胶东蓬家夼式金矿床矿床成因模型与找矿模型研究

The dynamic environments of mineralization in Mesozoic Jiaodong gold mine concentrated area can be devided into two types, compressive environment which related to intracontinental collision and extensional environment which related to intracontinental volcanic rift. The altered rock type (Jiaojia type) and quartz vein type (Linglong type) which related to the former one, were discovered for several years, and became the main types of gold deposits in recent years. A new type gold deposit, syn-detachment altered tectonic breccia type gold deposit, such as Pengjiakuang gold deposit and Songjiagou gold deposit has been discovered on the northeastern margin of Jiaolai Basin. In this paper, the new type of gold deposit has been studied in detail. The study area is located at the northeastern boundaries of Jiaolai Basin, and between the Taocun-Jimo Fault and Wji-Haiyang Fault, in the eastern part of the Jiaodong Block. Pengjiakuang gold deposit and Songjiagou gold deposit occur in a arc-shape detachment fault zone between conglomerate of Lower Cretaceous Laiyang Formation and metamorphic complex of Lower Proterozoic Jingshan Group. Regional geological studies show that Kunyuanshan and Queshan granite intrusions and Qingshanian volcanism were formed in different period of lithospheric thinning of East China in Mesozoic. Granite intrusions were formed in compressive environment, while Qingshanian volcanism were formed in extensional environment. They are all related to the detachment of Sulu Orogenic Belt and the sinistral motion of Tanlu Fault. The Pengjiakuang detachment systems which were formed in the the sinistral motion of Tanlu Fault are the important ore-controlling and ore-containing structure. The Pengjiakuang type gold deposit, controlled by detachment structure, was formed before Yanshanian volcanic period concerning with mixture of meteoric water and magmatic water found in fluid inclusions of gold ores. The minerogenetic epoch has been proposed in 90～120Ma. the host rocks have been extensively subjected to pyritization, silicification, sericitization and carbonatization. Individual ore-body has maximum length of 800m, oblique extension of 500～700m and gold grade of 1～43 * 10~(-6). Native gold is disseminated in silicified, phyllic or carbonatized tectonic breccia. Sulfur, carbon and lead isotope studies on gold ores and wall rocks show that the sulfur come from the metamorphic complex of Lower Proterozoic Jingshan Group, carbon comes from the marble in Jingshan Group, while a part of lead comes from the mantle. The mineralizing fluid is rich in Na~+ and Cl~-, but relatively impoverished in K~+ and F~-. According to the date from hydrogen and oxygen isotopic compositions (δ~(18)OH_2O = 0.59%～4.03%, δDH_2O = -89.5%～97.9%), the conclusion can be reached that the mineralizing fluid of Pengjiakuang gold deposit was a kind of mixed hydrothermal solution which was mainly composed of meteoric water and magmatic water. A genetical model has been formulated. Some apparent anomaly features which show low in the central part and high in the both sides corresponding to the gold-bearing structure, were sum up after analying a vast amount of date by prospecting the orebodies using gamma-ray spectrometer, electrogeochemical parameter technique, controlled source audio magnetic telluric (CSAMT) and shallow surface thermometry in Pengjiakuang gold deposit. The location forecasting problem of buried orebodies has been solved according to these features, and the successful rate is very high in well-drilling. The structural geological-geophysical-geochemical prospecting model has been formulated on the base of the study of geological, geophysical and geochemical characteristics of Pengjiakuang type gold deposit, and the optimum combinational process of geophysical and geochemical prospecting techniques has been summed up. A comparative study shows that the Pengjiakuang type gold deposit, the syn-detachment altered tectonic breccia type gold deposit, is different from Jiaojia type gold deposits and Linglong type gold deposits, in Jiaodong Block. In general, if formed under an extensional tectonic condition and located at detachment fault zone along the margin of Mesozoic Jiaolai basin, and the gold mineralization has also close genetic relationship with alkaline magamtism. Being a new type of gold deposit in Jiaodong gold mine concentrated area, it could be potential to explore in the same regions which processed the same ore-forming geological conditions and mineralization informations.

