Southwestern Guizhou Province Research Articles

Research progress in metallogenic rules of antimony ores in western guizhou province

The research progress in metallogenic rules of antimony ores is analyzed based on previous materials. It is found that basic properties of antimony ores in southwestern Guizhou Province have been clearly explored, whereas their provenances and metallogenic epoch are still controversial. Content such as ore-forming processes and properties of ore-forming fluids remain to be further studied.

Analysis on metallogenic mechanism of gold ores in western guizhou province

The metallogenic mechanism of gold ores in western Guizhou Province is analysed based on previous research data. These ores have been deeply explored in previous studies, which have suggested that Emeishan Basalt and source beds arising from the basalt eruption are major provenances of gold ores in south-western Guizhou Province. The source beds form under the impacts of paleogeography of land-ocean transitional facies/lithofacies, ores with special structures and hydrothermal sedimentation. The substances exposed on the surface of the earth are enriched on quaternary red earth after weathering. The times and time of cyclic hydrothermal alteration need to be further examined.

Geological Features of Gold Ores in Western Guizhou Province

Geological features of gold ores in southwestern Guizhou Province are summarized according to previous studies. It is discovered that the gold ores of the area have been studied so intensively that ores, ore bodies and geochemical properties have been ascertained. Carlin-type gold ore bodies have similar features. Combination of elements which are closely associated with gold and isotope anomalies may be used as prospecting indicators, whereas integrated exploration technologies of remote sensing, prospecting and chemical prospecting remain to be strengthened.

Research Progress in Metallogenic Rules of Gold Ores in Southwestern Guizhou Province

After a comprehensive analysis of previous studies, it is known that features, distribution laws, geochemical characteristics and provenances of ores in gold mines of southwestern Guizhou Province have been studied relatively thoroughly, whereas metallogenic epoch and metallogenic paleogeography remain to be further studied deeply.

Multistage pyrite in the Getang sediment-hosted disseminated gold deposit, southwestern Guizhou Province, China: Insights from textures and in situ chemical and sulfur isotopic analyses

Getang is a representative sediment-hosted disseminated gold (SHDG) deposit in the southwestern Guizhou Province, China. The majority of gold is present as structurally bound Au+ in pyrite, with a minor amount occurring as nanoparticles (Au0). Four generations of pyrite (Py0, Py1, Py2, and Py3) were distinguished based on morphology and paragenesis. Electron microprobe (EMP), laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and laser-ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) analyses were conducted to determine the chemical and sulfur isotopic composition of the pyrite.The pre-ore diagenetic pyrite (Py0) has a framboidal texture and is characterized by relatively high concentrations of As, Co, Ni, Cu, Zn, Pb, and Mo. It has negative δ34S values of −38.4 to −4.0‰, indicating the derivation of sulfur by bacterial reduction of marine sulfate during sedimentation and diagenesis. The early ore stage pyrite (Py1) coexists with arsenopyrite as subhedral-anhedral grains, and contains high concentrations of As, Ni, Cu, and Zn, with large variation in Co and Pb content. It has positive δ34S values of +3.8 to +17.7‰, which are interpreted to be complete thermochemical reduction of marine sulfate. The intermediate ore stage pyrite (Py2) is disseminated in the host rocks, and occurs as overgrowths on Py0 and Py1. It is enriched in Au and Ag but depleted in As, Co, Ni, Cu, and Bi. The late ore stage pyrite (Py3) occurs as acicular to columnar aggregates, and is intergrown with calcite. It contains high concentrations of As and low concentrations of Pb, Mo, and Bi. Py2 and Py3 display a comparable narrow range of δ34S values from +1.9 to +8.4‰, which are interpreted to result from a magmatic source.All the stable isotope data together with the gravity and magnetic evidences suggests that sulfur, gold, and the mineralizing fluids in the Getang deposit were probably originated from deep magmatic hydrothermal systems. The absence of igneous intrusions in southwestern Guizhou may be attributed to the relatively shallow denudation depth in this area.

Contribution to the knowledge of the cavernicolous beetle genus Aspidaphaenops Uéno from Guizhou (Coleoptera: Carabidae: Trechinae).

