A Comparison of Carlin-type Gold Deposits：Guizhou Province,Golden Triangle,Southwest China,and Northern Nevada,USA

Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada.USA,were examined to identify similarities and differences between the two districts.Samples were collected along transects from lowto high-grade rock,where possible,and fram stockpiles at the Shuiyindong,Zimudang,Taipingdong,Yata and Jinfeng(formerly Lannigou)deposits.Methods used to examine ore and alteration minerals included hand-sample description:reflectance spectroscopy using an ASD Terraspec spectrometer;analyses of hand samples by carbonate staining with Alizaren red and potassium ferricyanide;transmitted and reflected light petrography;chemical analyses,mineral identification,and imaging using a JEOL.JSM-5610 scanning electron microscope:and quantitative chemical analyses using a JEOL JXA-8900 electron probe microanalyzer.Geochemical analyses of hand samples for 52 elements were done by ALS Chemex.Results indicate both similarities and differences between the two districts.Both districts have similar geologic histories.and deposits at both locations appear to have formed as a result of similar tectonic events.though the district in southwest China lacks evidence of eoeval felsic igneous activity;however,the ore-stage minerals and the fluids that produced the minerals and deposits have some significant differences.The Nevada deposits were dominated by fluid-rock reaction in which host rock Fe was sulfidized to form Au-bearing pyrite.Although ore fluids sulfidized host rock Fe in the Cuizhou deposits.the timing of Fe metasomatism is unknown,so whether the deposits formed in response to sulfidation or pyritization is unclear.Fluid-rock reaction between an acidic,aqueous fluid and highly reactive calcareous rocks in Nevada caused extensive decarbonatization of host rocks,jasperoid replacemerit of carbonate minerals,and alteration of silty rock components to illite and kaolinite.In Guizhou,CO2-bearing ore fluids with temperatures and pressures approaching 100℃ and 500 bars greater than temperatures and pressures detemained for ore fluids in the Nevada deposits,deposited Aubearing pyrite.In examined Guizhou deposits these fluids carbonatized host rocks and farmed both replacement and open-space-filling ore.The fluids,which may have been immiscible,were sufficiently overpressured to fracture wall rocks and to create significant open space filled by vein quartz.While deposit architecture,tectonic setting,and host rocks in Guizhou are quite similar to northern Nevada,ore and alteration minerals suggest that ore-forming processes in examined Guizhou deposits have important similarities to processes associated with formation of orogenic Au systems.The Guizhou deposits display characteristics of both Carlin-type and orogenic systems,perhaps indicating formation at conditions somewhat intermediate to conditions for Carlin-type deposits and orogenic systems.

S, C, O, H, and Pb isotopic studies for the Shuiyindong Carlin-type gold deposit, Southwest Guizhou, China: constraints for ore genesis

The Shuiyindong gold deposit is one of the most famous and largest Carlin-type gold deposits in China and is located in southwest Guizhou, in the eastern part of the Huijiabao anticline. The Shuiyindong's gold mineralization occurred in bioclastic limestone of the Permian Longtan Formation. Sulfur, carbon, hydrogen, oxygen, and lead isotopic compositions are reported in this paper. The properties and sources of ore-forming fluid have been discussed and a metallogenic model for the Shuiyindong gold deposit has been proposed. The d34 S values of stibnite, realgar, orpiment, pyrite from orebodies, and pyrite from quartz veins are similar to or slightly higher than the d34 S values of mantle sulfur. It is suggested that the sulfur of hydrothermal sulfides was likely of magmatic origin with minor heavy sulfur contributed from the country rocks. The measured d D values and calculated d18OH2 O values of inclusion fluid in quartz plotted within or below a magmatic hydrothermal fluid field far from the meteoric water line. This indicates that the ore-forming fluid for the main-stage gold mineralization could have been derived mainly from a magmatic source and mixed with a small amount of meteoric water. The carbon and oxygen isotopic compositions of calcites in the d18 O vs. d13 C diagram suggest that the CO2 in ore-forming fluid was derived from dissolution of bioclastic limestone and oxidation of sedimentary organic carbon in limestone. However, the d13 C values of ore-related calcites, which contain intergrown realgar and/or orpiment, are similar to those of mantle carbon. Although no igneous intrusive rock has been observed in the vicinity of the gold deposits, the possibility of mantle fluid integrated into the ore-forming fluid cannot be eliminated based on the d13 C values of ore-related calcites. The lead isotopes of sulfides are distributed near the growth curves of upper crust and orogenic belt in the plumbotectonic diagram. Their calculated Dc and Db values plotted within the magmatism field of crust-mantle subduction zone in the Dc- Db diagram. This suggests that the lead of sulfides has an intimate connection with magmatism. Our S, H, O, C, and Pb isotopic studies for the Shuiyindong Carlin-type gold deposit in Guizhou manifest a concordant possibility that the ore-forming fluid was mainly derived from magmatic fluid with minor contribution from the surrounding strata. With the integration of comprehensive geology and isotopic geochemistry, we have proposed a magmatic hydrothermal model for the origin of the Shuiyindong gold deposit.