内蒙古赤峰红花沟地区早中生代构造－岩浆活动特征及金成矿作用

Honghuagou gold field, Inner Mongolia, is selected as the study area for the dissertation. The geological background for gold mineralization, geology of gold deposits, ore-controlling factors, physical and chemical conditions, material sources, genesis and ore-forming epoch for gold mineralization are studied in the dissertation. Especially, the Early Mesozoic tectonic and magmatic activities and their relationship with gold mineralization are studied with special efforts. Based on the study, the criteria for ore-prospecting are systemically summarized, target areas for ore-prospecting are circled and their gold reserves is estimated. Based on the first discovery of Early Mesozoic ductile zone which show the detachment features and the study on the emplacement of Early Mesozoic maficintermediate dyke swarms, the author present that the studied area was mainly in extensional uplift state during Early Mesozoic. The tectonic evolution can be divided into two stages. The extension was dominated by ductile metamorphose at early stage, whose geodynamics was related with the post orogenic extension after the collision between the Northern China Plate with Siberia Plate. The extension at late stage was featured by the intrusion of diorite and the emplacement of dyke swarms, whose geodynamics was related with mantle uplift. The gold deposits in the area are just the products of the tectonic and magmatic activities resulted from Early Mesozoic extension. The plagio-amphibolite from Archean metamorphic rocks is partially melted under the influence of underplating caused by mantle uplift, result in the formation of diorite magma. The gold in metamorphic rocks will also be melted into magma pond, and ascend into the upper parts of crust along with the intrusion of magma. The gold-bearing hydrothermal fluids is formed during magma differentiation, and caused the precipitation and concentration of gold in favorable geological conditions, result in the formation of gold deposits. The fracture caused by the emplacement of dyke swarms break a path for the ascending and movement of hydrothermal fluids, some of them become parts of ore-controlling and host structure. The gold is thought to be formed in Early Mesozoic, not in Yanshanian epoch.

宣龙式赤铁矿含矿岩系的成矿过程研究

Xuanlong-type Hematite Deposits, distributed in Xuanhua and Longguang area in Hebei province and hosted in the Changchengian Chuanlinggou Formation of Mesoproterozoic, is an oldest depositional iron deposit characterized by oolitic and stromatolitic hematite and siderite. This thesis made an systematic study of its sedimentary, sedimentology, geochemistry, mineralogy and sequence stratigraphy. Based on above, the mechanism and background of biomineralization are discussed. There are four types of hematite ores including stromatolite, algal oolite, algal pisolite and oncolite. Based on detailed study on ore texture, the authors think both algal oolite and algal pisolite ores are organic texture ores, and related to the role of microorganisms. The process of blue-green algae and bacteria in the Xuanlong basin absorbing, adsorbing and sticking iron to build up stromatolite is the formation process of Xuanlong-type hematite deposit. Researches on ore-bearing series and ore geochemistry show that the enrichment of elements is closely related to the microorganism activities. Fe_2O_3 is enriched in dark laminations of stromatolite with much organic matter and SiO_2 in light laminations with detrital matters. The trace elements, especially biogenic elements, including V, P, Mo are enriched in ores but relatively low in country rocks. The paper also demonstrates on the sequence stratigraphy of hematite deposits and five sequences and twelve systems are divided. The characteristics of sequence stratigraphy show that the deposit-forming location has obviously selectivity and always exists under a transgressive setting. The oxygen isotope in hematite is about -2.2～5.7‰, which is similar to that of Hamlys iron formation of Australia but more negative than that of volcanic or hydrothermal iron deposits characterized by high positive values. The calculation by the result of oxygen isotope analysis shows that the temperature of ancient sea water was 48.53℃. The negative value of carbon isotope from siderite indicates its biogenic carbon source. Meanwhile, the occurrence of seismite in the ore-beds, which indicates the formation of hematite deposits is associated with frequent shock caused by structural movement such as distal volcano or ocean-bottom earthquake etc, show the occurrence of hematite deposits is eventual, not gradual. In shorts, Xuanlong-type hematite deposits were the result of interaction among geological setting of semi-isolated Xuanglong basin, favorable hot and humid climate condition, abundant iron source, microorganism such as algae and bateria as well as the fluctuation of the sea level.