The hypogean ground beetle genus Aspidaphaenops Uéno, 2006 is reviewed. Some new information of A. reflexus Uéno, 2006 is provided, including the male genital characteristics as well as a new locality. Two new species are described and illustrated from southwestern Guizhou Province, southwest China: A. xiongda n. sp. (Guizhou: Anlong: Fengyan Dong), A. dudou n. sp. (Guizhou: Xingyi: Xiaozi Dong). A key to all Aspidaphaenops species is also provided.

Gold mineralization associated with Emeishan basaltic rocks: Mineralogical, geochemical, and isotopic evidences from the Lianhuashan ore field, southwestern Guizhou Province, China

A number of gold deposits are newly discovered in the Lianhuashan ore field, southwestern Guizhou Province, China. The gold orebodies are restricted to the Emeishan basaltic rocks and the interlayer fractures between the Emeishan basaltic rocks and the limestone of the Maokou Formation. Three generations of pyrite (Py0, Py1, and Py2) have been recognized in these deposits based on morphology and paragenetic relationships. Electron microprobe (EMP), laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and laser-ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) analyses were carried out to characterize their chemical and sulfur isotopic compositions.The framboidal Py0 is enriched in As but depleted in most of the other trace elements. It has negative δ34S values of −14.5–−1.9‰, which are typical of diagenetic pyrites resulted from bacterial reduction of marine sulfate. Py1 and arsenopyrite exhibit high concentrations of Au and As, making them the most dominant auriferous minerals. They yield comparable δ34S values of −2.8– + 2.1‰, consistent with the derivation of sulfur from the Emeishan basaltic rocks. Py2 is characterized by well developed oscillatory-zoned textures, that are interpreted in terms of internal self-organization processes. It contains low concentrations of Au and highly variable concentrations of As, Sb, Co, and Ni. The Py2 grains show slightly positive δ34S values of + 0.4– + 7.0‰, indicating that the sulfur was mainly sourced from the Emeishan basaltic rocks with variable amounts of contamination from reduced marine sulfate.The Emeishan basaltic rocks may have provided not only ore-hosting space but also Au, S, and other associated elements for gold mineralization in the Lianhuashan ore field. Similar gold deposits are expected to be discovered in the areas of Emeishan basaltic rocks with high Au backgrounds and small thicknesses.

Carbon-oxygen isotopes and rare earth elements as an exploration vector for Carlin-type gold deposits: A case study of the Shuiyindong gold deposit, Guizhou Province, SW China

The Shuiyindong gold deposit is a deeply concealed strata-bound Carlin-type deposit in southwestern Guizhou Province, China. The deposit lies on the eastern limb of the Huijiabao anticline with ores mainly along the anticline axis and hosted in bioclastic limestone, containing calcite veins, of the Permian Longtan Formation units. In this study, we measured carbon and oxygen isotopic ratios and rare earth element (REE) concentrations of the host rocks and calcite veins along a profile across the Shuiyindong deposit. Orebodies in the upper unit of the Longtan Formation have higher δ18O values (20.6–22.4‰) and lower δ13C values (−3.7 to −0.5‰) than the country rocks (δ18O: 18.8–21.4‰; δ13C: −0.7 to 0.8‰). However, there are no obvious trends of δ18O and δ13C values from the country rocks to the orebodies in the middle unit of the Longtan Formation. The spatial distribution of the calcite veins displays distinct halos of δ13C and δ18O values and REE concentrations. Calcite veins along the anticlinal axis and major reverse fault are enriched in Middle REE (Sm, Eu, Gd, and Tb) and 18O and depleted in 13C. Surficial veining calcite-filled fractures/faults that connect to deep concealed strata-bound gold mineralization systems can be vectors toward deep ores in southwestern Guizhou Province, China.

Geochemical characteristics of dissolved rare earth elements in acid mine drainage from abandoned high-As coal mining area, southwestern China.