In-situ sulfur isotope and trace element of pyrite constraints on the formation and evolution of the Nibao Carlin-type gold deposit in SW China

The fault-controlled Nibao Carlin-type gold deposit,together with the strata-bound Shuiyindong deposit,comprise a significant amount of the disseminated gold deposits in southwestern Guizhou Province,China.Five main types and two sub-types of pyrite at the Nibao deposit(Py1a/Py1b,Py2,Py3,Py4,Py5)were distinguished based on detailed mineralogical work.Py1,Py2and Py3 are Au-poor,whereas Py4 and Py5 are Au-rich,corresponding to a sedimentary and hydrothermal origin,respectively.Through systematic in situ analyses of NanoSIMS sulfur isotopes,the framboid pyrite Py1a with negative δ^34S values(-53.3 to-14.9%)from the Nibao deposit were found to originate from bacterial sulfate reduction(BSR)processes in an open and sulfate-sufficient condition while the superheavy pyrite Py1b(73.7–114.8%)is probably due to the potential influence of closed-system Rayleigh fractionation or the lack of preservation of deepsea sediments.Data of Py2 and Py3 plot within the area of S isotope compositions from biogenic and abiogenic sulfate reduction.In view of few coeval magmatic rocks in the mining district,the near zero δ^34S values of the Au-rich pyrites(Py4 and Py5)may discount the potential involvement of magmatic but metamorphic or sedimentary origin.LA-ICP-MS and TEM work show that Au in ore-related pyrite is present as both nanoparticles and structurally bound.LA-ICP-MS analyses show that the Au-rich pyrite also contains higher As,Cu,Sb,Tl and S than other types of pyrite,which inferred a distal manifestation of deep hydrothermal mineralization systems.

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 Carlintype 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 Th of 220℃± 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 overpres-sured 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 sys-tem 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.

Geochemical characteristics and metallogenesis of Carlin-type gold deposits in the Sandu-Danzhai metallogenic zone,Guizhou Province,China

Geochemical studies of the Paiting and Miaolong Carlin-type gold deposits in the Sandu-Danzhai metal-logenic zone,Guizhou Province,have shown that the mineralized-altered rocks show LREE-enrichment patterns,generally displaying negative Eu anomalies(δEu=0.51?0.97) and unobvious negative Ce anomalies(δCe=0.86?0.99).Calcite and fluorite in relation with metallogenesis show MREE-enrichment patterns,generally displaying rather weak negative Eu anomalies(δEu=0.74?0.93) and weak negative Ce(δCe=0.70?0.98) anomalies.The δ13CPDB values of carbon in calcite are-1.61‰?-5.82‰,the δ18OSMOW values of oxygen are 13.97‰?19.24‰,and the δ34SCDT values of sulfur in stibnite are 17.72‰?21.68‰.In regard to δD and δ18O,ore-forming fluids pos-sess the characteristics of metamorphic water.The process of metallogenesis of the Carlin-type gold deposits is con-trolled by the Yanshanian tectonic activities.The Yanshanian movement promoted the migration and mobilization of metamorphic fluids in the extensively developed medium-to high-grade metamorphic rocks in this region,carrying primarily enriched gold and associated elements such as Hg,As,and Sb in the Sinian metamorphosed black shales and Lower Cambrian black shales.The ore-forming fluids found their way into a suitable metallogenic environment along the fault zone,followed by gold precipitation to form gold deposits.

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 Long-tan 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.