山东平度大庄子金矿床地质地球化学特征及成因——兼论层间滑动角砾岩型金矿成矿模式

The author selected the geological and geochemical characteristics and the genesis of the Dazhuangzi gold deposit in the Pingdu City as the central content of the study. The author summarized geological features of the other gold deposits formed within the same geological setting along the margin of the Jiaolai pull-apart basin and compared these gold deposits with the Dazhuangzi gold deposit. On the basis of the first-hand data obtained from field investigation and from mining production reports, ore-controlling structures, geological characteristics and mineralization regularities of the Dazhuangzi gold deposit are studied in detail. According to the analyzing results of petrochemistry, trace element, rare earth element and fluid inclusion etc., the geochemical characteristics, the genesis and the ore-forming material source of the Dazhuangzi gold deposit and that of the other similar gold deposits along the margin of the Jiaolai Basin are proposed. The study results suggest that the Dazhuangzi gold deposit belongs to the typical interstratified glide breccia type gold deposit, which is controlled by the interstratified glide fault structure located along the margin of the Mesozoic pull-apart Jiaolai basin. The interstratified glide fault structure is in the outer part of unconformity belt between the overlying strata and the basement of the pull-apart basin, being along the marble strata of the Jingshan group. The formation of the ore-controlling structure is related closely with the evolution of the Jiaolai Basin in the Mesozoic. The ore-controlling structure underwent the structural stress changes from compressive to tensional and then to compressive stress with strike slipping features sequentially, which were coincided with the regional tectonic stress evolution. The interstratified glide breccia type gold mineralization mainly occurs in the siliceous-marble breccias and cataclastic rocks within the interstratified glide fault structure. The gold minerogenetic epoch is later than 120Ma when the ore-controlling structure was tensioning and strike-slipping. The occurrences of the ore controlling structure and the gold ore bodies are the same as that of the unconformity belt. The geological and geochemical studies show that the source of the ore-forming material is alike with that of the volcanic rocks of the Qingshan formation, which is widespread in the Jiaolai Basin. Both of them came from the deep crust or even the upper mantle. Based on the geological characteristics and the minerogenetic regularities of the Dazhuangzi gold deposit, a genetic model of the deposit is constructed. In addition, the author used the remote sensing image and exploration results of geochemical and geophysical methods to point out several prospecting areas for further exploration. Through comprehensive study on the interstratified glide fault structure and on the interstratified glide breccia type gold deposits along the Jiaolai pull-apart basin, three types of interstratified glide structures and related gold mineralization are set up according to evolution and distribution of main fault as well as related secondary faults in time and space. They are named as Penjiakuang type, Dazhuangzi type and Fayunkuang type. The author summarized up the minerogenetic characteristics and regularities controlled by these three different types of interstratified glide structures respectively, and set up a general minerogenetic model of the interstratified glide breccia type gold deposit.

