577 My) are characterized by a large number of quartz veins. The veins are more abundant in higher-temperature metamorphic zones and, together with lower metamorphic zones, form an aureole centered in the batholith. Most of the fluid inclusions are two-phase (H2O-CO2 and liquid/vapor), but three-phase varieties (liquid/vapor/salt cubes; liquid/liquid/vapor) occur locally. The analyzed veins come from the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite metamorphic zones. CO2 melting temperatures (TmCO2) vary from -62.6 to -56.7°C, suggesting CH4 and/or N2. Eutectic temperatures (Te) in quartz veins show average values of -30.8°C in the biotite + chlorite + muscovite and biotite + garnet zones, and -38.6°C in the cordierite + andalusite and cordierite + sillimanite zones. Ice-melting temperatures (Tmice) are lower in the higher-temperature metamorphic zones. The mode values are -3.8, -5.5, -5.6, and -7.3°C, corresponding respectively to the biotite + chlorite + muscovite, biotite + garnet, cordierite + andalusite, and cordierite + sillimanite zones. A fluid characterized by the H2O-Na-Cl (KCl)-MgCl2-FeCl2-CaCl2 system is defined by: Tmice from near -1.9 to -32°C, the presence of salt cubes mainly in the cordierite + andalusite and cordierite + sillimanite zones, and recorded eutectic temperatures (Te) from -16.5 to -59.1°C. In addition, total homogenization temperatures (Tht) ranging from 117 to 388°C were obtained for primary aqueous fluid inclusions. This indicates a long period of fluid circulation under conditions of falling temperatures. Our results are consistent with an increase in the salinity of the aqueous fluid across the thermal aureole toward the granitic batholith.


2017 ◽  
Vol 17 (3) ◽  
pp. 39-56 ◽  
Author(s):  
Sérgio Roberto Andrade Dantas ◽  
Fulvio Vittorino ◽  
Kai Loh

Abstract Contact of facades with degradation agents and direct incidence of ultraviolet radiation on external coatings make them more opaque over time, affecting their colour and reflectance characteristics. This study evaluated the effect of adding different TiO2 contents to mortars applied in concrete substrates in order to verify the reflectance maintenance on surfaces after exposure over time. Mortar with different concentrations of TiO2 (1%, 5%, 10%) were produced in relation to the total dry premix, added as a powder and compared to unpainted mortar without TiO2 (type "A") and painted mortar without TiO2 (type "B"), both used as a reference for colour and reflectance. Exposed over 16 months to climate conditions in São Paulo, regarding the maintenance of reflectance and solar radiation, the results showed that type "B" (0%TiO2) painted mortar presented the best performance. Type "C" (1%TiO2) and type "D" (5%TiO2) unpainted mortar remained more stable. Type "A" (0%TiO2) and type "E" (10%TiO2) unpainted mortar showed greater differences according to the Just Noticeable Difference (JND) range caused by dirt pick up.


1977 ◽  
Vol 42 (2) ◽  
pp. 199-209 ◽  
Author(s):  
Betty Z. Liles ◽  
Martin D. Shulman ◽  
Susan Bartlett

Fifteen linguistically normal children and 15 linguistically deviant children were presented with three types of agrammatical sentences. The subjects were asked to judge the sentences as right or wrong and to change the sentences judged as wrong, rendering them correct. The three types of agrammatical sentences represented rule violations of syntactic agreement (Type A), lexical restrictions (Type B), and word order (Type C). The two groups of children were compared in terms of the number of sentences of each type that were recognized as agrammatical. Those productions which represented the child’s correction of agrammatical sentences were subjected to descriptive analyses (percentages) with specific reference to the number of attempted changes and the number of those changes which demonstrated corrections of the specific deviation from well formedness. Results indicated that the two groups of subjects were significantly different in their ability to recognize grammatical errors in sentence Types A and C, but did not differ in their ability to recognize errors in sentence Type B. The descriptive comparison of the groups' verbal corrections reflected this trend, in that the language-disordered subjects made corrections specific to the error on more of the Type B sentences (for example, “The dog writes the food.”) than on Types A (for example, “'She will pick some flowers last week.”) or C (for example, “Get and come your dinner.”). Linguistically normal children accurately corrected 90.7% of the sentences judged as agrammatical; this percentage did not vary more than 1% across sentence types.