Geochemical Tracing of Ore-forming Material Sources of Carlin-type Gold Deposits in the Yunnan-Guizhou-Guangxi Triangle Area --A Case Study of the Application of the Combined Silicon Isotopes Geochemistry and Siliceous Cathodoluminescence Analysis

Abstract This paper deals with characteristics of silicon isotope compositions and siliceous cathodoluminescence of host rocks, ores and hydrothermal silicified quartz of the Carlin-type ore deposits in the Yunnan-Guizhou-Guangxi triangle area. The study shows that primary silicified quartz is nonluminescent but quartz in host rocks and secondary silicified quartz are luminescent by the action of cathode rays. Correspondingly, silicon isotope compositions of host rocks, ores and hydro6thermal quartz veins are clearly distinguished. In strata from the Middle Triassic to the “Dachang” host bed, δ30Si of the host rocks ranges from 0.0% ?0.3%, while that of primary ore-forming silicified fluids from ?0.1% to ?0.4%; in the Upper Permian and Lower Carboniferous strata and Indosinian diabase host beds, δ30Si of the host rocks is from ?0.1% to ?0.2% and that of the primary silicified quartz veins from 0.3 % ?0.5 %. This pattern demonstrates the following geochemical mineralization process, primary ore-forming siliceous fluids migrated upwards quickly along the main passages of deep-seated faults from mantle to crust and entered secondary faults where gold deposits were eventually formed as a result of permeation and replacement of the siliceous ore-forming fluids into different ore-bearing strata. This gives important evidence for the fact that ore-forming fluids of this type of gold deposits were mainly derived from upper mantle differentiation and shows good prospects for deep gold deposits and geochemical background for large and superlarge gold deposits.

Carlin-Type Gold Deposits in Qinling and Some Related Problems

The sediment hosted disseminated gold deposits in the Qinling region are of sedimentation slight metamorphic origin superimposed by hydrothermal reworking at moderate low temperatures and are well comparable with the typical Carlin gold deposits in the United States. In view of the confusing concept concerning the \!sediment hosted" and \!Carlin type" gold deposits, the authors propose that the term \!sediment hosted gold deposit" should be used in a broad sense which encompasses at least the four subtypes, i.e., the Carlin type, the metamorphic fine clastic type, the hydrothermal sedimentary type and the vein type. In other words, the \!Carlin type" should not be used as a synonym for \!sediment hosted" but is recommended as a subtype under the general category of \!sediment hosted gold deposits".

Trace Elements in Fluid Inclusions in the Carlin-Type Gold Deposits, Southwestern Guizhou Province

Fluid inclusions in quartz from the Lannigou and Yata Carlin\|type gold deposits in southwestern Guizhou were analyzed by inductively coupled plasma\|mass spectrometry for their trace elements (Co, Ni, Cu, Pb, Zn, Pt, etc.). The results show that quartz fluid inclusions entrapped at different ore\|forming stages contain higher Co, Ni, Cu, Pb and Zn. It has been found for the first time that the ore\|forming fluids responsible for the Carlin\|type gold deposits are rich in Pt. From this it can be concluded that basic volcanic rocks seem to be one of the important sources of ore\|forming materials for the Carlin\|type gold deposits.

Red Clay Type Gold Deposits in China

Red clay type gold deposits,located in the south of China,are situated not only in orogenic belts,but also in inner cratons,where climate is tropical-subtropical with clear arid and humid.The lateritic weathering crust often can be divided into five zones,including topsoil,siliceous duricrust zone,multi-color zone(or red clay zone in some deposits),pallid zone and saprolite zone from surface to the base rock,several of which are absent in some deposits.The base rocks are composed mainly of carbonate rocks with minor clastic rocks,intermediate-basic volcanic rocks and intermediate-acid and alkalic intrusions.The orebodies are mainly located in the multi-color zone with part of them in the pallid and saprolite zones.The ore sources include orebodies of Carlin-type gold deposits and porphyry gold deposits,as well as gold-rich base rocks.The red clay type gold deposits experienced early-stage endogenic gold mineralization and laterization during the Tertiary and Quaternary.The areas with endogenic gold deposits,especially Carlin-type gold deposits and porphyry gold deposits in karst depressions on the plateau,structual erosional platforms in the middle-lower mountains,and intermountain basins in southern China are well worth studying to trace red clay type gold deposits.