胶东地区三类金矿成矿系统地质地球化学及动力学

The East Shandong gold province is located on the southeastern margin of the North China Craton and features uplift in the north and depression in the south. The uplift area is made up of the Archaean Jiaodong Group, the Proterozoic Jingshan Group and Yanshannian granites. Most gold deposits in the uplift area are spatially associated with the Yanshannian granites. Two types of gold mineralization occur in the region: the quartz-vein type hosted in the Linglong granite suite, and the shear zone type hosted by either the Linglong granite or Guojialing granitoid suites. The mineralization ages are 113～126 Ma. The southern part of East Shandong contains the Mesozoic Jiaolai basin, which formed during regional extension. The basin is bounded by the Wulian-Rongcheng fault in the southeast and the Tanlu fault in the west. The Pengjiakuang, Fayunkuang and Dazhuangzi gold deposit occurs on the northeastern margin of the basin. The mineralization ages of these deposits are 110～128 Ma. This paper focuses on a low-angle detachment fault developed between the Proterozoic Jingshan Group metamorphic complex and the northeastern margin of the basin. Our field work shows that the distribution of the Pengjiakuang gold deposit was controlled by the detachment fault. Moreover, the Fayunkuang, Guocheng and Liaoshang gold deposits also occurr in the periphery of the basin, and their features are similar to Pengjiakuang gold deposit. The study of geological geochemistry of the gold deposits has shown: ①three-type gold deposit was situated in the Jiaodong area, including altered rock type (Jiaojia type), quartz vein type (Linglong type) and breccia type (Pengjiakuang type); the ore-forming materials and fluid for Pengjiakuang type gold deposit shows multiple source; ②the ore materials of Jiaojia and Linglong type deposits are mainly from deep source. The author has studied geological-geochemical dynamics of three types deposits in Jiaodong area. The study of tectonic dynamics shows that ore-forming structure differential stress values of Pengjiakuang gold deposit is 100 * 10~6～130 * 10~6 Pa, and that of Jiaojia gold deposit is 100 * 10~5～194 * 10~6 Pa. Dynamics of hydrothermal ore-forming fluid has also been studied in this paper. Author applies Bernoulli equation to dynamic model of hydrothermal fluid motion in brittle fracture and cracks (quartz vein type gold mineralization), and applies Darcy law to dynamic model of hydro thermal fluid motion in porous medium (altered rock type gold mineralization). Author does daring try in order to study quantitativly transport mechanism of hydrothermal ore-forming fluid in this paper. The study of fluid inclusions and crystal dynamics shows that reaction system of hydrothermal ore-forming includes three types, as follows: ore-forming reaction, controlling reaction and buffer controlling reaction. They depend on each other, controlling each other, which form a organic system. Further research shown that formation of ore shoots was controlled by coincidence processes of tectonic dynamic condition and thermodynamic evolution. This paper has summaried reginoal metallogenic laws and seted up metallogenic(dynamics) models for Jiaodong gold ore belt.

山东莱州金城金矿床构造-流体成矿特征

This paper studied the metallotectonics, altered rocks, altered minerals and fluid inclusions. The conclusions are: (1)The gold deposits in Jiaodong district were formed quickly uplifted tectonic setting which was induced by the Mantle doming in Mesozoic era. (2)Both Jiaojia-type and Linglong-type gold mineralizations were formed in the same tectonic-fluid system. (3) The Ar-Ar age of the earlier stage of the gold mineralization is 114～116Ma. (4)The development of the plaiting ore-control tectonic system underwent four stagesrcounterclockwise ductile compresso-shearing, clockwise brittle tenso-shearing and counterclockwise brittle compresso-shearing and brittle normal faulting after mineralization. (5)The mineralization has five stages: quartz and k-feldspar stage, quartz and ferro-carbonate and pyrite stage, quartz and chalcopyrite stage, pyrite and sericite and quartz stage and carbonate stage, and they make up four ore-types: red ore, vein ore, mottled ore and grey ore. (6) The features of mineralizations and ore-forming fluids in different stages are different. But the ore-forming fluids are rich in Si, Fe, P_2O_5, H_2O, CO_2, SO_4~(2-), K~+, Na~+, Ca~(2+) and Cl~- in general and their salinities are from 4 to 18 NaClwt%. (7) The ore-forming fluids came mainly from the Mantle in early stage, then mainly from magma, and mainly from meteoric water in the last stage. (8) Au in the ore-forming fluid was mainly carried in the form of complex of Au and S. (9)The temperature of ore-forming fluid is from 350℃ to 120℃and its pressure is from 20MPa to 38MPa. (10)The gold vein composed by quartz, ferro-carbonate, chalcopyrite and pyrite (vein ore) was filled in the tensional fracture in the top of the magma dome. The disseminated ore bodies composed by pyrite, sericite and quartz (grey ore) was metasomatized in the shearing fault which developed along the contact zone between Linglong intrusive body and Jiaodong Group, which is placed in the flank top of magma dome. In the joint and fracture induced by the shearing fault which developed along the contact zone between Linglong intrusive body and Jiaodong Group, veiniet and stockwork ore (red ore) and veinlet-disseminated ore (mottled ore) composed by quartz and pyrite was formed. (ll)Fluid boiling maybe one of the form of the ore-forming substances precipitation.