2018 ◽  
Vol 37 (1) ◽  
pp. 251-272 ◽  
Author(s):  
Junjian Zhang ◽  
Chongtao Wei ◽  
Gaoyuan Yan ◽  
Guanwen Lu

To better understand the structural characteristic of adsorption pores (pore diameter < 100 nm) of coal reservoirs around the coalbed methane production areas of western Yunnan and eastern Guizhou, we analyzed the structural and fractal characteristics of pore size range of 0.40–2.0 nm and 2–100 nm in middle–high rank coals ( Ro,max = 0.93–3.20%) by combining low-temperature N2/CO2 adsorption tests and surface/volume fractal theory. The results show that the coal reservoirs can be divided into three categories: type A ( Ro,max < 2.15%), type B (2.15% <  Ro,max <2.50%), and type C ( Ro,max > 2.15%). The structural parameters of pores in the range from 2 to 100 nm are influenced by the degree of coal metamorphism and the compositional parameters (e.g., ash and volatile matter). The dominant diameters of the specific surface areas are 10–50 nm, 2–50 nm, and 2–10 nm, respectively. The pores in the range from <2 nm provide the largest proportion of total specific surface area (97.22%–99.96%) of the coal reservoir, and the CO2-specific surface area and CO2-total pore volume relationships show a positive linear correlation. The metamorphic degree has a much greater control on the pores (pore diameter less than 2 nm) structural parameters than those of the pore diameter ranges from 2 to 100 nm. Dv1 and Dv2 can characterize the structure of 2–100 nm adsorption pores, and Dv1 (volume heterogeneity) has a positive correlation with the pore structural parameters such as N2-specific surface area and N2-total pore volume. This parameter can be used to characterize volume heterogeneity of 2–10 nm pores. Dv2 (surface heterogeneity) showed type A > type B > type C and was mainly affected by the metamorphism degree. Ds2 can be used to characterize the pore surface heterogeneity of micropores in the range of 0.62–1.50 nm. This parameter has a good correlation with the pore parameters (CO2-total pore volume, CO2-specific surface area, and average pore size) and is expressed as type C < type B < type A. In conclusion, the heterogeneity of the micropores is less than that of the meso- and macropores (2–100 nm). Dv1, Dv2, and Ds2 can be used as effective parameters to characterize the pore structure of adsorption pores. This result can provide a theoretical basis for studying the pore structure compatibility of coal reservoirs in the region.


Author(s):  
Yutaro Koike ◽  
Aritoshi Hattori ◽  
Takeshi Matsunaga ◽  
Kazuya Takamochi ◽  
Shiaki Oh ◽  
...  

AbstractOBJECTIVESSegmentectomy has become an increasingly popular surgical procedure for small-sized lung lesions. Left upper trisegmentectomy (LUTS) is one of the most common segmentectomies performed because of its relative ease and simplicity; however, limited information is currently available on the specific postoperative complications associated with this procedure.METHODSAmong 2060 surgically resected cases in our institute between 2009 and 2016, 129 (6.2%) underwent LUTS. Postoperative chest X-rays and/or thoracic computed tomography (CT) scans were retrospectively assessed for all cases to assess postsurgical residual lung complications following LUTS. We categorized cases into 4 groups: type A (atelectasis of the lingular segment), type B (lung torsion of the lingular segment), type C (necrosis of the ‘isolated segment’) and type D (haematoma along stapling lines).RESULTSPostsurgical lung complications following LUTS were observed in 17 (13.1%) patients (type A: n = 7, type B: n = 1, type C: n = 4 and type D: n = 5). Three patients (2.3%) required surgical intervention because of type B (n = 1) and type C (n = 2), namely, decreased permeability and remaining ground glass opacities in the residual lung, showing an exacerbated systemic inflammatory response. In contrast, type A and D cases were successfully observed by chest CT without any surgical intervention, and patients recovered within a few months of surgery.CONCLUSIONSWe identified several postoperative residual lung complications following LUTS. Lung torsion or necrosis of the residual segment may require intensive care, including reoperation. Potentially serious complications always need to be ruled out after LUTS when radiological consolidation is detected postoperatively.


2013 ◽  
Vol 295-298 ◽  
pp. 3162-3165
Author(s):  
Lu Lu Zhou ◽  
Zi Nan Li ◽  
Jun Gang Liu ◽  
Yan Yun Zhang ◽  
Guang Qiang Shu

Taking the example of the fourth member of the Lower Cretaceous Quantou formation reservoirs in fault block Sheng554 of Sanzhao sag, this article discusses the methodology of flow units in extra-low permeability reservoirs. The research on flow units in such reservoirs can be divided into two ranks, one is to determine the distribution of seepage barriers and inner connected sands, the other is to analyze the differentia of fluid flow in the inner connected sands so as to subdivide the flow units. The result shows that the pelitic barriers are rather developed in fault block Sheng554. Through the analysis of differentia of fluid flow, according to the value of flow zone index (FZI), the inner connected sands can be classified into three types of flow units, among which type A with FZI value greater than 1.0 has better permeable property and higher intensity of water injection, and the ability of permeability and water injection of type B with FZI value between 0.5 and 1.0 takes the second place, and type C is the worst flow unit with the worst permeable property and intensity of water injection with FZI value less than 0.5. Among the three types of flow units, type A poorly develops, while type B and type C develops well. The research on flow units can provide reliable geologic bases for forecasting the distribution of remaining oil in extra-low permeability reservoirs and for developing remaining oil in the study area.


