Mechanism of spatial emplacement of Shanhou gold ore body in Laixi of Shandong and its prospecting significance

Through analysis of geological characteristics of the gold deposit,the shape,occurrence,and spatial distribution of ore-controlling fault plane in the Shanhou mining area were investigated,and the regularities of enrichment and emplacement of ore body were summarized. The analysis shows that the Shanhou gold deposit was controlled by NE-NNE Zhaoping fault zone; the fault gouge developed in fault zone provides a barrier to ore-bearing hydrothermal solution,and the industrial ore body is all distributed within 40 m of footwall of main fault plane. The industrial ore body is mainly enriched in the NE positions of fault where the deep dips changed to flat dips,and shows the obvious regularity of NE lateral trending with angle around 75°. The stress analysis of fault in mineralization epoch showed that the ore-controlling structure presented the characteristics of righthanded rotation inverse-fault activity in mineralization epoch,and the host space tended to occur in NE regional tension positions where the dips become flat in the strike of fault,causing emplacement of ore body. It is thought by combining equal interval distribution of deposit with spatial variation of industrial ore body and orecontrolling fault structure that the Shanhou gold deposit recurred in regularity and the non-ore interval occurred in the ore body. Meanwhile,it is predicted that the favorable target area of prospecting lies in the areas of deep main fault plane with NE strike( > 30°) and the deep dips changing to flat dips in the Shanhou mining area,and the prospecting should be emphasized. The favorable deep mineralization prospect exists in middle Beibo mining area,where is the key area for future prospecting.

World-class Xincheng gold deposit： An example from the giant Jiaodong gold province

The Jiaodong gold deposits are currently the most important gold resources（with Au reserves of〉4000 t） in China,and the leading gold-producing country globally（with Au production of ～428 t in2013）.Jiaodong is also considered as perhaps the only world-class to giant gold accumulation on the planet where relatively young gold ores（ca.130-120 Ma） were deposited in rocks that are 2 Ga older.The Xincheng world-class high-grade gold deposit,with a proven reserve of 〉200 t gold,is one of the largest deposits in the giant gold province of the Jiaodong Peninsula.It is located in the northwestern part of the jiaobei Uplift,and hosted by ca.132-123 Ma Xincheng quartz monzonites and monzogranites.Ore zones are structurally controlled by the NE-trending and NW-dipping Jiaojia Fault and subsidiary faults,and are mainly restricted to the footwall of the fault.The dominant disseminated- and stockworkstyle ores are associated with strong sericitization,silicification,sulfidation and K-feldspathization,and minor carbonate wallrock alteration halos.The four mineralization stages are pyrite-quartz-sericite（stage 1）,quartz-pyrite（stage 2）,quartz-polysulfide（stage 3） and quartz-carbonate（stage 4）.Gold occurs dominantly as electrum,with lesser amounts of sulfide-hosted native gold and rare native silver and argentite,normally associated with pyrite,chalcopyrite,galena and sphalerite：the latter with proven resources of about 105 t Ag,713 t Cu,and 5100 t S.There are three types of ore-related fluid inclusions：type 1 aqueous-carbonate（H2O-CO2）,type 2aqueous（liquid H2O＋vapor H2O）,and type 3 CO2（liquid CO2 and vapor CO2） inclusions.Homogenization temperatures range from 221 to 304℃ for type 1 inclusions,with salinities of 2.4-13.3 wt.%NaCl eq.,and bulk densities of 0.858-1.022 g/cm～3.The δ～（34）S（CDT） values of hydrothermal sulfides are 4.3-10.6‰and δ～（18）O values of hydrothermal quartz have a median value of 13.0‰.δD values of fluid inclusions in hydrothermal quartz have a median value of-75‰.Calculated δ～（18）Owater has a median value of 5.2‰.The timing of gold mineralization at the Xincheng gold deposit is younger than 123±1 Ma,and likely between 120.9 and 119.9 Ma.A minerals system genetic model for the probable epizonal orogenic Xincheng deposit suggests an initial medium temperature,CO2-rich,and low salinity H2O-CO2 deeply sourced metamorphic ore fluid associated with dehydration and decarbonization of subducting Paleo-Pacific lithosphere.The Jiaojia Fault constrained the migration of ore-forming fluids and metals at the brittle-ductile transition.Fluid immiscibility,caused by episodic pressure drops,led to significant high-grade gold deposition in the giant Xincheng gold deposit.

Effect of chloride ion on bacterial pre-oxidation of arsenic-containing gold concentrate

The bacterial pre-oxidation process of arsenic-containing gold concentrates and the bacterial activity under different chloride ion concentrations were studied by using a mixture of thermophilic strains TCJ domesticated in production.The experimental result shows that with different samples and leaching systems,the adaptability and Cl- tolerance of bacteria are different,and that appropriate chloride ion concentration is conductive to bacterial oxidation,while higher chloride ion concentration will inhibit the bacterial activity and affect the pre-oxidation performance.Under the present production conditions,TCJ can adapt to the changes of water quality in the source of water and its critical chloride ion tolerance value is 2.7 g/L.

Countermeasures of heavy metal pollution

This article gives a review on heavy metal pollution prevention and control,and it also discusses heavy metal pollutant discharge,prediction and evaluation of environmental impact,and pollution prevention and monitoring.

双向荷载作用下被充填矿柱的力学特性

在矿柱周边进行充填形成的矿柱-充填体协同承载结构是充填开采的关键,也是维持地下采场稳定性的重要支撑结构。通过双向加载试验,研究了被充填矿柱在不同侧向应力、充填率和充填体力学特性条件下的承载能力和破坏模式,分析了矿柱-充填体复合结构的承载特性及相互作用过程。结果表明,随着侧向应力的增加,矿柱与充填体之间的界面摩擦力(充填率<100%)和有效充填体强度(充填率=100%)比矿柱强度增加更加显著,故前两者是双向加载条件下矿柱-充填体支撑结构承载力增加的主要原因。此外,由于矿柱和充填体两者之间显著的刚度差异,双轴加载试验中充填体的有效强度会低于其单轴抗压强度,而侧向应力的增加,不仅会提高界面摩擦力和充填体的有效强度,也会影响矿柱和充填体的破坏模式。该研究对分析矿柱-充填体相互作用和共同承载机制具有参考和借鉴价值。