新疆萨吾尔金矿带构造-流体地球化学及成矿作用

The Sawuer gold belt is located in the transition belt between Siberian plate and Kazakhstan-Junggar plate. Based on the geological and geochemical studies on the Kuoerzhenkuola and Buerkesidai gold deposits, in Sawuer gold mineralization belt, the time-space structure of mineralization and mineralizing factor are studied, the metallogenic regularity is concluded in thistheses. The ore bodies have the regularity that orebody are of the extensive and compressive in the sallow and depth of volcanic apparatue, respectively, and the vertical extension of orebody is more intensive than the horizontal extension. The gold deposits were controlled by the fractures of volcanic apparatus and regional faults, and featured by the hydrothermal alteration and metasomatism type disseminated mineralization and filling type vein mineralization. By virtue of the geological and geochemical studies on the two deposits that the formation of the two deposits are significantly related to the volcanic activity, we propose new ideas about their origin: (1) the two deposits are located in the same strata, and share the same genesis. (2) both of two deposits are volcanogenic late-stage hydrothermal gold deposits. Based on mapping of volcanic lithofacies and structure for the first time, it is discovered that a volcanic apparatus existed in the study area. Volcanic-intrusive activity can be divided into three cycles and nine lithofacies. where the two deposits are hosted in the same volcanic cycle, in this case, the wall-rock should belong to the same strata. The 40Ar-39Ar age method is employed in this work to analyze the fluid inclusions of quartz in the ore bodies from Kuoerzhenkuola and Buerkesidai gold deposits. The results show that the main mineralization occurred in 332.05 + 2.02-332.59 + 0.5IMa and 335.53 + 0.32Ma~336.78 + 0.50Ma for Kuoerzhenkuola and Buerkesidai gold deposits respectively, indicating that the two deposits are formed almost at the same time, and the metallogenic epoch of the tow deposits are close to those of the hosting rocks formed by volcanic activity of Sawuer gold belt. This geochronological study supplies new evidence for determining the timing of gold mineralization, the geneses of gold deposits? and identifies that in Hercynian period, the Altai developed tectonic-magmatic-hydrothermal mineralization of Early Carboniferous period, except known two metallogenic mineralization periods including tectonic-magmatic-hydrothermal mineralization of Devonian period and Late Carboniferous-Permian period respectively. The study of fluid inclusions indicates that the ore-forming fluid is a type of NaCl-HbO fluid with medium-low temperature and low salinity, Au is transported by the type of auric-sulfur complex (Au (HS)2-), the ore is formed in reduction condition. Hydrogen and oxygen isotopes of fluid inclusions in the major mineralizating stage show that the solutions mainly originated from magmatic water and meteoric water. The fluid mixing and water-rock reaction cause the deposition of Au. The helium and argon isotope compositions of fluid inclusions hosted in pyrite have been measured from Kuoerzhenkuola and Buerkesidai gold deposits in Sawuer gold belt. The results show that the ore-forming fluids of two deposits possessed the same source and is a mixture of mantle- and partial meteoric water-derived fluid, and the reliability of He and Ar isotopic compositions in Hercynian period is discussed. Isotopic studies including H, O, He, C, S, Pb and Sr reveal the same result that the ore-forming fluids of two deposits possessed the same source: the water derived mainly from magmatic water, partially from meteoric water; the mineralizers and ore materials derived mainly from mantle beneath the island arc, and partially from crust. The ore-forming fluids of two deposits are a mixture of mantle-derived fluids being incorporated by crust-derived fluid, and shallow partial meteoric water. Based on these results, it is proposed that the geneses of the two gold deposits are the same, being volcanogenic late-stage hydrothermal gold deposits that the ore-forming fluids filled in fractures of volcanic apparatus and metasomatized the host rocks in the volcanic apparatus. It is the first time we carried out the geophysical exploration, that is, the EH-4 continuous electrical conductivity image system measurement, the results show that relative large-size mineralizing anomalies in underground have been discovered.lt can confirm the law and genesis of the deposits mentioned above, and change the two abandoned mines to current large-size potenial exploration target.

