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141.
142.
A. L. Perchuk M. Burchard H.-P. Schertl W. V. Maresch T. V. Gerya H.-J. Bernhardt O. Vidal 《Contributions to Mineralogy and Petrology》2009,157(5):573-592
We demonstrate the possibility of studying several diffusion couples in a single run, i.e. under almost similar P–T–t– conditions, allowing direct comparison of the diffusion rates in different diffusion couples. Thus the duration of experimental
study and the risk of failure of expensive experimental equipment can be decreased considerably. The diffusion experiments
were carried out in piston-cylinder apparatus. Gem-quality garnets of almandine, spessartine and grossular compositions together
with inclusion-rich eclogitic garnets were embedded in a powder of natural pyrope and annealed together under dry conditions
at P = 1.9–3.2 GPa and T = 1,070–1,400°C. Diffusion profiles were measured by electron microprobe and fitted numerically on the basis of multicomponent
diffusion theory. The datasets derived from different diffusion couples yields parameters of the Arrhenius equation for Ca,
Mg and Fe in natural eclogitic garnets and Mg, Mn and Fe in gem-quality garnets. We have also studied the effect of grain-boundary
diffusion in the sintered pyrope matrix on interdiffusion on the basis of 2D modeling. Under conditions analogous to those
of our experimental runs, we show that observed irregularities in some measured diffusion profiles (not applied for the diffusion
modeling) can be directly related to the superposition of local grain-boundary diffusion on dominant volume diffusion. 相似文献
143.
秘鲁铜硫矿石的主要回收对象是铜和硫矿物,由于铜矿物嵌布复杂、粒度过细以及与各种脉石矿物或金属矿物交生关系紧密,利用传统工艺矿物学研究方法如化学分析、光学显微镜检测等较难准确定量其工艺矿物学参数。本文采用化学分析、X射线衍射、扫描电镜、偏光显微镜及矿物参数自动分析系统(MLA)等技术手段,研究秘鲁铜硫矿石的化学成分、矿物组成和主要矿物的嵌布特征、粒度分布及单体解离特性等,并对影响选矿指标的主要矿物学因素进行分析。结果表明:矿石中主要元素为Cu(0.65%)和S(9.53%)。矿石中黄铁矿(16.57%)含量较高,形态较为规则,与其他矿物之间的交生关系相对简单,粒度普遍偏粗,其中粒径大于0.30mm的黄铁矿占95.06%。铜矿物主要以不规则粒状、皮壳状、网脉状、纤维状、尘粒状、斑点状分布于脉石中或与黄铁矿、闪锌矿、磁铁矿等金属矿物交生紧密,粒度极不均匀,使得铜矿物解离难度加大,且矿石中云母(12.51%)、绿泥石(3.74%)、滑石(3.34%)、高岭石、蒙脱石(3.59%)等黏土质矿物含量较高,在磨矿过程中易发生泥化从而恶化分选环境。根据该类型矿石的工艺矿物学特性,本文建议采用"粗磨-部分优先浮铜-铜硫混浮-混合精矿再磨再选分离"的工艺流程,可得到质量高的铜、硫精矿。 相似文献
144.
《China Geology》2019,2(4):407-421
The Nyasirori gold deposit, located in the middle-western end of the Musoma-Mara Archean greenstone belt in Tanzania, is a tectonic altered rock type gold deposit controlled by shear tectonic zone. This work conducted high-precision ground magnetic measurements to delineate fault structures and favorable prospecting targets, utilized induced polarization (IP) intermediate gradient to roughly determine the distribution and extension of the tectonic altered zone and gold ore (mineralized) bodies, and further carried out IP sounding and magnetotelluric sounding to locate the tectonic altered zone and gold ore (mineralized) bodies. The anomalous gradient belt of the combination of positive and negative micromagnetic measurements reflects the detail of shallow surface tectonic alteration zone and gold mineralization body. Micromagnetic profile anomalies indicate the spatial location and occurrence of concealed tectonic alteration zone and gold (mineralized) ore bodies. Soil geochemical measurements indicate that the ore-forming element Au correlates well with As and Sb, and As and Sb anomalies have a good indication to gold orebodies. Based on the multi-source geological-geophysical-geochemical information of the Nyasirori gold deposit, this work established an integrated prospecting model and proposed a set of geophysical and geochemical methods for optimizing prospecting targets. 相似文献
145.
