Southwest Guizhou Province Research Articles

Geochemical Evidence of Ore-Forming Processes in the Shuiyindong Gold Deposit of Southwest Guizhou Province, China.

The Shuiyindong deposit is one of the ultralarge Carlin-type gold deposits in Southwest Guizhou Province, China. Gold mineralization mainly occurs in the Permian Longtan Formation and the early Triassic Yelang Formation. It is controlled by both strata and faults. Detailed studies of the mineralogy and geochemistry characteristics of the Shuiyindong deposit are conducted to investigate the ore-forming process. Arsenian pyrite and arsenopyrite are the main Au-hosting minerals. Three types of pyrite can be recognized, including euhedral and subhedral pyrite, framboidal pyrite, and bioclastic pyrite. The euhedral and subhedral pyrite is the main Au-hosting type. The Au appears as a solid solution (Au+) and natural nanoscale gold (Au0) in the sulfide minerals. The Co/Ni ratios of sulfides (0.07-3.13) reveal that the ore-forming fluids were mainly affected by hydrothermal activity, but magmatic activity cannot be excluded. Organic matter in the ores is abundant (0.11-3.04%), which might provide sulfur for pyrite and favor an increase in the porosity and permeability of the host rocks by releasing organic acids. The REE and trace element results suggest that halogens (F and Cl) were contained in the reducing magmatic hydrothermal fluids. The sulfur isotopic data (from -8.64‰ to 27.17‰) suggest that the source of sulfur is complicated and is probably a combination of a magmatic source, the reduction of marine sulfate, and bacterial sulfate reduction. The Pb isotopic data of the sulfides indicate that Pb is from a mixture of crust and mantle sources. The obvious enrichment zones exist along the boundary faults in the geochemical map of As, implying that As may originate from the deep crust and then move to the strata with basinal fluids. By combining these results, it can be inferred that the ore-forming fluids were a mixture of basinal and deep source fluids. A probable ore-forming model of the Shuiyindong gold deposit is established.

Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou Province, China: mineralogical and geochemical evidence from sulfur-bearing minerals

Metallogenesis of the Baidi Au-Sb deposit, southwest Guizhou Province, China: mineralogical and geochemical evidence from sulfur-bearing minerals

Investigation on pollution sources of a Karst Underground River in southwest Guizhou

by means of karst hydrogeology investigation, pollution source investigation, water pollution status investigation, water quality sampling and detection, The water pollution of large karst underground river in Muerdong of southwest Guizhou Province was investigated and demonstrated. The analysis shows that:(1) the catchment area of groundwater unit in Muerdong-qingping River is about 270 km2, and there are many karst pipelines in the area, and finally discharge at the exit of the underground river at the lowest discharge datum level in the area. (2)there are mainly four replenishment subsystems in the underground river, it is found that the karst water system of Dajiang and Tanping river is finally discharged through the Q4, Q5 and Q6 karst springs or the underground river of Muerdong River, and neither the spring water nor the underground river is polluted, the outcrops of Yangjiaba Karst water system and Bayan karst water system in Muerdong underground river are Q1, Q2 And K35. The spring water and groundwater in the cave are polluted (3) the main pollution of the underground river of Muerdong is from the excrement of livestock and poultry in DK farm in the karst water system of yangjiaba, which is discharged into the underground pipeline of the underground karst river through the falling water cave. The water source area of Muerdong underground river is located in the strong karst area, the geological environment is fragile, and the suitability of developing large-scale aquaculture industry is poor. The government needs to enhance the understanding and use for reference in attracting investment.