Acid mine drainage (AMD) represents a major source of water pollution in the small watershed of Xingren coalfield in southwestern Guizhou Province. A detailed geochemical study was performed to investigate the origin, distribution, and migration of REEs by determining the concentrations of REEs and major solutes in AMD samples, concentrations of REEs in coal, bedrocks, and sediment samples, and modeling REEs aqueous species. The results highlighted that all water samples collected in the mining area are identified as low pH, high concentrations of Fe, Al, SO42- and distinctive As and REEs. The spatial distributions of REEs showed a peak in where it is nearby the location of discharging of AMD, and then decrease significantly with distance away from the mining areas. Lots of labile REEs have an origin of coal and bedrocks, whereas the acid produced by the oxidation of pyrite is a prerequisite to cause the dissolution of coal and bedrocks, and then promoting REEs release in AMD. The North American Shale Composite (NASC)-normalized REE patterns of coal and bedrocks are enriched in light REEs (LREEs) and middle REEs (MREEs) relative to heavy REEs (HREEs). Contrary to these solid samples, AMD samples showed slightly enrichment of MREEs compared with LREEs and HREEs. This behavior implied that REEs probably fractionate during acid leaching, dissolution of bedrocks, and subsequent transport, so that the MREEs is primarily enriched in AMD samples. Calculation of REEs inorganic species for AMD demonstrated that sulfate complexes (Ln(SO4)+and Ln(SO4)2-) predominate in these species, accounting for most of proportions for the total REEs species. The high concentrations of dissolved SO42- and low pH play a decisive role in controlling the presence of REEs in AMD, as these conditions are necessary for formation of stable REEs-sulfate complexes in current study. The migration and transportation of REEs in AMD are more likely constrained by adsorption and co-precipitation of Fe-Al hydroxides/hydroxysulfate. In addition, the MREEs is preferentially captured by poorly crystalline Fe-Al hydroxides/hydroxysulfate, which favors that sediments also preserve NASC-normalized patterns with MREEs enrichment in the stream.

The Au-Hosting Minerals and Process of Formation of the Carlin-Type Bojitian Deposit, Southwestern China

The recently discovered middle-sized Bojitian Carlin-type Au deposit is located in southwestern Guizhou Province, China, near the well-known Shuiyindong super-large-sized deposit. To improve the understanding on this deposit, here we investigate the minerals that host Au and the occurrence of Au in the deposit, using a combination of microscopic work and electron probe microanalysis (EPMA). Based on the results, the formation of the deposit was addressed. Results indicate that the dominant minerals that host Au include arsenian pyrite and arsenopyrite. Au in the cores of zoned pyrite exists mainly as natural nanoscale Au (Au0), while Au in the rims exists mainly as solid solution Au (Au+), but it likely also exists in the rims as natural nanoscale Au. The framboidal, coarse-grained, and banded pyrite types contain both natural nanoscale Au0 and solid solution Au+. The arsenopyrite is of hydrothermal origin, and Au within the arsenopyrite exists as gold solution Au+. The Bojitian deposit was formed from As-bearing, H2S-rich, low-to-medium-temperature fluids that migrated along faults and other channels. Au that was already present in the strata or source beds migrated with the fluids in the form of Au(HS)− and ore-forming fluids were then formed in the reducing environment. The ore-forming fluids interacted with Fe-rich carbonates to form an abundance of Au-hosting arsenian sulfides.

Two new cave-dwelling species of the millipede genus Paracortina Wang & Zhang, 1993 from southern China (Diplopoda, Callipodida, Paracortinidae).

Two new species of the millipede genus Paracortina Wang & Zhang, 1993 are described. Both are presumed troglophiles: Paracortina zhangi sp. n. from a cave in Ceheng County, southwestern Guizhou Province and Paracortina yinae sp. n. from a cave in Longlin County, western Guangxi Zhuang Autonomous Region. A distribution map and a key to all 12 Paracortina species are also provided.

Ore-forming process of the Huijiabao gold district, southwestern Guizhou Province, China: Evidence from fluid inclusions and stable isotopes