《China Geology》2019,2(3):342-353
Intermediate acid-complex rock masses with low-density characteristics are the most important prospecting sign in the Beiya area, of western Yunnan province, and provide a physical basis for good gravity exploration. It is usually difficult to obtaining solutions in connection with actual geological situations due to the ambiguity of the conventional gravity-processing results and lack of deep constraints. Thus, the three-dimensional (3D) inversion technology is considered as the main channel for reducing the number of solutions and improving the vertical resolution at the current stage. The current study starts from a model test and performs nonlinear 3D density-difference inversion called “model likelihood exploration”, which performs 3D inversion imaging and inversion of the known model while considering the topographic effects. The inversion results are highly consistent with those of the known models. Simultaneously, we consider the Beiya gold mine in Yunnan as an example. The nonlinear 3D density-difference inversion technology, which is restricted by geological information, is explored to obtain the 3D density body structure below 5 km in the mine area, and the 3D structure of the deep and concealed rock masses are obtained using the density constraints of the intermediate-acid-complex rock masses. The results are well consistent with the surface geological masses and drilling-controlled deep geological masses. The model test and examples both show that the 3D density-difference nonlinear inversion technology can reduce inversion ambiguity, improve resolution, optimize the inversion results, and realize “transparency” in deeply concealed rock masses in ore-concentrated areas,which is useful in guiding the deep ore prospecting. 相似文献
146.
Logistic regression has been used in the study to integrate indicator patterns for estimation of the probability of occurrence of gold deposits in a part of the auriferous Archaean Hutti–Maski schist belt. Data used consist of categorical and continuous variables obtained from a coded lineament map and geochemical anomaly maps of the pathfinder elements of gold in soil and groundwater. Main effects and interactions of the variables studied were used in formulating the logistic regression model. Regression models using lineament-proximity data, combined with soil and groundwater geochemical anomalies were tested on parts of the schist belt with data not used in estimation of model parameters. Predicted probabilities greater than 0.9 identified known deposit locations in the area. 相似文献
147.
148.
武山铜矿北矿带ICu矿体砷的分布规律 总被引:1,自引:0,他引:1
武山铜矿化矿带ICu矿体是高砷矿体,分析了砷在各金属矿物中含量及分配情况和含砷量的分布规律,确定了高砷采场或矿段,指出了进行矿石质量控制,配矿管理的降砷途径。 相似文献
149.
进入市场经济,地勘单位要生存和发展,必须充分发挥地勘行业自身优势,走兴办矿业经济之路,应抓住当前的机遇,开发市场紧销矿产品,要用好矿权,采用多种模式,多渠道吸引社会资金,减少投资风险,争取最高效益,同时要十分重视整理和利用积累的地质资料,为兴办矿业提供必要的科学依据。 相似文献
150.
Alfons M. van den Kerkhof Geoffrey H. Grantham 《Contributions to Mineralogy and Petrology》1999,137(1-2):115-132
In the Port Edward area of southern Kwa-Zulu Natal, South Africa, charnockitic aureoles up to 10 m in width in the normally
garnetiferous Nicholson's Point Granite, are developed adjacent to intrusive contacts with the Port Edward Enderbite and anhydrous
pegmatitic veins. Mineralogical differences between the country rock and charnockitic aureole suggest that the dehydration
reaction Bt + Qtz → Opx + Kfs + H2O and the reaction of Grt + Qtz → Opx + Pl were responsible for the charnockitization. The compositions of fluid inclusions
show systematic variation with: (1) the Port Edward Enderbite being dominated by CO2 and N2 fluid inclusions; (2) the non-charnockitized granite by saline aqueous inclusions with 18–23 EqWt% NaCl; (3) the charnockitic
aureoles by low-salinity and pure water inclusions (<7 EqWt% NaCl); (4) the pegmatites by aqueous inclusions of various salinity
with minor CO2. As a result of the thermal event the homogenization temperatures of the inclusions in charnockite show a much larger range
(up to 390 °C) compared to the fluid inclusions in granite (mostly <250 °C). Contrary to fluid-controlled charnockitization
(brines, CO2) which may have taken place along shear zones away from the intrusive body, the present “proximal” charnockitized granite
formed directly at the contact with enderbite. The inclusions indicate contact metamorphism induced by the intrusion of “dry”
enderbitic magma into “wet” granite resulting in local dehydration. This was confirmed by cathodoluminescence microscopy showing
textures indicative for the local reduction of structural water in the charnockite quartz. Two-pyroxene thermometry on the
Port Edward Enderbite suggests intrusion at temperatures of ∼1000–1050 °C into country rock with temperature of <700 °C. The
temperature of aureole formation must have been between ∼700 °C (breakdown of pyrite to form pyrrhotite) and ∼1000 °C. Charnockitization
was probably controlled largely by heat related to anhydrous intrusions causing dehydration reactions and resulting in the
release and subsequent trapping of dehydration fluids. The salinity of the metamorphic fluid in the contact zones is supposed
to have been higher at an early stage of contact metamorphism, but it has lost its salt content by K-metasomatic reactions
and/or the preferential migration of the saline fluids out of the contact zones towards the enderbite. The low water activity
inhibited the localized melting of the granite. Mineral thermobarometry suggests that after charnockite aureole genesis, an
isobaric cooling path was followed during which reequilibration of most of the aqueous inclusions occurred.
Received: 8 November 1998 / Accepted: 21 June 1999 相似文献