ORE FLUID GEOCHEMISTRY OF THE JINLONGSHAN CARLIN-TYPE GOLD ORE BELT IN SHAANXI PROVINCE, CHINA

The Jinlongshan gold ore belt in southern Shaanxi Province contains a number of Carlin-type gold deposits in the Qinling collisional orogenic belt. Their fluid inclusions are of the Na-Cl- type. From the main metallogenic stage to later stages, the total quantity of anions and cations, temperature and deoxidation parameter (R) for fluid inclusions all gradually decreased, suggesting the gradual intensification of fluid oxidation, the reduction of metallogenic depth and the input of meteoric water and organic components. The deposits were formed during crustal uplifting and hence had similar tectonic settings to orogenic gold deposits. The CO-2 contents and CO-2/H-2O values of the ore fluid increased from early to late stages, and the wall-rock alteration is represented by decarbonation, which is inconsistent with the characteristics of orogenic gold deposits. It is also discovered that Na, K, SO{2-}-4, Cl- and the total amounts of anions and cations in the inclusions in quartz are higher than those in the coexisting calcite. The H, O and C isotope ratios indicate that the ore fluid was sourced from meteoric water and metamorphic devolatilisation of the sedimentary rocks that host the ores. The high background {δ{}{18}O} and {δ{}{13}C} values of wall rocks resulted in high {δ{}{18}O} and {δ{}{13}C} values of ore fluid and also high {δ{}{18}O} and {δ{}{13}C} values of hydrothermal minerals such as quartz and carbonate. The carbon in ore fluid stemmed largely from the hosting strata. The {δ{}{18}O} and {δ{}{13}C} values of Fe-calcite and the δD values of fluid inclusions are lower than those of calcite and quartz. In terms of the theory of coordination chemistry, all these differences can be ascribed to water-rock interaction in the same fluid system, instead, to the multi-source of ore fluid.

Geological and geochemical characteristics of the Baogudi Carlintype gold district(Southwest Guizhou, China) and their geological implications

The newly discovered Baogudi gold district is located in the southwestern Guizhou Province,China,where there are numerous Carlin-type gold deposits.To better understand the geological and geochemical characteristics of the Baogudi gold district,we carried out petrographic observations,elemental analyses,and fluid inclusion and isotopic composition studies.We also compared the results with those of typical Carlin-type gold deposits in southwestern Guizhou.Three mineralization stages,namely,the sedimentation diagenesis,hydrothermal(main-ore and late-ore substages),and supergene stages,were identified based on field and petrographic observations.The main-ore and late-ore stages correspond to Au and Sb mineralization,respectively,which are similar to typical Carlin-type mineralization.The mass transfer associated with alteration and mineralization shows that a significant amount of Au,As,Sb,Hg,Tl,Mo,and S were added to mineralized rocks during the main-ore stage.Remarkably,arsenic,Sb,and S were added to the mineralized rocks during the late-ore stage.Element migration indicates that the sulfidation process was responsible for ore formation.Four types of fluid inclusions were identified in ore-related quartz and fluorite.The main-ore stage fluids are characterized by an H2O–NaCl–CO2–CH4±N2system,with medium to low temperatures(180–260℃)and low salinity(0–9.08%NaCl equivalent).The late-ore stage fluids featured H2O–NaCl±CO2±CH4,with low temperature(120–200℃)and low salinity(0–7.48%Na Cl equivalent).The temperature,salinity,and CO2and CH4concentrations of ore-forming fluids decreased from the main-ore stage to the late-ore stage.The calculated δ^13C,d D,and δ^18O values of the ore-forming fluids range from-14.3 to-7.0%,-76 to-55.7%,and 4.5–15.0%,respectively.Late-ore-stage stibnite had δ^34S values ranging from-0.6 to 1.9%.These stable isotopic compositions indicate that the ore-forming fluids originated mainly from deep magmatic hydrothermal fluids,with minor contributions from strata.Collectively,the Baogudi metallogenic district has geological and geochemical characteristics that are typical of Carlin-type gold deposits in southwest Guizhou.It is likely that the Baogudi gold district,together with other Carlin-type gold deposits in southwestern Guizhou,was formed in response to a single widespread metallogenic event.