The Huijiabao gold district is one of the major producers for Carlin-type gold deposits in southwestern Guizhou Province, China, including Taipingdong, Zimudang, Shuiyindong, Bojitian and other gold deposits/occurrences. Petrographic observation, microthermometric study and Laser Raman spectroscopy were carried out on the fluid inclusions within representative minerals in various mineralization stages from these four gold deposits. Five types of fluid inclusions have been recognized in hydrothermal minerals of different ore-forming stages: aqueous inclusions, CO2 inclusions, CO2–H2O inclusions, hydrocarbon inclusions, and hydrocarbon–H2O inclusions. The ore-forming fluids are characterized by a H2O+CO2+CH4±N2 system with medium to low temperature and low salinity. From early mineralization stage to later ones, the compositions of the ore-forming fluids experienced an evolution of H2O+NaCl→H2O+NaCl+CO2+CH4±N2→H2O+NaCl±CH4±CO2 with a slight decrease in homogenization temperature and salinity. The δ18O values of the main-stage quartz vary from 15.2‰ to 24.1‰, while the δDH2O and calculated δ18OH2O values of the ore-forming fluids range from −56.9 to −116.3‰ and from 2.12‰ to 12.7‰, respectively. The δ13CPDB and δ18OSMOW values of hydrothermal calcite change in the range of −9.1‰ to −0.5‰ and 11.1–23.2‰, respectively. Stable isotopic characteristics indicate that the ore-forming fluid was mainly composed of ore- and hydrocarbon-bearing basinal fluid. The dynamic fractionation of the sulfur in the diagenetic pyrite is controlled by bacterial reduction of marine sulfates. The hydrothermal sulfides and the diagenetic pyrite from the host rocks are very similar in their sulfur isotopic composition, suggesting that the sulfur in the ore-forming fluids was mainly derived from dissolution of diagenetic pyrite. The study of fluid inclusions indicates that immiscibility of H2O–NaCl–CO2 fluids took place during the main mineralization stage and caused the precipitation and enrichment of gold.

Restudy of conodont biostratigraphy of the Permian–Triassic boundary section in Zhongzhai, southwestern Guizhou Province, South China

New conodont samples have been systematically collected at high stratigraphic resolution from the upper part of the Longtan Formation through to the lower part of the Yelang Formation at the Zhongzhai section, southwestern Guizhou Province, South China, in an effort to verify the first local occurrence of Hindeodus parvus in relation to the Permian–Triassic boundary at this section. The resampled conodont fauna from the Permian–Triassic boundary interval comprises five identified species and two undetermined species in Hindeodus and Clarkina. Most importantly, the first local occurrence of Hindeodus parvus is found for the first time from the bottom of Bed 28a, 18cm lower than the previously reported first local occurrence of this species at this section. Considering the previously accepted PTB at the Zhongzhai section, well calibrated by conodont biostratigraphy, geochronology and carbon isotope chemostratigraphy, this lower (earlier) occurrence of H. parvus suggests that this critical species could occur below the Permian–Triassic boundary. As such, this paper provides evidence that (1) the first local occurrences of H. parvus are diachronous in different sections with respect to the PTB defined by the First Appearance Datum (FAD) of this species at its GSSP section in Meishan, China and that (2) the lower stratigraphic range of H. parvus should now be extended to latest Permian.

A new Changhsingian (Late Permian) Rugosochonetidae (Brachiopoda) fauna from the Zhongzhai section, southwestern Guizhou Province, South China

Zhang, Y., He, W.-H., Shi, G.R. & Zhang, K.-X., 2013. A new Changhsingian (Late Permian) Rugosochonetidae (Brachiopoda) fauna from the Zhongzhai section, southwestern Guizhou Province, South China. Alcheringa 37, 221–245. ISSN 0311-5518. This paper describes 20 species (including three undetermined species) of Rugosochonetidae (Brachiopoda) in an upper offshore fauna from the Permian–Triassic Boundary Zhongzhai section, southwestern Guizhou Province, South China. New taxa are Tethyochonetes sheni, Tethyochonetes cheni, Neochonetes (Huangichonetes) archboldi, Neochonetes (Sommeriella) waterhousei, Neochonetes (Sommeriella) rectangularis and Neochonetes semicircularis. Yang Zhang [zyan@deakin.edu.au] and G.R. Shi [guang.shi@deakin.edu.au] (corresponding author), School of Life and Environmental Sciences, Deakin University, Melbourne Burwood Campus, 221 Burwood Highway, Burwood, Victoria 3125, Australia; Weihong He [whzhang@cug.edu.cn] (corresponding author) and Kexin Zhang [kx_zhang@cug.edu.cn], State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, 388 Lumo Road, Hongshan, Wuhan 430074, PR China. Received 8.6.2012; revised 19.9.2012; accepted 7.10.2012.