2015 ◽  
Vol 20 (2) ◽  
pp. 90-101 ◽  
Author(s):  
Sung-Wook Jeong ◽  
Lee-Suk Kim

Objectives: The aims of this study were to introduce a new classification of cochleovestibular malformation (CVM) and to investigate how well this classification can predict speech perception ability after cochlear implantation in children with CVM. Methods: Fifty-nine children with CVM who had used a cochlear implant for more than 3 years were included. CVM was classified into 4 subtypes based on the morphology of the cochlea and the modiolus on temporal bone computed tomography (TBCT): normal cochlea and normal modiolus (type A, n = 16), malformed cochlea and partial modiolus (type B, n = 31), malformed cochlea and no modiolus (type C, n = 6), and no cochlea and no modiolus (type D, n = 6). Speech perception test scores were compared between the subtypes of CVM using analysis of covariance with post hoc Bonferroni test. Univariate and multivariate regression analyses were used to identify the significant predictors of the speech perception test scores. Results: The speech perception test scores after implantation were significantly better in children with CVM type A or type B than in children with CVM type C or type D. The test scores did not differ significantly between the implanted children with CVM type A or type B and those without CVM. In univariate regression analysis, the type of CVM was a significant predictor of the speech perception test scores in implanted children with CVM. Multivariate regression analysis revealed that the age at cochlear implantation, cochlear nerve size and preimplantation speech perception test scores were significant predictors of the postimplantation speech perception test scores. The chance of cochlear nerve deficiency increased progressively from CVM type A to type D. Conclusion: The new classification of CVM based on the morphology of the cochlea and the modiolus is simple and easy to use, and correlated well with postimplantation speech perception ability and cochlear nerve status. This simple classification of CVM using TBCT with cochlear nerve assessment by magnetic resonance imaging is helpful in the preoperative evaluation of children with CVM.


1961 ◽  
Vol 39 (2) ◽  
pp. 297-306 ◽  
Author(s):  
E. W. B. Ward ◽  
J. B. Lebeau ◽  
M. W. Cormack

Isolates of an unidentified low-temperature basidiomycete, associated with snow mold in Western Canada, were divided into three types, A, B, and C, on the basis of their general cultural appearance. Support for this classification was obtained when representative isolates of each type were examined to determine: the effect of temperature and pH on growth; tolerance of antibiotics and HCN; ability to liberate HCN in culture and in the host plant; pathogenicity.Type A isolates grew slowly under most conditions and were least tolerant of the extremes of temperature and pH employed, moderately inhibited by antibiotics, and strongly inhibited by HCN. They produced HCN in large quantities in host plants and none in culture. They were moderately pathogenic on grass and highly pathogenic on alfalfa. Type B isolates grew somewhat more rapidly than type A, especially at the upper and lower temperatures, and grew over a wider pH range. These isolates were more tolerant of antibiotics and HCN. They produced smaller quantities of HCN than type A in infected alfalfa plants but released large amounts in culture. They were less pathogenic than type A on alfalfa but similarly pathogenic on grass. Type C isolates were fast-growing forms which were strongly inhibited by antibiotics and HCN. They did not liberate HCN under any conditions and were not pathogenic.


2017 ◽  
Vol 748 ◽  
pp. 29-34 ◽  
Author(s):  
Jing Zhu ◽  
Xiu Ying Zhao ◽  
Meng Song ◽  
Yue Han ◽  
Li Liu ◽  
...  

This work was try to study the number and types of hydrogen bonds (H-bonds) formed in hindered phenol AO-70/nitrile butadiene rubber (NBR) composites and their contributions to the damping properties by molecular dynamic (MD) simulation and experimental methods. MD simulation results showed that there were four types of H-bonds, namely, type A (AO-70) –OH...NC– (NBR) H-bonds in AO-70/NBR composites, type B (AO-70) –OH...O=C– (AO-70) H-bonds, type C (AO-70) –OH...OH–(AO-70) and D (AO-70) –OH...O–C– (AO-70) H-bonds, what's more, type A and type B H-Bonds formed more easily than others. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of H-bonds. Meanwhile, the AO-70/NBR composites with AO-70 content of 109 phr had the largest number of H-bonds, smallest fractional free volume (FFV) and resulting in the optimistic damping performance of the composites.


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