Secondary Sulfate Minerals from Pyrite Oxidation in Lanmuchang Hg-Tl Deposit, Southwest Guizhou Province, China: Geochemistry and Environmental Significance

Thallium (Tl) is a highly toxic trace metal posing a significant threat to human health. Tl pollution in soils and chronic Tl poisoning related to Tl-rich sulfides weathering in the Lanmuchang mine of southwest Guizhou province, China, have been intensively studied in recent years. And yet, there are few studies on the role of secondary sulfate minerals associated with Tl mobility in this area. The sulfate minerals were characterized by XRD and SEM-EDS. The concentrations of Tl and other elements were determined by ICP-MS. The results show that sulfate minerals are predominantly melanterite, halotrichite, and fibroferrite. The average contents of Tl in rock, sulfate minerals, and soil samples were 156.4, 0.11, and 72.1µg g-1, respectively. This study suggests that Tl in the mineralized rocks entered soils by pyrite oxidation with less scavenged of the sulfate minerals. The dissolution of the ferric sulfate minerals accelerates pyrite oxidation and maintains soil acidity, and this likely enhances Tl mobility from soil to crops.

Study on the allocation of soil and water conservation measures for photovoltaic power station in rocky desertification mountainous area of Guizhou province

Stony desertification is widespread and, and the ecology is very fragile in the southwest Guizhou province. The careless and unreasonable water and soil conservation measures have caused serious water and soil loss and serious damage to the ecological environment. This paper takes a photovoltaic project in this area as an example to study soil and water conservation measures. Based on the author’s practical experience, a scientific and reasonable arrangement system of soil and water conservation measures and preventive management measures are proposed, which can not only provide reference for the prevention and treatment of soil and water conservation of similar projects, but also can be used to guide the main design and site construction, which has a strong guiding significance.

Magmatic Origin for Sediment-Hosted Au Deposits, Guizhou Province, China: In Situ Chemistry and Sulfur Isotope Composition of Pyrites, Shuiyindong and Jinfeng Deposits

Abstract The southwest Guizhou Province, China, contains numerous sediment-hosted Au deposits with Au reserves greater than 700 tonnes. To date, the source of ore fluids that formed the Guizhou sediment-hosted Au deposits is controversial, hampering the formulation of genetic models. In this study, we selected the Shuiyindong and Jinfeng Au deposits, the largest strata-bound and fault-controlled deposits in Guizhou, respectively, for detailed research on pyrite chemistry and S isotope composition using laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICP-MS), respectively. Petrography and pyrite chemistry studies distinguished five generations of pyrite. Among these, pre-ore pyrite 2 and ore pyrite are the most abundant types in the deposits. Pre-ore pyrite 2 is anhedral to euhedral and with ~2,639 ppm As and wider ranges of Cu, Sb, and Pb (<~22–4,837 ppm, <~6 to 532 ppm, and <~4 to 1,344 ppm, respectively). Gold in pre-ore pyrite 2 is below the detection limit of LA-ICP-MS (~2 ppm). Pre-ore pyrite 2 is interpreted to have a sedimentary (syngenetic or diagenetic) origin. Ore