Thallium at the interface of soil and green cabbage (Brassica oleracea L. var. capitata L.): Soil–plant transfer and influencing factors

Thallium (Tl) is a non-essential and toxic trace metal found in many plants, but it can accumulate at particularly high concentration in green cabbage (Brassica oleracea L. var. capitata L.). The aim of this study is to explore the transfer and accumulation of Tl at the interface of rhizospheric soil and green cabbage from a long-term Tl contaminated site in southwestern Guizhou Province, China. Influencing factors such as Tl distribution in various soil fractions and physical–chemical characteristics of rhizospheric soil were also investigated. Our results demonstrated that green cabbage had high accumulation of Tl, with most bioconcentration factor (BF) values exceeding 1, and up to a maximum level of 11. The enrichment of Tl in the green cabbage tissues followed a descending order, i.e. old leaves>fresh leaves>stems≈roots. The stems functioned as a channel for Tl transportation to the leaves, where most of the Tl (greater than 80%) was found to accumulate. In the rhizospheric soils, 62–95% of Tl existed in the residual fraction, while lower concentrations of Tl (on average, 1.7% of total T1 in rhizospheric soil) were found in the water and acid soluble fractions. The major fraction of labile Tl was located in the reducible fraction (9%). Our results also suggested that the uptake and enrichment of Tl in green cabbage were affected by Tl concentrations, soil water content, soil pH, soil organic material (SOM) and cation exchange capacity (CEC) in rhizospheric soil.

A new eosauropterygian (Diapsida, Sauropterygia) from the Triassic of China

ABSTRACT A new Middle Triassic sauropterygian, Qianxisaurus chajiangensis, gen. et sp. nov., is described on the basis of a skeleton from the Zhuganpo Member (Ladinian) of the Falang Formation, Xingyi, southwestern Guizhou Province, China. It is primarily characterized by a premaxilla with eight teeth, marginal teeth with a slightly constricted peduncle and short conical crown, snout longer than the rest of skull, postorbital with a truncated dorsal process and forked posterior process, a very small supratemporal fenestra, a short retroarticular process posteriorly truncated and lacking a dorsal concavity, an elongate trunk with 28 vertebrae, a stout sacrum with four vertebrae, a longitudinal groove on proximodorsal surface of the dorsal ribs, and a coracoid with a narrow lateral portion and a foot-shaped medial portion. Q. chajiangensis appears similar to the European pachypleurosaurs, but a global phylogenetic analysis failed to support close relationships with these taxa. Instead, Q. chajiangensis is an eosauropterygian and most probably the sister group of a clade consisting of the European pachypleurosaurs and the Nothosauroidea. The discovery of Q. chajiangensis certainly enriches our knowledge of the early history of the Eosauropterygia and leads to a better understanding of the phylogenetic relationships among known eosauropterygians.

Relationship Between Vegetation Restoration and Soil Microbial Characteristics in Degraded Karst Regions: A Case Study

The mechanism of vegetation restoration on degraded karst regions has been a research focus of soil science and ecology for the last decade. In an attempt to preferably interpret the soil microbiological characteristic variation associated with vegetation restoration and further to explore the role of soil microbiology in vegetation restoration mechanism of degraded karst regions, we measured microbial biomass C and basal respiration in soils during vegetation restoration in Zhenfeng County of southwestern Guizhou Province, China. The community level physiological profiles (CLPP) of the soil microbial community to were estimated determine if vegetation changes were accompanied by changes in functioning of soil microbial communities. The results showed that soil microbial biomass C and microbial quotient (microbial biomass C/organic C) tended to increase with vegetation restoration, being in the order arboreal community stage > shrubby community stage > herbaceous community stage > bare land stage. Similar trend was found in the change of basal respiration (BR). The metabolic quotient (the ratio of basal respiration to microbial biomass, qCO 2) decreased with vegetation restoration, and remained at a constantly low level in the arboreal community stage. Analyses of the CLPP data indicated that vegetation restoration tended to result in higher average well color development, substrate richness, and functional diversity. Average utilization of specific substrate guilds was highest in the arboreal community stage. Principle component analysis of the CLPP data further indicated that the arboreal community stage was distinctly different from the other three stages. In conclusion, vegetation restoration improved soil microbial biomass C, respiration, and utilization of carbon sources, and decreased qCO 2, thus creating better soil conditions, which in turn could promote the restoration of vegetation on degraded karst regions.