Fluid inclusion, siliceous rock geochemistry of Shewushan lateritic gold deposit, Hubei Province, eastern China: Implication for the genesis of primary orebody

The Shewushan gold deposit is located 16 km southwest of Jiayu County, Hubei Province, eastern China, which is the largest lateritic gold deposit in Asia, consisting of a series of mineralized faults containing gold grades of 1.0–19.5 g/t set within a larger, lower-grade(0.2–1.0 g/t) zone. According to the fluid inclusions study, the homogenization temperature ranges from 70–350℃, and concentrates between 140–220℃. The laser Rama results show that the CO2 and CH4 exist in mineralized fluid. In addition, the major and trace element and REE geochemical data show that the genesis of the siliceous rocks is hydrothermal genesis, formed by mineralized fluid bearing SiO2 transmitted along faults to the surface, and replace the carbonate rocks to begin deposition. Primary gold mineralization is attributed to hydrothermal activity that followed the main period of tectonic deformation of the Indosinian orogeny, which caused the regional detachment regime in southeast Hubei. The reversed fold and the fault system formed the fluid migration channel in the Shewushan area. EPMA results show that Au exists in arsenopyrite(850×10-6–1550×10-6 Au) and pyrite(470×10-6–1340×10-6 Au). Therefore, based on the above results and combined with the field observation, we suggest that the genesis of primary orebody in Shewushan deposit is carlin type, while not weathered residual type.

Physicochemical Conditions of Differential Mineralization of Au and As in Gold Deposits,Southwest Guizhou Province, China

The conditions under which gold and arsenic are enriched separately during mineralization in gold deposits in southwestern Guizhou Province were described and the thermodynamic calculations gave: 200-150℃ at 400×10-6-300×10 6 Pa （corresponding to a depthbetween 1 .6 km and 1 .2 km）; lgfO2-40 t0 - 35 Pa; lgfs2- 20 to -16 Pa; pH 5. 0 -4. 2 and Eh - 0. 53 V.

右江盆地卡林型金矿成矿年代学研究进展

右江盆地是全球仅次于美国内华达地区的第二大卡林型金矿床集中分布区。由于成矿时代的不确定性,盆地内卡林型金矿床的成矿动力学背景一直不清。为准确确定这些金矿床的成矿时代,近四十年来国内外矿床学家进行了孜孜不倦的探索,从早期以石英裂变径迹和流体包裹体Rb-Sr等时线法为代表的定年,到中期以硫化物Re-Os等时线法为代表的单矿物溶样法定年,再到最新以热液金红石、独居石和磷灰石U-Th-Pb法为代表的微区原位定年,其定年对象和方法见证了同位素地质年代学的发展历程。现已基本明确,右江盆地主要发育两期卡林型金矿成矿作用,分别为215~200 Ma和155~140 Ma,相当于印支期和燕山期,其动力学背景分别对应于印支-华南-华北地块碰撞后的印支期陆内造山过程以及燕山期软流圈上涌诱发的岩石圈伸展作用。

黔西南卡林型金矿隐伏矿找矿中弱信息提取方法研究

黔西南地区是中国卡林型金矿的集中分布区,金矿成矿地质条件优越,找矿潜力巨大。但区内浅表金矿资源已基本找寻殆尽,找矿工作全面进入“攻深找盲”阶段。隐伏金矿由于矿体埋深较大,地表的矿化信息必然非常微弱甚至没有信息显示,深部成矿信息获取困难。如何识别并获取与深部成矿作用有关的地球化学信息,成为制约找矿突破的关键因素。黔西南卡林型金矿的形成及就位主要受背斜及断裂构造的控制,元素地球化学的分布、分异和成矿同样受到构造应力的影响,深部成矿信息通过断裂、裂隙与浅部及地表相联系,浅部构造岩石中的地球化学异常能在一定程度上反映深部的矿致异常。因此,以构造地球化学理论为基础,分析黔西南地区成矿地质条件和相应元素组合的迁移和富集规律,对卡林型金矿隐伏矿找矿地球化学弱信息提取的关键环节进行深入剖析,总结构造地球化学弱信息提取方法指标参数,有效提取深部成矿元素沿构造裂隙向上渗滤扩散形成的弱异常,对深部隐伏矿进行初步定位预测。弱信息识别及提取的相关研究成果对丰富黔西南地区卡林型金矿的成矿理论具有一定的学术价值,同时使用该方法在黔西南金矿隐伏矿找矿上能有效圈定并优选找矿靶区,对落实新一轮找矿突破战略行动任务具有积极的现实意义。

