Modes of Occurrence and Geological Origin of Beryllium in Coals from the Pu'an Coalfield, Guizhou, Southwest China

The concentration, modes of occurrence and geological origin of beryllium in five workable coal beds from the Pu＇an Coalfield of Guizhou were studied using the inductively coupled-plasma mass spectrometry （ICP-MS）, floating and sinking experiments （FSE） and sequential chemical extraction procedures （SCEP）. The results show that the average concentration of beryllium in coals from the Pu＇an Coalfield is 1.54 μg/g, much lower than that in most Chinese and worldwide coals. Beryllium in the Pu＇an coals was not significantly enriched. However, it should be noted that the No. 8 coal bed from the study area has a high concentration of beryllium, 6.89 μg/g, three times higher than the background value of beryllium in coal. Beryllium in coal mainly occurs as organic association and has predominantly originated from coal-forming plants when its concentration is relatively low. The concentration of beryllium occurring as organic association is close to that distributed in inorganic matter when beryllium concentration of coal is similar to its background value, and in addition to coal-forming plants, beryllium is mainly derived from detrital materials of terrigenous origin. When beryllium is anomalously enriched in coal, it mainly occurs as organic association and is derived from volcanic tonsteins leached for a long geological time and then adsorbed by organic matter in peat mire.

Geological characteristics and the origin of ore-forming materials of(Laozhaiwan gold deposit, Yunnan Province

"Golden triangle"area bordered on Yunnan-Guizhou-Guangxi was one of the most important Carlin-type gold deposits concentration areas.Deep understanding of Carlin-type gold deposits in Guizhou and Guangxi Province had reached through several decades studies,but geological environment was very complex in the southeastern Yunnan,and Carlin-type gold deposits produced in the southeastern Yunnan were different from that of America,few studies were taken there.Based on a large number of field work,studies on the geological characteristics combining with geochemistry characteristics were taken,and analysis the genesis of Laozhaiwan gold deposit.The types of alteration in Laozhaiwan gold deposit were mainly silicification and pyritization,and Gold grade was high when silicification and pyritization were both occurred.It could be caculated that fluid density(g/cm3)varied from 0.7 to 4.9,salinity varied from 0.76%to 0.95%and ore-forming pressure(Pa)varied from 1.81×105 to 49.96×105 according to fluid inclusion test results,showed that Laozhaiwan gold deposit was hypabyssal hydrothermal deposit in low temperature and low salinity.According to composition of fluid inclusion analysis,combining with H-O isotope,made theδD-δ18O figure,showed that the fluid of the deposit rooted in formation water and mixed with meteoric waters later.

Geotechnical Risk Assessment and Geological Origin of Building Fracturation in Agadez City(North Niger)

The Agadez city is built on the faulted and fractured sandstones formation of the“Agadez Sandstones”,which deposit in unconformity on the Precambrian basement of the Aïr Mountain.The present study focuses on the geotechnical risk assessment and geological origin of building fracturation in Agadez city.A methodological approach integrating measurement of fractures planes affecting the buildings and their statistical analysis has been implemented.Statistical analysis of obtained data showed that in 100 fractured buildings,about 3%buildings are at risk of collapse(very high risk),64%buildings are fractured(medium risk of collapse),and 34%buildings are cracked(lower risk of collapse).These results showed as well that the nature of the material(rheology)influences the buildings fracturation.Indeed,the buildings made from cement are more easily fractured than buildings made from clay materials.Statistical analysis of fracture planes reveals that the geotechnical risk associated with buildings fracturation propagates in NW-SE,corresponding to the major directions of risk propagation,mainly dipping in northwest sectors(zones)of the Agadez city.The interpretation of geological and geophysical data combined to those obtained in the case of this study,reveals that the risk associated with buildings fracturation in Agadez city is caused by geological seismic events and or anthropogenic activities(explosive firing on the uranium mining sites like Somaïr and Cominak).