Biomonitoring of testate amoebae (protozoa) as toxic metals absorbed in aquatic bryophytes from the Hg-Tl mineralized area (China)

Toxic metal pollution in bodies of water is a source of danger to the health of people living in developing countries. The untreated mine wastes located near some Chinese ore mines may cause water pollution, which ultimately results in various diseases. The aim of the present study is to assess the response of testate amoebae communities to pollution by toxic metals in groundwater, stream water, and aquatic bryophytes in Lanmuchang stream located in the Hg-Tl mineralized area in southwestern Guizhou Province, China. Measurements were made of the levels of Hg, As, Cd, Tl, Cu, Zn, and Pb in three mosses: Hyophila propagulifera, Rhynchostegium riparioides, and Hygroamblystegium tenax. Mean moss concentrations of Hg, As, Cu, Pb, and Zn were significantly higher than stream water values and testate amoebae species richness and abundance were significantly lower in the 'polluted' group. We then studied the correlation between toxic metals and testate amoebae. The total species abundance is correlated negatively to Hg and Cu concentrations. Our results indicated that testate amoebae are sensitive to toxic metal pollution and aquatic bryophytes are bioaccumulators of trace metals, and results also showed potential microecosystem health risks.

Metallogenic model and prognosis of the Shuiyindong super-large strata-bound Carlin-type gold deposit, southwestern Guizhou Province, China

The Shuiyindong deposit is one of the largest (more than 100 tonnes of Au) and highest grade (more than 7×10−6–10×10−6), strata-bound Carlin-type gold deposits in southwestern Guizhou Province, China. The deposit is controlled by both structure and favorable lithology. It is situated near the axis of the striking Huijiabao anticline and is hosted in bioclastic limestone of the Permian Longtan Formation. Gold mineralization occurred under low temperature with T h of 220°C ± and is closely associated with decarbonation, silicification, sulfidation and dolomitization. The deposit has a characteristic elemental assemblage of Au-As-Hg-Tl. Studies of geochemistry and isotope compositions indicated that the ore-bearing materials and fluids of the gold deposit mainly originated from a plutonic source, and possess a mixing feature with the strata matter during transportation from mantle to crust. Fluid inclusions in vein quartz from the gold deposit are rich in volatile flux, indicating that metallogenic fluid is an overpressured one. The activity and geothermal state of the Earth’s crust in the long period of time are favorable for the formation of overpressured fluids in a large area, and extensive structures would drive the fluids into ore-forming system and make gold deposits formed. The complexity of structural movement in the upper crust of southwestern Guizhou Province resulted in complicated gold mineralization. Through metallogenic prognosis and exploration, the proven reserves of the deposit increased by tens of tonnes of Au and the deposit has become a super-large strata-bound Carlin-type gold deposit.

A study on the genetic relations between Permian Longtan Formation coal series strata and Carlin-type gold deposits, southwestern Guizhou Province, China

A large number of the Carlin-type gold deposits occur in the Longtan Formation in southwestern Guizhou Province. The Longtan Formation contains abundant basalt, tuff and siliceous rocks. All rocks of the Longtan Formation are enriched in gold, which were deposited in a limited platform environment in the transition zone from marine to continental. The process of sedimentation was accompanied by the eruption of Emeishan basalt and hydrothermal deposition controlled by co-sedimentary submarine deep faults in the west, which led to the formation of a peculiar gold-bearing formation with coal series strata. This formation controlled the occurrence of the Carlin-type gold deposits in southwestern Guizhou Province. In response to the remobilization of the Emei mantle plume during the Yanshanian period, As, Au and other ore-forming materials were continuously extracted by deeply circulating waters from the Emeishan basalt and coal seams, thereafter forming ore-forming hydrothermal solutions. When these elements were transported in the coal seams, large amounts of As, Au and other elements were enriched in pyrite within the coal seams, thus forming high-As coal and Carlin-type gold deposits in the Longtan Formation coal series strata.