贵州某卡林型金矿工艺矿物学研究

运用工艺矿物学参数自动分析系统(BPMA)、X射线衍射(XRD)、X射线荧光光谱仪(XRF)等多种测试手段,对矿石的化学成分、矿物组成、金的赋存状态及载金矿物与脉石矿物的嵌布特征、元素赋存状态进行了详细研究。研究表明:卡林型金矿中Au含量为4.75g/t,是最主要的有价元素,59.36%的金以包裹金的形式存在,其中硫化矿中包裹金最高,为42.95%。次以碳质含金的形式存在,微量以裸露金的形式存在。包裹金含量较多,即使在细磨条件下也很难实现单体解离或裸露,不利于提高金矿的回收率。主要的载金硫化矿物为黄铁矿和毒砂。脉石矿物主要有白云石、石英、方解石、黏土矿物等;黄铁矿主要集中在0.015~0.02mm粒级,毒砂主要集中在0~0.005mm粒级,白云石主要集中在0.104~0.147mm粒级,方解石主要集中在0.104~0.147mm粒级,石英主要集中在0.104~0.147mm粒级,5种矿物当中,毒砂的细颗粒最多,黄铁矿其次,方解石、白云石和石英的粗颗粒较多。随着物料粒度的降低,矿石中黄铁矿品位会随着升高;黄铁矿作为最主要的载金矿物,颗粒较细,且主要嵌布在绢云母、石英、白云石等矿物中,也有部分单体存在。为了使黄铁矿能够充分单体解离,建议在磨矿阶段提高磨矿时长或是采用多段磨矿的工艺流程。

酸性体系下硫化矿浮选因素的交互影响研究

在酸性体系中,碱性脉石矿物溶解受磨矿细度、酸用量的影响明显,矿物溶解改变了体系pH值,使可溶性离子增加,影响了硫化矿物的浮选。为探究酸性体系下卡林型金矿浮选硫化矿过程中的影响因素及其交互作用,在单因素试验的基础上进行了响应曲面优化试验,并分析了磨矿细度、H_(2)SO_(4)用量、丁基黄药用量三因素的交互作用对浮选的影响。研究结果表明:最优的浮选指标的药剂制度为磨矿细度-0.075mm粒级占比90%,H_(2)SO_(4)用量为800g/t,水玻璃用量为400g/t,CuSO_(4)用量为300g/t,丁基黄药用量为200g/t,松醇油用量为75g/t。单因素试验可获得硫回收率为75.28%,品位为10.46%,金品位为6.73%,回收率为58.19%的选矿指标。探究的三种因素对硫精矿回收率的影响大小为:磨矿细度>丁基黄药用量>H_(2)SO_(4)用量;对硫精矿品位的影响大小为:丁基黄药用量>磨矿细度>H_(2)SO_(4)用量。磨矿细度对浮选指标的影响较大,为显著影响因素;磨矿细度与捕收剂用量的交互作用对浮选指标的影响显著。响应曲面优化预测结果与实际结果基本一致,可见该模型所得预测结果可靠,为该矿的酸性废水再用于浮选过程提供了技术参考。

微纳米金颗粒对卡林型金矿成矿的指示

卡林型金矿中金的赋存状态一直是矿物学和矿床学的研究重点之一。我国右江盆地卡林型金矿中金的赋存状态长期存在纳米金颗粒(包裹体金)和晶格金之争(Feng Hongye et al.,2021)。黄铁矿在金矿床中通常作为主要载金矿物出现,其晶体内部结构及微量元素组份特征可以用来限定成矿流体的性质、来源与演化规律、反映成矿过程、约束矿床成因等,离散不可见金的形成途径.

广西明山——那林金矿床地质特征及找矿方向

明山—那林金矿床位于广西凌云县与凤山县交界处,是桂西北一处典型的卡林型金矿床。矿体赋存于中三叠统百逢组二段,北西西向断裂控制了金矿体的产出,矿石金属硫化物以黄铁矿和毒砂为主,金多以包裹金形式赋存于硫化物中。研究区内已开展过各类地质研究工作,但对矿床解剖尚不够深入,制约了后续找矿工作的开展。为探讨明山金矿后续找矿方向,本文系统总结了矿床地质特征,对其控矿构造进行了分析。结果表明,矿床主控矿断裂F2具有先挤压后拉张的特征,矿体形成于F2由挤压向拉张转换的阶段。结合前人研究成果,推断矿床形成于右江盆地由碰撞挤压到碰撞后伸展的构造转换期——晚三叠世,矿床成矿物质主要来源于地层,但印支末期的岩浆活动可能为成矿流体运移提供了热源。通过总结矿床地质特征,研究矿体的矿化富集规律、成矿物质及成矿动力来源,对研究区后续找矿方向提出了建议。