pyrite commonly rims the four identified pre-ore pyrites or occurs as individual, anhedral to euhedral crystals. Ore pyrite is enriched in Au (~641 ppm), As (~9,147 ppm), Cu (~1,043 ppm), Sb (~188 ppm), Hg (~43 ppm), and Tl (~22 ppm) in both deposits. Ore pyrite formed mainly by sulfidation of Fe in Fe-bearing host rocks, mainly Fe dolomite, and As, Cu, Sb, Hg, and Tl, also in ore fluids, were incorporated into ore pyrite. In situ δ34S isotope ratios for pre-ore pyrite 2 and ore pyrite were measured by LA-MC-ICP-MS. Pre-ore pyrite 2 from Shuiyindong and Jinfeng deposits resulted in δ34S values ranging from −0.8 to +3.4‰ and from 5.1 to 10.5‰, respectively. Analyses of ore pyrite from the Shuiyindong have δ34S values that vary from −3.3 to +2.5‰, with a median of 0.7‰; analyses of ore pyrite from the Jinfeng range from 8.9 to 11.2‰, with a median at 10.3‰. Available bulk and in situ δ34S data in the literature for pre-ore pyrites 1 and 2 and ore-related sulfide minerals including ore pyrite, arsenopyrite, and late ore-stage stibnite, realgar, orpiment, and cinnabar from several Guizhou sediment-hosted Au deposits were compiled for comparison. Pre-ore-stage pyrites from Guizhou sediment-hosted Au deposits have a broad range of δ34S values, from −33.8 to + 17.9‰ (including in situ and available bulk δ34S data). Ore-related sulfide minerals in all Guizhou sediment-hosted Au deposits, except Jinfeng, have very similar δ34S values, and most data plot between ~−5 and +5‰. In the Jinfeng deposit, the ore-related sulfide minerals exhibit δ34S values ranging from 1.9 to 18.1‰, with most data plotting between 6 and 12‰. The broad range of S isotope compositions for the sedimentary pyrites (pre-ore pyrites 1 and 2) indicate that S in these pre-ore pyrites was most likely generated by bacterial reduction from marine sulfate. The narrow range of δ34S values (~−5–+5‰) for ore-related sulfide minerals in all Guizhou sediment-hosted Au deposits, excepting the Jinfeng deposit, suggests that the deposits may have formed in response to a single widespread metallogenic event. As the S isotope fractionation between hydrothermal fluids and sulfide minerals in a sulfide-dominated system is small (<2‰) at ~250°C, the initial ore fluids that formed the Guizhou sediment-hosted Au deposits would have had δ34S values similar to the ore-related sulfide minerals, between ~−5 and +5‰. At Jinfeng, initial ore fluids may have mixed with local fluids with heavier δ34S, possibly basin brine (δ34Sbasin brine >18‰), resulting in elevated δ34S values of ore-related sulfide minerals and especially late ore-stage sulfide minerals. Although few igneous rocks are exposed in the mining area around these deposits, there is evidence of magmatic activity ~20 km away. Furthermore, gravity and magnetic geophysical investigations indicate the presence of a pluton ~5 km below the surface of the Shuiyindong district. Based on in situ S isotope results and recent data indicating proximal intrusions, we interpret a deep magmatic S source for the ore fluids that formed the Guizhou sediment-hosted Au deposits. However, as the age for Au mineralization of Guizhou sediment-hosted Au deposits is still debated, the mineralization-magma connection remains hypothetical. Identifying an ore fluid source and time frame for Guizhou Au mineralization continues to be a critically important research goal for this district.