Relations between A-type granites and copper mineralization as exemplified by the Machangqing Cu deposit

This paper deals with the relations between the Machangqing rockbody which corresponds to the A-type granites and porphyry copper mineralization in terms of petrochemistry, trace element geochemistry, fluid inclusion geochemistry and isotope geochemistry. The results show that the Machangqing porphyry copper deposit was formed from the fluid predominated by mag-matic fluid. This kind of ore-forming fluid was just differentiated from the magma responsible for the A-type granites. therefore,as viewed from whereer they contain water or not,the A-type granites can,at least,be divided into two types: water-bearing and water-free.The water-bearing A-type granites can serve as the host ofporphyry copper deposits under certain geological conditions.

Mantle-derived gaseous components in ore-forming fluids of the Xiangshan uranium

The Xiangshan U deposit, the largest hydrothermal U deposit in China, is hosted in late Jurassic felsic volcanic rocks although the U mineralization post dates the volcanics by at least 20 Ma. The mineralization coincides with intrusion of local mantle-derived mafic dykes formed during Cretaceous crustal extension in South China. Ore-forming fluids are rich in CO2, and U in the fluid is thought to have been dissolved in the form of UO2 (CO3)22− and UO2 (CO3) 34− complexes. This paper provides He and Ar isotope data of fluid inclusions in pyrites and C isotope data of calcites associated with U mineralization (pitchblende) in the Xiangshan U deposit. He isotopic compositions range between 0.1 and 2.0Ra (where Ra is the 3He/4He ratio of air=1.39×10−6) and correlates with 40Ar/36Ar; although there is potential for significant 3He production via 6Li(n,α)3H(β)3He reactions in a U deposit (due to abundant neutrons), nucleogenic production cannot account for either the 3He concentration in these fluids, nor the correlations between He and Ar isotopic compositions. It is more likely that the high 3He/4He ratios represent trapped mantle-derived gases. A mantle origin for the volatiles of Xiangshan is consistent with the δ13C values of calcites, which vary from −3.5‰ to −7.7‰, overlapping the range of mantle CO2. The He, Ar and CO2 characteristics of the ore-forming fluids responsible for the deposit are consistent with mixing between 3He- and CO2-rich mantle-derived fluids and CO2-poor meteoric fluids. These fluids were likely produced during Cretaceous extension and dyke intrusion which permitted mantle-derived CO2 to migrate upward and remobilize U from the acid volcanic source rocks, resulting in the formation of the U deposit. Subsequent decay of U within the fluid inclusions has reduced the 3He/4He ratio, and variations in U/3He result in the range in 3He/4He observed with U/3He ratios in the range 5–17×103 likely corresponding to U concentrations in the fluids b0.2 ppm.