15 research outputs found
Deep-source ore-forming materials and prospecting of gold deposits in Eastern Hebei, China
The isotopic composition of noble gases in gold deposits and the source of ore-forming materials in the region of North Hebei, China
The Thermal and Dynamic Process of Core ā Mantle ā Crust and the Metallogenesis of Guojiadian Mantle Branch in Northwestern Jiaodong
The Jiaodong gold mineral province, with an overall endowment estimated as >3000 t, located at the eastern segment of the North China Craton (NCC), ranks as the greatest source of Au in China. The structural evolution, magmatic activity and metallogenesis during the Mesozoic played important roles in the large scale regional gold, silver and polymetallic mineralization in this area; among them, the intensive activation of fault structures is the most important factor for metallogenesis. This study takes the regional deep faults as main thread to discuss the controlling role of faults in large scale metallogenesis. The Jiaojia fault and Sanshandao faults in the northwest margin of the Guojiadian mantle branch not only are dominant migration channels for hydrothermal fluid but are very important favorable spaces for ore-forming and ore-hosting during the formation of world-class super large gold deposits in this area. The deep metallogenic process can be summarized as involving intensive Earth’s core, mantle and crust activity → magmatism → uplifting of metamorphic complex → detachment of cover rocks → formation of mantle branch → penetration of hydrothermal fluid along deep faults → concentration of metallogenic materials → formation of super large deposits
First-principles study of ZrāN crystalline phases: phase stability, electronic and mechanical properties
International audienceUsing a variable-composition ab initio evolutionary algorithm, we investigate stability of various ZrāN compounds. Besides the known ZrN and Zr3N4, new candidate structures with Zrā:āN ratios of 2ā:ā1, 4ā:ā3, 6ā:ā5, 8ā:ā7, 15ā:ā16, 7ā:ā8 and 4ā:ā5 are found to be ground-state configurations, while Zr3N2 has a very slightly higher energy. Besides Zr2N, the newly discovered ZrxNy compounds adopt rocksalt structures with ordered nitrogen or zirconium vacancies. The electronic and mechanical properties of the zirconium nitrides are further studied in order to understand their compositionāstructureāproperty relationships. Our results show that bulk and shear moduli monotonically increase with decreasing vacancy content. The mechanical enhancement can be attributed to the occurrence of more ZrāN covalent bonds and weakening of the ductile ZrāZr metallic bonds. These simulations could provide additional insight into the vacancy-ordered rocksalt phases that are not readily apparent from experiments