The analysis for mitochondrial genome sequencing of Triplophysa lewanggensis

Triplophysa lewanggensis revealed that the complete length of its mitochondrial genome was 16,568 bp, composed of A (31.7%), T (27.1%), G (15.9%), C (25.4%), and A + T (58.8%). Its genetic constitution and arrangement were consistent with other Triplophysa, including 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 1 control area (D-loop). All genes were encoded by the H-strand, except for one protein-coding gene (ND6) and eight tRNA genes (tRNAGln, tRNAAla, tRNACys, tRNAAsn, tRNATyr, tRNASer(UCN), tRNAGlu, tRNAPro) are encoded by the L chain, and the remaining genes are encoded by the H chain. The phylogenetic tree was divided into two main clades: one just including Triplophysa and the other including Oreonectes, Homatula, Schistura, Nemacheilus, Traccatichthys. T. lewanggensis is distributed in Southwest Guizhou Province attached to Yunnan–Guizhou Plateau, T. xiangxiensis is distributed in Hunan Province, they are near relatives, but their kinship with Triplophysa distributed in Tibetan Plateau is farther.

The Nature of Ore‐forming Fluids of the Carlin‐type Gold Deposit in Southwest China: A Case from the Zimudang Gold Deposit

AbstractThe Zimudang gold deposit is a large Carlin‐type gold deposit in the Southwest Guizhou Province, China, with an average Au content of 6.2 g/t. Gold is mainly hosted in the fault zone and surrounding strata of the F1 fault and Permian Longtan Formation, and the ore bodies are strictly controlled by both the faults and strata. Detailed mineralogy and geochemistry studies are conducted to help judge the nature of ore‐forming fluids. The results indicate that the Au is generally rich in the sulfides of both ores and wall rocks in the deposit, and the arsenian pyrite and arsenopyrite are the main gold‐bearing sulfides. Four subtypes of arsenian pyrite are found in the deposit, including the euhedral and subhedral pyrite, framboidal pyrite, pyrite aggregates and pyrite veins. The euhedral and subhedral pyrite, which can take up about 80% of total pyrite grains, is the dominant type. Au distributed unevenly in the euhedral and subhedral pyrite, and the content of the Au in the rim is relatively higher than in the core. Au in the pyrite veins and pyrite aggregates is lower than the euhedral and subhedral pyrite. No Au has been detected in the points of framboidal pyrites in this study. An obvious highly enriched As rim exists in the X‐ray images of euhedral pyrites, implying the ore‐forming fluids may be rich in As. The relationship between Au and As reveals that the Au may host as a solid solution (Au+) and nanoparticles of native gold (Au0) in the sulfides. The high Co/Ni ratio (>1) of sulfides and the enrichment of W in the ores all reflect that the gold‐bearing minerals and ore‐forming process were mainly related to the hydrothermal fluids, but the magmatic and volcanic activities cannot be neglected. The general existence of Au and As in the sulfides of both ores and wall rocks and the REE results suggest that the ore‐forming fluids may mainly be derived from the basin itself. The enrichment of Tl suggests that the ore‐forming fluids may be enriched in Cl. The Ce and Eu show slightly or apparently negative anomalies, which means the ore fluids were probably formed under reducing environment. The Y/Ho ratios of ore samples fluctuate around 28, implying the bicarbonate complexation and fluorine were both involved in the ore‐forming process. Combined with the previous studies and our results, we infer that the ore‐forming fluids enriched Au, As, HS− and halogen (F, Cl) were derived from the mixture of reducing basinal fluids and magmatic or volcanic hydrothermal fluids.

A new type of micro-disseminated gold deposits in association with diabase found in Yunnan and Guizhou provinces and Guangxi Zhuang Autonomous Region—Their geological characteristics and metallogenic conditions

With the continuous development of gold ore prospecting and exploration in recent years a new type of micro-disseminated gold deposits have been found in the regions of Southwest Guizhou Province and Northwest Guangxi Zhuang Autonomous Region, with the orebodies directly occurring in diabase or in the contact zone between diabase and strata. The orebodies are strictly controlled by fault structures. The discovery of this type of gold deposits has brought about new prospects for gold ore prospecting in the Yunnan-Guizhou-Guangxi Golden Triangle region. From the preliminary analysis of the geological characteristics of the Qiaoxiang gold deposit in Wangmo County, in combination with the results of research work in the adjacent areas in recent years, this paper roughly described the geological characteristics and metallogenic conditions of this type of gold ore deposits with an attempt to make more and more geologists pay enough attention to this type of gold ore deposits, so as to promote gold ore prospecting in Guizhou Province to develop toward a variety of types of gold deposits in all round way.

The volatilization of trace elements during oxidative pyrolysis of a coal from an endemic arsenosis area in southwest Guizhou, China

Household coal combustion has caused endemic poisoning in southwest Guizhou Province of China. The mineralogy, geochemistry and mode of occurrence of trace elements (TEs) of coal from this area were examined, and oxidative pyrolysis experiments of the coal were conducted in a box resistance reactor at 300–1200°C to evaluate the volatilization of trace elements. In coal, As, Sb, Pb, Zn, W, Mo, and Cr are highly enriched when compared to both the world coal and Chinese coal. Cadmium, Sr, and Ba are all slightly higher than the average value for Chinese coal. The volatility of trace elements exhibits a close correlation with the mode of element occurrence. The considerable volatilization of As, Sb, Pb, Zn, Cd and Cr below 450°C is thought to be related to the organic form of these elements. In the temperature range of 450–1200°C, the volatility of all trace elements except As increases slowly with temperature because these elements are highly associated with silicates. Among the hazardous trace elements, As is the most volatile, and Sb, Pb, Zn, Cd and Cr are moderately volatile. Arsenic exhibits a uniquely high release at 900–1000°C, which could be attributed to the high proportion of As association with sulfide. Because TEs are primarily inorganically-associated, the volatilization of TEs is not comparable to the loss of coal weight during pyrolysis. At high temperatures, a significantly low coal weight loss can result in a significant volatility of TEs.

The Value of the Miao People's Traditional Ecological Knowledge for a Solution to Rocky Desertification in Mashan

There are many branches of the Miao people in China, one of which is the Mashan Miao, who have been living in karst mountainous areas in southwest Guizhou Province. The Mashan Miao have adopted various measures for the conservation and effective utilization of the local ecological system and have made great achievements in this area. From the 1950s, their social environment has changed a lot due to political and economic movements. The rocky desertification in the Mashan area has gradually expanded. After the 1990s, relief work was carried out to address the desertification problem, but it was not very effective. We have been doing fieldwork in this area for more than 20 years and from our fieldwork records, we have found that the local Miao people have traditional ecological knowledge and skills that are of irreplaceable valuable for finding a solution for rocky desertification. Using the Miao knowledge we think a feasible way to control this disaster can be found.

Geochronological and geochemical constraints on the petrogenesis of alkaline ultramafic dykes from southwest Guizhou Province, SW China

Geochronological, geochemical and whole-rock Sr–Nd isotopic analyses have been completed on a suite of alkaline ultramafic dykes from southwest (SW) Guizhou Province, China with the aim of characterising their petrogenesis. The Baiceng ultramafic dykes have a LA-ICP-MS zircon 206Pb/ 238U age of 88.1 ± 1.1 Ma ( n = 8), whereas two phlogopites studied by 40Ar/ 39Ar dating methods give emplacement ages of 85.25 ± 0.57 Ma and 87.51 ± 0.45 Ma for ultramafic dykes from Yinhe and Lurong, respectively. In terms of composition, these Late Mesozoic ultramafic dykes belong to the alkaline magma series due to their high K 2O (3.31–5.04 wt.%) contents. The dykes are characterised by enrichment of light rare earth element (LREE) and large-ion lithosphile elements (LILEs) (Rb and Ba), negative anomalies in high field strength elements (HFSEs), such as, Nb, Ta and Ti relative to primitive mantle, low initial 87Sr/ 86Sr ratios (0.7060–0.7063) and positive ε Nd( t) values (0.3–0.4). Such features suggest derivation from low degree (< 1%) partial melting of depleted asthenospheric mantle (garnet-lherzolite), and contamination to various degrees (∼ 10%) by interaction with upper crustal materials.

Clinic analysis in 291 cases of penetrating injuries on eyeball of children in southwest Guizhou province

目的 探讨贵州省黔西南州少数民族地区儿童眼球穿孔伤临床特点,分析眼球穿孔伤的原因.方法 对我科15年间291例(318眼)2～14岁儿童眼球穿孔伤进行回顾性分析.结果 儿童眼球穿孔伤发生的年龄段主要集中在5～10岁,平均年龄6.8岁.农村儿童较多,男性多于女性,损伤重.绝大部分均须手术治疗.术后盲74眼占(26.06%)及低视力140眼(49.30%).二者共占75.36%之多.结论 儿童眼球穿孔伤大多伤势严重,没有及时到医院就诊,治疗结果较差.故必须加强宣传教育并且提高基层医院眼科医生眼外伤的认识和诊疗技术水平,才能提高儿童眼球穿孔伤的诊治水平。

Arsenic content and distribution pattern in Chinese coals

About 500 samples of coal, pyritic coal balls, pyritic gangue and coal seam gangue were collected from different coal basins and geologic periods of coal formation to determine the arsenic (As) content and distribution pattern in China. The Permian-Carboniferous and Jurassic coals in the North China Plate and Northwest China account for nearly 85% of total Chinese coal reserves and data showed that As content ranged from 0.1 to 94 mg kg−1, with the majority between 1 and 14.9 mg kg−1. The As content of some Late Permian coals in Southwest Guizhou Province and stone coal in the South Qinling Mountain area were exceedingly high (30–534 mg kg−1), but the majority of coal in the Southwest Guizhou Province contained low to medium amounts. Only the coals, which are situated in or near igneous rocks and are not considered a part of Chinese coal reserves, possessed unusually high As content (>30 mg kg−1). Arsenic was also concentrated in pyritic coal balls and the pyritic gangue of the coal seam with values ranging from 21.5 to 142.46 mg kg−1 and an average of 69 mg kg−1 in Shaanxi and 78 mg kg−1 in Shandong. Arsenic contents in coal gangue in the Northwest and North China Plate is about 0.2–15 mg kg−1, a little lower than coals in the same seam. Washing gangue (waste from coal washing) generally contained more As than coal, because the washed gangue has more pyrite than the natural gangue (black shale). Washing coal reduced the content of the pyritic sulfur, heavy metals and As. Based on amounts of coal used with different As content in Chinese coal reserves, the average As content of Chinese coals is about 4.5 mg kg−1.

Endemic Arsenosis Caused by Indoor Combustion of High-As Coal in Guizhou Province, P.R. China

The arsenic (As) content of coal relating with mineralization of gold in Southwest Guizhou Province, China is up to 35,000 ppm. The coal is burned indoors in open pits for daily cooking and crop drying. As a result, arsenic is precipitated and concentrated in corn (5-20 ppm), chili (100-800 ppm) and other foods. Arsenic concentrations in the drinking water of high-As coal areas are lower than 50 ppb. The estimated main sources of As exposure in this area are from polluted food. Approximately, 3000 arsenosis patients were found by 1998, and more than 100,000 people from six counties were under the threat in China. This paper presents the major ingestion pathway of this type arsenosis and relative geochemistry of high-As coal.

HFSE, REE, and PGE geochemistry of three sedimentary rock-hosted disseminated gold deposits in southwestern Guizhou Province, China

The sedimentary rock-hosted disseminated gold (SRHDG) deposits in southwest Guizhou Province, China, are located near the buried edge of the Yangtze Craton. Three deposits, Lannigou, Getang and Zimudang, were chosen for this study. The deposits are hosted by fine-grained clastic and calcareous sedimentary rocks and formed at low temperatures from low salinity solutions of low to intermediate pH and low f O2 . Chemical analyses of the ores and host rocks show that high field strength elements, such as Nb, Ta, Zr and Hf, were immobile during hydrothermal alteration. However, rare earth elements (REE) were mobile. Light rare earth elements (LREE) were depleted, whereas heavy rare earth elements (HREE) were enriched. A differentiation of platinum group elements (PGE) concentrations was documented. The ores are enriched in Pd and Pt, consistent with the higher solubility of these two elements in ore fluids. The Pd/Ir ratios of the ores are lower than those of the ultramafic rocks and the Emeishan basalts in the region. Thus, the ultramafic intrusives and basalts could not have been the main source of the PGEs and gold in the SRHDG deposits. Rather, these metals were derived mainly from the sedimentary host rocks as evidenced by the trace element and stable isotopic characteristics of the ores. Our data suggest that the SRHDG deposits in southwest Guizhou are most likely of amagmatic origin, which is consistent with the lack of igneous intrusives in the vicinity of the deposits, the very weak metamorphic grade of the rocks, the lack of metamorphic effects within the time range of the SRHDG deposits, and coincidence in time of gold mineralization with regional extension.

Groundwater-related thallium transfer processes and their impacts on the ecosystem: southwest Guizhou Province, China

The small karstic watershed of Lanmuchang, in a Hg–Tl mineralized area in SW Guizhou Province, China, exhibits an enrichment of toxic Tl in groundwater and related stream water. This affords an excellent demonstration of the natural processes of Tl dispersion, and the resultant impact on the local ecosystem. The distribution of Tl in the water system follows a decreasing concentration pattern from deep groundwater to stream water to shallow groundwater. Tl shows high levels (13–1100 μg/L) in deep groundwater within the Tl-mineralized area, decreasing with distance away from the mineralized area to background levels (0.005 μg/L). The distribution of Tl in the water system is constrained by Tl mineralization, water–rock interactions and hydrogeological conditions. Tl concentrations in waters generally correlate with concentrations of total dissolved solids, sulphate, Ca and pH values, suggesting the contribution of water-rock interactions to water geochemistry. Water–rock interactions are driven by weathering of Tl-bearing sulfides which decreases pH values in groundwater, and by dissolution of limestone enhanced by acid fluids. Tl in stream water in both the base-flow and flood-flow regimes shows higher concentrations than it does in shallow groundwater that serves as the stream's source (mainly springs, dug-well flows and karstic cave waters). Concentrations of Tl in stream water in the flood-flow regime are generally lower than in the base-flow regime due to dilution effects, but those in the waters of mid-stream are almost the same as in the base-flow regime, probably due to contribution from Tl-rich soil water seepage or from acid mine drainage (AMD). Unexpectedly, Tl concentrations in stream water in both regimes are remarkably higher (2–30 fold) downstream than up- and mid-stream. These pronounced increases of Tl concentration are likely caused by unidentified discharges of deep groundwater through fractured zones to the downstream trace. The groundwater-related Tl transfer processes affect the ecosystem through contamination of water supply and arable soil and ultimately the food chain with undoubted risks to human health. Therefore, the results of this study are important for environmental planning and regulations, and will also serve as baseline data for future research on Tl natural dispersion processes.

Geological and geochemical characteristics of high arsenic coals from endemic arsenosis areas in southwestern Guizhou Province, China

Southwest Guizhou Province is one of the most important areas of disseminated, sediment-hosted-type Au deposits in China and is an important area of coal production. The chemistry of most of the coals in SW Guizhou is similar to those in other parts of China. Their As content is near the Chinese coal average, but some local, small coal mines contain high As coals. The highest As content is up to 3.5 wt.% in the coal. The use of high As coals has caused in excess of 3000 cases of As poisoning in several villages. The high As coals are in the Longtan formation, which is an alternating marine facies and terrestrial facies. The coals are distributed on both sides of faults that parallel the regional anticlinal axis. The As content of coal is higher closer to the fault plane. The As content of coal changes greatly in different coal beds and different locations of the same bed. Geological structures such as anticlines, faults and sedimentary strata control the distribution of high As coals. Small Au deposits as well as Sb, Hg, and Th mineralization, are found near the high As coals. Although some As-bearing minerals such as pyrite, arsenopyrite, realgar (?), As-bearing sulfate, As-bearing clays, and phosphate are found in the high As coals, their contents cannot account for the abundance of As in some coals. Analysis of the coal indicates that As mainly exists in the form of As5+ and As3+, perhaps, combined with organic compounds. The occurrence of such exceptionally high As contents in coal and the fact that the As is dominantly organically associated are unique observations.

Preliminary study on the mode of occurrence of arsenic in high arsenic coals from southwest Guizhou Province

Coal samples from high arsenic coal areas have been analyzed by electron micropbe analyzer (EMPA), scanning electron microscopy with an energy dispersive X-ray analyzer (SEM-EDX), X-ray diffinction analysis (XRD), low temperature ashing (LTA), transmission electron microscopy (TEM), X-ray absorption fine structure (XAFS), instnunent neutron activation analysis (INAA) and wet chemical analysis. Although some As-bearing minerals such as pyrite, arsenopyrite, realgar (?), As-bearing sulfate, and As-bearing clays are found in the high arsenic coals, their contents do not account for the abundance of arsenic in the some coals. Analysis of the coal indicates that arsenic exists mainly in the form of As 5+ and As 3+, combined with compounds in the organic matrix. The occurrence of such exceptionally high arsenic contents in coal and the fact that the arsenic is dominantly organically associated are unique observations. The modes of occurrence of arsenic in high As-coals are discussed.

China Hopes to Move FAST on Largest Telescope

RADIO ASTRONOMYBEIJING-- China has embarked on a project to build the world's largest radio telescope, a spherical dish 500 meters in diameter, in southwest Guizhou Province--a terrain of hundreds of round depressions, each surrounded by hills a few hundred meters high. The facility could make China a major player in the field. But Chinese scientists are hoping for even more: They see the telescope as the forerunner of a billion-dollar, internationally funded radio array that would probe the very earliest stages of the universe.